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Causes of visual impairment in children with low vision

Authors:
  • Pakistan Institute of Community Ophthalmology Hayatabad Medical Complex Peshawar Pakistan

Abstract

To determine the main causes of visual impairment in children with low vision. To assess the need of spectacles and low vision devices (LVDs) in children and to evaluate visual outcome after using their LVDs for far and near distance. Observational study. Khyber Institute of Ophthalmic Medical Sciences, Peshawar, Pakistan, from June 2006 to December 2007. The clinical record of 270 children with low vision age 4-16 years attending the Low Vision Clinic were included. All those children, aged 4-16 years, who had corrected visual acuity (VA) less than 6/18 in the better eye after medical or surgical treatment, were included in the study. WHO low vision criteria were used to classify into visually impaired, severe visually impaired and blind. Results were described as percentage frequencies. One hundred and eighty nine (70%) were males and 81 (30%) were females. The male to female ratio was 2.3:1. The main causes of visual impairment included nystagmus (15%), Stargardt's disease (14%), maculopathies (13%), myopic macular degeneration (11%) and oculocutaneous albinism (7%). The percentages of visually impaired, severe visually impaired and blind were 33.8%, 27.2% and 39.0% respectively. Spectacles were prescribed to 146 patients and telescopes were prescribed to 75 patients. Spectacles and telescope both were prescribed to 179 patients while Ocutech telescope was prescribed to 4 patients. Retinal diseases nystagmus and macular conditions were mainly responsible for low vision in children. Visually impaired children especially with hereditary/congenital ocular anomalies benefit from refraction and low vision services which facilitate vision enhancement and inclusive education.
88 Journal of the College of Physicians and Surgeons Pakistan 2011, Vol. 21 (2): 88-92
INTRODUCTION
The control of childhood blindness is a priority of "Vision
2020 - the right to sight", a global initiative for the
elimination of avoidable blindness.1The importance of
providing care for children with low vision is recognized
by many initiatives, such as Vision 2020, the 2004 Oslo
Workshop on low vision and the United Nation's global
campaign - 'Education for All'.2
The prevalence and major causes of childhood
blindness vary between countries and over time. The
prevalence of blindness in children ranges from
approximately 0.3/1000 children in affluent regions to
1.5/1000 in the poorest communities.3Reliable
population-based data on the causes of blindness in
children are difficult to obtain in developing countries. In
middle income countries the pattern of causes is mixed,
with retinopathy of pre-maturity emerging as an
important cause in Latin America and some Eastern
European countries.4,5 Currently un-avoidable causes
(the biggest group in affluent countries) include
hereditary retinal dystrophies, disorders of the central
nervous system, and congenital anomalies. Un-
corrected refractive errors cause visual impairment and
blindness in all regions, particularly myopia in south
East Asia.6
The prevalence of childhood blindness was 0.3 per
1,000 children in industrialized countries and 1.2 per
1,000 children in the developing countries in the year
2000. Accordingly, it was estimated that there were
nearly 1.4 million blind children in the world. Each year,
an additional 50,000 children become blind and are
added to this pool.7A population- based cross- sectional
study in India has found low vision to have a prevalence
of 1.05% in the year 2000, with a burden of 10.6 (95%
confidence interval, 8.4-12.8) million people requiring
low vision services.8In another hospital-based study,
the age group < 16 years was the leading age group of
low vision.9
WHO definition for low vision (6/60 < VA < 6/18, 10°
<VF < 20°),10 severe vision impairment (3/60 < VA
< 6/60, 5° < VF < 10°), and blindness or profound
vision impairment (VA < 3/60, VF < 5°) are considered
reliable.10
ABSTRACT
Objective: To determine the main causes of visual impairment in children with low vision. To assess the need of
spectacles and low vision devices (LVDs) in children and to evaluate visual outcome after using their LVDs for far and near
distance.
Study Design: Observational study.
Place and Duration of Study: Khyber Institute of Ophthalmic Medical Sciences, Peshawar, Pakistan, from June 2006 to
December 2007.
Methodology: The clinical record of 270 children with low vision age 4-16 years attending the Low Vision Clinic were
included. All those children, aged 4-16 years, who had corrected visual acuity (VA) less than 6/18 in the better eye after
medical or surgical treatment, were included in the study. WHO low vision criteria were used to classify into visually
impaired, severe visually impaired and blind. Results were described as percentage frequencies.
Results: One hundred and eighty nine (70%) were males and 81 (30%) were females. The male to female ratio was 2.3:1.
The main causes of visual impairment included nystagmus (15%), Stargardt's disease (14%), maculopathies (13%),
myopic macular degeneration (11%) and oculocutaneous albinism (7%). The percentages of visually impaired, severe
visually impaired and blind were 33.8%, 27.2% and 39.0% respectively. Spectacles were prescribed to 146 patients and
telescopes were prescribed to 75 patients. Spectacles and telescope both were prescribed to 179 patients while Ocutech
telescope was prescribed to 4 patients.
Conclusion: Retinal diseases nystagmus and macular conditions were mainly responsible for low vision in children.
Visually impaired children especially with hereditary /congenital ocular anomalies benefit from refraction and low vision
services which facilitate vision enhancement and inclusive education.
