Causes of blindness in children attending four schools for the blind in Thailand and the Philippines. A comparison between urban and rural blind school populations

Evaluating the efficacy of UNav: A computer vision-based navigation aid for persons with blindness or low vision

UNav is a computer-vision-based localization and navigation aid that provides step-by-step route instructions to reach selected destinations without any infrastructure in both indoor and outdoor environments. Despite the initial literature highlighting UNav's potential, clinical efficacy has not yet been rigorously evaluated. Herein, we assess UNav against standard in-person travel directions (SIPTD) for persons with blindness or low vision (PBLV) in an ecologically valid environment using a non-inferiority design. Twenty BLV subjects (age = 38 ± 8.4; nine females) were recruited and asked to navigate to a variety of destinations, over short-range distances (<200 m), in unfamiliar spaces, using either UNav or SIPTD. Navigation performance was assessed with nine dependent variables to assess travel confidence, as well as spatial and temporal performances, including path efficiency, total time, and wrong turns. The results suggest that UNav is not only non-inferior to the standard-of-care in wayfinding (SIPTD) but also superior on 8 out of 9 metrics, as compared to SIPTD. This study highlights the range of benefits computer vision-based aids provide to PBLV in short-range navigation and provides key insights into how users benefit from this systematic form of computer-aided guidance, demonstrating transformative promise for educational attainment, gainful employment, and recreational participation.

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.

Retinopathy of prematurity in Indonesia: Incidence and risk factors

BACKGROUND

Retinopathy of prematurity (ROP) is a vaso-proliferative disease of the eye, which mainly affects preterm newborn infants with an incompletely vascularized retina. The incidence of ROP has increased in industrialized countries due to the increased survival of extremely low birth weight (ELBW) infants. ROP is also increasing in developing countries like Indonesia, where it is most likely due to the improved survival of ELBW infants.

OBJECTIVE

To ascertain the incidence of ROP and possible risk factors associated with the development of ROP in preterm infants in Indonesia.

METHODS

We reviewed the literature on the incidence and potential risk factors for the development of ROP in Indonesia, obtained data from three referral eye clinics and added data from our institution.

RESULTS

The reported incidence of all stages of ROP in infants with a gestational age of <32 weeks ranged from 18-30%. One study showed that ROP also occurred at older gestational ages. Blindness due to ROP was seen in infants up to 35 weeks and with a birth weight of 2000 g.

CONCLUSION

Retinopathy of prematurity is an important cause of ocular morbidity and blindness in Indonesia. The overall incidence of ROP in infants born below 32 weeks in Indonesia is higher than in developed countries, and it is seen in infants with older gestational ages. This might be due to a less strict monitoring during the use of oxygen in Indonesia compared to industrialized countries.

Validation of the existing modified screening criteria for detection of all cases of Retinopathy of Prematurity in preterm babies - 11 year study from a governorate referral hospital in Oman

PURPOSE

To study appropriateness of our modified screening criteria for detection of all cases of Retinopathy of Prematurity (ROP) among preterm babies.

METHOD

Retrospective observational cohort study among preterm neonates who underwent ROP screening as per set protocol for 11 years at Nizwa Hospital, Al Dhakilya Governorate, Oman. We screened all babies with gestational age ⩽32 weeks or BW ⩽ 1500 g. Preterm babies >32 weeks of GA or BW > 1500 g with unstable clinical course believed to be at high risk by the attending neonatologist also were screened.

RESULTS

During the study period 528 babies were screened for ROP of which 76 babies were excluded due to death, associated congenital ocular malformation and loss for follow-up either due to transfer to other institution or defaulting. Thus 452 babies were included in the final analysis. Incidence of ROP was 46.4% of which 27.9% had mild ROP, 11.3% had severe ROP which regressed and 7.3% had severe ROP who were treated. The incidence of ROP among infants with GA < 26 wks, 26-28 wks, 29-30 wks, 31-32 wks and above 32 weeks was 100.0%, 80.0%, 59.3%, 34.4% and 19.4% respectively. 56 babies of this cohort belonged to Extended (modified) criteria group. Among these 12 babies had ROP out of which 9 had mild ROP and 3 had severe ROP. Among cases with severe ROP, two cases regressed spontaneously and one case needed treatment. Multivariate analysis using stepwise regression model showed statistically significant association of GA and BW to development of ROP. We would have missed few babies with ROP if we had followed other criteria.

