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Abstract

  The prevalence of astigmatism, its axis and determinants were determined in the 40- to 64-year-old population of Shahroud, Iran.   Population-based cross sectional study.   Using random cluster sampling, 6311 subjects were invited for eye examinations. Of 5190 participants (response rate=82.2%), data of 5020 were eligible for analysis. Participants received visual acuity measurement, manifest refraction and eye examinations. The prevalence of astigmatism based on cylinder powers of more than 0.5, 1 and 3 D were studied. The prevalence (and 95% confidence interval) of astigmatism based on a cylinder power worse than 0.5, 1, and 3 D was 49.1% (47.6-50.5), 24.1% (22.9-25.3), and 3.4% (2.9-3.9), respectively. In a multiple logistic regression model, the prevalence of astigmatism was higher in men (odds ratio=1.25) and increased with age (odds ratio for each 5 years=1.21). Higher education was found to be inversely correlated to astigmatism (P < 0.001). The prevalence of with-the-rule, against-the-rule and oblique astigmatism was 12.6%, 25.9% and 10.6%, respectively. Oblique astigmatism was significantly higher in women and the older age groups (P < 0.001). Against-the-rule astigmatism increased with age from 19.9% in the age group of 40-44 to 37.0% in the age group of 60-64 (P < 0.001).   In comparison with those studies conducted in Iran and other countries, the prevalence of astigmatism was higher in this study. Astigmatism was higher in men and age had an important role in astigmatism and its axis. The prevalence of against-the-rule and oblique astigmatism increased with age.

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... Eight reports from the first phase of the study had been accepted and published in peer-reviewed journals by April 2012. [53][54][55][56][57][58][59][60] The prevalence of visual impairment in the city of Shahroud was determined to be lower than that reported in most studies carried out in the region. Refractive errors and cataract were shown to contribute to 85% of visual impairment in the population. ...
... 59 The prevalence of astigmatism based on a cylinder power worse than 0.5D was 49.1%. 54 The prevalence of myopia and astigmatism was higher than that found in other parts of the Middle East. 54,59 The prevalence of hyperopia was lower than that previously reported in Iran. ...
... 54 The prevalence of myopia and astigmatism was higher than that found in other parts of the Middle East. 54,59 The prevalence of hyperopia was lower than that previously reported in Iran. 59 The prevalence of a need for spectacles was found to be 13.7%; however, 41.7% of those who required spectacles were still without them. ...
Article
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The Shahroud Eye Cohort Study was set up to determine the prevalence and incidence of visual impairment and major eye conditions in the 40-64-year-old population of Shahroud as a Middle Eastern population. The first phase of the study was conducted in 2009-10. Using random cluster sampling, 6311 Shahroud inhabitants were invited for ophthalmologic examinations; of these, 5190 participants completed phase 1 (participation rate of 82.2%). All participants were interviewed to collect data on participants' demographics, occupation status, socioeconomic status, history of smoking, and medical and ophthalmic history, as well as history of medication, and the quality and duration of their insurance. DNA and plasma samples, as well as four dots of whole blood were collected from participants. Extensive optometric and ophthalmologic examinations were performed for each participant, including lensometry of current glasses, testing near and far visual acuity; determining objective and subjective refraction; eye motility; cycloplegic refraction; colour vision test; slit-lamp biomicroscopy and intraocular pressure measurement; direct and indirect fundoscopy; perimetry test; ocular biometry; corneal topography; lens and fundus photography; and the Schirmer's (1008 participants) and tear breakup time tests (1013 participants). The study data are available for collaborative research at Noor Ophthalmology Research Center, Tehran, Iran.
... 13,20 Although the prevalence of astigmatism has been reported in many studies, fewer studies have investigated the astigmatism axis and corneal astigmatism in addition to the prevalence of astigmatism in a normal population. 11,17,20,21 In Iran, some studies have reported the prevalence of astigmatism along with myopia and hyperopia. 1,2,5,10,22 Only two studies have reported the prevalence of astigmatism without myopia and hyperopia in Tehran and Shahroud. ...
... 1,2,5,10,22 Only two studies have reported the prevalence of astigmatism without myopia and hyperopia in Tehran and Shahroud. 11,16 Previous studies 11,16 have reported a relatively high prevalence of astigmatism in Iran. Hence, greater details of astigmatism in an Iranian population can provide valuable information about this refractive error. ...
... 1,2,5,10,22 Only two studies have reported the prevalence of astigmatism without myopia and hyperopia in Tehran and Shahroud. 11,16 Previous studies 11,16 have reported a relatively high prevalence of astigmatism in Iran. Hence, greater details of astigmatism in an Iranian population can provide valuable information about this refractive error. ...
Article
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The prevalence of astigmatism, and the astigmatic axis, and their determinants were evaluated in a rural population of Iran. In a cross-sectional study conducted from May to August 2011, 13 villages in the vicinity of the city of Khaf in northeast Iran were investigated in this study. All the examinations including visual acuity, refraction, slit-lamp biomicroscopy and fundoscopy were performed in a Mobile Eye Clinic. Written informed consent was obtained from all participants. Only phakic eye that could be reliably refracted without a previous history of ocular surgery were included. Out of 2635 participants who were screened, 2124 were analysed for this study of whom 52% were female. The prevalence of astigmatism was 32.2% (95% confidence intervals (CI): 30.2-34.2). Astigmatism significantly increased from 14.3% in the under 15-year-old age group to 67.2% in the age group of over 65-years old (P < 0.001). The prevalence of With-The-Rule (WTR), Against-The-Rule (ATR), and oblique astigmatism was 11.7%, 18.1%, and 2.4 %, respectively. ATR significantly increased with age (P < 0.001). The mean corneal astigmatism was 0.73 D which linearly increased with age (P < 0.001). Attention must be paid to astigmatism in rural areas due to the high prevalence. Further studies are suggested to discover the role of the environmental and genetic factors. It seems that environmental and occupational factors in the villages cause a significant increase in the prevalence of astigmatism with age. A high percentage of participants had ATR astigmatism, which was more common at older ages.
... In longitudinal studies, 'natural' infantile astigmatism, against the rule (ATR, correction of axis of the negative cylinder in a vertical direction) in particular, has been associated with school age myopia (Fledelius et al. 2014). Several studies have shown an increase in the prevalence and amount of RA with age in adulthood (Vitale et al. 2008;Schellini et al. 2009;Hashemi et al. 2012). ...
... Changes in the prevalence and mean amount of RA with age are also accompanied by changes in its axis. The main change in the direction of astigmatism from adulthood to older ages is a shift in the direction of RA from predominantly with the rule (WTR) (axis of the negative correction cylinder in a horizontal direction) to more ATR and oblique (Fledelius & Stubgaard 1986;Hashemi et al. 2012). In the study of Hashemi et al. (2012) ATR astigmatism increased from 19.9% in the age group of 40-44 to 37.0% in the age group of 60-64. ...
... The main change in the direction of astigmatism from adulthood to older ages is a shift in the direction of RA from predominantly with the rule (WTR) (axis of the negative correction cylinder in a horizontal direction) to more ATR and oblique (Fledelius & Stubgaard 1986;Hashemi et al. 2012). In the study of Hashemi et al. (2012) ATR astigmatism increased from 19.9% in the age group of 40-44 to 37.0% in the age group of 60-64. ...
Article
PurposeTo study the prevalence of and changes in astigmatism from the onset of myopia at school age.Methods Two hundred and forty myopic schoolchildren (mean age 10.9 years), with no previous spectacles, were recruited during 1983–1984 to a randomized 3-year clinical trial of bifocal treatment of myopia. Three annual examinations with subjective cycloplegic refraction were performed for 237–238 subjects. Subsequent examinations were performed at the mean ages of 23.2 and 33.9 years for 178 and 163 subjects, and the last examination, including data from prescriptions of different ophthalmologists, for 32 subjects. Corneal topography was studied at baseline, at the 3-year follow-up and at the two adulthood follow-ups. Prevalence and changes in refractive astigmatism (RA), in its polar values J0 and J45, and corneal astigmatism (CA) were studied.ResultsMean RA of the right eye increased during follow-up from 0.26 D (SD) ± 0.30 to 0.79 D ± 0.74. Mean CA was 1.07 D ± 0.74 at study end. The prevalence of RA ≥0.25 or ≥1.00 D increased from 54.9 and 3.8% to 83.4 and 34.4%, respectively. The main direction of the axis of RA and its polar value J0 and CA changed mainly through sphericity, from against the rule (ATR) to with the rule during the follow-up. There was a negative correlation between RA and spherical refraction in the ATR group at end of follow-up. Changes in RA were associated with increase in myopia and with changes in CA.Conclusions The prevalence and mean amount of RA associated with CA increased, and the axis of astigmatism changed among myopics during the 23-year follow-up.
... Fozailoff (2011) obtain the prevalence of astigmatism in children Hispanic and African-American, was greater in men than in women in the Hispanic, while in the African American group there was not significant difference. 21 Hashemi et al (2011) find higher prevalence of astigmatism in men. In this study, patients with astigmatism are higher in women (63.4%). ...
... In this study, patients with astigmatism are higher in women (63.4%). 22 This result is probably because women pay more attention to their health so they come to the hospital sooner if there is something wrong with their health. ...
... Raju (2004) get 9.80% type of WTR astigmatism, and 77.44% type of ATR astigmatism. 23 Hashemi et al (2011) obtain the prevalence of WTR astigmatism 12.6%, ATR astigmatism 25.9%, while 10.6% oblique. 22 Shih et al (2004) get the type of astigmatism in school children in 1995 was 83.3% WTR astigmatism, 16,6% ATR astigmatism, 0.1% oblique astigmatism, 89.8% WTR astigmatism, 9.7% ATR astigmatism, 0,4% oblique astigmatism. ...
Article
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Objective: Refractive disorders are one of the most common causes of visual impairment worldwide and become the second leading cause of blindness that can be cured. This study aims to know the characteristic of refractive errors patients in Sanglah General Hospital in the period of 1st January until 31st December 2011.Method: This is a retrospective analytical descriptive study. Data were collected retrospectively from patient’s medical records with refractive errors and shown as frequency andpercentage. Visual acuity before and after corrections were investigated and analyzed using McNemar Test.Results: from 579 patients, the most common diagnosis was astigmatism (40.1%), 63% were woman, 39.7% were older than 40 years old, and 60.2% live in Denpasar. In myopia cases, 69.7% patients were woman and 25.1% were between 11-20 years old. In astigmatism cases, 63.4% were woman, 57% were older than 40 years old. Of the hypermetropic cases, 61,3% were woman, 79.5% were older than 40 years. Among presbyopia cases, 53.2% patients were woman with 84.4% were older than 40 years. In McNemar test, there were a significant difference between visual acuity before and after correction in both eyes (p=0.0001). Most astigmatism was with the rule cases on both eyes. On the right eye 54.3% shows mild astigmatism, whereas on the left eye 50.8% shows moderate astigmatism. In hypermetropic cases 92.4% are mild degrees. While 55.5% presbyopic patients needadditional glasses of +1.00 D up to +2.00 D. About 97.9% patients with refractive error were given glasses prescription. Conclusion: mostly refractive errors patient are woman and the most common diagnosis is astigmatism. There were significant differences of visual acuity before and aftercorrection on both eyes (p=0.001).
... The prevalence of myopia and hyperopia in adults is reported to be up to 38.3 and 58.6 per cent, respectively. 8 Studies in Iran have mostly been in urban areas and certain age groups (usually preschool age). [8][9][10][11][12][13][14] Compared to urban populations, rural dwellers of the same region have more children and especially elderly people, weaker economic status and less access to health-care services. ...
... 8 Studies in Iran have mostly been in urban areas and certain age groups (usually preschool age). [8][9][10][11][12][13][14] Compared to urban populations, rural dwellers of the same region have more children and especially elderly people, weaker economic status and less access to health-care services. 15 All the above mentioned issues can impact the health status of rural dwellers. ...
... however the odds of being anisometropic increased by about 5% for each year of increasing age (P<0.001). The prevalence of anisometropia was significantly higher after the age of 59 compared to [40][41][42][43][44][45][46][47][48][49] year-old subjects ( Table 2). There was no significant difference between urban and rural populations regarding the prevalence of anisometropia (P=0.196). ...
... 52,53 Similar to other studies, the prevalence of astigmatism significantly increased with age in our study. 40,54 Alterations in corneal curvature as a result of aging is an explanation for this finding. The observed decreased prevalence of with-therule and increased prevalence of against-the-rule astigmatism with age in our study have already been reported in other studies. ...
Article
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To determine the prevalence of refractive errors in Yazd, central Iran. This population-based study was performed in 2010-2011 and targeted adults aged 40 to 80 years. Multi-stage random cluster sampling was applied to select samples from urban and rural residents of Yazd. Manifest refraction, visual acuity measurement, retinoscopy and funduscopy were performed for all subjects. Myopia, hyperopia, astigmatism and anisometropia were defined as spherical equivalent (SE) <-0.50 diopters (D), SE >+0.50 D, cylindrical error >0.5 D and SE difference ≥1 D between fellow eyes, respectively. From a total of 2,320 selected individuals, 2,098 subjects (90.4%) participated out of which 198 subjects were excluded due to previous eye surgery. The prevalence (95% confidence interval) for myopia, hyperopia, astigmatism, anisometropia, -6 D myopia or worse, and 4 D hyperopia or worse was 36.5% (33.6-39.4%), 20.6% (17.9-23.3%), 53.8% (51.3-56.3%), 11.9% (10.4-13.4%), 2.3% (1.6-2.9%) and 1.2% (0.6-1.8%), respectively. The prevalence of hyperopia, astigmatism and anisometropia increased with age. The prevalence of myopia was significantly higher in female subjects. The prevalence of with-the-rule, against-the-rule and oblique astigmatism was 35.7%, 13.4% and 4.6%, respectively. The prevalence of against-the-rule astigmatism increased with age (P<0.001); with-the-rule astigmatism was more common in women (P=0.038). More than half of the study population had refractive errors; the prevalence of myopia and astigmatism was higher than earlier studies in Iran. Since refractive errors are a major cause of avoidable visual impairment, their high prevalence in this survey is important from a public health perspective.
... 4,40,48,49 The axis of astigmatism also shows consistent variations with age ( Figure 2). 25,29,33,39,[42][43][44]48,[51][52][53][54][55] In childhood and early adulthood, astigmatism is predominantly with-the-rule (WTR) in axis (i.e. negative cylinder axis close to horizontal), 29,[48][49][50]54 whereas in older age a shift towards a predominance of against-the-rule (ATR) astigmatism (where the negative cylinder axis is close to the vertical) usually occurs. ...
... Figure 2. Changes in the prevalence of different astigmatic axes with age based upon a range of population studies. 25,29,33,39,[42][43][44]48,[51][52][53][54][55] tomography (OCT), have provided an improved understanding of the topographical characteristics of the posterior cornea and the crystalline lens, which has contributed to our understanding of the origins of internal/residual astigmatism. Recent studies utilising rotating Scheimpflug instruments to measure anterior and posterior corneal curvature in relatively large clinical populations of subjects with a wide range of ages have estimated the astigmatism contributed by the posterior cornea to be approximately 0.30 D in magnitude (with individual measured values ranging from 0.01 to 1.10 D, and approximately 9% of eyes exhibiting more than 0.50 D posterior corneal astigmatism 65 ) and ATR in axis (i.e. the steepest meridian of the posterior cornea oriented close to the vertical). ...