Key words: Childhood blindness. Low vision. Low vision devices. Vision 2020. Nystagmus. Stargardt's diseases. Maculopathy.
Myopic macular degeneration.
Department of Ophthalmology, Hayatabad Medical Complex,
Peshawar.
Correspondence: Dr. Mufarriq Shah, Doctor’s Hostel No. 1,
R. No. 12, Hayatabad Medical Complex, Peshawar.
E-mail: mufarriq1@hotmail.com
Received March 17, 2009; accepted January 19, 2011.
Causes of Visual Impairment in Children with Low Vision
Mufarriq Shah, Mirzaman Khan, Muhammad Tariq Khan, Mohammad Younas Khan and Nasir Saeed
ORIGINAL ARTICLE
Many children with incurable visual loss benefit from
low-vision rectification services, which facilitate near
vision and inclusive education. This study aimed to
determine the main causes of low vision in Pakistani
children and to assess their visual outcome after using
low vision devices for distance and near tasks.
METHODOLOGY
This study was conducted at Low Vision Clinic in Khyber
Institute of Ophthalmic Medical Sciences, Hayatabad
Medical Complex, Peshawar, Pakistan. The clinical
record of 270 children, aged 4-16 years, attending
the low vision clinic from June 2006 to December
2007 were included in the study. They were seen first
by ophthalmologists and then referred to low vision
clinic for assessment, where they are refracted and
assessed for LVDs by an optometrist. Optometric
examination included detailed history of the patient, his/
her family history, functional, occupational and
clinical assessment. The anterior segment examination
was performed using a slit-lamp. Posterior segment
examination was performed by direct or indirect
ophthalmoscopy after mydriasis. The diagnosis was
confirmed by at least one ophthalmologist and one
optometrist.
Distance visual acuity was measured using a range of
techniques. Those included Lea symbols, Snellen
charts and logarithm of the minimum angle of resolution
(Log.MAR) chart with five optotypes on each line at 4 m
and, if necessary, at 3, 2 m on each eye separately while
the patient wear his or her current spectacles (if worn).
Feinbloom chart for the partially sighted and Illiterate E
were used for patient who could not read English,
depending on the level of co-operation. If visual acuity
could not be measured with these charts, a sequential
approach was used with fingers counting, hand
movement, and light perception. Visual fields were
assessed by confrontation and arc perimeter. Refraction
with cycloplegia was carried out on all patients, followed
by subjective refraction using standard techniques. The
best corrected distance and near acuity, the refractive
error and eye to chart distance were recorded for each
eye.
For near visual acuity “Near Reading Card for the
partially sighted” by William Feinbloom and Lea Cards
for near visual acuity were used. For the purpose of this
study near acuity was banded in three groups; 1M (news
paper size) or better which would allow access to most
printed materials, < 1M to 3.2 M (display materials)
which would allow only limited access to ink print; and
< 3.2 M.9Low vision devices like telescopes stand and
hand magnifiers, and closed circuit television were used
during the low vision assessment. The category of
visual impairment was classified by vision in the better
eye for all untreatable causes other than uncorrected
refractive error.
All these variables were translated into SPSS version 10
databsae. Mean values and standard deviation were
calculated for continuous variables while proportions
and percentages were calculated for categorical
variables.
RESULTS
Two hundred and seventy children aged 4-16 years were
assessed at low vision clinic. Mean age was 11 + 2.8
years. Among the children examined, 189 (70%) were
males and 81(30%) were females. The leading cause of
low vision amongst this group was nystagmus (15%)
followed by Stargardt's maculopathies (14%). The next
most common cause was maculopathies (other than
Stargardt's disease) (13%) followed by myopic macular
degeneration (11%), oculocutaneous albinism (7%), and
amblyopia (6%). As a whole retinal disease, including
Stargardt's disease and maculapathies, was the major
cause of visual impairment present in 32% children.
Retinitis pigmentosa was found in 3% cases. The
causes of vision impairment are given in Table I.
Based on vision at initial examination, 3 patients (1.1%)
had VA 6/18. Two of them had retinitis pigmentosa while
one had Stargardt's disease. On presentation 116
children (43%) had visual impairment (having visual
acuity < 6/18 to 6/60 in the better eye), and 62 children
(23%) were severely visually impaired (with visual acuity
< 6/60 to 3/60 in the better eye) while 89 children (33%,
95%CI) were blind (having VA < 3/60 in the better eye)
according to the WHO categories of visual loss. With
best correction, 42 (15.6%) children achieved VA 6/18 or
better. One hundred and sixty four (60.7%) were visually
impaired and 31 (11.5%) were severely visually
impaired while 33 (12.2%) of children continued to be
blind. Amongst 270 children, 42 were prescribed only
glasses for distance while the remaining 228 children
were assessed for low vision devices. With low vision
Journal of the College of Physicians and Surgeons Pakistan 2011, Vol. 21 (2): 88-92 89
Causes of visual impairment in children with low vision
Table I: Causes of vision impairment.