CONCLUSION

Our modified screening criteria seem to be appropriate as no infant with severe ROP was missed during the study period. Incidence of severe ROP among babies in the extended criteria group (5.4%) is low but significant compared to lower gestational age. We plan to formulate a scoring system following all risk factor analysis to enable us to optimize the number of infants screened. Detection of all babies with ROP is important as they need long-term follow-up for the timely detection and management of associated ocular comorbidities.

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.

Trends in the incidence and causes of severe visual impairment and blindness in children from Israel

PURPOSE

To describe trends in the incidence and causes of legal childhood blindness in Israel, one of the few countries worldwide that maintain a national registry of the blind.

METHODS

We performed a historical cohort study of annual reports of the National Registry of the Blind (NRB) between 1999 and 2013. All data regarding demographic information, year of registration and cause of blindness of children 0-18 years of age registered for blind certification were obtained from the annual reports of the NRB. Causes of legal blindness analyzed were optic atrophy, retinitis pigmentosa, retinopathy of prematurity (ROP), albinism, other retinal disorders, cataract, and glaucoma. The main outcome measure was the incidence of new cases of certified legal blindness.

RESULTS

The incidence of newly registered legally blind children in Israel almost halved from 7.7 per 100,000 in 1999 to 3.1 per 100,000 in 2013. The decline was mainly attributable to a decreased incidence of blindness resulting from retinitis pigmentosa and ROP. The incidence of registered cases due to cerebral visual impairment increased.

CONCLUSIONS

During the past decade the incidence of severe childhood visual impairment and blindness declined in Israel. A continuous decline in consanguineous marriages among the Jewish and Arab populations in Israel may have contributed to the decrease in the rate of vision loss due to retinitis pigmentosa in children.

Survey of low vision among students attending schools for the blind in Nigeria: a descriptive and interventional study

Purpose:

The aim of this study is to determine the prevalence of low vision among students attending all the schools for the blind in Oyo State, Nigeria. The study set out to determine the proportion of students with low vision/severe visual impairment after best correction, to determine the causes of the low vision, to document the associated pathologies, to determine the types of treatment and visual aid devices required, and to provide the visual aids needed to the students in the schools.

Materials and Methods:

All schools students for the blind in Oyo State were evaluated between August 2007 and January 2008. All the students underwent a thorough ophthalmic examination that included measurement of visual acuity, retinoscopy and subjective refraction, tests for visual aids where indicated, and a structured questionnaire was administered.

Results:

A total of 86 students were included in the study and the mean age was 19.4 ± 8.19 years. Twenty six (30%) were under 16 years of age. The most common cause of blindness was bilateral measles keratopathy/vitamin A deficiency (VAD) in 25 students (29.1%). The most common site affected was the cornea in 25 students (29.1%), the lens in 23 (26.7%), and the retina/optic nerve in 16 (18.6%). Preventable blindness was mainly from measles keratopathy/VAD (29.1%). Eleven students benefited from refraction and correction with visual aids; two having severe visual impairment (SVI), and nine having visual impairment (VI) after correction.

Conclusion:

The prevalence of low vision in the schools for the blind in Oyo State is 2.3%, while the prevalence of visual impairment is 10.5%. These results suggest that preventable and treatable ocular conditions are the source of significant childhood blindness in Oyo State.

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.

Serum retinol binding protein as an indicator of vitamin A status in cirrhotic patients with night blindness

BACKGROUND/AIM

Vitamin A deficiency is known to be associated with night blindness. Plasma retinol binding protein (RBP) estimation highly correlates with plasma retinol concentration to predict vitamin A status. Serum RBP estimation is reasonably simple, inexpensive, and highly applicable in less technologically developed settings. We studied the correlation of plasma vitamin A levels (by RBP estimation) and ocular manifestation in patients with liver cirrhosis.

MATERIALS AND METHODS

This prospective, cohort study included 137 patients with liver cirrhosis. Ocular manifestations in these patients were recorded along with detailed history and clinical examination. Blood samples after overnight fasting were measured for RBP levels. The characteristics of cirrhotic patients with and without eye findings were compared.

