Causes of childhood blindness in Malaysia: results from a national study of blind school students

A 12-year follow up survey of childhood blindness at schools for the blind in Cambodia

BACKGROUND

Cambodia is a low-income country in South East Asia with a population of 15.5 million people of whom 4.9 million (38%) are under the age of 16. The causes of childhood blindness in Cambodia have not been investigated since the first survey of schools for the blind done in 2009 by our group. Given the large demographic and economic shifts in Cambodia since 2009 it is important to determine if these causes have changed in order to ensure intervention programmes are appropriately targeted. The purpose of the present study is to investigate the prevalence of causes of childhood blindness at schools for the blind in Cambodia.

METHODS

Students between the ages of 5 and 16 years who were attending schools for the blind in Cambodia were examined by a consultant paediatric ophthalmologist and had clinical photographs taken. Distance visual acuity was measured using a logMAR tumbling E chart and the WHO definitions of blindness and severe visual impairment were used. The examining ophthalmologist recorded the anatomical site and aetiology of vision loss using the WHO Prevention of Blindness eye examination record for children. Collected data were compared to a previous survey from 2009.

RESULTS

Data from 73 students were included for analysis. The most common anatomical location of abnormality causing vision loss was the cornea (n = 20, 33.9%) followed by the lens and retina (n = 11, 18.64% each). Hereditary factors (n = 29, 49.15%) and childhood diseases (n = 27, 45.76%) were the most common aetiological causes of childhood blindness. The majority (71.19%) of childhood blindness was avoidable. The present study did not demonstrate 0a significant difference in the causes of childhood blindness compared to 2009.

CONCLUSIONS

Corneal pathologies continue to represent the most common cause of vision loss amongst the surveyed population and the majority of causes of childhood blindness continue to be avoidable. These findings will facilitate the development of evidence-based targeted interventional programmes in Cambodia.

Prevalence of Pediatric Cataract in Asia: A Systematic Review and Meta-Analysis

Purpose

To conduct a systematic review and meta-analysis for estimating the prevalence of pediatric cataracts across Asia.

Methods

A detailed literature search of PubMed, Embase, Web of Science, Cochrane Library, and Google Scholar databases, from 1990 to July 2021, was performed to include all studies reporting the prevalence of cataracts among children. Two researchers performed the literature search and screening of articles independently, and a third researcher critically reviewed the overall search and screening process to ensure the consistency. The JBI Critical Appraisal Checklist for studies reporting prevalence data was used to assess the methodological quality of the included studies.

Results

Of the 496 identified articles, 35 studies with a sample size of 1,168,814 from 12 Asian countries were included in this analysis. The estimated pooled prevalence of pediatric cataracts in Asian children is 3.78 (95% confidence interval: 2.54-5.26)/10,000 individuals with high heterogeneity (I[2] = 89.5%). The pooled prevalence by each country per 10,000 was 0.60 in Indonesia, 0.92 in Bangladesh, 1.47 in Iran, 2.01 in Bhutan, 3.45 in Laos, 3.68 in China, 4.27 in Thailand, 4.47 in India, 5.33 in Malaysia, 5.42 in Nepal, 9.34 in Vietnam, and 10.86 in Cambodia.

Conclusions

This study utilizes existing literature to identify the prevalence of cataracts in Asian children. Moreover, it highlights the need for more epidemiological studies with large sample sizes from other countries in Asia to accurately estimate the burden of disease.

Reading Performance and Compensatory Head Posture in Infantile Nystagmus after Null Zone Training

This study aimed to assess the visual function, reading performance, and compensatory head posture (CHP) in schoolchildren with infantile nystagmus. A total of 18 participants aged between 13 to 18 years old were divided into spectacle (n = 9) and null zone group (n = 9) based on their visual acuity. Visual acuity (LogMAR), contrast sensitivity (Pelli–Robson), reading time and rate (Tobii TX300), and CHP were measured pre and post null zone reading training. Participants in the null zone group received 10 sessions of training (5 weeks). Visual acuity and contrast sensitivity of participants in the spectacle and null zone groups were not significantly different pre and post training. Reading performance, i.e., reading time (z = −1.36; p = 0.173) and reading rate (z = −0.06; p = 0.953), of participants in the spectacle group was not significantly different after 5 weeks. Reading time (z = −2.55; p = 0.011) and reading rate (z = −2.07; p = 0.038 of participants in the null zone group showed significant improvement post training. After 5 weeks, CHP improved in six out of the nine participants (66.7%) of the null zone group and was unchanged in all participants in the spectacle group. Null zone reading training could benefit children with infantile nystagmus in improving reading performance and compensatory head posture.