Causes Number Percentage
Nystagmus 40 14.8
Stargardt's disease 37 13.7
Myopic degeneration 30 11.1
Maculopathies 36 13.3
Others (< 2%) 32 11.9
Oculocutaneous albinism with
nystagmus 18 6.7
Amblyopia 17 6.3
Retinitis pigmentosa 9 3.3
Marfan's syndrome 6 2.2
Congenital cataract 8 3.0
Optic atrophy 6 2.2
Corneal opacities 6 2.2
Congenital glaucoma 6 2.2
Rod cone dystrophy 6 2.2
Unknown 13 4.8
Total 270 100
devices, amongst 228 children, 192 children (84.2%)
achieved distance visual acuity 6/18 or better in the
better eye while 13 patients (5.7%) were visually
impaired and 23 (10.1%) remained in the blind category.
The distribution of visual acuities is given in Table II. On
presentation the difference in percentage amongst male
and female was not very significant regarding categories
of visual impairment, severe visual impairment and
blindness (Table III).
The results from near visual acuity measurements are
shown in Table IV. One hundred and thirty four patients
(49.6%) with low vision were able to discern 1 M
(newspaper print) or better in the better eye without near
addition. Sixty two had near visual acuity < 1 M to 3.2 M
and 74 had < 3.2 M. With low vision aids the number of
children with near visual acuity of 1 M (0.8 print size) or
better increased to 239 (88%), and 26 patients (9.6%)
had < 3.2 M.
Spectacles were prescribed to 146 patients and
telescopes were prescribed to 75 patients. Spectacles
and telescope both were prescribed to 179 patients
while Ocutech telescope were prescribed to four
patients. Forty six patients were feeling better with
filters. For near visual acuity, glasses (included prismatic
glasses) were prescribed to 96 patients, stand
magnifiers to 42 patients, hand-held magnifier to 27
patients and CCTV and Ocutech telescope with cap to 2
patients each.
DISCUSSION
Children with low vision can improve their quality of life
through vision rehabilitation services to teach them how
to use their remaining vision more effectively. Using a
variety of visual and adaptive aids may bring them back
or help them keep their independence. Integrated
education of visually impaired children is now preferred
when possible. Various studies have found low vision
devices as an effective means of providing visual
rehabilitation.11-13
In the present study, hereditary / congenital ocular
anomalies (mainly Stargardt's disease and oculocu-
taneous albinism) accounted for 21% of low vision
patients. The reason for the high proportion of
hereditary / congenital anomalies in this study may be
due to inter-family marriages because consanguineous
marriages are common in this part of the world. Most of
these hereditary / congenital conditions are not treatable
but prevention is possible through genetic counselling.
Gothwal has been shown that in the subjects aged < 30
years the leading causes of low vision were genetic.9
Prior to refraction, 3 children had a visual acuity > 6/18,
with 42 (15.6%) more children moving from the group
with low vision, but having useful residual vision,
improving to the no impairment group after accurate
refraction but none of them improved to 6/12 or better in
the better eye. This greater number was due to the fact
that in the retinal diseases, including Stargardt's disease
and maculopathies, vision is good in early childhood but
deteriorate with the passage of time. This also illustrates
the importance of accurate refraction in children with low
vision and shows that, even in the absence of a special
low vision services, many eye units can help many
children with low vision by providing accurate refraction
services. Moreover, children with corrected VA of 6/18 or
better but having obvious cause of visual impairment
should be considered for follow-up as their VA will
deteriorate with age. Refractive error is also one of the
most common causes of visual impairment. Due to
uncorrected refractive error, there are 145 million people
with VA ranging from < 6/18 to 3/60 and 8 million people
who are blind (VA < 3/60).14
In this study the number of male children is more than
twice the number of female children. Other studies
undertaken by the author did show that the number of
male is more than twice the number of female.9,11 Girls
have poorer access to low vision care than boys. Many
factors may contribute towards the fewer females
referral. These include comparatively small number of
female patients examined in the out patients
department; very low literacy ratio in females; long
distances involved for visiting the only low vision clinic in
the province.9Girls may therefore, need to be
approached directly for eye care and not only indirectly
via community leaders.
90 Journal of the College of Physicians and Surgeons Pakistan 2011, Vol. 21 (2): 88-92
Mufarriq Shah, Mirzaman Khan, Muhammad Tariq Khan, Mohammad Younas Khan and Nasir Saeed
Table II: Distribution of presenting distance VA (visual acuity), best
corrected VA and VA with LVDS (low vision devices) (n = 228).
VA Presenting VA Best corrected VA VA with LVDs
n (%) n (%) n (%)
6/18 or better 0 (0.0) 0 (0.0) 192 (84.2)
< 6/18 to 6/60 77 (33.8) 164 (72.0) 13 (5.7)
< 6/60 to 3/60 62 (27.2) 31 (13.6) 0 (0)
< 3/60 89 (39.0) 33 (14.4) 23 (10.1)
Total 228 (100) 228 (100) 228 (100)
Table III: Presenting visual acuity and visual acuity with low vision
devices by gender (n = 228).
VA on presentation VA with low vision devices
Male Female Male Female
n (%) n (%) n (%) n (%)
6/18 or better 0 (0) 0 (0) 137 (87.0) 55 (78.6)
< 6/18 to 6/60 54 (34) 23 (33) 7 (4) 6 (8.6)
< 6/60 to 3/60 41 (26) 21 (30) 0 (0) 0 (0)
< 3/60 63 (40) 26 (37) 14 (9) 9 (12.8)
Total 158 (100) 70 (100) 158 (100) 70 (100)
Table IV: Near visual acuity at presentation and with low vision aids
(n =270).