Article
To provide a comprehensive overview of research examining the impact of astigmatism on clinical and functional measures of vision, the short and longer term adaptations to astigmatism that occur in the visual system, and the currently available clinical options for the management of patients with astigmatism. The presence of astigmatism can lead to substantial reductions in visual performance in a variety of clinical vision measures and functional visual tasks. Recent evidence demonstrates that astigmatic blur results in short-term adaptations in the visual system that appear to reduce the perceived impact of astigmatism on vision. In the longer term, uncorrected astigmatism in childhood can also significantly impact on visual development, resulting in amblyopia. Astigmatism is also associated with the development of spherical refractive errors. Although the clinical correction of small magnitudes of astigmatism is relatively straightforward, the precise, reliable correction of astigmatism (particularly high astigmatism) can be challenging. A wide variety of refractive corrections are now available for the patient with astigmatism, including spectacle, contact lens and surgical options. Astigmatism is one of the most common refractive errors managed in clinical ophthalmic practice. The significant visual and functional impacts of astigmatism emphasise the importance of its reliable clinical management. With continued improvements in ocular measurement techniques and developments in a range of different refractive correction technologies, the future promises the potential for more precise and comprehensive correction options for astigmatic patients.
... Astigmatism is a common optical disorder and exists in most human eyes in subtle amounts. Numerous studies have reported the prevalence of astigmatism in different ages [1][2][3][4][5][6][7], rural and urban populations [8][9][10] and ethnic groups [1][2][3][4][5][6][7][8][9][10]. Previous studies have reported the prevalence of astigmatism from 11.3% up to 70% in related studies [5,7,8]. ...
... Astigmatism is a common optical disorder and exists in most human eyes in subtle amounts. Numerous studies have reported the prevalence of astigmatism in different ages [1][2][3][4][5][6][7], rural and urban populations [8][9][10] and ethnic groups [1][2][3][4][5][6][7][8][9][10]. Previous studies have reported the prevalence of astigmatism from 11.3% up to 70% in related studies [5,7,8]. ...
Article
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To investigate the correlation of major components of ocular astigmatism in myopic patients in an academic hospital. This cross-sectional study was conducted on 376 eyes of 188 patients who were referred to Farabi Eye Hospital for refractive surgery. Preoperative examinations including refraction and corneal topography were performed for all candidates to measure refractive and corneal astigmatism. Ocular residual astigmatism was calculated using vector analysis. Pearson's correlation and ANOVA analysis were used to evaluate the strength of the association between different types of astigmatism. Both eyes were defined as cluster and the Generalized Estimating Equations (GEE) analysis were performed. Mean age of 119 women (63.3%) and 69 men (36.7%) was 27.8±5.7 years. Mean refractive error based on spherical equivalent was -3.59±1.95D (range, -0.54 to -10.22D). Mean refractive and corneal astigmatism was 1.97±1.3D and 1.85±1.01D, respectively. Mean amount of ORA was 0.65±0.36D.There was a significant correlation between ORA and refractive astigmatism(r=0.23, p<0.001), corneal and refractive astigmatism (r=0.91, p<0.001) and a weak correlation between ORA and corneal astigmatism (r=0.13, p=0.014). There was a significant correlation between J0 and J45 values of ORA and corneal astigmatism (p<0.001). There is a significant correlation between ORA and refractive astigmatism, refractive and corneal astigmatism and a weak correlation between ORA and corneal astigmatism in refractive surgery candidates. Identifying the type of astigmatism and preoperative measurement of ocular residual astigmatism is highly recommended prior to any refractive surgery, especially in cases with significant astigmatism. Copyright © 2015 Elsevier Ltd. All rights reserved.
... As regard astigmatism, we found a prevalence of 26.0%, which is comparable with studies that used a similar methodology as our study showing a range between 18.5-29.6% (12,15,40). On the other hand, the prevalence is much higher in studies that use a >0.50 D criterion to define astigmatism (40)(41)(42). ...
... (12,15,40). On the other hand, the prevalence is much higher in studies that use a >0.50 D criterion to define astigmatism (40)(41)(42). In spite of a majority of with-the-rule astigmatism found in our sample, there was a tendency to increase to against-the-rule astigmatism with age ( Table 4). ...
Article
Background: Refractive errors are among the most frequent reasons for demand of eye-care services. Publications on refractive errors prevalence in our country are few. This study has the purpose to assess the prevalence of refractive errors in an adult population of Villa Maria, Córdoba, Argentina. Methods: The Villa Maria Eye Study is a population-based cross-sectional study conducted in the city of Villa Maria, Córdoba, Argentina from May 2008 to November 2009. Subject’s aged 40+ received a demographic interview and complete ophthalmological exam. Visual acuity was obtained with an ETDRS chart. Cycloplegic auto refraction was performed. The spherical equivalent was highly correlated between right and left eyes, so only data of right eyes are presented. Myopia and hyperopia were defined with a ±0.50 diopters (D) criterion and astigmatism >1 D. Results: This study included 646 subjects, aged 40 to 90 (mean age: 59.6±10.3 years old). Four hundred and sixty two (71.5%) were females. The mean spherical equivalent was +0.714±2.41 D (range, −22.00 to +8.25 D) and the power of the cylinder was, on average, −0.869±0.91 D (range, 0 to −6.50 D). In this sample, 61.6% subjects were hyperopic, and 13.5% were myopic. Myopia prevalence was lower in men (9.8% versus 14.9%) but this difference among genders was not statistically significant. There were 141 subjects (21.8%) with anisometropia greater than 1 D, and 168 subjects (26.0%) with astigmatism greater than 1 D. Conclusions: The present study shows the prevalence of cycloplegic refractive errors in an adult population of Argentina. The prevalence of hyperopia was high, while myopia prevalence was very low.
... As regard astigmatism, we found a prevalence of 26.0%, which is comparable with studies that used a similar methodology as our study showing a range between 18.5-29.6% (12,15,40). On the other hand, the prevalence is much higher in studies that use a >0.50 D criterion to define astigmatism (40)(41)(42). ...
... (12,15,40). On the other hand, the prevalence is much higher in studies that use a >0.50 D criterion to define astigmatism (40)(41)(42). In spite of a majority of with-the-rule astigmatism found in our sample, there was a tendency to increase to against-the-rule astigmatism with age ( Table 4). ...
Article
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Introduction According to World Health Organization (WHO) report in 2004, refractive errors are the second leading cause of Years Lost due to Disability (YLD) in low-and middle-income countries (1). There have been numerous population surveys all over the world in the last 20 years (2-22), showing the prevalence of refractive errors in adults. However, only one population-based study of refractive error is currently available in Argentina (23). As refractive errors are among the most frequent reasons for demand of eye-care services, prevalence data are important for public health care planning, in order to improve vision-specific quality of life. The paper by Barrenechea et al. showed that the prevalence of severe visual impairment and blindness in subjects older than 50 years old in Argentina was 2.5% and uncorrected refractive errors were the main cause of visual impairment. Background: Refractive errors are among the most frequent reasons for demand of eye-care services.
... [5] Against-the-rule (ATR) astigmatism is more common in old age, wherein the horizontal curvature is more curved than the vertical curvature. [6][7][8][9] It can be postulated that a curvilinear incision on the temporal side can produce a desirable flattening effect on the more curved horizontal axis which is seen in patients with ATR astigmatism. ...
... [12] ATR astigmatism, wherein horizontal meridian is more curved than the vertical meridian is more common in aged patients who require cataract surgery. [6][7][8][9] A curvilinear incision (limbus parallel) near the temporal limbus is capable of flattening the horizontal meridian. Hence, this study was conducted to look for any benefit in the decrease in ATR astigmatism that can occur if MSICS is done with temporal curvilinear incision and also to compare this with the reduction of ATR astigmatism that can occur when done by temporal straight line incision MSICS and temporal phacoemulsification. ...
Article
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Background: To address the issue of ATR astigmatism in patients who undergo temporal manual small incision cataract surgery (MSICS) surgery. Aim: The aim is to find out whether an incision that is made parallel to the limbus (curvilinear) while doing temporal MSICS can reduce the preexisting against-the-rule astigmatism (ATR). Settings and Design: The study was conducted on those patients who came for cataract surgery in a government general hospital. Materials and Methods: One hundred and five patients with cataract and ATR astigmatism of ≥1D were divided into three groups each with 35 patients. Group A patients underwent curvilinear incision temporal MSICS, Group B straight line incision temporal MSICS, and Group C limbal incision temporal phacoemulsification. The amount of change in ATR astigmatism in each group was calculated by comparing preoperative and postoperative keratometry readings. Statistical Analysis: All data were evaluated using SPSS version 19.0. To test the significant difference between pre- and post-operative astigmatism in each group, paired t-test was used. To test the significant difference in astigmatism between the three groups, ANOVA was used. Results: The reduction in the mean astigmatism in Group A was 0.89D, in Group B 0.62D, and in Group C 0.086D. The significant reduction of the ATR astigmatism in Group A and Group B could be due to the flattening of the horizontal curvature which is higher in patients with ATR astigmatism. Among these two groups, the curvilinear incision produced more flattening than the straight line incision. Conclusion: If a curvilinear (limbus parallel) is done while doing temporal MSICS in patients with higher ATR astigmatism, there can a significant reduction of ATR astigmatism giving a better uncorrected visual acuity.
... Therefore, it is important to study the characteristics of corneal astigmatism and its influencing factors among the elderly population. However, most previous empirical studies on astigmatism enrolled all the young, middle-aged, and elderly patients [1][2][3][4][5][6][7][8][9][10][11][12][13] . Studies focused on the elderly population are needed, especially for patients over 50 years of age because they have a higher morbidity of cataract and distinctive refractive characteristics compared to the younger adults. ...
... Up to 65% of patients had a corneal astigmatism ≥ 0.75D and 47% of patients had a corneal astigmatism ≥ 1.0D, which was higher than most previous studies [1][2][3][4][5][6][7][8][9][10][11][12][13]21] (Table 4). The most possible reason is that our study focused on patients over 50 years old. ...
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Background: To investigate the relationship between corneal astigmatism and age, axial length (AL) among Chinese over fifty years old. Methods: This study enrolled 1,082 right eyes of age-related cataract patients over 50 years old in the clinic of Peking University People’s Hospital, Beijing, China. Axial length, magnitude and meridian of anterior corneal astigmatism were measured by IOLMaster. Restricted cubic splines and Spearman rank correlation coefficients were used to investigate the relationship of the magnitude of cornea astigmatism to age and AL. Power vector analysis method and linear regression analysis were used to assess the relationship of the meridian of astigmatism to age and AL. Results: For this study , mean age, AL, and corneal astigmatism value were 72.45 ±9.28 years, 23.90±1.93mm, and 1.12±0.74D, respectively. The magnitude of corneal astigmatism was 0.75D or higher in 63.8% eyes. The magnitude of corneal astigmatism increased with age after 65 years old. This correlation was statistically significant when AL was between 22.00mm and 26.00mm. The vector value in J 0 was inversely correlated with age. The mean vector value change from with-the-rule (WTR) to against-the-rule (ATR) corneal astigmatism was 0.22D/10 years during 50-65 years old and 0.15D/10 years during 65-85 years old, and was 0.22D/10 years in male and 0.12D/10 years in female, respectively. Conclusions: A large proportion of elderly Chinese cataract patients over 50 years old have corneal astigmatism more than 0.75D . There was a non-linear trend from WTR astigmatism towards ATR astigmatism with age, which was more obvious in elder age and in male. When AL is between 22.00mm and 26.00mm, the magnitude of corneal astigmatism increases with age after 65 years old.
... The age-related changes in different types of isorule astigmatism, including WW, AA, and OO, were similar to the findings of previous studies, such that with-the-rule astigmatism had a decreasing trend, against-the-rule astigmatism had an increasing trend, and oblique astigmatism had a relatively steady trend. 14,27,32,33 Since this is not a new finding and is addressed in most previous studies, we found no need to discuss it further. ...
Article
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Purpose: To evaluate the relationship patterns between astigmatism axes of fellow eyes (rule similarity and symmetry) and to determine the prevalence of each pattern in the studied population. Methods: This population-based study was conducted in 2015 in Iran. All participants had tests for visual acuity, objective refraction, subjective refraction (if cooperative), and assessment of eye health at the slit-lamp. Axis symmetry was based on two different patterns: direct (equal axes) and mirror (mirror image symmetry) or enantiomorphism. Bilateral astigmatism was classified as isorule if fellow eyes had the same orientation (e.g. both eyes were with-the-rule) and as anisorule if otherwise. Results: Of the total cases of bilateral astigmatism, 80% were isorule, and in the studied population, the prevalence of isorule and anisorule astigmatism was 14.89% and 3.53%, respectively. The prevalence of isorule increased with age (p<0.001). The prevalence of both isorule and anisorule increased at higher degrees of spherical ametropia (p<0.001). Median inter-ocular axis difference was 10° in mirror symmetry and 20° in direct symmetry with no significant difference between two genders (p>0.288). Both symmetry patterns reduced with age (p<0.001). Among cases of bilateral astigmatism, 15.5% and 19.8% had exact direct and mirror symmetry, respectively. Conclusion: Bilateral astigmatism is mainly isorule in the population and anisorule astigmatism is rare. The enantiomorphism is the most common pattern in the population of bilateral astigmatism.
... With ageing, the shape of the cornea undergoes a transition from with-the-rule to against-the-rule astigmatism. 24 The age-related shift to against-therule astigmatism has been demonstrated in many ethnicities, including Caucasian, 13 Iranian, 25 Singapore Malaysian 26 and South Indian. 27 The proposed theories for this shift include decreased eyelid tension with ageing 28 and repeated near work involving downward gaze and near vision accommodation. ...
Article
Background Aim to investigate ethnic variation, in presentation and biometric parameters, within the population undergoing cataract surgery in Auckland.DesignRetrospective study.Samples4931 eyes of 3524 consecutive patients undergoing cataract surgery in Auckland Public Hospital over 18 months.Methods Analysis of pre-operative medical records.Main Outcome MeasuresAge, gender, self-reported ethnicity, keratometry, anterior chamber depth (ACD), axial length and intraocular lens (IOL) power.ResultsMāori (4.7%) were under-represented compared to the proportion of Māori attending the eye clinic (5.5%) and in the major patient catchment area (8.2%). People of Māori, Pacific and Indian ethnicities presented at a significantly younger age (66.4, 65.9, and 67.9 years respectively) than those of Caucasian and Asian ethnicities (76.4, 71.3 years respectively, p < 0.001). Advanced cataract was more likely in Pacific peoples and Māori than Caucasians. The mean axial length was longest in Asian eyes (23.83 ± 1.52 mm). The mean ACD in eyes of Pacific peoples (3.20 ± 0.39 mm) was significantly greater than that of Caucasians (3.09 ± 0.42 mm, p = 0.001) and Asians (3.05 ± 0.49 mm, p < 0.001). The mean IOL power in Asian eyes was 19.45D. This was significantly lower than the IOL power required by Caucasian (20.72D, p < 0.001) and Pacific ethnicities (20.61D, p = 0.001). With-the-rule astigmatism was highly prevalent in Māori and Pacific peoples, whereas, in all other ethnicities, against-the-rule astigmatism was more common.Conclusions This study identified significant ethnic variation in presentation for cataract surgery and ocular biometric parameters. These data may help identify potential biometric refinements and those at risk of developing ocular morbidities known to be associated with these parameters. This article is protected by copyright. All rights reserved.
... In response to optical defocus imposed by a spherical positive lens (myopic defocus) or negative lens (hyperopic defocus), animals ranging from chickens to macaque monkeys develop compensatory hyperopia or myopia, respectively, to make their eyes functionally emmetropic (see: Wallman and Winawer, 2004 for review). These ocular compensatory responses are due mainly to alterations in axial growth; thus the axial growth rate of a myopically defocused eye slows, whereas that of a hyperopically defocused eye Atkinson et al., 1980;Bourne et al., 2004;Edwards, 1991;Fulton et al., 1980;Gwiazda et al., 1984;He et al., 2007He et al., , 2004He et al., , 2009Howland et al., 1978;Huynh et al., 2006, Huynh et al., 2007Landers et al., 2010;Li et al., 2009;Mohindra et al., 1978;Robaei et al., 2006;Santonastaso, 1930;Saunders, 1995;Schellini et al., 2009;Thorn et al., 2005;Anera et al., 2009;Anton et al., 2009;Cheng et al., 2003;Dandona et al., 2002;Dirani et al., 2010;Fan et al., 2011aFan et al., , 2004Fotouhi et al., 2007Fotouhi et al., , 2011Fozailoff et al., 2011;Goh et al., 2005;Gronlund et al., 2006;Gupta et al., 2008;Harvey et al., 2010Harvey et al., , 2006Hashemi et al., 2005Hashemi et al., , 2012Hashim et al., 2008;Jamali et al., 2009;Kleinstein et al., 2003 accelerates, and this e in concert with the natural decreases in corneal and lens powers during early eye growth e causes their retinal planes finally to match the experimentally displaced focal planes. These active, vision-dependent mechanisms would encounter a more challenging task in the presence of astigmatic error: because astigmatism produces orientation-dependent blur at different image planes, alterations in axial growth per se could at best improve retinal image quality along a single orientation (e.g., a point object will become an elongated line). ...