RESULTS

Out of 137 patients, 55% were males. The causes of cirrhosis were hepatitis C virus in 61%, hepatitis B virus in 32%, alcoholics in 3%, and primary biliary cirrhosis in 3%. Ocular manifestations were found in 47% patients. RBP levels were found to be low in 44%, normal in 40%, and relatively high in 16% patients. Low levels of RBP compared to normal were associated with opthalmological findings of hypovitaminosis A (P < 0.001).

CONCLUSION

The measurement of plasma RBP as an alternative to serum retinol estimation to detect relative hypovitaminosis A is simple, easy and reliable. Vitamin A level is strongly related to the severity of liver disease. Opthalmological manifestations in patients with liver cirrhosis may be preventable by early detection of hypovitaminosis A with serum RBP level, but larger studies are required before recommendation of vitamin A supplementation.

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.

Characteristics of severe retinopathy of prematurity patients in China: a repeat of the first epidemic?

AIM

To describe the characteristics of babies treated for severe retinopathy of prematurity (ROP) in a tertiary referral unit in China, to provide information to assist in determining screening criteria.

METHODS

Information on consecutive babies referred to one eye department for treatment of stage 3 (prethreshold and threshold disease), and stages 4 and 5 ROP between January 2001 and May 2005 were retrieved from medical records.

RESULTS

Data from 114 babies were analysed. The number of babies treated increased from nine in 2001 to 52 in 2004. The numbers of infants in each stage of ROP were as follows: stage 3, 40 babies; stage 4, 19 babies, and stage 5, 55 cases. The mean gestational age (GA) was 29.8 (SD 1.9) weeks (range 26-34 weeks) and the mean birth weight (BW) was 1432 (319) g (range 760-2500 g). 31 babies had BWs more than 1500 g (27.2%). 10 cases (8.8%) had GAs more than 32 weeks, and 82 (71.9%) had GAs more than 28 weeks. Overall, 18 (16.2%) infants exceeded UK screening criteria, and 34 (30.4%) exceeded the criteria used in the United States. The median age at presentation was 5.5 months (range 1-72 months).

CONCLUSION

Comprehensive screening programmes for ROP are urgently needed in China. Screening criteria recommended by the American Academy of Pediatric Ophthalmology and Strabismus and the Royal College of Ophthalmologists, United Kingdom, may not be suitable for China where bigger, more mature babies are developing severe disease.

Measles blindness

Measles remains a major problem in developing countries, where it affects an estimated 30 million children a year and causes up to one million deaths annually. Measles blindness is the single leading cause of blindness among children in low income countries, accounting for an estimated 15,000 to 60,000 cases of blindness per year. There is a close synergism between measles and vitamin A deficiency that can result in xerophthalmia, with corneal ulceration, keratomalacia, and subsequent corneal scarring or phthisis bulbi. High-dose oral vitamin A supplementation is recommended for all children with measles in developing countries. Higher measles immunization coverage to interrupt measles transmission and interventions aimed at improving vitamin A nutriture of children are the main strategies to prevent measles blindness.

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.

Retinopathy of prematurity: recent advances in our understanding

Retinopathy of prematurity (ROP) has been recognised as an important cause of childhood visual impairment and blindness since the 1940s when improved facilities and treatment increased the survival rate of premature infants. Although its incidence and severity have been decreasing in developed countries over the past two decades, both are increasing in developing nations. ROP is consequently targeted as an important but avoidable disease. This review provides an updated summary and discussion of much of the work that has been produced through population, animal, cell culture, and genetic research. The authors examine the prevalence, risk factors, and possible causes of the disease with a particular focus on genetic studies. They conclude that while significant reductions in the disease have occurred in developed countries, further research is required to fully understand and prevent the disease. In the meantime, development and implementation of appropriate screening and treatment strategies will be critical in reducing blindness in developing countries.

Retinopathy of prematurity: recent advances in our understanding

Retinopathy of prematurity (ROP) has been recognised as an important cause of childhood visual impairment and blindness since the 1940s when improved facilities and treatment increased the survival rate of premature infants. Although its incidence and severity have been decreasing in developed countries over the past two decades, both are increasing in developing nations. ROP is consequently targeted as an important but avoidable disease. This review provides an updated summary and discussion of much of the work that has been produced through population, animal, cell culture, and genetic research. The authors examine the prevalence, risk factors, and possible causes of the disease with a particular focus on genetic studies. They conclude that while significant reductions in the disease have occurred in developed countries, further research is required to fully understand and prevent the disease. In the meantime, development and implementation of appropriate screening and treatment strategies will be critical in reducing blindness in developing countries.