VA Presenting near VA Near VA with LVDs
n (%) n (%)
1M or Better 134 (53.1) 239 (93.8)
< 1 M to 3.2M 62 (31.3) 5 (0)
< 3.2 M 74 (15.6) 26 (6.2)
Total 270 (100) 270 (100)
This study showed that even with low vision aids in
female, 8.6% had visual impairment and 12.8% were
blind while in male 4.0% were visually impaired and
9.0% were still blind. However, there was none in the
category of severe visual impairment in both male and
female after low vision aids. Hence the percentage of
visually impaired and blind remained greater in female
as compared to male even with low vision aids. This
finding shows that females have significantly higher
odds of having severe impairment and blindness which
may be reflective of their relatively disadvantaged social
status.
In this study, out of 16 patients with amblyopia, 12 had
visual impairment and 3 were in the blind category. VA
was enhanced to 6/18 or better with LVDs in all cases.
In our other studies amblyopia is a major cause of visual
defects in children.9,15 It is estimated that amblyopia
affects between 1-4% of the world’s population.16
Amblyopia develops during the sensitive period of visual
maturation, which continues until about 8 years of age.17
In this study we found that about 50% children had
normal near visual acuity. These children thus had
sufficient near vision to read the print used in school
books. Most visually impaired children have useful sight
but there is under provision of visual aids, inadequate
training in their uses, specially use of stand magnifiers,
and poor understanding of simple methods of visual
function for daily living. For low vision devices to be used
effectively by children, support, follow-up, training and
motivation is needed. With higher power devices,
specially stand magnifiers, more supervised practice
and greater motivation is required.
The overall visual function of a child has four major
components; communication, mobility, daily living
activities and sustained near vision tasks like reading
and writing, including colour vision and contrast
sensitivity assessment.18 Changes in environment do
not cost much and should be an integral part of the low
vision care of these children.
Comparison of causes of severe visual impairment (SVI)
and blindness in this age group needs to be interpreted
cautiously, as the data are not population-based and
only a small proportion of low vision children who
attended the Low Vision Clinic are presented in this
study. The study results are, therefore, likely to differ
from whole population studies.
Though the need for low vision aids may have been
underestimated in the present study (due to the use of
high addition plus / microscopic lenses and prismatic /
Fonda glasses), which is affordable and easily available
option in our setting. High powered near spectacles can
be readily manufactured using conventional aspheric
lenses.
CONCLUSION
The present study shows that hereditary / congenital
ocular anomalies (mainly Stargardt's disease and
oculocutaneous albinism) were more common in these
children. On the basis of the analysis made in the study
we concluded that visually impaired children especially
with hereditary / congenital ocular anomalies benefit
from accurate refraction and low vision services which
facilitate vision enhancement and inclusive education in
these children.
REFERENCES
1. World Health Organization. Preventing blindness in children:
report of WHO/IAPB scientific meeting. Geneva: WHO; 2000.
2. Toward a reduction in the global impact of low vision [Internet].
New York: The International Society for low vision research and
rehabilitation; 2005. Available from: http://www2.nutn.edu.tw/vhc/
english/Oslo%20Workshop%20Report.pdf
3. Gilbert C, Rahi J, Eckstein M, O'Sullivan J, Foster A.
Retinopathy of pre-maturity in middle-income countries. Lancet
1997; 350:12-4.
4. Kocur I, Kuchynka P, Rodny S, Barakova D, Schwartz EC.
Causes of severe visual impairment and blindness in children
attending schools for the visually handicapped in the Czech
Republic. Br J Ophthalmol 2001; 85:1149-52. Comment in: p.
1145-6.
5. World Health Organization. Elimination of avoidable visual
disability due to refractive errors. Geneva: WHO; 2000.
6. Gilbert C, Foster A. Childhood blindness in the context of vision
2020-the right to sight. Bull World Health Organ 2001; 79:227-32.
Epub 2003 Jul 7.
7. Dandona R, Dandona L, Srinivas M, Giridhar P, Nutheti R, Rao
GN. Planning low vision services in India: a population-based
perspective. Ophthalmology 2002; 109:1871-8.
8. Shah M, Khan MD. Causes of low vision amongst the low vision
patients attending the Low Vision Clinic at Khyber Institute of
Ophthalmic Medical Sciences (KIOMS), Hayatabad Medical
Complex, Peshawar, Pakistan. J Visual Impairment Res 2004; 6:
89-97.
9. World Health Organization. Strategies for the prevention of
blindness in national programmes: a primary health care
approach. Geneva: WHO; 1984.
10. Shah M, Zaman M, Khan MT, Khan MD. Visual rehabilitation of
patients with Stargardt's disease. J Coll Physicians Surg Pak 2008;
18:294-8.
11. Hornby S, Adolph S, Gothwal VK, Gilbert CE, Dandona L, Foster
A. Evaluation of children in six blind schools of Andhra Pradesh.
Indian J Ophthalmol 2000; 48:195-200.
12. Silver J, Gilbert CE, Spoerer P, Foster A. Low vision in east
African blind school students: Need for optical low vision
services. Br J Ophthalmol 1995; 79:814-20.
13. Resnikoff S, Pascolini D, Mariotti SP, Pokharel GP. Global
magnitude of visual impairment caused by un-corrected
refracted errors in 2004. Bull World Health Organ 2008; 86:63-70.