Article
Astigmatism is a common refractive error caused by the difference in refractive power of the eye along different meridians. This causes two line foci that cannot be corrected by changing viewing distance or accommodation. Although human studies have ascribed astigmatism to multiple factors, its cause remains unclear. Studies in chicks and monkeys suggest that imposed astigmatic error may alter emmetropization, but McLean and Wallman (2003) showed that the early compensatory response to spherical defocus was not affected by concurrent high astigmatism in chicks. This review will focus on possible mechanisms leading to astigmatism and the influence of astigmatism on emmetropization in animal studies.
... Some studies have even suggested the role of decreased eyelid pressure in increasing the prevalence of ATR astigmatism with age. 33,34 Available data on the type of astigmatism and gender shows that the type of astigmatism is probably affected by race since in our study and in Shahroud study, 35 women mostly had ATR astigmatism while studies conducted by Mandel et al 36 Huynh et al, 37 have reported higher prevalence of WTR astigmatism in women. ...
Article
abstract: Purpose : To determine the prevalence of the refractive errors in the elderly population of Sari, Iran Methods : In this study, after selecting the participants through random cluster sampling, they all received ocular examinations including visual acuity (VA) measurement, refraction, fundoscopy and tonometry. After measuring uncorrected visual acuity (UCVA), non-cycloplegic refraction was performed for all participants with an autorefractometer and the results were checked with manual retinoscopy. Results : The prevalence of myopia, hyperopia, astigmatism and anisometropia were 19.7% [95% confidence interval (CI) 17.0-22.4], 39.5% (95% CI 36.1-42.9), 23.6% (95% CI 20.7-26.4), and 7.8% (95% CI 6.0-9.6), respectively. Male gender and cataract were also correlated with myopia significantly. Female gender and age were correlated with hyperopia. Astigmatism was significantly correlated with cataract and a decrease in age. With-the-rule (WTR), against-the-rule (ATR) and oblique astigmatisms were detected in 7.5%, 13.1% and 3.5% of the participants, respectively. Overall, the prevalence of at least one type of refractive error was 64.0% (95%CI 60.7-67.3) among the participants. Conclusion : The results of this study indicated that hyperopia was the major anomaly in our population. Since the combination of presbyopia and hyperopia results in an undesirable visual condition in the elderly, it is important to pay proper attention to visual problems in this age group.
... In other studies, the prevalence of against the rule astigmatism was higher in the elderly population such as Shahroud [20], Singapore [22] and Bangladesh [23]. ...
... A previous study in Shahroud showed that 1 in every 2 adults had astigmatism, which is a high prevalence in adults. 27 It must be noted that when comparing different studies the criteria of astigmatism and the method and accuracy of measurement must be taken into account. The limited number of studies on astigmatism in children and its high prevalence in adults in Shahroud encouraged us to investigate the prevalence of astigmatism in Shahroud children. ...
Article
Full-text available
Purpose To determine the prevalence of astigmatism and its determinants in schoolchildren aged 6–12 years. Methods The students selected by stratified cluster random sampling in Shahroud, north of Iran. Optometric examination included uncorrected visual acuity, refraction with autorefractometer, manifest refraction with retinoscopy followed by subjective and cycloplegic refraction (after two drops of cyclopentolate 1% with 5 min interval were instilled in each eye). A cylinder power ≥0.75 diopter (D) in at least one eye was considered as astigmatism. The prevalence of astigmatism was reported based on a cylinder power higher than 0.50, 1.00, and 2.00 D in cycloplegic refraction, followed by power vector analysis. Results After applying the inclusion criteria, the data of 5528 children were analyzed. The prevalence of astigmatism was 16.7% (95% CI: 15.6–17.7) in total, 16.6% (95% CI: 15.2–18.0) in boys and 16.8% (95% CI: 15.2–18.3) in girls (p = 0.920) and decreased from 21.5% in 6-year-old children to 13.7% in 10-year-olds, and then again increased to 18.3% in children aged 12 years. Moreover, 17.2% (95% CI: 16.0–18.3) of urban and 12.1% (95% CI: 10.0–14.1) of rural children had astigmatism (p < 0.001). The prevalence of with-the-rule, against-the-rule, and oblique astigmatism was 14.2%, 2.1%, and 0.33%, respectively. The mean cylinder power was −1.31, −0.46, and −0.44 D in children with spherical myopia, emmetropia, and hyperopia, respectively (p < 0.001). Urban students had a higher J0 and boys had a higher J45. Conclusion The prevalence of astigmatism in this study was lower than previous studies. Astigmatism prevalence was markedly higher in urban children.
... Leung et al. (2012) have also previously reported similar changes in median RA with age. In terms of outcomes from linear regression analysis, we noted a per 10-year increase in cylinder power of 0.18 D, and this is comparable to that calculated by Hashemi et al. (2012) in an Iranian population of over 5000 40-64-yearolds. ...
Article
PurposeAstigmatism is a common cause of refractive error and is known to vary in prevalence with age. Although the search for genes associated with spherical refractive errors (especially myopia) has met with limited success, current efforts to identify genetic variants implicated in astigmatism development have been less rewarding. We aimed to assess the association between astigmatism and age to identify appropriate age cut-offs for maximizing power in genetic studies of astigmatism. Methods We performed a cross-sectional analysis of right eye astigmatism data from four Australian-based eye studies comprising 3841 participants aged 5-90years. Measurements were performed under cycloplegia using an autorefractor, and individuals with a history of cataract, refractive surgery or corneal pathology were excluded from the analysis. In addition to the magnitude and type (against-the-rule, with-the-rule, and oblique) of astigmatism, we calculated the vector components (J(0), J(45)) and evaluated the association of these outcome measures with age. ResultsThe magnitude of refractive astigmatism (RA) remained relatively stable [meanSD (-0.44D +/- 0.50)] until individuals reached the age of 50, thereafter increasing in average magnitude by approximately 1.00D for those subjects aged 90. In contrast, corneal astigmatism (CA) remained relatively stable from childhood until the age of 80 (-0.76D +/- 0.61). The prevalence of clinically significant RA (1.00D) increased with age and was highest in those aged >70years [55.1% (47.2-62.7%)]. Age was significantly associated with RA in adults [odds ratio (OR)=1.04 per 1year, p<0.001]. A weaker relationship was observed between CA and age (OR=1.007 per 1year, p=0.02). Conclusions We have confirmed the previously documented association between RA and age. Our results indicate that most of the observed change occurs after the age of 50, providing a recommended cut-off for participants in genetic studies of this refractive condition.
... In Iran, a high prevalence of astigmatism has been reported in different populations with average ages of about 51 years (5), 32 years (6, 7) and 12 years (8). To our knowledge, no population-based study has been conducted on children under six years old and data on the amount and axis of astigmatism is not available in this age group. ...
Article
Background: Astigmatism is a correctable cause of visual impairment in childhood. It increases the incidence of amblyopia in children. Objectives: In this report, we intended to describe the prevalence of the amount and axis of astigmatism, astigmatism components, and associations of astigmatism with age, gender and spherical equivalent in under six years old children through a population-based study. Patients and Methods: This report was a part of the cross-sectional Mashhad Eye Study in which 3675 of 4-6 years old children in Mashhad kindergartens were selected through random cluster sampling, of which, 3701 participated in the study (response rate: 98.3%). Refractive astigmatism was determined using a retinoscope (HEINE BETA-200, Germany) and defined as a cylinder power of more than 0.5 diopter (D). Corneal astigmatism was measured using Pentacam (Oculus Optikgerate GmbH, Germany). Results: The prevalence of refractive astigmatism of more than 0.5D in at least one eye was 51.4% (95% confidence interval (CI): 50.7-52.1); 52.1% in girls and 50.7% in boys (P = 0.412). Prevalence of astigmatism decreased with age, but not statistically significant (odds ratio: 0.97; 95% CI: 0.87-1.07). Mean corneal astigmatism was 1.01 D (95% CI: 0.99-1.03); 1.00 D (95% CI: 0.98-1.02) and 1.02 D (95% CI: 1.00-1.04) in girls and boys, respectively (P = 0.243). Mean corneal astigmatism was not significantly different between different age groups (P = 0.410). Conclusions: The prevalence of astigmatism was high in children under six years old in this study, and to control amblyopia, it is necessary to consider astigmatism at younger ages. Keywords:Prevalence; Astigmatism; Children; Population- Based Planning
... It is rather difficult to discuss astigmatism in university students since a limited number of studies have investigated astigmatism in this age group; however, our findings showed that the prevalence of astigmatism in university students was higher than children and lower than elderly people. 12,58 In other words, its prevalence was midrange in our study population. As mentioned earlier, the prevalence of astigmatism increased significantly with age. ...
Article
Full-text available
Purpose: To determine the prevalence of refractive errors in the students of Mashhad University of Medical Sciences, Iran Methods: In this cross-sectional study, we used cluster sampling for selecting participants from every department of Mashhad University of Medical Sciences, proportional to the number of students in each department. Each participant received refraction examination with an autorefractometer and check up with a retinoscope. Myopia and hyperopia were defined as spherical equivalent (SE) less than -0.5 and more than +0.5 D, respectively. Astigmatism was defined as cylinder power worse than 0.5 D. Results: Out of 1,745 selected individuals, the data of 1,431 participants were analyzed after implementing the exclusion criteria; 58.8% of the participants were female and the mean age of the participants was 23.8±3.8 years (range, 18-32 years). Myopia, hyperopia, and astigmatism were seen in 41.7% (95%CI 38.7-44.7), 7.8% (95%CI 6.2-9.4), and 25.6% (95%CI 23-28.3) of the students in this study, respectively. The prevalence of myopia increased significantly with age (OR=1.16 1.12-1.20 p<0.001). The prevalence of hyperopia was significantly higher in females (OR=2.1 1.1-3.7 p=0.025) and decreased significantly with age (OR=0.87 0.81-0.94 p=0.001). The prevalence of astigmatism increased significantly with age. Moreover, 6% of the students had anisometropia and 1.2% had high myopia. Conclusion: The prevalence of myopia was considerably high in these students; therefore, attention to this age group to identify and correct the refractive errors should receive priority in the health system.
... Some studies have even suggested the role of decreased eyelid pressure in increasing the prevalence of ATR astigmatism with age. 33,34 Available data on the type of astigmatism and gender shows that the type of astigmatism is probably affected by race since in our study and in Shahroud study, 35 women mostly had ATR astigmatism while studies conducted by Mandel et al 36 Huynh et al, 37 have reported higher prevalence of WTR astigmatism in women. ...
Article
Purpose: To determine the prevalence of the refractive errors in the elderly population of Sari, Iran Methods: In this study, after selecting the participants through random cluster sampling, they all received ocular examinations including visual acuity (VA) measurement, refraction, fundoscopy and tonometry. After measuring uncorrected visual acuity (UCVA), non-cycloplegic refraction was performed for all participants with an autorefractometer and the results were checked with manual retinoscopy. Results: The prevalence of myopia, hyperopia, astigmatism and anisometropia were 19.7% [95% confidence interval (CI) 17.0-22.4], 39.5% (95% CI 36.1-42.9), 23.6% (95% CI 20.7-26.4), and 7.8% (95% CI 6.0-9.6), respectively. Male gender and cataract were also significantly correlated with myopia. Female gender and age were correlated with hyperopia. Astigmatism was significantly correlated with cataract and a decrease in age. With-the-rule (WTR), against-the-rule (ATR) and oblique astigmatisms were detected in 7.5%, 13.1% and 3.5% of the participants, respectively. Overall, the prevalence of at least one type of refractive error was 64.0% (95%CI 60.7-67.3) among the participants. Conclusion: The results of this study indicated that hyperopia was the major anomaly in our population. Since the combination of presbyopia and hyperopia results in an undesirable visual condition in the elderly, it is important to pay proper attention to visual problems in this age group.
... The prevalence of AnisoAST (≥1 D) in their study population was 5.6% as compared with 11.6% in our study. The amount of AnisoAST, similarly to the mean amount of AST, clearly increases with age ( Hashemi et al. 2012). Hashemi et al. (2013) compared asymmetry in all the different biometric components of refraction with anisometropia. ...
Article
Purpose: To examine the prevalence of anisometropia of spherical refraction (AnisoSR), astigmatism (AnisoAST) and spherical equivalent (AnisoSE) and their associations with spherical refraction (SR), refractive astigmatism (AST), spherical equivalent (SE) and interocular differences of ocular biometric parameters among elderly female twins. Methods: Refraction of 117 monozygotic (MZ) and 116 dizygotic (DZ) female twin subjects aged 66-79 years was assessed with an auto-refractor (Topcon AT) and controlled by subjective refraction. Corneal refraction, anterior chamber depth and axial length were measured with a Zeiss IOL Master. Participants with eyes operated for cataract or glaucoma were excluded, but the grade of nuclear opacity was not recorded. The associations between the absolute values of AnisoSR, AnisoAST and AnisoSE with SR, AST, SE, corneal refractive power (CR), corneal astigmatism (CAST), anterior chamber depth (ACD) and axial length (AL) and with their interocular differences were calculated. When calculating the interdependencies of the differences, the real and absolute differences between the right and left eye were used. Results: Means ± standard deviations for AnisoSR, AnisoAST and AnisoSE were 0.67 ± 0.92 D, 0.42 ± 0.41 D and 0.65 ± 0.71 D, respectively. AnisoSR, AnisoAST and AnisoSE >1.0 D were present in 14.7%, 4.2% and 17.7% of cases, respectively. Anisometropia of spherical refraction (AnisoSR), AnisoAST and AnisoSE were higher the more negative the values of SR or SE. Hyperopic ametropia did not increase these anisometropia values. The correlations of AnisoSR and AnisoSE with the absolute values of interocular differences in CR and AL were non-significant. Using the real values of the interocular differences, the respective correlations were significant. The correlation between the real interocular differences in CR and AL was negative (r = -0.258, p < 0.001). Thus, the combined effect of the real interocular differences in CR and AL was a decrease in AnisoSR and AnisoSE (emmetropization). Conclusion: Higher AnisoSR and AnisoSE were associated with more myopic refraction and longer AL. Higher AnisoAST was associated with more negative SR and higher AST and CAST. The negative correlation between real interocular differences in CR and AL indicated their influence of emmetropization in AnisoSR and AnisoSE.
... As previously shown in Asian and Australian populations [7,9,[13][14][15], we found a statistically significant relationship between age and the orientation of refractive astigmatism, indicating a shift from with-the-rule astigmatism to againstthe-rule astigmatism. Sanfilippo et al. published that this shift occurs after the age of 50 years in individuals with a previously relatively stable refractive astigmatism [7], and we were able to demonstrate this relationship over the entire study population with an age range of 35 years to 74 years. ...