Causes of Permanent Severe Visual Impairment and Blindness among Jordanian Population

PURPOSE

To report the causes of permanent severe visual impairment and blindness among Jordanian blind people.

MATERIALS AND METHODS

This study was conducted on 1422 legally blind or worse vision people of all ages who attended the ophthalmic division of a medical committee for evaluation of disabled persons from July 2013 through November 2014. They were divided into two age groups: adult group (998 cases) and childhood group (<16 years, 424 cases). Patients presented reports from their ophthalmologists detailing their eye examination including best-corrected visual acuity, slit-lamp examinations, and if applicable, intraocular pressure, dilated ophthalmoscopy, and visual field and the primary cause of visual impairment. Blind defined as best-corrected visual acuity < 6/60 (20/200) and/or visual field of 20° or less.

RESULTS

Retinitis pigmentosa was the most common cause of blindness among adult group (29.7%) followed by diabetic retinopathy (19.9%) and glaucoma (15.8%). Congenital whole-globe malformations were the most common cause of blindness among childhood cases (16.7%) followed by retinopathy of prematurity (ROP) (15.8%) and retinal dystrophies (13.9%). Overall, blindness related to genetic diseases, illnesses, and trauma was present at 56.5% (803), 41.7% (593), and 1.8% (26) of cases, respectively.

CONCLUSIONS

Genetic diseases such as retinitis pigmentosa, diabetic retinopathy, and glaucoma were the dominant causes of blindness among adults, while whole-globe malformation, ROP, and retinal dystrophies were the dominant causes of childhood blindness. These major causes of blindness should be considered in future public health and nongovernmental organizations strategies for blindness prevention in Jordan.

The Paediatric Cataract Register (PECARE): an overview of operated childhood cataract in Sweden and Denmark

AIM

To report basic epidemiological data concerning surgically treated childhood cataract in Sweden and Denmark.

METHODS

Data were derived from the Paediatric Cataract Register (PECARE), a binational, web-based surgical register representing Sweden and Denmark. All children operated before 8 years of age between 1 January 2007 and 31 December 2013 were included. Age-specific prevalence per 100 000 population was calculated.

RESULTS

A total 574 operations in 213 boys (51.7%) and 199 girls (48.3%), altogether 412 children, were registered, the vast majority (n = 395/412; 95.9%) being individuals with congenital/infantile cataract. Of these 412, a total of 294 (147 boys and 147 girls) were Swedish and 118 (66 boys and 52 girls) were Danish. The age-specific prevalence of operated cataract in Sweden was 31/100 000 and in Denmark 28/100 000. In 454 of 574 eyes (79.1%), the cataract was dense. Altogether, 266 of 574 (46.3%) were operated during the first year of life, 193 during the first 12 weeks representing 33.6% of all operations. A primary intraocular lens (IOL) implantation was done in altogether 411 of 574 eyes (71,6%). In total, 210 unilateral cataract operations (210/574; 36.6%) were performed. Persistent fetal vasculature (PFV) was present in 64 of 193 (33.1%) of those with a congenital unilateral cataract. In 84 individuals (84/395; 21.3%) with congenital or infantile cataract, a coexisting disorder was found.

CONCLUSION

The age-specific binational prevalence of operated congenital/infantile cataract in Sweden and Denmark is 30/100 000. About half of the operations are performed within the first year of life, one-third within the first 3 months. In our study population, a primary IOL was implanted in the majority of cases.

Etiology of Childhood Blindness in Izmir, Turkey

PURPOSE

To identify the anatomic sites and the etiology of childhood blindness and to discern treatable and preventable causes.

METHODS

The records of 998 patients seen in the authors' pediatric ophthalmology unit between June 1998 and May 2002 were examined retrospectively. A total of 148 patients who had visual impairment and blindness according to World Health Organization criteria were included in the study. They are classified according to the etiology based on time of insult and the anatomic site of visual loss.

RESULTS

The most common anatomic site of visual loss was retina, with a rate of 25.0%. The etiology according to the time of insult was unknown in 45.2% of the patients, of whom 20.2% had cataract. Genetic disorders were responsible in 25.0% of the patients. In 69.6% of the patients, the causes of visual impairment were considered either preventable or treatable, including cataract, retinopathy of prematurity, genetic disorders, and refractive errors.