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

A national study was conducted in children attending six schools for the blind in Malaysia to identify the anatomical site and underlying causes of blindness (BL) and severe visual impairment (SVI), with a view to determine the potentially preventable and treatable causes so that appropriate control measures can be implemented in the future. The standardized clinical examination of eyes was performed and the findings were recorded on the WHO Prevention of Blindness Programme eye examination record form for children with blindness and low vision. A total of 358 children aged between 7 and 17 years were examined, of whom 332 (92.7%) were blind or severely visually impaired. The results relate to these 332 children. Lens was the major anatomical site (22.3%) of visual loss followed by retina (20.8%), whole globe (17.2%), cornea (15.1%), optic nerve (8.7%) and uvea (5.1%). Glaucoma was responsible for BL/SVI in 7.2% and others in 3.6% of cases. Hereditary diseases were responsible for visual loss in 29.5%, intrauterine factors in 4.5%, perinatal factors in 9% and childhood factors in 7.8% of cases. However, the aetiology was unknown in 49.1% of cases which included congenital anomalies of the globe. Childhood cataract and corneal scarring are major treatable causes of BL/SVI that can benefit from future intervention strategies. Perinatal screening for intrauterine factors and hereditary eye diseases, and appropriate interventional therapy will help in reducing the prevalence of childhood blindness.

Ocular manifestation of vitamin A deficiency among Orang asli (Aborigine) children in Malaysia

This study determined the prevalence of ocular manifestation of vitamin A deficiency in Orang Asli (Aborigine) children. Night blindness was found in 16.0% of the children, conjunctiva xerosis in 57.3%, Bitot's spot in 2.8%, corneal xerosis in 0.5% and corneal scars in 5.6%. These findings show that history of night blindness had sensitivity, specificity and predictive value (positive) of 47.2, 98.1 and 96.2%, respectively, compared with the standard diagnosis procedure using luxometer readings.

Causes of childhood blindness in the People's Republic of China: results from 1131 blind school students in 18 provinces

AIMS

To determine the anatomical site and underlying causes of blindness and severe visual impairment in children under 16 years of age in special education in the People's Republic of China with a view to determining potentially preventable and treatable causes.

METHODS

A national study of children attending schools for the blind in China was conducted between April and June 1998 using the WHO Prevention of Blindness Programme (WHO/PBL) eye examination record for children with blindness and low vision. Eight Chinese ophthalmologists attended a training workshop before conducting the study. 36 blind schools in 18 provinces of China were included.

RESULTS

1245 children aged between 5 and 15 years were examined, of whom 1131 (91%) were blind or severely visually impaired (visual acuity less than 6/60 in the better eye). The commonest anatomical sites of visual loss were whole globe (mainly microphthalmos) 25.5% and retina (mainly dystrophies) 24.9%. Lens was the major site in 18. 8%, optic nerve in 13.6%, and glaucoma in 9%. Corneal scarring was not a major cause of visual loss. The aetiology was unknown in 52.9%, hereditary factors were responsible in 30.7%, and childhood causes in 14%. 15% of cases were considered potentially preventable and 22. 5% potentially treatable.

CONCLUSION

The pattern of childhood blindness seen in this study is likely to reflect the improved health and socioeconomic status of China but may partly reflect bias in admission to, and location of, blind schools, with higher socioeconomic groups overrepresented. Nutritional and infective causes of blindness are uncommon, and hereditary and unknown factors are now the predominant causes.

Childhood blindness in Uzbekistan

PURPOSE

To elucidate the aetiology of childhood blindness in the Republic of Uzbekistan and to assess the needs for future provision of ophthalmic services for children.

METHODS

Six hundred and seventy-one children in seven schools for the blind and visually impaired throughout Uzbekistan were examined using the WHO/PBL (World Health Organization Prevention Of Blindness) childhood blindness proforma. The locations were chosen to give a representation of the major areas of population within the country.

RESULTS

Of the 671 children examined, 506 (75.4%) were blind or severely visually impaired (corrected visual acuity of less than 6/60 (20/200) in the better eye). Cataract-related blindness (35%), retinal dystrophies (24%) and microphthalmos (23%) formed the three largest diagnostic categories.

