Central corneal thickness and its association with ocular and general parameters in Indians: the Central India Eye and Medical Study.
ABSTRACT To evaluate the distribution of central corneal thickness (CCT) and its associations in an adult Indian population.
The Central India Eye and Medical Study is a population-based study performed in a rural region close to Nagpur in Central India; it included 4711 subjects (ages 30+ years) of 5885 eligible subjects (response rate, 80.1%).
The participants underwent a detailed ophthalmic and medical examination, including 200 standardized questions on socioeconomic background, lifestyle, social relations, and psychiatric depression. This study was focused on CCT as measured by sonography and its associations. Intraocular pressure was measured by applanation tonometry.
Central corneal thickness and intraocular pressure.
Central corneal thickness measurement data were available on 9370 (99.4%) eyes. Mean CCT was 514+/-33 microm (median, 517 microm; range, 290-696 microm). By multiple regression analysis, CCT was associated significantly with younger age (P<0.001), male gender (P<0.001), higher body mass index (P = 0.006), lower corneal refractive power (P<0.001), deeper anterior chamber (P = 0.02), thicker lens (P = 0.02), and shorter axial length (P = 0.006). Central corneal thickness was not associated significantly with refractive error (P = 0.54) or cylindrical refractive error (P = 0.20). If eyes with a corneal refractive power of 45 or more diopters were excluded, the relationship between CCT and axial length was no longer statistically significant (P>0.05), whereas all other relationships remained significant. Intraocular pressure readings increased significantly (P<0.001) with both higher CCT and higher corneal refractive power.
Indians from rural Central India have markedly thinner corneas than do Caucasians or Chinese, and, as in other populations, CCT is greater in men. CCT was associated with younger age, higher body mass index, lower corneal refractive power, deeper anterior chamber, thicker lens, and shorter axial length. Intraocular pressure readings were associated with CCT, with high readings in those eyes that had thick corneas or steep corneas. Central corneal thickness and steepness of the anterior corneal surface may thus both have to be taken into account when applanation tonometry is performed.
The author(s) have no proprietary or commercial interest in any materials discussed in this article.
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ABSTRACT: To examine the relationship between retinal nerve fiber layer (RNFL) measurements obtained using scanning laser polarimetry with variable corneal compensation and corneal thickness measurements in ocular hypertension (OHT) patients. Observational cross-sectional study. The study included 1 eye each from 44 OHT patients and 48 healthy subjects, all of similar age. All subjects had normal optic discs and normal standard automated perimetry (SAP) visual fields. Ocular hypertension patients had intraocular pressure (IOP) measurements higher than 22 mmHg. All patients underwent imaging with the GDx VCC (Laser Diagnostic Technologies, Inc., San Diego, CA) scanning laser polarimeter. We examined the relationship between GDx VCC RNFL measurements and central corneal thickness, a risk factor for development of visual field loss among OHT patients. We also examined the relationship of GDx VCC measurements and age, IOP, SAP pattern standard deviation, and vertical cup-to-disc ratio. Central corneal thickness (CCT) and GDx VCC RNFL thickness parameters. Central corneal thickness measurements in OHT patients were significantly higher than those in healthy subjects (575+/-30 microm vs. 555+/-32 microm; P = 0.002). Higher GDx VCC parameter nerve fiber indicator (NFI) scores, indicating thinner RNFL, were correlated significantly with thinner CCT measurements in OHT patients (r = -0.502; P = 0.001). Ocular hypertension patients with thinner corneas (n = 22; mean CCT, 553+/-21 microm) had significantly higher NFI scores than OHT patients with thicker corneas (n = 22; mean CCT, 598+/-18 microm) and healthy control subjects (NFI mean +/- standard deviation, 26.9+/-9.5, 20.7+/-9.8, and 19.7+/-7.0, respectively; P = 0.004, analysis of variance). The NFI values were not significantly different between OHT patients with thicker corneas and healthy subjects. In multivariate analysis, only age and CCT measurement were associated significantly with GDx VCC RNFL measurements in OHT eyes. Ocular hypertension patients with thinner corneas had significantly thinner RNFL than OHT patients with thicker corneas and healthy control subjects. These findings support the notion that RNFL defects as assessed by the GDx VCC may represent early glaucomatous damage in OHT eyes.Ophthalmology 03/2005; 112(2):251-6. · 5.56 Impact Factor
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ABSTRACT: To examine the association between central corneal thickness (CCT) and potential systemic and ocular factors affecting CCT in an Asian population. Population-based cross-sectional study. A total of 3,280 (78.7% response) adults aged 40 to 80 years of Malay ethnicity living in Singapore underwent a standardized interview and ocular and systemic examination at a centralized study clinic. CCT was measured with an ultrasound pachymeter. Blood samples were obtained to determine serum glucose, cholesterol, and triglyceride levels, and urine samples to determine glomerular filtration rate. The presence of diabetes, hypertension, chronic kidney disease (CKD), and metabolic syndrome were defined based on a combination of investigation results and participant's history. CCT was obtained from 3,239 individuals. CCT was normally distributed with a mean of 541.2 microm in the right eye. While controlling for age and gender, CCT was greater in individuals with higher body mass index (BMI) (P = .038), greater intraocular pressure (IOP) (P < .001), greater axial length (P = .005), and greater radius of corneal curvature (P < .001). Individuals with CKD (P = 0.012) and metabolic syndrome (P < .001) also had greater CCT. CCT is associated with higher IOP, longer axial length, and greater radius of corneal curvature, as well as higher BMI, metabolic syndrome, and CKD.American journal of ophthalmology 01/2009; 147(4):709-716.e1. · 3.83 Impact Factor
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ABSTRACT: To investigate the association between central corneal thickness (CCT) and the degree of myopia among Chinese. In this prospective observational study, 714 consecutive patients were recruited from a refractive surgery clinic. CCT was measured in both eyes of each patient using the Orbscan (Bausch and Lomb, Rochester, New York, USA), and data of the right eye were selected for analysis. CCT was correlated with the degree of myopia in dioptres (D) using Pearson's correlation coefficient and Dunnett's t test with multiple comparisons. The age of the patients ranged from 15 to 59 years. The mean CCT was 534.5 microm, with a standard deviation (SD) of 38.1 (range 305-684) microm. The mean (SD) myopic spherical equivalent was 5.30 (2.74) D, range -17.5--0.625 D. No correlation was found between CCT and the degree of myopia (r = -0.13, p = 0.719). Among Chinese with myopia, CCT was distributed over a large range but did not correlate with the degree of myopia.British Journal of Ophthalmology 01/2007; 90(12):1451-3. · 2.73 Impact Factor