Comment in: Bull World Health Organ 2008; 86(8):B-C; author
reply C.
Journal of the College of Physicians and Surgeons Pakistan 2011, Vol. 21 (2): 88-92 91
Causes of visual impairment in children with low vision
14. Shah M, Rahman H, Khan MT. Khan MD, Habib-ur-Rehman.
Clinical profile of amblyopia in Pakistani children age 3 to 14
years. J Coll Physicians Surg Pak 2005; 6:353-7.
15. Simons K. Pre-school vision screening: rationale, methodology
and outcome. Surv Ophthalmol 1996; 41:3-30.
16. Newman DK, Hitchcock A, McCarthy H, Moore AT. Pre-school
vision screening: outcome of children referred to the hospital eye
services. Br J Ophthalmol 1996; 80:1077-82.
17. Hyvarinen L. Assessment of low vision for educational
purposes and early intervention [Internet]. [updated 1999].
Available from: http://www.näkötestit.fi/en/assessme/comenius/
index.html.
92 Journal of the College of Physicians and Surgeons Pakistan 2011, Vol. 21 (2): 88-92
Mufarriq Shah, Mirzaman Khan, Muhammad Tariq Khan, Mohammad Younas Khan and Nasir Saeed
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... Several studies have shown that children with global developmental delay are at risk to have primary sensory impairments of vision and hearing. Estimates of vision impairment or other visual disorders range from 13% up to 50% whereas significant audiological impairments occur in about 18% of children based on data in one series of patients 10 . However, it is recommended that children with global developmental delay undergo appropriate vision and audiometric assessment at the time of their diagnosis. ...
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Background: Childhood visual impairment has a significant effect on social life, educational performance, and professional choices, and can lead to poverty. Aims: To summarize the available data on the prevalence and causes of visual impairment in children aged 5–17 years in the Eastern Mediterranean Region (EMR). Methods: The study was conducted in 2021 using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) method. We searched Google Scholar, PubMed, Web of Science, Scopus, Index Medicus for the Eastern Mediterranean Region, and Medline for studies published between January 2000 and April 2020, to assess the prevalence and causes of paediatric visual impairment in the EMR. The articles included were epidemiological studies of prevalence and causes of childhood visual impairment and were published in peer-reviewed journals. Results: Of 12 705 articles screened, 23 from 9 countries met the inclusion criteria. The pooled prevalence of uncorrected, presenting, and best-corrected childhood visual impairment was 11.57%, 8.34%, and 1.21%, respectively. The most common causes of childhood visual impairment were refractive error (51.89%), amblyopia (11.15%), retinal disorders (3.90%), corneal opacity (3.0%), and cataract (1.88%). There was highly significant heterogeneity between the studies (P < 0.0001). Conclusion: The prevalence of visual impairment among children in the EMR was high, and the leading causes were uncorrected refractive error and amblyopia, which were avoidable. Therefore, access to eye care services may lead to early diagnosis and treatment of preventable causes of childhood visual impairment.
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Objective To identify the ocular pathologies that are reported as causes of low vision in children. Material and methods The systematic search was carried out in Medline (PubMed), Embase and Lilacs. Observational studies with populations between 0−18 years of age, reporting visual acuity data between 20/60–20/400 and reporting the frequency of ocular pathologies were selected. Studies in which the diagnosis of the condition had not been verified by a professional, or which covered only cases of blindness, uncorrected refractive errors, or amblyopia, were excluded. The methodological quality of the articles was evaluated using the Joanna Briggs Institute instrument for prevalence studies. Results 27 studies conducted in Asia (13 publications), Africa (6 studies), Oceania (4 studies), Europe and South America (2 studies each) were included. The most reported causes of low vision were: cataract, with prevalence between 0.8% and 27.2%; albinism with from 1.1% to 47%; nystagmus, with prevalence between 1.3% and 22%; retinal dystrophies between 3.5% and 50%; retinopathy of prematurity (ROP) with prevalence between 1.1% and 65.8%, optic atrophy between 0.2% and 17.6%, and glaucoma from 2.4% to 18.1%. Conclusions Cataract, albinism and nystagmus are the ocular pathologies most mentioned by studies as a cause of low vision in children, as well as retinal diseases such as ROP and optic nerve diseases such as atrophy. However, there are numerous eye conditions that can result in low vision in the pediatric population.