Article
Full-text available
Purpose: Worldwide, the most frequent cause of visual impairment is uncorrected refractive error. This analysis focused on the distribution and associations of refractive, corneal and ocular residual astigmatism. Methods: As part of the Gutenberg Health study, a population-based cross-sectional study was conducted in the general population of Germany. A comprehensive ophthalmological examination including refraction, tonometry, and Scheimpflug imaging of the anterior cornea (Pachycam) was performed. In addition to the magnitude and type (with-the-rule, against-the-rule, oblique) of the refractive or corneal astigmatism, we calculated the vector components (J0, J45) of both astigmatisms and calculated the ocular residual astigmatism. We performed multiple quantile regression analysis to evaluate the factors associated with refractive, corneal and ocular residual astigmatisms. Results: A total of 13,558 subjects (49% female) with a mean age of 54.0 years (range 35-74 years) were included in this study. The prevalence of refractive astigmatism (>1.0D) was 13.0% in right eyes and 12.0% in left eyes, and 85% of these subjects wore spectacles. The distribution of refractive astigmatism showed a two-peak distribution with high astigmatism for with-the-rule and against-the-rule astigmatism. The associated factors were corneal curvature, age and sex for the different astigmatisms (p < 0.001). Conclusions: We analyzed the prevalence of different astigmatisms within a European population. We confirmed a shift with aging from with-the-rule to against-the-rule astigmatism to refractive and corneal astigmatism. Astigmatism has a large impact on visual perception; more than 85% of people with astigmatism over one diopter wore glasses for distance vision.
... 38 However, some studies have shown that incyclotorsion during near work causes astigmatism. 44 There was no significant association between sex and myopia, hyperopia, astigmatism, anisometropia, and refractive errors. Although some studies in children found no association between gender and myopia, 17,21,22,24 studies in the elderly population have shown a higher prevalence in men. ...
Article
Full-text available
Purpose To determine the prevalence of refractive errors and visual impairment and the correlation between personal characteristics, including age, sex, weight, and height, with different types of refractive errors in a population of university students in the south of Iran. Methods In this cross-sectional study, a number of university majors were selected as clusters using multi-stage sampling in all universities located in Kazerun (27 clusters of 133 clusters). Then, proportional to size, a number of students in each major were randomly selected to participate in the study. Uncorrected and corrected visual acuity, non-cycloplegic objective refraction and subjective refraction were measured in all participants. Results The prevalence and 95% confidence interval (CI) of presenting visual impairment and blindness was 2.19% (1.48–3.23) and 0.27% (0.12–0.62), respectively. Refractive errors comprised 75% of the causes of visual impairment. The prevalence (95% CI) of myopia [spherical equivalent (SE) ≤ −0.5 D], hyperopia (SE ≥ 0.5 D), and astigmatism (cylinder power < −0.5 D) was 42.71% (39.71–45.77), 3.75% (2.85–4.51), and 29.46% (27.50–31.50), respectively. Totally, 49.03% (46.39–51.68) of the participants had at least one type of refractive error. There was a positive association between weight and myopia (1.01; 95% CI: 1.01–1.02), anisometropia (1.03; 95% CI: 1.01–1.06), and refractive errors (1.01; 95% CI: 1.01–1.02). In comparison with the age group 18–19 years, the odds ratio (OR) of astigmatism in the age group 26–27 years was 1.64 (95% CI: 1.03–2.61), and the OR of anisometropia in the age group ≥30 years was 0.21 (95% CI: 0.04–0.98). Conclusions The prevalence of refractive errors, especially myopia, is higher in university students than the general population. Since refractive errors constitute a major part of visual impairment, university students should receive special services for providing corrective lenses and glasses to reduce the burden of these disorders.
Article
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Purpose The aim of the study was a systematic review of refractive errors across the world according to the WHO regions. Methods To extract articles on the prevalence of refractive errors for this meta-analysis, international databases were searched from 1990 to 2016. The results of the retrieved studies were merged using a random effect model and reported as estimated pool prevalence (EPP) with 95% confidence interval (CI). Results In children, the EPP of myopia, hyperopia, and astigmatism was 11.7% (95% CI: 10.5–13.0), 4.6% (95% CI: 3.9–5.2), and 14.9% (95% CI: 12.7–17.1), respectively. The EPP of myopia ranged from 4.9% (95% CI: 1.6–8.1) in South–East Asia to 18.2% (95% CI: 10.9–25.5) in the Western Pacific region, the EPP of hyperopia ranged from 2.2% (95% CI: 1.2–3.3) in South-East Asia to 14.3% (95% CI: 13.4–15.2) in the Americas, and the EPP of astigmatism ranged from 9.8% in South-East Asia to 27.2% in the Americas. In adults, the EPP of myopia, hyperopia, and astigmatism was 26.5% (95% CI: 23.4–29.6), 30.9% (95% CI: 26.2–35.6), and 40.4% (95% CI: 34.3–46.6), respectively. The EPP of myopia ranged from 16.2% (95% CI: 15.6–16.8) in the Americas to 32.9% (95% CI: 25.1–40.7) in South-East Asia, the EPP of hyperopia ranged from 23.1% (95% CI: 6.1%–40.2%) in Europe to 38.6% (95% CI: 22.4–54.8) in Africa and 37.2% (95% CI: 25.3–49) in the Americas, and the EPP of astigmatism ranged from 11.4% (95% CI: 2.1–20.7) in Africa to 45.6% (95% CI: 44.1–47.1) in the Americas and 44.8% (95% CI: 36.6–53.1) in South-East Asia. The results of meta-regression showed that the prevalence of myopia increased from 1993 (10.4%) to 2016 (34.2%) (P = 0.097). Conclusion This report showed that astigmatism was the most common refractive errors in children and adults followed by hyperopia and myopia. The highest prevalence of myopia and astigmatism was seen in South-East Asian adults. The highest prevalence of hyperopia in children and adults was seen in the Americas.
Article
We decided to conduct a study to determine the prevalence of visual impairment, blindness, refractive errors, and other visual functions in nursing homes of Iran. In this cross-sectional study, 133 elderly persons were selected from seven nursing homes using proportional-to-size random sampling. A Snellen chart was used to measure visual acuity (VA). Refraction was measured in all participants using autorefractometry and retinoscopy. A cover test was applied to assess ocular deviation. Stereopsis, color vision, and contrast sensitivity were evaluated with distance glasses. The prevalence (95% confidence interval [CI]) of visual impairment (VI) (<20/60), low vision (<20/60 to <20/400), and blindness (⩽20/400) was 41.88% (32.81–50.95), 32.48% (23.87–41.09), and 9.40% (4.03–14.77), respectively, based on best-corrected visual acuity (BCVA). The prevalence of myopia (spherical equivalent (SE) < −0.5 D), hyperopia (SE < 0.5 D), and astigmatism (cylindrical power < 0.5 D) was 53.50% (44.19–62.58), 36.84% (28.38–46.19), and 86.84% (79.17–91.97), respectively. VI and refractive errors had no association with age and sex (p-value > .05 for all). The prevalence of other ocular diseases was as follows: cataract 66.06% (57.02–75.09), glaucoma 1.52% (1.85–5.40), one eyed caused by injury 6.10% (2.67–11.67), and corneal opacity 3.81% (1.25–8.68). The prevalence of VI was 4–20 times and the prevalence of cataract was 3–4 times higher in NHRs compared with community-dwelling older people, indicating the grave situation of vision in these people. It is necessary to conduct further studies to find the reasons behind this disparity and perform interventions, including periodic and screening examinations upon entry to nursing homes to decrease the burden of ocular diseases in NHRs.
Article
Purpose: Studying the prevalence of astigmatism and its related factors in underprivileged rural areas in Iran. Methods: Using random cluster sampling, two rural areas in the north and southwest of Iran were randomly selected, and 3851 persons over 1 year of age were invited to the study. In addition to recording demographics, retinoscopic refraction was conducted using baseline auto-refraction results. The prevalence of astigmatism was determined based on cylinder error cut-off points of 0.50 dioptre (D), 1.00, 2.00 and 3.00 D. Multiple logistic regression was used to assess variables' relationship with astigmatism. Results: The prevalence of astigmatism as a cylinder error greater than 0.50 D was 35.6% (95% CI: 33.7-37.6); this was 34.0% (95% CI: 31.4-36.6) in women and 36.9% (95% CI: 33.9-39.9) in men. The lowest prevalence was seen in the 6-20 year old age group (13.6%) and the highest prevalence was found in individuals older than 70 years (82.5%). In the multiple logistic regression model, age and education level were significantly related to astigmatism. The prevalence rates of with-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism were respectively 15.0%, 17.2%, and 3.5%. The prevalence of WTR astigmatism decreased with age, while the prevalence of ATR (and oblique astigmatism to a lesser extent) increased. Conclusion: The prevalence of astigmatism was similar to previous studies; however, there were considerable age-related changes. In particular, the prevalence of astigmatism in elderly people was substantial and of concern, particularly given that virtually none of this age group were wearing distance spectacles.
Article
Worldwide, more than one billion people suffer from poor vision because they do not have the eyeglasses they need. Their uncorrected refractive errors are a major cause of global disability and drastically reduce productivity, educational opportunities, and overall quality of life. The problem persists most prevalently in low-resource settings, even though prescription eyeglasses serve as a simple, effective, and largely affordable solution. In this review, we discuss barriers to obtaining, and approaches for providing, refractive eye care. We also highlight emerging technologies that are being developed to increase the accessibility of eye care. Finally, we describe opportunities that exist for engineers to develop new solutions to positively impact the diagnosis and treatment of correctable refractive errors in low-resource settings. Expected final online publication date for the Annual Review of Biomedical Engineering Volume 16 is July 01, 2014. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
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PurposeTo assess the relationship between age, corneal astigmatism, and ocular dimensions with reference to astigmatism correction during cataract surgery.Methods In this cross-sectional study of right eyes of 2247 consecutive patients attending cataract surgery preassessment, data on patient demographics, axial length (AL), anterior chamber depth (ACD), and keratometric astigmatism were collected. Astigmatism was further analyzed as against-the-rule (ATR: steepest meridian 180±30°), with-the-rule (WTR: 90±30°), and oblique (OB: 30-60°or 120-150°).ResultsMean age, AL, and ACD were 72.28±13.84 years, 23.99±1.85 mm and 3.08 ±0.52 mm, respectively. In all, 20.4% eyes had ≤0.50 diopters (D), 55.2% had 0.51-1.50 D, 7.9% had 2.01-3.00 D, and 3.7% eyes had >3.00 D of astigmatism. Overall, 44.2% of eyes had corneal astigmatism >1.00 D. Average astigmatism in age ranges 40-49, 50-59, 60-69, 70-79, 80-89, and 90+ years were 0.82, 1.04, 1.04, 1.02, 1.15 and 2.01 D, respectively. The magnitude of preoperative astigmatism positively correlated with age (P<0.0001), with increasing and decreasing prevalence of ATR and WTR astigmatism, respectively, with advancing age. The magnitude of ATR astigmatism inversely correlates to AL (P<0.0001). ATR astigmatism is more prevalent with increasing magnitude of astigmatism (P<0.0001).ConclusionsA majority of patients for cataract surgery have astigmatism between 0.51 and 1.5 D. ATR astigmatism increases, whereas WTR decreases with age. ATR astigmatism inversely correlates to AL. With increasing age, the magnitude of astigmatism increases and ATR astigmatism becomes increasingly prevalent. The likelihood of a patient requiring astigmatic correction increases with age.Eye advance online publication, 22 January 2016; doi:10.1038/eye.2015.274.
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To assess the frequency of amount and axis of astigmatism with respect to age and gender. The prospective, observational study was carried out from September 2009 to January 2010 at Armed Forces Institute of Ophthalmology, Rawalpindi. Patients from 5-70 years of age were included from both genders with no previous history of eye abnormality, surgery or eye pathology. An auto refractor-keratometre was used for measurement. Descriptive statistics were used to analyse data on SPSS 15. Among the total 288 patients, with-the-rule astigmatism (n = 21; 55%) had greater frequency in the 26-35 years sub-group. In terms of gender, 88 (48%); against-the-rule in 81 (44%); and oblique astigmatism in 14 (7.6%). In females, with-the-rule astigmatism was found in 52 (50%); against-the-rule in 36 (34.2%); and oblique in 17 (16%). The frequency of astigmatism > or = 0.25 ranged from 0.8% (n = 1) to 74% (n = 28) across all age groups. The amount of astigmatism which was noted to be the most common and prominent in the sample was < 1D. The amount and axis of astigmatism varied within the age sub-groups and within the gender.
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Introduction: To assess the prevalence of refractive errors, identifying the associated factors, and to correlate demographic characteristics (sex, and family history) with different types of refractive errors among Mansoura University students.
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Introduction: To assess the prevalence of refractive errors, identifying the associated factors, and to correlate demographic
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Purpose To investigate longitudinal changes in refraction and biometry in Chinese adults. Design Population-based prospective cohort study. Methods 1817 subjects aged ≥ 35 years were randomly recruited from Yuexiu district, Guangzhou, China in 2008. Of which 1595 (87.8%) were reexamined in 2010 and 1427 (78.5%) were reexamined in 2014. Non-cycloplegic automated refraction and visual acuity test were performed at baseline and the 6-year follow-up examination for all participants. In addition, 50% of the participants were randomly selected for axial length (AL), anterior chamber depth (ACD) and lens thickness (LT) measurements using non-contact partial coherence laser interferometry. Lens power (LP) was calculated with the Bennett’s equation. Results A total of 1300 participants were included in current analysis (2008 mean [SD] age, 51.4 [10.6] years; 54.5% women). Mean change in spherical equivalence (SE) was +0.24 (95% confidence interval [CI], +0.19 to +0.30), +0.51 (95% CI, +0.46 to +0.57), +0.26 (95% CI, +0.15 to +0.38) and -0.05 (95% CI, -0.21 to +0.10) diopters (D) for individuals in the age groups of 35 to 44, 45 to 54, 55 to 64 and 65+ years at baseline, respectively. Corneal power, AL and LT increased while ACD and LP decreased during the follow-up. Baseline SE and changes in biometric factors could explain 97.2% of the variance in longitudinal SE change while LP solely could explain 65.2%. Six-year mean change in cylinder power was -0.16 (95% CI, -0.19 to -0.13) D, the axis of astigmatism changed from “with-the-rule” to “against-the-rule” in 16.4% of the participants and to “oblique” in 0.9%. Conclusions This study confirms a hyperopic shift in the elderly before 65 years old and a myopic shift thereafter. Longitudinal refraction change could be well explained by corresponding biometry changes, especially LP. There is also a shift to “against-the-rule” astigmatism for the adult population.
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Objective: To analyze the magnitude, orientation, and age-related changes of corneal astigmatism and its correlation with biometric parameters in healthy eyes. Methods: Patients over 15 years of age were enrolled in our study. Exclusion criteria were previous ocular surgery, corneal disease, or contact lens wear. Axial length (AL), keratometric readings, and anterior chamber depth (ACD) were assessed using IOLMaster. Results: In our study, 1092 eyes were examined. The mean age was 69.64 ± 15.25 years (range 15-100 years). The AL was 23.32 ± 1.49 mm and ACD was 3.17 ± 2.03 mm. Higher AL and ACD values were observed in male patients. The overall astigmatism was 0.89 ± 0.72 D. The magnitude of astigmatism was ≥0.5 D in 73.53% of the cases, ≥1.0 D in 32.78%, ≥1.5 D in 13.55%, and ≥2.0 D in 6.86%. In our population, 582 eyes (53.3%) showed with-the-rule astigmatism, 309 (28.3%) against-the-rule, and 201 (18.4%) oblique astigmatism, regardless of sex. Significant against-the-rule astigmatic shift was verified with aging. Significant correlation was found between age and ACD (r = -0.39, p<0.001), age and AL (r = -0.15, p<0.001), and AL and flat (r = -0.54, p<0.001) and steep keratometric readings (r = -0.49, p<0.001). Conclusions: In order to obtain adequate refraction results, at the time of cataract surgery distinct attention should be drawn to ophthalmologic biometric parameters, which are continuously changing even in adulthood, and to astigmatism above 1.0 D, present in >32% of the population.