CONCLUSIONS

A high percentage of our patients had avoidable causes of childhood blindness. Genetic counseling services, as well as national screening programs for amblyopia, red fundus reflex, and retinopathy of prematurity, should be established.

Causes of Severe Visual Impairment and Blindness: Comparative Data From Bhutanese and Laotian Schools for the Blind

PURPOSE

To determine and compare the major causes of childhood blindness and severe visual impairment in Bhutan and Laos.

DESIGN

Independent cross-sectional surveys.

METHODS

This survey consists of 2 cross-sectional observational studies. The Bhutanese component was undertaken at the National Institute for Vision Impairment, the only dedicated school for the blind in Bhutan. The Laotian study was conducted at the National Ophthalmology Centre and Vientiane School for the Blind. Children younger than age 16 were invited to participate. A detailed history and examination were performed consistent with the World Health Organization Prevention of Blindness Eye Examination Record.

RESULTS

Of the 53 children examined in both studies, 30 were from Bhutan and 23 were from Laos. Forty percent of Bhutanese and 87.1% of Laotian children assessed were blind, with 26.7% and 4.3%, respectively, being severely visually impaired. Congenital causes of blindness were the most common, representing 45% and 43.5% of the Bhutanese and Laotian children, respectively. Anatomically, the primary site of blinding pathology differed between the cohorts. In Bhutan, the lens comprised 25%, with whole globe at 20% and retina at 15%, but in Laos, whole globe and cornea equally contributed at 30.4%, followed by retina at 17.4%. There was an observable difference in the rates of blindness/severe visual impairment due to measles, with no cases observed in the Bhutanese children but 20.7% of the total pathologies in the Laotian children attributable to congenital measles infection.

CONCLUSIONS

Consistent with other studies, there is a high rate of blinding disease, which may be prevented, treated, or ameliorated.

A comparative analysis of avoidable causes of childhood blindness in Malaysia with low income, middle income and high income countries

To determine the avoidable causes of childhood blindness in Malaysia and to compare this to other middle income countries, low income countries and high income countries. Data were obtained from a school of the blind study by Patel et al. and analysed for avoidable causes of childhood blindness. Six other studies with previously published data on childhood blindness in Bangladesh, Ethiopia, Nigeria, Indonesia, China and the United Kingdom were reviewed for avoidable causes. Comparisons of data and limitations of the studies are described. Prevalence of avoidable causes of childhood blindness in Malaysia is 50.5 % of all the cases of childhood blindness, whilst in the poor income countries such as Bangladesh, Ethiopia, Nigeria and Indonesia, the prevalence was in excess of 60 %. China had a low prevalence, but this is largely due to the fact that most schools were urban, and thus did not represent the situation of the country. High income countries had the lowest prevalence of avoidable childhood blindness. In middle income countries, such as Malaysia, cataract and retinopathy of prematurity are the main causes of avoidable childhood blindness. Low income countries continue to struggle with infections such as measles and nutritional deficiencies, such as vitamin A, both of which are the main contributors to childhood blindness. In high income countries, such as the United Kingdom, these problems are almost non-existent.

The trend of retinopathy of prematurity in Malaysia from 1992 to 2001 based on a nationwide blind schools study

Retinopathy of prematurity (ROP) is one of the most important causes of childhood blindness worldwide. The trend of ROP in Malaysia was unclear because there was no national registry before 2002. The purpose of this study is to analyze ROP students of different ages in the schools for the blind in Malaysia in order to evaluate the trend of ROP from 1992 to 2001. Data were obtained from a previous survey of 24 blind schools. It was found that 78 students or 17.4% were blind/severely visual impaired as a result of ROP. There was a significant surge in the number of ROP students who were born in 1994 when the use of synthetic surfactants was first introduced in Malaysia; otherwise there was no increasing trend in the number of students with ROP. However, the percentage of ROP in total was increasing, which indicates that ROP is becoming a more important cause of childhood blindness in this country.

Childhood blindness and severe visual impairment in Malaysia: a nationwide study

AIM

To determine the causes of childhood blindness and severe visual impairment (BL/SVI) in schools for the blind in Malaysia.

METHODS

All children ≤ 15 years attending 24 schools for the blind throughout the country were examined using the WHO Prevention of Blindness Programme (WHO/PBL) eye examination record for children, and visual loss was classified according to the International Classification of Disease (ICD).