Resumen Objetivo Identificar las enfermedades oculares que se reportan como causas de la baja visión en los niños. Material y métodos La búsqueda sistemática se realizó en Medline (PubMed), Embase y Lilacs. Se seleccionaron estudios observacionales con poblaciones entre 0-18 años de edad, que reportaran datos de agudeza visual entre 20/60-20/400, y que informaran sobre la frecuencia de enfermedades oculares. Se excluyeron los estudios en los que el diagnóstico de la condición no hubiera sido verificado por un profesional, o que abarcaran únicamente casos de ceguera, defectos refractivos no corregidos o ambliopía. La calidad metodológica de los artículos se evaluó mediante el instrumento del Instituto Joanna Briggs para estudios de prevalencia. Resultados Fueron incluidos 27 estudios realizados en Asia (13 publicaciones), África (6 estudios), Oceanía (4 estudios) y Europa y Sudamérica (2 estudios cada uno). Las causas de la baja visión más reportadas fueron: la catarata, con prevalencias comprendidas entre el 0,8 y el 27,2%; el albinismo desde el 1,1 al 47%; el nistagmo, con prevalencias entre el 1,3 y el 22%; las distrofias de retina entre el 3,5 y el 50%; la retinopatía del prematuro (ROP) con prevalencias entre el 1,1 y el 65,8%; la atrofia óptica entre el 0,2 y el 17,6% y el glaucoma entre el 2,4 y el 18,1%. Conclusiones La catarata, el albinismo y el nistagmo son las enfermedades oculares más mencionadas por los estudios como causas de la baja visión en los niños, también enfermedades de la retina tales como la ROP y del nervio óptico como la atrofia. Sin embargo, son numerosas las condiciones oculares que pueden causar la baja visión en la población pediátrica.
Article
Endothelial Corneal Dystrophy (ECD) is, by definition, an endogenous degeneration that progresses slowly in the corneal endothelium as a result of genetic predisposition. A transverse study was conducted from September 2018 to June 2019, and the subjects affected with ECD were examined by visiting various city hospitals in Punjab including Sahiwal, Narowal, Okara, Gujranwala, Kasur, Lahore, and Multan. The basic objective of the current investigation was to find the frequency of different types of ECD in the population of different cities in Punjab. Data was collected based on relevant parameters such as age, gender, and visual acuity. The visual acuity was assessed by ophthalmologists via Snellen chart and Visual acuity test. Among 3000 patients, 6.6 % (n=198) cases of ECD were recognized which includes more males 52.52 % (n=104) as compared to females 47.48 % (n=94). Maximum cases of ECD 31.82 % (n=63) were observed in the 41-50 years of age group. In all types of ECD, FECD was observed most abundant with 38.38 % (n=76) and XECD with the least abundance of 6.67 % (n=13). The frequency of CHED and PPCD was 25.25 % (n=50) and 29.79 % (n=59) respectively. The results of recent research finalize that endothelial corneal dystrophy is a rare disease prevailing in Pakistan with a proportion of only 6.6 %. This study benefits in updating the data about the frequency of endothelial corneal dystrophy in Pakistan. Careful clinical evaluation, initial diagnosis, genetic counseling, genotyping, and correct treatment are necessary for the restoration of vision loss due to ECD.
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Purpose: As the prevalence of eye diseases increases, demand for effective, accessible and equitable eye care grows worldwide. This is especially true in lower and middle-income countries, which have variable levels of infrastructure and economic resources to meet this increased demand. In the present study we aimed to review the literature on eye care in Pakistan comprehensively, with a particular focus on eye care pathways, patient priorities and economics. Methods: A systematic scoping review was performed to identify literature relating to eye care in Pakistan. Searches of relevant electronic databases and grey literature were carried out. The results were analysed through a mixed methods approach encompassing descriptive numerical summary and thematic analysis. To consolidate results and define priority areas for future study, expert consultation exercises with key stakeholders were conducted using qualitative semi-structured interviews. Results: One hundred and thirty-two papers (published and unpublished) were included in the final review. The majority (n = 93) of studies utilised a quantitative design. Seven interlinked themes were identified: eye care pathways, burden of eye disease, public views on eye-related issues, workforce, barriers to uptake of eye care services, quality of eye care services and economic impact of blindness. Research priorities included investigating the eye care workforce, the quality and efficiency of current eye care services, eye care services available in rural Pakistan and the costs and benefits related to eye care provision and sustaining eye care programmes. Conclusions: To the best of our knowledge, this is the first review to synthesise evidence from papers across the field relating to eye care in Pakistan. As such, this work provides new insights into the achievements of the national eye health programme, challenges in eye care in Pakistan and priority areas for future research.
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Estimates of the prevalence of visual impairment caused by uncorrected refractive errors in 2004 have been determined at regional and global levels for people aged 5 years and over from recent published and unpublished surveys. The estimates were based on the prevalence of visual acuity of less than 6/18 in the better eye with the currently available refractive correction that could be improved to equal to or better than 6/18 by refraction or pinhole. A total of 153 million people (range of uncertainty: 123 million to 184 million) are estimated to be visually impaired from uncorrected refractive errors, of whom eight million are blind. This cause of visual impairment has been overlooked in previous estimates that were based on best-corrected vision. Combined with the 161 million people visually impaired estimated in 2002 according to best-corrected vision, 314 million people are visually impaired from all causes: uncorrected refractive errors become the main cause of low vision and the second cause of blindness. Uncorrected refractive errors can hamper performance at school, reduce employability and productivity, and generally impair quality of life. Yet the correction of refractive errors with appropriate spectacles is among the most cost-effective interventions in eye health care. The results presented in this paper help to unearth a formerly hidden problem of public health dimensions and promote policy development and implementation, programmatic decision-making and corrective interventions, as well as stimulate research.