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Purpose: Consistent astigmatism correction with implantation of a toric intraocular lens (IOL) requires accurate preoperative keratometry. This article compares corneal astigmatism determined by an autokeratometer (Topcon KR-7100) and a partial coherence interferometry keratometer (IOLMaster 500) and considers if any discrepancy ultimately alters in final cylindrical power of the toric IOL for implantation. Methods: Keratometry of 235 eyes was performed using both instruments. Corneal astigmatism was transformed into vector components J0 and J45 and cylindrical power at the IOL plane calculated. Comparisons were made using paired t test and correlation and Bland-Altman analyses. Results: Although interinstrument differences for J0 (p = 0.013), J45 (p = 0.012), and toric IOL cylindrical power (p < 0.001) were statistically significant, a high correlation for these (R = 0.96, 0.90, and 0.90, respectively) was observed. IOLMaster tended to overestimate corneal astigmatism by 0.13 (±0.31) diopters and toric IOL cylinder by 0.11 (±0.18) diopters. Difference in calculated toric IOL cylindrical power correlated poorly with corneal curvature (R = 0.007) and astigmatism (R = -0.004). Conclusions: The two keratometers were generally concordant in measuring corneal astigmatism. However, the resultant choice of toric IOL cylinder power differed appreciably in 40% of eyes examined. Therefore, postoperative visual outcome with toric IOL implantation may be optimized by a thorough analysis of biometry data before IOL selection, paying special attention to any difference in corneal astigmatism as measured by more than one instrument.
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Background: The latest WHO report indicates that refractive errors are the leading cause of visual impairment throughout the world. The aim of this study was to determine the prevalence of myopia, hyperopia, and astigmatism in 7 yr old children in Iran. Methods: In a cross-sectional study in 2013 with multistage cluster sampling, first graders were randomly selected from 8 cities in Iran. All children were tested by an optometrist for uncorrected and corrected vision, and non-cycloplegic and cycloplegic refraction. Refractive errors in this study were determined based on spherical equivalent (SE) cyloplegic refraction. Results: From 4614 selected children, 89.0% participated in the study, and 4072 were eligible. The prevalence rates of myopia, hyperopia and astigmatism were 3.04% (95% CI: 2.30-3.78), 6.20% (95% CI: 5.27-7.14), and 17.43% (95% CI: 15.39-19.46), respectively. Prevalence of myopia (P=0.925) and astigmatism (P=0.056) were not statistically significantly different between the two genders, but the odds of hyperopia were 1.11 (95% CI: 1.01-2.05) times higher in girls (P=0.011). The prevalence of with-the-rule astigmatism was 12.59%, against-the-rule was 2.07%, and oblique 2.65%. Overall, 22.8% (95% CI: 19.7-24.9) of the schoolchildren in this study had at least one type of refractive error. Conclusion: One out of every 5 schoolchildren had some refractive error. Conducting multicenter studies throughout the Middle East can be very helpful in understanding the current distribution patterns and etiology of refractive errors compared to the previous decade.
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Aim: To report the prevalence, risk factors and associated population attributable risk percentage (PAR) for refractive errors in the South Indian adult population. Methods: A population-based cross-sectional epidemiologic study was conducted in the Indian state of Andhra Pradesh. A multistage cluster, systematic, stratifi ed random sampling method was used to obtain participants (n = 10293) for this study. Results: The age-gender-area-adjusted prevalence rates in those � 40 years of age were determined for myopia (spherical equivalent [SE] � −0.5 D) 34.6% (95% confi dence interval [CI]: 33.1–36.1), high-myopia (SE � −5.0 D) 4.5% (95% CI: 3.8–5.2), hyperopia (SE � +0.5 D) 18.4% (95% CI: 17.1–19.7), astigmatism (cylinder � −0.5 D) 37.6% (95% CI: 36–39.2), and anisometropia (SE difference between right and left eyes � 0.5 D) 13.0% (95% CI: 11.9–14.1). The prevalence of myopia, astigmatism, high-myopia, and anisometropia signifi cantly increased with increasing age (all p � 0.0001). There was no gender difference in prevalence rates in any type of refractive error, though women had a signifi cantly higher rate of hyperopia than men (p � 0.0001). Hyperopia was signifi cantly higher among those with a higher educational level (odds ratio [OR] 2.49; 95% CI: 1.51–3.95) and signifi cantly higher among the hypertensive group (OR 1.24; 95% CI: 1.03–1.49). The severity of lens nuclear opacity was positively associated with myopia and negatively associated with hyperopia. Conclusions: The prevalence of myopia in this adult Indian population is much higher than in similarly aged white populations. These results confi rm the previously reported association between myopia, hyperopia, and nuclear opacity.
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To report the prevalence, risk factors and associated population attributable risk percentage (PAR) for refractive errors in the South Indian adult population. A population-based cross-sectional epidemiologic study was conducted in the Indian state of Andhra Pradesh. A multistage cluster, systematic, stratified random sampling method was used to obtain participants (n = 10293) for this study. The age-gender-area-adjusted prevalence rates in those >/=40 years of age were determined for myopia (spherical equivalent [SE] < -0.5 D) 34.6% (95% confidence interval [CI]: 33.1-36.1), high-myopia (SE < -5.0 D) 4.5% (95% CI: 3.8-5.2), hyperopia (SE > +0.5 D) 18.4% (95% CI: 17.1-19.7), astigmatism (cylinder < -0.5 D) 37.6% (95% CI: 36-39.2), and anisometropia (SE difference between right and left eyes >0.5 D) 13.0% (95% CI: 11.9-14.1). The prevalence of myopia, astigmatism, high-myopia, and anisometropia significantly increased with increasing age (all p < 0.0001). There was no gender difference in prevalence rates in any type of refractive error, though women had a significantly higher rate of hyperopia than men (p < 0.0001). Hyperopia was significantly higher among those with a higher educational level (odds ratio [OR] 2.49; 95% CI: 1.51-3.95) and significantly higher among the hypertensive group (OR 1.24; 95% CI: 1.03-1.49). The severity of lens nuclear opacity was positively associated with myopia and negatively associated with hyperopia. The prevalence of myopia in this adult Indian population is much higher than in similarly aged white populations. These results confirm the previously reported association between myopia, hyperopia, and nuclear opacity.
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To determine the epidemiology of refractive errors in an adult Chinese population in Singapore. A disproportionate, stratified, clustered, random-sampling procedure was used to select names of 2000 Chinese people aged 40 to 79 years from the 1996 Singapore electoral register in the Tanjong Pagar district in Singapore. These people were invited to a centralized clinic for a comprehensive eye examination, including refraction. Refraction was also performed on nonrespondents in their homes. Myopia, high myopia, and hyperopia were defined as a spherical equivalent (SE) in the right eye of less than -0.5 D, less than -5.0 D, and more than +0.5 D, respectively. Astigmatism was defined as less than -0.5 D of cylinder. Anisometropia was defined as a difference in SE of more than 1.0 D between the two eyes. Only phakic eyes were analyzed. From 1717 eligible people, 1232 (71.8%) were examined. Adjusted to the 1997 Singapore population, the overall prevalence of myopia, hyperopia, astigmatism, and anisometropia was 38.7% (95% confidence interval [CI]: 35.5, 42.1), 28.4% (95% CI: 25.3, 31.3), 37.8% (95% CI: 34.6, 41.1), and 15.9% (95% CI: 13.5, 18.4), respectively. The prevalence of high myopia was 9.1% (95% CI: 7.2, 11.2), with women having significantly higher rates than men. The age pattern of myopia was bimodal, with higher prevalence in the 40 to 49 and 70 to 81 age groups and lower prevalence between those age ranges. Prevalence was reversed in hyperopia, with a higher prevalence in subjects aged 50 to 69. There was a monotonic increase in prevalence with age for both astigmatism and anisometropia. Increasing educational levels, higher individual income, professional or office-related occupations, better housing, and greater severity of nuclear opacity were all significantly associated with higher rates of myopia, after adjustment for age and sex. The results indicate that whereas myopia is 1.5 to 2.5 times more prevalent in adult Chinese residing in Singapore than in similarly aged European-derived populations in the United States and Australia, the sociodemographic associations are similar.
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This study examined the prevalence rate of astigmatism and its epidemiological risk factors in Singapore school children. In a study of school children aged 7 to 9 years old in two schools in Singapore in 1999, a detailed questionnaire was administered to parents regarding reading or close-work habits, past history of close-work, family history, and socioeconomic factors. Cycloplegic refraction was performed five times in each eye. Defining astigmatism as worse than or equal to 0.5, 0.75, and 1 D cylinder in the right eye, the prevalence of astigmatism was calculated. The study population consisted of 1028 children. The prevalence rate of astigmatism (worse than or equal to 1 D cylinder) was 19.2% (95% confidence interval, 16.8 to 21.6). This was not different between genders, ethnic groups, or age (p > 0.05). With-the-rule astigmatism was more common than against-the-rule astigmatism. The prevalence of astigmatism and myopia was 9.8% (95% confidence interval, 8.0 to 11.6). A high AC/A ratio was associated (p = 0.003) with astigmatism, even after exclusion of myopic children. On vectorial analysis, J0 and J45 were associated with the number of hours of playing video games, whereas J45 was also associated with computer use. Only J45 was associated to male gender, a high AC/A ratio, and a family history of myopia. The prevalence rate of astigmatism (> or = 1 D) was 19%. Playing video games and computer use may be associated with astigmatism severity, although the presence of astigmatism (> or = 1 D) was not associated with any nearwork factors. A family history of myopia was associated with oblique astigmatism severity. A high AC/A ratio is associated with astigmatism, and this requires further investigation.
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To determine the prevalence rates of myopia, hyperopia, astigmatism, and anisometropia in a prevalence survey of adults in Sumatra, Indonesia. A population-based prevalence survey of 1043 adults 21 or more years of age was conducted in five rural villages and one provincial town of the Riau Province, Sumatra, Indonesia. A one-stage household cluster sampling procedure was used wherein 100 households were selected from each village or town. Refractive error measurements were obtained with one of two handheld autorefractors. Household interviews were conducted to obtain information on relevant lifestyle risk factors. The age-adjusted overall prevalence rates of myopia (SE [spherical equivalent] at least -1.0 D), hyperopia (SE of at least +1.0 D), astigmatism (cylinder of at least -1.0 D), and anisometropia (SE difference of +1.0 D) were 26.1% (95% confidence interval [CI]: 23.4-28.8), 9.2% (95% CI: 7.4-11.0), 18.5% (95% CI: 16.2-20.8), and 15.1% (95% CI: 12.9-17.4), respectively. The age-adjusted overall prevalence rate of high myopia (SE at least -6.0 D) was 0.8% (95% CI: 0.2-1.5). In a multiple logistic regression model, myopia rates varied with age and increased with income. Hyperopia, astigmatism, and anisometropia rates were independently higher in older adults. The prevalence rates of myopia in provincial Sumatra are higher than the rates in white populations, but lower than the rates in other urbanized Asian countries such as Singapore. The prevalence rate of high myopia is lower than in most other populations, and other refractive errors are common.
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To assess the prevalence of refractive error and visual impairment in school-age children in a metropolitan area of southern China. Random selection of geographically defined clusters was used to identify children 5 to 15 years of age in Guangzhou. Children in 22 clusters were enumerated through a door-to-door survey and examined in 71 schools and 19 community facilities from October 2002 to January 2003. The examination included visual acuity measurements, ocular motility evaluation, retinoscopy, and autorefraction under cycloplegia and examination of the external eye, anterior segment, media, and fundus. A total of 5053 children living in 4814 households were enumerated, and 4364 (86.4%) were examined. The prevalence of uncorrected, presenting, and best-corrected visual acuity 20/40 or worse in the better eye was 22.3%, 10.3%, and 0.62%, respectively. Refractive error was the cause in 94.9% of the 2335 eyes with reduced vision, amblyopia in 1.9%, other causes in 0.4%, and unexplained causes in the remaining 2.8%. External and anterior segment abnormalities were seen in 1496 (34.3%) children, mainly minor conjunctival abnormalities. Media and fundus abnormalities were observed in 32 (0.73%) children. Myopia (spherical equivalent of at least -0.50 D in either eye) measured with retinoscopy affected 73.1% of children 15 years of age, 78.4% with autorefraction. The prevalence of myopia was 3.3% in 5-year-olds with retinoscopy and 5.7% with autorefraction. Females had a significantly higher risk of myopia. Hyperopia (+2.00 D or more) measured with retinoscopy was present in 16.7% of 5-year-olds, 17.0% with autorefraction. The prevalence of hyperopia was below 1% in 15-year-olds, with both methods. Astigmatism (cylinder of > or = 0.75 D) was present in 33.6% of children with retinoscopy and in 42.7% with autorefraction. The prevalence of reduced vision because of myopia is high in school-age children living in metropolitan Guangzhou, representing an important public health problem. One third of these children do not have the necessary corrective spectacles. Effective strategies are needed to eliminate this easily treated cause of significant visual impairment.
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To report the prevalence of refractive errors in a rural south Indian population. Four thousand eight hundred subjects (age, >39 years) from rural south India were enumerated for a population-based study. All participants underwent complete ophthalmic evaluation. Subjects who were phakic in the right eye with best corrected visual acuity of 20/40 or better were included for analysis. Association of refractive errors with age, sex, cataract, and diabetes mellitus were analyzed. Of the 3924 responders, 2508 were eligible. The unadjusted prevalence of emmetropia (spherical equivalent [SE], -0.50 to +0.50 diopter sphere [DS]), myopia (SE < -0.50 DS), high myopia (SE < -5.00 DS), and hyperopia (SE > 0.50 DS) were 50.60%, 26.99%, 3.71%, and 18.70% and age and gender adjusted for the rural Tamil Nadu population were 46.77%, 30.97%, 4.32%, and 17.94%, respectively. The prevalence of emmetropia decreased significantly with age (P < 0.0001), and the prevalence of myopia and high myopia increased significantly with age (P < 0.001) and were significantly associated with nuclear sclerosis (P < 0.001). The prevalence of hyperopia increased until 60 years of age and then decreased. Hyperopia was more common among women than men (P < 0.001) and was negatively associated with nuclear sclerosis (P < 0.001) and positively with diabetes mellitus (P = 0.008). Of the participants with astigmatism (cylindrical error greater than 0.50 DC), 9.80% had with-the-rule (WTR) and 77.44% against-the-rule (ATR) astigmatism. The prevalence of WTR and ATR astigmatism significantly decreased (P < 0.001) and increased (P = 0.006) with age, respectively. The pattern of refractive errors in this rural south Indian population is similar to those reported in other tropical regions of the world.
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To determine the prevalence of refractive errors among schoolchildren in urban and rural areas of Dezful County, Iran. In a cross-sectional study, using random cluster sampling, 5721 Dezful schoolchildren were selected from 39 clusters. The participants in the study totalled 5544; 3673 elementary and middle school students and 1871 high school students. For the former group, cycloplegic refraction and for the latter, non-cycloplegic refraction was tested. In all participants, uncorrected visual acuity and best corrected visual acuity were determined, and those with a visual acuity of 20/40 or worse, underwent a complete ophthalmic examination to determine the cause of visual impairment. A spherical equivalent of -0.5 diopter (D) or worse was defined as myopia, +2.0 D or more was defined as hyperopia, and a cylinder refraction greater than 0.75 D was considered astigmatism. The uncorrected visual acuity was 20/40 or worse in the better eye of 224 schoolchildren (3.8% of participants). This figure (percentage) was 14 (0.03%) based on their best corrected visual acuity and 96 (1.7%) with their presenting vision. According to results of cycloplegic refraction, 3.4% (95% confidence interval (CI), 2.5 to 4.4) of the primary and middle school students were myopic and 16.6% (95% CI, 13.6 to 19.7) were hyperopic. For high school students, these rates were 2.1% (95% CI, 0.7 to 3.5) and 33.0% (95% CI, 24.9 to 41.1), respectively, with non-cycloplegic refraction. In the multivariate logistic regression for primary and middle school students, myopia was correlated with age (p = 0.030), and hyperopia was correlated with age (p<0.001) and area of residence (p = 0.007). In high school students, hyperopia again showed a correlation with their area of residence (p = 0.029). The present study reveals the considerable prevalence rates of refractive errors among schoolchildren in Dezful County and the high rate of an unmet need for their correction. Although myopia is not very prevalent, the high rate of hyperopia in the studied population emphasises its need for attention.