RESULTS

In all, 469 children were examined, of whom 448 (95.6%) had BL/SVI. The major causes of visual loss were retinal disorders (n=148, 33%; mainly retinopathy of prematurity (n=78, 17.4%)), cataract/pseudophakia/aphakia (n=77, 17.2%), and anomalies affecting the whole globe. (n=86, 19.2%). The major underlying etiology was undetermined (n = 193, 43.1%), followed by hereditary factors, 21.7% (mainly retinal dystrophies), and perinatal factors, 20.5%. More than 34 (7.6%) cases were considered potentially preventable and 192 (42.9%) potentially treatable.

CONCLUSION

Diseases of the retina are the major cause of visual impairment, with retinopathy of prematurity being an important avoidable cause. This reflects expansion of neonatal services in Malaysia, and improved survival of very low birth weight and preterm babies. Lens-related causes of visual impairment reflect the need to further improve pediatric ophthalmology services in Malaysia.

A survey of visual impairment and blindness in children attending four schools for the blind in Cambodia

PURPOSE

To identify the causes of blindness and severe visual impairment (BL/SVI) in children attending four schools for the blind in Cambodia and to provide spectacles, low vision aids, orientation and mobility training and ophthalmic treatment.

METHODS

Children < 16 years of age were recruited from all 4 schools for the blind in Cambodia. Causes of visual impairment and blindness were determined and categorized using World Health Organization methods.

RESULTS

Of the 95 children examined, 54.7% were blind (BL) and 10.5% were severely visually impaired (SVI). The major anatomical site of BL/SVI was the lens in 27.4%, cornea in 25.8%, retina in 21% and whole globe in 17.7%. The major underlying etiologies of BL/SVI were hereditary factors (mainly cataract and retinal dystrophies) in 45.2%, undetermined/unknown (mainly microphthalmia and anterior segment dysgenesis) in 38.7% and childhood factors in 11.3%. Avoidable causes of BL/SVI accounted for 50% of the cases; 12.9% of the total were preventable with measles being the commonest cause (8.1% of the total); 37.1% were treatable with cataracts and glaucoma being the commonest causes (22.6% and 4.8% respectively). More than 35% of children required an optical device and 27.4% had potential for visual improvement with intervention.

CONCLUSION

Half of the BL/SVI causes were potentially avoidable. The data support the need for increased coverage of measles immunization. There is also a need to develop specialized pediatric ophthalmic services for the management of surgically remediable conditions, to provide optometric, low vision and orientation and mobility services. Genetic risk counseling services also may be considered.

Childhood blindness in a rural population of southern India: prevalence and etiology

PURPOSE

To determine the prevalence and etiology of childhood blindness in a rural population in southern India through a population based study.

METHODS

A cross sectional, house-to-house survey to screen for childhood blindness included 14,423 children < 16 years. Blindness was defined as best corrected visual acuity < 3/60 in the better eye. The first stage of screening for blindness was done by interns under supervision of ophthalmology residents. Senior residents examined the referred cases from the first stage. Those detected to be blind were brought to a tertiary care hospital for detailed examination.

RESULTS

Fifty-four children were referred after first stage of screening of 13,241 children. Of these 14 were bilaterally blind giving a prevalence of 1.06/1000 (95% confidence interval (CI), 0.50 to 1.61); 6 (42.9%) had lens and related complications, 4 (28.6%) had globe anomalies (2 Microphthalmos and 2 Anophthalmos), 2 (14.3%) had retinal dystrophy and 1 (7.1%) each of glaucoma and optic atrophy. Among the parents of blind children, 71.4% (p = 0.002) had consanguineous marriage (83.3% in cataract blind children).

CONCLUSIONS

More than half of the blindness detected was potentially avoidable. Genetic counseling, early identification and access to tertiary care would reduce the burden of childhood blindness in the local community.

Causes and temporal trends of childhood blindness in Indonesia: study at schools for the blind in Java

AIMS

To ascertain the causes of blindness and severe visual impairment (BL/SVI) in schools for the blind in Java, to identify preventable and treatable causes and to evaluate temporal trends in the major causes.

METHODS

From a total of 504 students, 479 were examined. Data was collected using a modified World Heath Organization Prevention of Blindness (WHO/PBL) eye examination record for children.