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Purpose: I. To determine the causes of low vision by age and sex. II. To assess the need of spectacles and low-vision devices (LVDs) in low-vision patients attending the clinic at the Khyber Institute of Ophthalmic Medical Sciences, Hayatabad Medical Complex Peshawar. III. To determine the proportion of patients with low vision whose distance visual acuity (VA) can be enhanced to 6/18 or better in the better eye and who have the potential to discern 1 M (newspaper print) after appropriate refraction and application of low-vision devices (LVDs). Design: Hospital-based, cross-sectional study. Methods: A total of 504 individuals attending the low-vision clinic between June 2000 and June 2002 were included in the study. Of this cohort, 372 (73.8%) were male and 132 (26.2%) were female. The inclusion criterion was that the individual had VA < 6/18 in the better eye after medical or surgical treatment and/or best available correction. Results: The leading cause of low vision in age group 16 years was nystagmus 28 (16.97%). While the leading cause amongst all patients was myopic degeneration (14.48%, 95% CI). The percentages of visually impaired, severe visually impaired, and blind (using the WHO low-vision criteria) were 41% (95%CI), 22.4% (95%CI), and 36.5% (95%CI), respectively. After appropriate refraction, 19% of the patients achieved a VA of 6/18 or better. With LVDs, 86% (95%CI) achieved a VA of 6/18 or better and 90% (95%CI) achieved essentially normal near visual acuity. Spectacles were the most common devices. Conclusions: Low-vision clinics have now become an integral part of comprehensive eye-care services. Any patient with some residual vision must be referred to a low-vision clinic for the possibility of exploiting his/her visual potential through LVDs or other means. With appropriate training in their use, counseling, and medical and social support, LVDs can make a significant change in the quality of life of affected individuals.
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There is increasing awareness of the needs of children with low vision, particularly in developing countries where programmes of integrated education are being developed. However, appropriate low vision services are usually not available or affordable. The aims of this study were, firstly, to assess the need for spectacles and optical low vision devices in students with low vision in schools for the blind in Kenya and Uganda; secondly, to evaluate inexpensive locally produced low vision devices; and, finally, to evaluate simple methods of identifying those low vision students who could read N5 to N8 print after low vision assessment. A total of 230 students were examined (51 school and 16 university students in Uganda and 163 students in Kenya, aged 5-22 years), 147 of whom had a visual acuity of less than 6/18 to perception of light in the better eye at presentation. After refraction seven of the 147 achieved 6/18 or better. Eighty two (58.6%) of the 140 students with low vision (corrected visual acuity in the better eye of less than 6/18 to light perception) had refractive errors of more than 2 dioptres in the better eye, and 38 (27.1%) had more than 2 dioptres of astigmatism. Forty six per cent of students with low vision (n = 64) could read N5-N8 print unaided or with spectacles, as could a further 33% (n = 46) with low vision devices. Low vision devices were indicated in a total of 50 students (35.7%). The locally manufactured devices could meet two thirds of the need. A corrected distance acuity of 1/60 or better had a sensitivity of 99.1% and a specificity of 56.7% in predicting the ability to discern N8 print or better. The ability to perform at least two of the three simple tests of functional vision had a sensitivity of 95.5% and a specificity of 63.3% in identifying the students able to discern N8 or better.
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The major causes of blindness in children vary widely from region to region, being largely determined by socioeconomic development, and the availability of primary health care and eye care services. In high-income countries, lesions of the optic nerve and higher visual pathways predominate as the cause of blindness, while corneal scarring from measles, vitamin A deficiency, the use of harmful traditional eye remedies, and ophthalmia neonatorum are the major causes in low-income countries. Retinopathy of prematurity is an important cause in middle-income countries. Other significant causes in all countries are cataract, congenital abnormalities, and hereditary retinal dystrophies. It is estimated that, in almost half of the children who are blind today, the underlying cause could have been prevented, or the eye condition treated to preserve vision or restore sight. The control of blindness in children is a priority within the World Health Organization's VISION 2020 programme. Strategies need to be region specific, based on activities to prevent blindness in the community--through measles immunization, health education, and control of vitamin A deficiency--and the provision of tertiary-level eye care facilities for conditions that require specialist management.
Article
Although population outcome studies support the utility of preschool screening for reducing the prevalence of amblyopia, fundamental questions remain about how best to do such screening. Infant photoscreening to detect refractive risk factors prior to onset of esotropia and amblyopia seems promising, but our current understanding of the natural history of these conditions is limited, thus limiting the prophylactic potential of early screening. Screening for strabismic, refractive and ocular disease conditions directly associated with amblyopia is more clearly proven, but the diversity of equipment, methods and subject populations studied make it difficult to draw precise summary conclusions at this point about the efficacy of photoscreening. Sensory-based testing of preschool-age children exhibits a similar combination of promise and limitations. The visual acuity tests most widely used for this purpose are prone to problems of testability and false negatives. Moreover, the utility of random-dot stereograms has been confused by misapplication, and new small-target binocularity tests, while attractive, are as yet inadequately field-proven. The evaluation standard for any screening modality is treatment outcome. However, variables in amblyopia classification and quantitative definition differences, timing of presentation, nonequivalent treatment comparisons, and compliance variability have been uncontrolled in virtually all extant studies of amblyopia treatment outcome, making it difficult or impossible to evaluate either the relative efficacy of different treatment regimens for amblyopia or the effects of age on treatment outcome within the preschool age range. The latter issue is a central one, since existence of such an age effect is the primary rationale for screening at younger rather than older preschool ages. The relatively low prevalence of amblyopia makes it difficult to achieve a high screening yield in terms of predictive value, but functionally increasing prevalence by selective screening of high risk populations causes further problems. Unless a "supertest" can be devised, with very high sensitivity and specificity, health policy decisions will be required to determine which of these two characteristics should be emphasized in screening programs. Performance of screening tests can be optimized, however, with adequate training, perhaps via instructional videotapes.