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To asses the effect of menopause on the corneal curvature changes using corneal computerized videokeratography (CVK) in premenopausal and postmenopausal healthy women. Thirty-six postmenopausal women with mean ages of 49.2 (range 39 to 57) were enrolled in this randomized, prospective study, comparing with 26 healthy controls with mean ages of 38.5 +/- 4.9 (range 32 to 49). Subjects were determined to be postmenopausal, by the Gynecology and Obstetrics Department, based on blood Follicular Stimulating Hormone (FSH), Luteinizing Hormone (LH), Estradiol, Progesterone levels and clinical complaints. Complete ophthalmic examination and CVK using Haag-Streit System was performed in both premenopausal and postmenopausal women. Mean horizontal curvature and vertical curvature of central corneal power in premenopausal women were 43.5 +/- 1.25 Diopter (D), and 44.1 +/- 1.53 D. Mean horizontal curvature and vertical curvature of central corneal power in postmenopausal women were 43.9 +/- 1.4 D, and 44.6 +/- 1.3 D. The mean keratometric astigmatisms of premenopausal and postmenopausal women were 0.81 +/- 0.57 D (4-179 degrees), 0.74 degrees +/- 0.5 D (1-180 degrees) respectively. No significant corneal curvature changes were detected between premenopausal and postmenopausal groups (P > 0.05). On the other hand, we only found negative but significant correlation between horizontal corneal curvature and estrogen level of postmenopausal women (r = -0.346, p = 0.038). Menopause is physiologic process and may also affect corneal topographic changes. In postmenopausal women, corneal steeping was observed minimally compared to premenopausal women. The results suggest that changes in estrogen level of women with menopause are associated with slightly alteration of horizontal curvature of cornea.
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Purpose: To investigate a possible relationship between the slanting of palpebral fissures and the magnitude and axis of astigmatism in children with astigmatism. Methods: Cross-sectional study at a referral center of 53 children with astigmatism of more than +1.50 D in at least 1 eye. Visual acuity testing, cycloplegic refraction, slit-lamp biornicroscopy, and ophthalmoscopy were done on every patient. Corneal topography was obtained in 40 cooperative patients. External photographs of the midface were taken in 45 children. The degree of slanting of the palpebral fissures was evaluated based on the photographs. The statistical analysis tool used was repeated measures analysis of variance. Patients in whom photographic analysis was not available were excluded from the part of the statistical analysis dealing with eyelid slant. Results: Palpebral fissure slant (P = .013) and gender (P = .0005) were highly correlated with the obliquity of cylinder axis. There was a possible correlation between gender and eyelid slant (P = .0594), with females having slightly larger degrees of upward palpebral fissure slanting and male more downward slanting of their fissures compared to published angles in an age-matched population. We found a statistically significant correlation between the degree of total astigmatism and a larger abnormal slant (P = .0192) and between the axis and magnitude of corneal astigmatism and abnormal slant (P = .0092). Higher degrees of eyelid slant (> 8degrees or < -4degrees) increased the risk of high cylinder magnitude (> 3.00 D) by an odds ratio of 4.17 (95% CI: 1.03, 19.95). Conclusions: Children with astigmatism with large degrees of slanting of their palpebral fissures are at higher risk for high astigmatism (> 3.00 D). The axis of the astigmatism is highly correlated with the slanting of the palpebral fissure.
Article
The palpebral fissure length was measured in 60 normal Chinese term infants in the first 48 hours of life. The measurement of the palpebral fissure length was performed with a vernier caliper by placing it across the greatest horizontal axis of the eye from the medial to the lateral canthus. The head circumference was measured by placing a tape anteriorly just above the eyebrows and posteriorly at the maximum point of the occiput. There was no difference according to sex or between the measurements in the right and the left eye. The palpebral fissure length was 1.94 ± 0.17 cm (mean ± standard deviation (SD)) and the head circumference was 34.0 ± 1.3 cm (mean ± SD). These data suggest that Chinese neonates have a shorter palpebral fissure length than do black American neonates and a longer palpebral fissure length than do white American and Turkish neonates.
Article
Few epidemiologic data are available on refractive status in elderly Asians. The purpose of the study was to determine prevalence and risk factors associated with refractive errors in a metropolitan elderly Chinese population in Taiwan. A population-based survey was conducted in the Shihpai district of Taipei, Taiwan. A total of 2045 residents aged 65 years or more were randomly selected and invited to complete a comprehensive questionnaire and undertake a detailed ocular examination, including best corrected visual acuity and measurements of refractive error, using autorefraction. Of the subjects, 1361 (66.6%) participated in the ocular examination. Spherical equivalent (SE) was calculated in diopters (D), and data from right eyes were reported. The age- and sex-adjusted prevalence rates were determined for myopia (SE<-0.5 D, 19.4%; SE<-1.0 D, 14.5%), high myopia (SE<-6.0 D, 2.4%), hyperopia (SE>+0.5 D, 59.0%; SE>+1.0 D, 44.2%), astigmatism (cylinder<-0.5 D, 74.0%; cylinder<-1.0 D, 45.3%), and anisometropia (SE difference between right and left eyes>0.5 D, 45.2%; SE difference>1.0 D, 21.8%). The prevalence of myopia, astigmatism, and anisometropia significantly increased with age (all P<0.01). The prevalence of hyperopia tended to decrease with age. There was no gender difference in prevalence rates in any type of refractive error, except that women had a higher rate of hyperopia (SE>+1.0 D) than men (P=0.004). Multivariate regression analysis showed that myopia was weakly associated with higher educational level. The severity of lens nuclear opacity was positively associated with the rates of myopia and negatively associated with the rates of hyperopia. The prevalence of myopia in this elderly Chinese population is not much higher than in similarly aged elderly white populations, compared with a much greater difference in prevalence among younger Chinese versus white people. This suggests that changing environmental factors may account for the increased prevalence of myopia in younger cohorts of Chinese.
Article
To determine the prevalence of refractive errors in Shiraz schoolchildren by age and gender. For this cross-sectional study, random cluster sampling was carried out from students of the 2008-2009 academic year. After the initial interview, ophthalmic examinations including tests of visual acuity, non-cycloplegic and cycloplegic refraction and binocular vision were performed. Myopia was defined as a spherical equivalent < or =-0.50 dioptre (D), hyperopia as > or =+2.0 D, and astigmatism as a cylinder refraction > or =0.75 D. All values for school grade and gender were directly standardized based on the total student population in the 2008-2009 school year. A total of 2130 students were sampled, of which 1872 participated in the study (response rate = 87.88%). The prevalence of uncorrected, best-corrected, presenting and spectacle corrected visual acuity of 6/12 or worse in the better eye was 6.46%, 0%, 1.49% and 0.9%, respectively. The prevalence rates of myopia, hyperopia and astigmatism were 4.35% (95% confidence interval [CI]: 2.89-5.82%), 5.04% (95% CI: 3.50-6.58%), and 11.27% (95% CI: 9.81-12.74%), respectively. Anisometropia was detected in 2.58% of schoolchildren. The prevalence of hyperopia significantly decreased with age (P = 0.021). Compared with other reported rates, the prevalence of myopia in the schoolchildren of Shiraz is similar to that in most places excluding East Asian countries, and that of hyperopia is in the mid range.
Article
To evaluate the refractive error and its associations in the adult population of rural Central India. Population-based study. The Central India Eye and Medical Study is a population-based study performed in a markedly rural region in Central India. It included 4711 subjects (aged 30 years or older) of 5885 eligible subjects (response rate, 80.1%). The participants underwent a detailed ophthalmic and medical examination, including standardized questions on the socioeconomic background, lifestyle, and social relations. This study was focused on the refractive error, the prevalence of hyperopia and myopia, and its factors. Refractive error. After exclusion of pseudophakic or aphakic eyes, 9076 (96.3%) eyes of 4619 (98.0%) subjects (2472 females) were included into the study. The mean refractive error was -0.20+/-1.51 diopters (D). Myopia of more than -0.50 D, -1.0 D, more than -6.0 D, and more than -8 D occurred in 17.0+/-0.6%, 13.0+/-0.5%, 0.9+/-1.4%, and 0.4+/-0.1% of the subjects, respectively. Hyperopia of more than 0.50 D was detected in 18.0+/-0.6% of the subjects. Refractive error was associated significantly (i.e., became more hyperopic) with lower age (P<0.001), lower best-corrected visual acuity (P<0.001), lower corneal refractive power (P<0.001), and shorter axial length (P<0.001). In multivariate analysis, refractive error was not significantly associated with the level of education (P = 0.56). High myopia (>-8 D) was associated significantly with male gender (P = 0.03) and lower best-corrected visual acuity (P<0.001). Mean anisometropia was 0.41+/-1.02 D. It was associated significantly with age (P<0.001), myopic refractive error (P<0.001), and lower best-corrected visual acuity (P<0.001). The mean astigmatic error was 0.29+/-0.60 D and was associated significantly with higher age (P<0.001), level of education (P = 0.01), lower best-corrected visual acuity (P<0.001), and higher corneal refractive power (P<0.001). The rural population of Central India has not experienced a myopic shift as described for many urban populations at the Pacific Rim. Correspondingly, the relatively low level of education was not associated with myopia. Urbanization may be a major factor for myopization. Proprietary or commercial disclosure may be found after the references.
Article
To evaluate parameters associated with astigmatism axis orientation. A retrospective population-based study was conducted on 67,899 (53% males) Israeli Defense Force conscripts aged 16 to 22 years with >or=0.25 D of astigmatism, using prerecruitment examination and demographic data that included a validated general intelligence score. Refractive errors were classified by the cylinder axis with the least deviation from emmetropia (LDE), a scheme intended to avoid confounding spherical classification by cylinder power. Perinatal photoperiod was determined from birth date and astronomical tables. With-the-rule (WTR) axis was associated with higher LDE (P < 0.001), higher cylinder power (P < 0.001), Eastern or Western compared with Israeli origin (P < 0.001), higher body mass index (P < 0.001), lower intelligence scores (P < 0.001), and longer perinatal photoperiod (P < 0.001), using univariate analysis. Multivariate logistic regression confirmed the independent association of these parameters and identified being of the female sex as another WTR axis association. Subjects' cylinder axis also was associated with their siblings' cylinder axis (odds ratio [OR] = 1.58; 95% confidence interval [CI] = 1.31-1.90), using siblings' refractive data for the 3852 available subjects in the regression model. However, the associations of these parameters with WTR, against-the-rule, or oblique astigmatism were neither parallel as a whole nor parallel between any two sets of axis orientations. Further, the directions of the associations of these parameters with astigmatism axis and power did not consistently conform to their previously reported associations for spherical ametropias. The results suggest both that distinctive mechanisms may account for the different astigmatism axis orientations and that mechanisms influencing astigmatism development are likely to vary from those governing the spherical component of refraction.
Article
To describe the prevalence of and risk factors for myopia and other refractive errors in a rural, adult, Chinese population. Population-based, cross-sectional study. A clustered, random sampling procedure was used to select 7557 Chinese people aged >or=30 years from Handan, China. All eligible subjects were invited to undergo a comprehensive eye examination, including standardized refraction. Myopia, high myopia, and hyperopia were defined as a spherical equivalent (SE) in the right eye of more than -0.5 diopter (D), less than -5.0 D, and 0.5 D or more, respectively. Astigmatism was less than -0.5 D of cylinder. Anisometropia was defined as a difference in SE of >1.0 D between the 2 eyes. Only phakic eyes were analyzed. Myopia and other refractive errors. We included 6491 (85.9% participation rate) eligible subjects in this study. Adjusted to the 2000 China population census, the prevalence rate of myopia was 26.7% (95% confidence interval [CI], 25.6-27.8), hyperopia 15.9 % (95% CI, 15.0-16.8), astigmatism 24.5% (95% CI, 23.5-25.5), and anisometropia 7.7% (95% CI, 7.0-8.4). The prevalence of high myopia was 1.8% (95% CI, 1.5-2.1). Using a multivariate regression model, current smoking (odds ratio [OR], 0.7, 95% CI, 0.5-0.9), hours of reading (OR, 1.2; 95% CI, 1.1-1.4), diabetes (OR, 8.4; 95% CI, 2.2-32.5), and number of family members with myopia (OR, 1.3; 95% CI, 1.1-1.7, for each family member) were associated with myopia in younger persons (30-49 years). High school or higher education (OR, 1.8; 95% CI, 1.1-3.1), diabetes (OR, 1.6; 95% CI, 1.2-2.7), nuclear opacity (OR, 1.7; 95% CI, 1.2-2.3), and number of family members with myopia (OR, 1.5; 95% CI, 1.2-1.9) were risk factors in persons >or=50 years of age. Myopia affects more than one quarter of rural Chinese persons >or=30 years of age. Myopia is more common in younger people and is associated with different risk factors than in older people.
Article
To determine the prevalence rates of refractive errors in elderly people in Mashhad, Iran. In a cross-sectional study with a cluster sampling method, the sample population was selected proportionate to the total population of Mashhad. The selected citizens were then invited for eye examinations at the clinic. After an interview, refractive data were collected using objective and subjective refractions. Refractive error data were converted into spherical equivalent (SE), and myopia was defined as an SE worse than -0.50 diopters (D) and hyperopia worse than +0.50 D. Of the 1540 selected samples, 93.5% participated in the study. Data were analyzed for 1367 adults without previous cataract surgery who had right eye refraction data; 35.4% were women, and 64.6% were men. The mean age was 63.7 +/- 7.1 years. The prevalence of myopia was 27.2% (95% confidence interval (CI) 24.8-29.5); 29.6% in men and 22.5% in women (P < 0.001). The rate of myopia showed an increase with age (P < 0.001). The prevalence of hyperopia was 51.6% (95% CI, 48.9% to 54.3%); 57.6% in women and 48.3% in men (P < 0.001). The rate of hyperopia showed a significant decrease with age. The prevalence of astigmatism in the studied sample was 37.5% (95% CI, 34.9% to 40.0%). Refractive errors are a major issue among the elderly and their prevalence rates vary greatly depending on age and gender. The present study was able to examine this public health issue among the elderly in Mashhad.
Article
The palpebral fissure length was measured in 60 normal Chinese term infants in the first 48 hours of life. The measurement of the palpebral fissure length was performed with a vernier caliper by placing it across the greatest horizontal axis of the eye from the medial to the lateral canthus. The head circumference was measured by placing a tape anteriorly just above the eyebrows and posteriorly at the maximum point of the occiput. There was no difference according to sex or between the measurements in the right and the left eye. The palpebral fissure length was 1.94 +/- 0.17 cm (mean +/- standard deviation (SD)) and the head circumference was 34.0 +/- 1.3 cm (mean +/- SD). These data suggest that Chinese neonates have a shorter palpebral fissure length than do black American neonates and a longer palpebral fissure length than do white American and Turkish neonates.
The influence of 3 different lid positions on the astigmatism of 50 young healthy eyes was investigated with an autorefractor. The results showed that a significant amount of astigmatism may be induced when the palpebral aperture is voluntarily narrowed.
Cross-sectional studies indicate that mean total astigmatism changes with age; varying from as much as 0.62 D with-the-rule during youth to as much as 0.37 D against-the-rule in samples of elderly patients. The present study involves the examination of adult patients who were seen regularly for a period of at least 40 years. Data are analyzed to determine whether the change in corneal astigmatism accounts for the total astigmatic change, and the magnitude of change with age at each of the principal corneal meridians. Results indicate that steepening of the cornea in the horizontal meridian accounts for a major portion of the increase in against-the-rule total astigmatism among older patients.