RESULTS

The majority of the students (95%) were blind and 4.6% were severely visually impaired. The major anatomical site of BL/SVI was whole globe in 35.9%, retina in 18.9%, lens in 16.4% and cornea in 16.1%. The major underlying aetiology of BL/SVI was undetermined/unknown in 32.7% (mainly microphthalmia, anterior segment dysgenesis and cataract), hereditary factors 31.9% (mainly retinal dystrophies), and childhood disorders 28.5%. Avoidable causes of BL/SVI accounted for 59.9% of the total students, whereas measles blindness was the underlying condition for 23.1% of the preventable causes; cataract and glaucoma accounted for 15.5% and 8.2% of the treatable causes, respectively. Exploration on trends of SVI/BL among two different age groups <16 years and > or = 16 years suggested that childhood disorders and corneal factors have declined, while hereditary disorders have increased. Optic nerve disorder, although not counted as a major cause of blindness, seems to be on the increase.

CONCLUSIONS

More than half of the BL/SVI causes are potentially avoidable. Cataract and corneal disorders related to measles or vitamin A deficiency were the major treatable and preventable causes. Declining proportions of childhood factors and corneal disorders over a period of 10-20 years could reflect improved vitamin A supplementation and measles vaccination coverage in Indonesia. This finding, and the increased proportion of hereditary disease causes, could suggest improving levels of socioeconomic development and health care services.

The key informant method: a novel means of ascertaining blind children in Bangladesh

BACKGROUND

Most information on the causes of blindness has come from examining children in special education. To obtain a more representative population-based sample of children, a novel method was developed for ascertaining severe visually impaired (SVI) or blind (BL) children by training local volunteers to act as key informants (KIs).

OBJECTIVE

To compare the demography and cause of blindness in children recruited by KIs with other ascertainment methods.

METHOD

Children with SVI/BL were recruited in all 64 districts of Bangladesh. Three sources for case ascertainment were utilised: schools for the blind (SpEdu), community-based rehabilitation (CBR) programmes and KIs. All data were recorded using the standard WHO/PBL Eye Examination Record.

RESULTS

1935 children were recruited. Approximately 800 KIs were trained. The majority of the children were recruited by the KIs (64.3%). Children recruited by KIs were more likely to be female (odds ratio (OR) 1.6, p<0.001), of pre-school age (OR 14.1, p<0.001), from rural areas (OR 5.9, p<0.001), be multiply impaired (OR 3.1, p = 0.005) and be suffering from treatable eye diseases (OR 1.3, p = 0.005) when compared with those in SpEdu. Overall a child with an avoidable causes of SVI/BL had 40% (adjusted CI 1.1 to 1.7, p = 0.015) and 30% (CI 1.0 to 1.7, p = 0.033) higher odds of being ascertained using the KIs compared with SpEdu and CBR methods, respectively.

CONCLUSION

Using this innovative approach has resulted in one of the largest studies of SVI/BL children to date. The findings indicate that KIs can recruit large numbers of children quickly, and that the children they recruit are more likely to be representative of all blind children in the community.

Causes of blindness at the "Wiyata Guna" School for the Blind, Indonesia

AIM

To determine the anatomical site and patterns of cause of blindness in one of the biggest schools for the blind in Indonesia with a view to determining potentially preventable and treatable causes.

METHODS

165 students in one school for the blind in Bandung, Indonesia, were examined clinically and data reported using the WHO/PBL childhood blindness assessment form.

RESULTS

Most of the students (96.4%) were blind (BL); 3% were severely visually impaired (SVI). The major causes of SVI/BL in this study were: (1) corneal staphyloma, corneal scar, and phthisis bulbi (mainly attributed to infection) in 29.7%; (2) retinal dystrophies (mainly Leber congenital amaurosis, early onset retinitis pigmentosa) in 20.6%; (3) congenital and familial cataract (13.3%); (4) microphthalmus, anophthalmus (10.9%). The whole globe was the major anatomical site of visual loss (32.7%), followed by the retina (26.0%), cornea (17.6%), lens (13.3%), optic nerve (6.1%), and uvea (4.3%).

CONCLUSIONS

This is a small study in a selected population and the results should be interpreted with caution. This blind school study, adopting the WHO/PBL eye form for data analysing, is the first reported for Indonesia. Hereditary disease and infective causes of blindness are the predominant causes of blindness, accounting for 42.4% and 29.7%, respectively. This pattern of causes is a mixed pattern which lies in an intermediate position between the patterns seen in developing countries and those seen in developed countries. The importance both of preventive public health strategies and of specialist paediatric ophthalmic and optical services in the management of childhood blindness in Indonesia are therefore strongly suggested to cover the problems that exist.