Article
To assess the outcome of children referred to the hospital eye service (HES) from an orthoptist based preschool vision screening programme. A retrospective study was conducted of children referred from screening during a 2 year period. Children were screened by community orthoptists at 3 1/2 years of age. The main outcome measures were (1) HES findings for children referred from screening, and (2) visual outcome for amblyopic children after completion of treatment. The attendance rate at screening was 79.3% (6794 children): 348 children (5.1% of those screened) were referred to the HES. The HES findings were refractive error (32.9%), amblyopia (29.9%), false positive referral (20.1%), strabismus (13.2%), and other ocular disorders (3.9%). The positive predictive value of screening was 79.9%. Screening detected 48 children with straight eyed amblyopia and 43 children with strabismic amblyopia. A visual acuity of 6/9 or better in the amblyopic eye was achieved by 87.2% of straight eyed amblyopes and 64.3% of strabismic amblyopes (chi 2 = 5.27, p = 0.02). Residual amblyopia of 6/24 or worse occurred in only 5.6% of amblyopic children. Most amblyopic children detected by preschool vision screening achieve a good visual outcome with treatment. While treatment earlier in the sensitive period might be expected to give improved results, it remains to be demonstrated that preschool screening results in a better outcome than screening at school entry. Preschool vision screening also detects a significant number of children without amblyopia who have reduced vision due to refractive errors. This group of children must be included in any analysis of the cost effectiveness of preschool vision screening.
Article
In the 1940s and 1950s retinopathy of prematurity (ROP) was the single commonest cause of blindness in children in many industrialised countries; it now accounts for only 6-18% of blindness registrations. It is not known what proportion of blindness is due to ROP in countries that do not have blindness registers. Information on blindness in children in these countries can be obtained by examining children in schools for the blind. Between 1991 and 1996, 4121 children in 23 countries with a visual acuity in the better eye of less than 6/60 were examined with a standard method. The proportion of severe visual impairment or blindness due to ROP ranged from 0% in most African countries to 38.6% in Cuba. These data suggest that ROP is becoming a major cause of potentially preventable blindness among children in middle-income countries that have introduced neonatal intensive-care services for preterm and low-birthweight babies.
Article
1. To determine the anatomical site and underlying causes of severe visual impairment and blindness in children in special education in Andhra Pradesh, India. 2. To compare the causes of blindness in two different regions in the state. 3. To evaluate improvement with correction of refractive error and low-vision devices (LVDs). Children in 6 schools for the blind and in 3 integrated education programmes were examined by one ophthalmologist, and were refracted and assessed for LVDs by an optometrist. The major anatomical site and underlying aetiology of severe visual impairment and blindness (SVI/BL; < 6/60 in the better eye) were recorded using the standardised WHO reporting form. Two hundred and ninety one students under 16 years were examined, and after refraction, 267 (91.7%) were classified as being severely visually impaired or blind. The most common anatomical sites of SVI/BL were retina in 31.1% children; cornea in 24.3%; and whole globe in 20.2%. The aetiology was unknown in 38.2%, hereditary in 34.8% and childhood causes in 24%. 114 children (39.2%) had functional low vision (i.e. visual acuity < 6/18 to light perception with navigational vision). In this group, 36 children improved with spectacles and 16 benefited by LVDs. 41 children (15.4%) were able to read N10 point though they were studying Braille. Overall 37.4% of children had "avoidable" causes of blindness. The major avoidable causes were vitamin-A deficiency and cataract. Vitamin-A deficiency and congenital anomalies were more common in the dry plateau areas of the state. One in seven children could read normal print with optical support.
Article
To describe the causes of severe visual impairment and blindness in children in schools for the visually handicapped in the Czech Republic in 1998. Pupils attending all 10 primary schools for the visually handicapped were examined. A modified WHO/PBL eye examination record for children with blindness and low vision was used. 229 children (146 males and 83 females) aged 6-15 years were included in the study: 47 children had severe visual impairment (20.5%) (visual acuity in their better eye less than 6/60), and 159 were blind (69.5%) (visual acuity in their better eye less than 3/60). Anatomically, the most affected parts of the eye were the retina (124, 54.2%), optic nerve (35, 15.3%), whole globe (25, 10.9%), lens (20, 8.7%), and uvea (12, 5.2%). Aetiologically (timing of insult leading to visual loss), the major cause of visual impairment was retinopathy of prematurity (ROP) (96, 41.9 %), followed by abnormalities of unknown timing of insult (97, 42.4%), and hereditary disease (21, 9.2%). In 90 children (40%), additional disabilities were present: mental disability (36, 16%), physical handicap (16, 7%), and/or a combination of both (19, 8%). It was estimated that 127 children (56%) suffer from visual impairment caused by potentially preventable and/or treatable conditions (for example, ROP, cataract, glaucoma). Establishing a study group for comprehensive evaluation of causes of visual handicap in children in the Czech Republic, as well as for detailed analysis of present practice of screening for ROP was recommended.