Article
To determine prevalence and associations with refractive errors in a defined older population. Cross-sectional study. A total of 3654 residents, aged 49-97, of the Blue Mountains, west of Sydney, Australia. Comprehensive questionnaire and detailed eye examination, including refraction. Refractive error of phakic eyes, age, gender, and education. Prevalence rates were determined for myopia (15%), hyperopia (57%), and emmetropia (28%). Hyperopia prevalence was age-related, increasing from 36% in persons aged <60 years to 71 % of persons aged > or = 80 (P < 0.0001), whereas myopia prevalence decreased with age, from 21 % in persons aged <60 years to 10% of persons aged > or = 80 years (P < 0.0001). Younger myopic subjects in this population reported first wearing distance correction at a significantly younger age than older subjects, P < 0.0001. After adjustment for age, women were slightly more hyperopic (mean +0.75 diopters [D]) than men (mean +0.59 D, P = 0.0012. The gender-adjusted mean spherical error increased with age from +0.03 D in persons aged <60 years to +1.2 D in persons aged > or = 80 years (P < 0.0001). The gender-adjusted mean cylinder power also increased with age, from -0.6 D in persons aged <60 years to -1.2 D in persons aged > or = 80 years (P < 0.0001). The mean axis of astigmatism was "against the rule" in all age groups. Anisometropia increased with age, from a mean of 0.4 D in persons aged <60 to 0.9 D in persons aged > or = 80 years (P < 0.0001). Higher education was associated with myopia in men (P = 0.009) but not in women (P = 0.21) after adjustment for age. This report has documented the detailed refractive status of an older population, confirming previously described trends but also finding an apparent higher prevalence of myopia among younger members of this community.
Article
To examine changes in spherical equivalent over a 5-year period in persons 43 to 84 years of age. All people 43 to 84 years of age and living in Beaver Dam, Wisconsin, in 1988 were invited for a baseline examination (1988-1990) and a 5-year follow-up examination (1993-1995). Refractions were determined according to the same protocol at both examinations. Aphakic and pseudophakic eyes were excluded as well as eyes with best corrected Snellen visual acuity of 20/40 and worse. After exclusions, refraction was obtained on 3007 right eyes and 3012 left eyes of the 3684 people participating in both examinations. Right and left eyes behaved similarly. Spherical equivalent became more positive in the youngest subjects and more negative in older subjects. After adjusting for other factors, the 5-year change in spherical equivalent of those 45, 55, 65, and 75 years of age was +0.15, +0.18, +0.10, and -0.07D, respectively. Severity of nuclear sclerosis was related to the amount of change. Those with mild nuclear sclerosis at baseline had a change of +0.2 D, whereas those with severe nuclear sclerosis had a change of -0.5 D. The amount of change was also related to gender, diabetes, and age at onset of myopia. It was unrelated to education and baseline spherical equivalent. Changes in spherical equivalent over a 5-year period were small. Before the age of 70, people became more hyperopic. After the age of 70, people became more myopic. Much of the myopic change may be related to increasing nuclear sclerosis.
Article
To evaluate the prevalence of astigmatism in infancy and childhood in a Spanish population. A total of 478 children with astigmatism from Valencia Province, Spain were examined. The patients, ranging in age from 2-12 years, were classified into groups according to age. Astigmatism error and axis orientation were determined using noncyclopegic retinoscopy over each eye. The overall prevalence of astigmatism (> or = 1.00 diopter of cylinder) decreased in relation to increasing age from 44.3% to 5.2%. The prevalence of against-the-rule astigmatism decreased from 61.5% (at 2 years) to 33.4% (at 12 years), with-the-rule astigmatism increased in prevalence from 23.1% (at 2 years) to 66.6% (at 12 years), and oblique astigmatism decreased with age from 15.4% (at 2 years) and 0% (at 12 years). These results do not vary from those observed in other populations. Factors such as race, nutrition, and environmental condition did not vary from the literature regarding the prevalence of astigmatism in infants and children.
Article
To describe the 5-year change in visual acuity and the incidence of visual impairment in a population-based cohort. Population-based epidemiologic study. Of the 3654 participants of the Blue Mountains Eye Study (BMES I) baseline examination (aged 49 years+ during 1992-1994), 2335 were reexamined during the 5-year follow-up examinations from 1997 to 1999 (BMES II), and 543 persons had died since BMES I. Visual acuity was measured using a logarithm of the minimum angle of resolution chart in both eyes separately before and after standardized refraction. Pupils were dilated and a detailed examination was performed. Visual impairment, after best refractive correction, was defined as any (visual acuity </=20/40; </=41 letters) and severe (visual acuity </=20/200; 0-5 letters) in keeping with the Beaver Dam Eye Study. Incident binocular visual impairment was defined as visual acuity </=20/40 in both eyes at follow-up, where visual acuity was >20/40 in both eyes at baseline. Incident binocular severe visual impairment was defined as visual acuity </=20/200 in both eyes at follow-up, where visual acuity was >20/200 in both eyes at baseline. The incidence for three other levels of visual impairment is also given: <20/40, <20/70, and <20/200. Monocular visual impairment was defined as impairment in one eye only at follow-up, where both eyes were unimpaired at baseline. Incident doubling and halving of the visual angle were calculated. Incidence rates for visual impairment increased significantly with age. Any incident impairment </=20/40 occurred binocularly in 41 persons (1.9%) and monocularly in 150 persons (7.1%). Severe incident impairment </=20/200 occurred binocularly in 3 persons (0.1%) and monocularly in 44 persons (2.1%). Incident impairment <20/40 occurred binocularly in 37 persons (1.7%) and monocularly in 134 persons (6.3%). Impairment <20/70 occurred binocularly in 15 persons (0.7%) and monocularly in 84 persons (3.8%). Impairment <20/200 occurred binocularly in 3 persons (0.1%) and monocularly in 44 persons (1.9%). Women consistently had a higher incidence of visual impairment than men, although this was often not statistically significant after adjusting for age. Increasing age was a strong predictor of visual impairment. This study has documented the 5-year incidence and causes of visual impairment in an older Australian population.
Article
To investigate a possible relationship between the slanting of palpebral fissures and the magnitude and axis of astigmatism in children with astigmatism. Cross-sectional study at a referral center of 53 children with astigmatism of more than +1.50 D in at least 1 eye. Visual acuity testing, cycloplegic refraction, slit-lamp biomicroscopy, and ophthalmoscopy were done on every patient. Corneal topography was obtained in 40 cooperative patients. External photographs of the midface were taken in 45 children. The degree of slanting of the palpebral fissures was evaluated based on the photographs. The statistical analysis tool used was repeated measures analysis of variance. Patients in whom photographic analysis was not available were excluded from the part of the statistical analysis dealing with eyelid slant. Palpebral fissure slant (P =.013) and gender (P =.0005) were highly correlated with the obliquity of cylinder axis. There was a possible correlation between gender and eyelid slant (P =.0594), with females having slightly larger degrees of upward palpebral fissure slanting and male more downward slanting of their fissures compared to published angles in an age-matched population. We found a statistically significant correlation between the degree of total astigmatism and a larger abnormal slant (P =.0192) and between the axis and magnitude of corneal astigmatism and abnormal slant (P =.0092). Higher degrees of eyelid slant (> 8 degrees or < -4 degrees ) increased the risk of high cylinder magnitude (> 3.00 D) by an odds ratio of 4.17 (95% CI: 1.03, 19.95). Children with astigmatism with large degrees of slanting of their palpebral fissures are at higher risk for high astigmatism (> 3.00 D). The axis of the astigmatism is highly correlated with the slanting of the palpebral fissure.
Article
To investigate whether there are significant changes in corneal topography during accommodation in normal corneas and corneas that are pathologically thinner due to keratoconus. A videokeratoscope was modified to present an accommodation stimulus that was coaxial with the instrument's measurement axis. Six subjects with normal corneas and four subjects with keratoconus were studied. Eighteen videokeratoscope measurements of one eye of each subject were taken at 0 diopter (D) accommodation demand and six for both of 4 D and 9 D accommodation demand. The effects of ocular micromovements on multiple topography maps were minimized using software algorithms. Average maps for the 4 D and 9 D accommodation demands were calculated and subtracted from the average map of the 0-D accommodation demand. A t test was applied at each point location within the topography maps to analyze the statistical significance of change (p < 0.001) within the difference maps. In the initial analysis, we found that a number of the subjects showed significant changes in corneal topography as accommodation changed. However, further analysis showed a significant group mean excyclotorsion of the topography maps of 1.6 +/- 1.1 degrees (p < 0.03) for the 4-D stimulus and 2.0 +/- 1.3 degrees (p < 0.01) for the 9-D stimulus compared with the 0-D stimulus. When we accounted for the excyclotorsion, we did not find clear evidence of statistically significant changes in corneal topography as a result of accommodation, either for the normal corneas or the keratoconic corneas. It appears unlikely that changes occur in central corneal shape during accommodation up to a level of 9 D in normal or keratoconic corneas. A small ocular excyclotorsion typically accompanies accommodation, and this changes the relative orientation of the topography of the cornea. This has significant implications for the interpretation of the optical characteristics of eyes during near viewing conditions.
Article
To understand the prevalence and distribution of astigmatism in schoolchildren in Taiwan, we analyzed and compared the nationwide survey data in 1995 and 2000. A total of 11,175 students were enrolled in 1995, and 10,878 students were enrolled in 2000. The refractive status of each student was measured with an autorefractor during cycloplegia and rechecked with retinoscopy. About half of schoolchildren (57.5% in 1995 and 49.0% in 2000) had no astigmatism (<0.5 D). About one third of schoolchildren's astigmatism was <1 D (27.9% vs. 32.6%). Eleven percent of schoolchildren in 1995 and 13% in 2000 had astigmatism between 1.0 and 2.0 D. Less than 2% of students had astigmatism >3.0 D (1.3% in 1995 and 1.8% in 2000). Most astigmatism was with-the-rule: 83.3% in 1995 and 89.9% in 2000. Only 16.6% of children in 1995 and 9.7% in 2000 had against-the-rule astigmatism. Very little astigmatism was oblique (0.1% in 1995 and 0.4% in 2000). The rate of myopic astigmatism increased with age. In contrast, the rate of hyperopic and mixed astigmatism decreased with age. In addition, the rate of with-the-rule astigmatism increased and the rate of against-the-rule decreased with respect to age, but oblique astigmatism was rather stable with age. Most schoolchildren had little or no astigmatism. In Taiwan, most astigmatism is <1 D and is myopic with-the-rule astigmatism. There was more myopic astigmatism and with-the-rule astigmatism in 2000 than in 1995.
Article
To determine the prevalence of refractive errors and to investigate factors associated with refractive error in adults 30 years of age and older in Bangladesh. Cross-sectional study. A nationally representative sample of 12 782 adults 30 years of age and older. The sample of subjects was selected based on multistage, cluster random sampling with probability-proportional-to-size procedures. The examination protocol consisted of an interview that included measures of literacy, education, occupation, and refractive correction. Visual acuity testing (logarithm of the minimum angle of resolution [logMAR]), automated refraction, and optic disc examination were performed for all subjects. Subjects with <6/12 (0.3 logMAR) acuity in either eye were graded additionally for cataract and underwent a dilated fundal examination. Subjects for whom no refractive error was recorded (312 subjects; 2.7%) or who had undergone cataract surgery (123 subjects; 1.1%) were excluded from the analysis. Refractive error and socioeconomic variables (literacy, education, occupation). Eleven thousand six hundred twenty-four subjects were examined (90.9% response rate; mean age+/-standard deviation, 44+/-12.6 years). Five thousand four hundred eighty-nine subjects (49.1%) were men and 5700 subjects (50.9%) were women. Mean spherical equivalent was -0.19 diopters (D; +/-1.50 D). Six thousand four hundred twelve subjects (57.3%) were emmetropic, 2469 (22.1%) were myopic (<-0.5 D), and 2308 (20.6%) were hypermetropic (>+0.5 D). Two hundred six subjects (1.8%) were highly myopic (<-5 D). Myopia was more common in men (26.3%) than in women (21.0%), whereas hyperopia was more common in women (27.4%) than in men (15.8%). Overall, myopia increased with age (17.5% of those aged 30-39 years were myopic, compared with 65.5% of those age 70 years and older). A subanalysis of subjects without cataract showed increasing hyperopia with age and an association between myopia and higher education. Myopia was more common among the employed than in unemployed subjects. Astigmatism (>0.5 D), present in 3625 subjects (32.4%), was more common among women, illiterate subjects, and unschooled subjects. Against-the-rule astigmatism was more common (58.7%) than oblique astigmatism (29.3%), which was more common than with-the-rule (WTR) astigmatism (12.1%). Against-the-rule astigmatism and oblique astigmatism increased with age, unlike WTR astigmatism. Of 830 (7.5%) subjects, women were more commonly anisometropic (>1.0 D). Anisometropia increased with age. Refractive error data are described for a country and region that previously have lacked population-based data. Prevalence and factors associated with refractive error are presented, with a detailed comparison with other population-based surveys regionally and internationally.
Article
The aim of this study was to compare age-related differences in the corneal topography of a normal population using a computerized corneal topography system. The randomized comparative study included 240 eyes of 120 subjects with normal corneas. Subjects were divided into six age groups: 5 to 10 years (group 1), 11 to 20 years (group 2), 21 to 30 years (group 3), 31 to 40 years (group 4), 41 to 50 years (group 5), and 51 years or older (group 6). Average corneal power and corneal astigmatism were examined. An average corneal topography map was constructed and the astigmatism pattern was determined in each age group. Average corneal power values were 41.64 +/- 0.85 diopters (D), 42.35 +/- 0.90 D, 42.63 +/- 0.99 D, 42.94 +/- 0.93 D, 43.38 +/- 0.77 D, and 43.53 +/- 0.88 D in groups 1 to 6, respectively (P < .001). Mean astigmatism values were similar in all age groups (P = .225). Younger subjects had with-the-rule astigmatism, but older subjects showed a shift to oblique or against-the-rule astigmatism. The averaged maps of groups 1 to 3 showed a vertical bow-tie pattern, but the central steep area gradually extended horizontally and it became a round configuration in groups 4 to 6. This study suggests that the normal cornea becomes steeper in the horizontal line and superior vertical quadrant and shifts from with-therule to against-the-rule astigmatism, but the amount of physiological corneal astigmatism does not change with age.
Article
To study refractive changes over the course of 5 years in citizens of Reykjavik 50 years and older at baseline. The cohort was a population-based random sample of citizens 50 years and older. Eight hundred forty-six of the 958 survivors (88.2%) underwent a 5-year follow-up examination. Refraction and keratometry were performed using a Nidek (Gamagori, Japan) ARK 900 autorefractor keratometer. Typing and grading of lens opacification was carried out using Scheimpflug slit-lamp and retroilluminated images (Nidek EAS 1000), and axial length was measured by Nidek Echoscan 800. Seven hundred fifty-seven right eyes were available for refraction analysis. In the 50- to 59-year age group and the 60- to 69-year age group at baseline, there was a hyperopic shift of 0.41 diopters (D) and 0.34 D, respectively, during the 5 years. There was a 0.02-D myopic shift for those 70 years of age and older at baseline during the same period. Considering all right eyes, there was a hyperopic shift of +0.29 D over the 5 years, whereas eyes with nuclear lens opacification grade II or more at baseline had a mean myopic shift of -0.65 D. There was a mean change of 0.13 D in the astigmatism against the rule during the 5 years. The data on axial length are available from the follow-up study only. The mean axial length for those 50 to 59 years of age at baseline was 23.56 mm (standard deviation [SD], 1.08 mm), as compared with 23.23 mm (SD, 1.27 mm) for those 70 years of age and older at baseline (P<0.04). We found a hyperopic shift for those younger than 70 years of age at baseline, although eyes with nuclear opacification grade of II or more at baseline were associated with a myopic shift. There was also an age-related shift against the rule for the axis of astigmatism during the 5-year period. Our results may be useful for predicting long-term outcome of refractive surgery.
Article
To study the effect of aging on astigmatism in adult Japanese. Measurements of refractive errors and keratometry were performed on 2161 randomly selected subjects (aged 40-79 years). The relation between age and the net value in diopters (D) of astigmatism was evaluated with a trend test. The relation between age and the polar value was also examined by linear regression analysis. The mean (+/-SD) value of total and corneal astigmatism was -0.97 +/- 0.72 D and -0.86 +/- 0.63 D, respectively, and the net value of both increased with age (P trend < 0.001). The prevalence of either type of astigmatism also increased with age, according to the Cochran-Mantel-Haenzel test (P < 0.0001 for total and P < 0.01 for corneal astigmatism). The prevalence of against-the-rule astigmatism increased with age for either type of astigmatism (P < 0.0001 for total, P < 0.0001 for corneal). According to the analysis of polar values by age, the regression coefficient (+/-SE) for total and corneal astigmatism was -0.024 +/- 0.002 (P < 0.0001) and -0.028 +/- 0.002 (P < 0.0001), respectively. There was no statistical difference between these two regression coefficients. The prevalence of astigmatism increases and the axis turns to against-the-rule with age. The result of the linear regression analysis indicates that the age-related change in astigmatism is mainly associated with changes in the cornea.
Article
To measure the changes of corneal curvature during contraction of the ciliary muscle. Department of Ophthalmology, St. Luke's International Hospital, Tokyo, Japan. Twenty-eight eyes of 14 healthy volunteers under 40 years old were enrolled in this prospective randomized controlled study and divided into pilocarpine and control groups. Intraocular pressure (IOP), pupil diameter, and corneal topography were measured before and 40 minutes after instillation of topical pilocarpine 4% or balanced salt solution. Corneal topography was analyzed for the mean ring-power of Placido rings 1 through 25, average corneal power (ACP), and for spherical equivalent, regular astigmatism, asymmetry, and high-order irregularity by Fourier analysis. Pilocarpine had no effect on IOP, but it did cause a significant decrease in mean pupil diameter. Simultaneously, pilocarpine increased the mean ring powers for Placido rings 1 through 4 and the ACP (+0.13 diopters (D) +/- 0.17 [SD]; P=.017). By Fourier analysis, the mean spherical component for the central 3.0 mm of the cornea increased in the pilocarpine group (+0.08 +/- 0.15 D; P=.020). There were no changes in components of regular astigmatism, asymmetry, and high-order irregularity. The central cornea steepened in curvature and increased in power owing to contraction of the ciliary muscle. The results suggest that changes in corneal curvature increase refractive power during accommodation.
Article
To evaluate refractive error and its demographic associations in an urban and rural population in northern China. Epidemiological study. The Beijing Eye Study is a population-based cohort study in northern China including 4439 subjects. Excluding pseudophakic and aphakic patients, the present study involved 4319 subjects. It was divided into a rural part (1905 [44.1%] subjects) and an urban part (2414 [55.9%] subjects). Mean age was 55.85+/-10.33 years (range, 40-90). Standardized ophthalmologic examination. For statistical analysis, the spherical equivalent was converted to binary variables, and logistic regression was used to investigate the association with continuous or categorical independent variables. Refractive error. Mean refractive error measured -0.33+/-2.22 diopters (D) (range, -20.88 to +7.88). Myopia of >-0.50 D, -1.0 D, >-6.0 D, and >-8 D, respectively, occurred in 22.9% (95% confidence interval [CI], 21.7-24.2), 16.9% (95% CI, 15.8-18.0), 2.6% (95% CI, 2.2-3.1), and 1.5% (95% CI, 1.1-1.9) of the subjects, respectively. Myopic refractive error was associated significantly with younger age (P<0.001), urban region (vs. rural region) (P<0.001), higher educational background (P<0.001), higher degree of nuclear cataract (P<0.001), decreasing uncorrected visual acuity (UCVA) (P<0.001), decreasing best-corrected visual acuity (BCVA) (P<0.001), and female gender (P<0.001). Prevalence of high myopia (myopic refractive error >-8 D) was associated with age (P<0.001), female gender (P = 0.020), urban region (P = 0.023), and lower BCVA (P<0.001). Mean anisometropia was 1.09+/-2.03 D (median, 0.38; range, 0-22.0). Prevalence of anisometropia of > or =1 D was associated significantly with age (P<0.001), refractive error (P<0.001), BCVA (P<0.001), and region (P<0.001). Mean astigmatic error measured 0.62+/-0.90 D (median, 0.25; range, 0-7.50). Astigmatism of > or =1 D was associated significantly with age (P<0.001), lower UCVA (P = 0.003), lower BCVA (P<0.001), urban area (P<0.001), and degree of cortical cataract (P = 0.027). As in other population-based studies on Chinese, myopia was more prevalent in younger subjects. Myopia was associated with urban region, educational background, female gender, decreasing visual acuity, and nuclear cataract. If longitudinal studies confirm the association of refractive error with age, refractive surgery may achieve emmetropia only for a limited time.
Article
To determine the prevalence of astigmatism and its epidemiological risk factors in Tehran via a population-based study. By means of a stratified random cluster sampling, 6497 citizens representing a cross-section of the population of Tehran were selected from 160 clusters. Eligible people were recruited through a door-to-door household survey in the selected clusters and transferred to a clinic for an extensive eye examination and interview. The refractive status was determined with manifest refraction. Astigmatism was defined as cylinder worse than or equal to 0.5 D. High astigmatism was defined as a manifest cylinder > or =1.5 D. Between August and December 2002, 4565 of the 6497 eligible individuals in the sample attended the interview and ophthalmic examination (a participation rate of 70.3%). The age- and gender-standardized prevalence of astigmatism was 50.2% (95% CI, 48.4% to 51.9%) on manifest refraction. High astigmatism was found in 490 right eyes (11.1%; 95% CI, 10.1% to 12.0%). Of 2532 participants with ametropia, 59.6 (95% CI, 57.6-61.5) had astigmatism. The percentages of with-the-rule, against-the-rule and oblique astigmatism were 33.6%, 36.9% and 29.3%, respectively. The proportion of type of astigmatism was significantly related to age (p < 0.001). The univariable analysis of astigmatism between family members yielded odds ratios of 1.47 (95% CI, 1.14 to 1.89, p = 0.003) for the association of astigmatism among siblings. After controlling for age, refractive errors and education, the pairwise sibling association remained statistically significant (OR 1.43, 95% CI, 1.08 to 1.88). These findings revealed a high prevalence of astigmatism in the population. Age, education and ametropia were the main predictors of astigmatism in Tehran. Our findings should be considered for case finding and astigmatism correction programs. Our data confirmed a modest familial aggregation for astigmatism.
Article
To determine the effect of upper eyelid gold weight implantation on corneal astigmatism. This is a prospective, cohort study. Eighteen eyes of 18 patients underwent upper eyelid gold weight implantation for facial nerve palsy. Nine of these patients recovered facial nerve function and underwent elective removal of the gold weight. Corneal topography was performed before and after gold weight implantation. Corneal topography was also performed after gold weight removal in patients who recovered from facial nerve paralysis. With-the-rule corneal astigmatism increased significantly by 1.4 diopters (D) +/-2.0, from a mean of 0.3 to 1.7 D after gold weight implantation (p = 0.034). With-the-rule corneal astigmatism in patients who had gold weight removal decreased by 1.2 +/- 2.1 D, from 2.2 to 1.0 D after gold weight removal (p = 0.136). Upper eyelid gold weight implantation causes an increase in corneal astigmatism, predominantly in the vertical axis, which appears to be reversible on removal of the gold weight.
Article
Astigmatism is a refractive condition encountered commonly in clinical practice. This review presents an overview of research that has been carried out examining various aspects of this refractive error. We examine the components of astigmatism and the research into the prevalence and natural course of astigmatic refractive errors throughout life. The prevalence of astigmatism in various ethnic groups and diseases and syndromes is also discussed. We highlight the extensive investigations that have been conducted into the possible aetiology of astigmatism, however, no single model or theory of the development of astigmatism has been proven conclusively. Theories of the development of astigmatism based on genetics, extraocular muscle tension, visual feedback and eyelid pressure are considered. Observations and evidence from the literature supporting and contradicting these hypotheses are presented. Recent advances in technology such as wavefront sensors and videokeratoscopes have led to an increased understanding of ocular astigmatism and with continued improvements in technology, our knowledge of astigmatism and its genesis should continue to grow.
Article
To investigate associations between the topography of the cornea and the morphology of the eyelids in a population of young adult subjects with a range of refractive errors. Corneal topography data and digital images of the anterior eye were acquired for 100 young adult subjects. The corneal topography data and palpebral fissure images were analyzed to determine a range of parameters describing the shape of the cornea and the morphology of the palpebral fissure. Correlation analysis was carried out to investigate for significant associations between the parameters describing the topography of the cornea and the parameters describing the morphology of the palpebral fissure. A number of highly significant correlations were found between the best-fitting corneal spherocylinder and the eyelid morphology parameters. The corneal best-fit sphere (M) was significantly correlated with the horizontal palpebral fissure width (r = -0.428; P < 0.001). Corneal astigmatism power vector J45 was significantly correlated with the angle of the palpebral fissure (r = 0.392; P < 0.001). The axis of corneal astigmatism was also found to be significantly correlated with the angle of the palpebral fissure (r = 0.317; P = 0.005). A number of significant associations exist between the corneal spherocylinder and the morphology of the eyelids in a normal adult population.
Article
To study the distributions of refractive (RA), corneal (CA), and internal astigmatism (IA) in 12-year-old Australian children and to explore differences from previous findings in 6-year-old children. Eligible year 7 students (2353/3144 [75.3%], median age, 12 years) from a random cluster sample of 21 high schools in Sydney, Australia, were examined by keratometry, cycloplegic autorefraction, and review of questionnaire data. Prevalence rates of RA, CA, and IA > or =1.0 D in right eyes were 6.7% (95% confidence interval [CI], 5.0-8.4), 26.6% (CI, 22.1-31.1), and 26.5% (CI, 22.9-30.0), respectively. RA was predominantly with-the-rule (WTR; 40.4%, CI, 32.6 to 48.2) and against-the-rule (ATR; 43.6%, CI, 35.7-51.5), CA was WTR (88.8%, CI, 86.3-91.3), and IA was ATR (90.2%, CI, 87.8-92.6). The girls had significantly greater CA and IA prevalence, with greater ATR astigmatism and lower oblique IA than did the boys. The European white-Australian children had lower CA prevalence than did the East Asian-Australian children and higher IA prevalence than did the South Asian-Australian children. Ethnic differences in RA prevalence were not significant, when adjusted for confounders. RA was more frequently ATR in European white than in other ethnic groups. Compensation between CA and IA reduced the magnitude of RA. Comparison with the data on 6-year-old children revealed minimal differences for all astigmatic components. There was a relatively low prevalence of RA, due to compensation between CA and IA. The minimal differences in all components of astigmatism between the two age cohorts suggest that astigmatism is stable between ages 6 and 12 years, although this conclusion needs to be confirmed in longitudinal studies.
Article
To determine the prevalence of refractive error and associated risk factors in the Meiktila District of central rural Myanmar. Population-based cross-sectional study. Randomized stratified cluster sampling of the inhabitants 40 years or older from villages in Meiktila was performed; 2481 eligible participants were identified, 2076 participated in the study, and adequate refractive data were obtained on 1863 individuals (75.1%). Demographic data including age, gender, and education level were obtained from all participants. The ophthalmic examination included autorefraction, nuclear opalescence (NO) grading at the slit lamp, and applanation tonometry. Refractive errors were classified by type of ametropia and their prevalence was determined. Univariate and multivariate analyses were performed and odds ratios were calculated for the predictors of refractive error within the statistical models. Mean refractive error measured -1.3 diopters (D) (standard deviation [SD], 2.9) and mean cylindrical error measured 1.1 D (SD, 1.5). Myopia of >-1.0 and >-6.0 D occurred in 42.7% (95% confidence interval [CI], 40.4%-44.9%) and 6.5% (95% CI, 5.4%-7.6%) of subjects, respectively. Myopic refractive error was associated significantly with a higher degree of NO (P<0.001) and age. Hypermetropia of >+1.0 D occurred in 15% (95% CI, 5.4%-7.6%) of the population and was associated with higher education levels (P<0.001). Astigmatism worse than 1.0 D occurred in 30.6% (95% CI, 28.5%-32.7%) of the population and was associated with age (P<0.001) and NO (P<0.001). Myopia was more prevalent in older subjects and in those with increased NO. The prevalence rates of myopia in the > or =40 age group are higher than those found in other Asian regions and are likely to contribute to visual impairment.
Article
To evaluate the prevalence of refractive errors associated with age, gender, and central corneal thickness and to evaluate astigmatism in the refraction and keratometry in a randomly sampled elderly Japanese population. Population-based epidemiologic survey. A random sampling of residents of Tajimi, Japan, aged 40 years or older. A total of 3021 residents (participation rate, 78.1%) participated. Each subject underwent screening examinations including autokeratorefractometry, subjective refraction, best-corrected visual acuity, central corneal thickness measurement, intraocular pressure measurement, slit-lamp examination, fundus photography, and visual field testing. The prevalence of myopia (spherical equivalent [SE], <-0.5 diopters [D]), high myopia (SE, <-5 D), hyperopia (SE, >0.5 D), refractive astigmatism (cylinder, >0.5 D), and anisometropia (difference in SE between eyes, >1.0 D), and the correlation of refractive errors with age, gender, and central corneal thickness. Astigmatism in the refraction and keratometry was analyzed using polar value analysis and the vector calculation method. The crude prevalence of myopia, high myopia, hyperopia, refractive astigmatism in the refraction, and anisometropia was 41.8% (95% confidence interval [CI], 40.0%-43.6%), 8.2% (95% CI, 7.2%-9.2%), 27.9% (95% CI, 26.3%-29.6%), 54.0% (95% CI, 52.1%-55.8%), and 15.1% (95% CI, 13.7%-16.4%), respectively. The prevalence of myopia decreased with age up to 70 to 79 years but increased slightly in patients 80 years and older; the prevalence of hyperopia showed the opposite trend. The prevalence of astigmatism and anisometropia was higher in the older age groups. No significant gender difference was found associated with the refractive status except for keratometric readings. Polar value analysis and the vector calculation method showed a trend toward against-the-rule astigmatism with increasing age in both refractive and keratometric astigmatism, with a discrepancy between the two. The overall prevalence of myopia (SE, <-0.5 diopters) was 41.8% in the study population, which is higher than that in population-based studies previously reported.
Article
To describe the prevalence and risk factors for myopia and other refractive errors in an urban Malay population in Singapore. Population-based, cross-sectional study. Persons of Malay ethnicity, between 40 and 80 years of age, living in Singapore. Refractive error was determined by subjective refraction and if unavailable by autorefraction. Data were analyzed for 2974 adults without previous cataract surgery and who had right eye refraction data. Risk factor data, such as education levels and near work activity, were obtained from a face-to-face interview. Myopia, defined as spherical equivalent (SE) refraction less than -0.5 diopters (D), astigmatism as cylinder less than -0.5 D, hyperopia as SE greater than 0.5 D, and anisometropia as the difference in SE greater than 1.0 D. The prevalence of myopia in the right eye was 30.7% (9.4% unilateral myopia and 21.3% bilateral myopia), the prevalence of astigmatism in the right eye was 33.3% (95% confidence interval [CI, 33.0-33.5), the prevalence of hyperopia in the right eye was 27.4% (95% CI, 24.7-27.6), and the prevalence of anisometropia was 9.9% (95% CI, 9.7-10.0). There was a U-shaped relationship between increasing age and the prevalence of myopia, which was partially explained by the age-related increase in the prevalence of cataract. In a multiple logistic regression model, female sex, age, higher educational level, and cataract were associated with myopia. Adults with myopia were more likely to have astigmatism (P<0.001) in multivariate analyses. A quarter of older adult Malay people in Singapore had myopia. Compared with previous reports of similarly aged Singapore Chinese adults, the prevalence of myopia, astigmatism, and anisometropia was lower, whereas the prevalence of hyperopia was similar.
Prevalence rates of refractive errors in Sumatra
  • Saw
  • Sm
  • G Gazzard
  • Koh
Saw SM, Gazzard G, Koh D et al. Prevalence rates of refractive errors in Sumatra, Indonesia. Invest Ophthal-mol Vis Sci 2002; 43: 3174–80.
The Authors Clinical and Experimental Ophthalmology © 2011 Royal Australian and New Zealand College of Ophthalmologists
  • Hashemi
254 Hashemi et al. © 2011 The Authors Clinical and Experimental Ophthalmology © 2011 Royal Australian and New Zealand College of Ophthalmologists