CONCLUSIONS

The commonest avoidable cause of blindness was found to be cataract; the cause of poor vision may be due to unoperated cataract, aphakia, amblyopia or post-operative capsular fibrosis. The high proportion of retinal dystrophies may be related to the common practice of consanguineous marriage. The frequent finding of microphthalmos is discussed and compared with findings from other surveys. Glaucoma accounted for approximately 5% of the avoidable blindness.

Results of screening low-birth-weight infants for retinopathy of prematurity

Retinopathy of prematurity (ROP) continues to be an important cause of potentially preventable blindness worldwide. The pattern of visual impairment from ROP in some middle-income countries--high rates affecting larger and more mature infants--resembles that seen in more developed countries two decades ago and has been called a "third epidemic" of the disease. Expert bodies in the United Kingdom and the United States have recently issued new guidelines for screening for ROP that utilize both birth weight and gestational age criteria. Studies in both countries suggest these criteria might be further revised to decrease time spent on screening without missing any significant disease. Population-based follow-up studies of extremely preterm infants suggest that although more preterm infants are surviving, with adequate screening and treatment, rates of blindness from ROP may be declining. Further information on the longer-term impact of ROP comes from a number of studies and particularly the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) study. The risk of both myopia and strabismus is increased with any and each higher stage of ROP. Evidence is emerging that laser therapy for threshold disease may be associated with better visual outcome than cryotherapy, although complications following the former remain a concern. The fight against ROP may be enhanced by new information on the pathogenesis, including possible genetic predisposition and the role of vascular endothelial growth factor.

Childhood blindness

PURPOSE

The objective of this study was to summarize available data regarding pediatric blinding diseases worldwide and to present the most up-to-date information on childhood blindness in the United States.

METHODS

We obtained data from a complete search of the world literature and from direct contact with each of the schools for the blind in the United States.

RESULTS

Five percent of worldwide blindness involves children younger than 15 years of age; in developing countries 50% of the population is in this age group. By World Health Organization criteria, there are 1.5 million children worldwide who are blind: 1.0 million in Asia, 0.3 million in Africa, 0.1 million in Latin America, and 0.1 million in the rest of the world. There are marked differences in the causes of pediatric blindness in different regions, apparently based on socioeconomic factors. In developing countries, 30% to 72% of such blindness is avoidable, 9% to 58% is preventable, and 14% to 31% is treatable. The leading cause is corneal opacification caused by a combination of measles, xerophthalmia, and the use of traditional eye medicine. There is no national registry of the blind in the United States, and most of the schools for the blind do not keep data regarding the cause of blindness in their students. From those schools that do have this information, the top 3 causes are cortical visual impairment, retinopathy of prematurity, and optic nerve hypoplasia. There has been a significant increase in both cortical vision loss and retinopathy of prematurity in the past 10 years.

CONCLUSIONS

There are marked regional differences in the prevalence and causes of pediatric blindness, apparently based on socioeconomic factors that limit prevention and treatment schemes. In the United States the 3 leading causes of pediatric blindness are cortical visual impairment, retinopathy of prematurity, and optic nerve hypoplasia. There is a need for more complete and more uniform data based on the established World Health Organization reporting format.

Retinopathy of prematurity in middle-income countries

BACKGROUND

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.

METHODS

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.

FINDINGS

The proportion of severe visual impairment or blindness due to ROP ranged from 0% in most African countries to 38.6% in Cuba.

INTERPRETATION

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.

Aetiology of childhood cataract in south India

AIM

To identify the causes of childhood cataract in south India with emphasis on factors that might be potentially preventable.

METHODS

A total of 514 consecutive children with cataract attending an eye hospital outpatient clinic were examined and their parents interviewed by a trained interviewer using a standardised questionnaire in the local language. Serology was performed on children under 1 year of age to detect congenital rubella syndrome (CRS). Other investigations were performed as clinically indicated.

RESULTS

Of the 366 children with non-traumatic cataract 25% were hereditary, 15% were due to congenital rubella syndrome, and 51% were undetermined. In children under 1 year of age 25% were due to rubella and cataract of nuclear morphology had a 75% positive predictive value for CRS. Mothers of children in the undetermined group were more likely to have taken abortifacients than a group of age matched controls (p = 0.1) but use of other medications in pregnancy was similar in both groups. Of the 148 (29%) children with traumatic cataracts three quarters were over the age of 6 years. Stick injuries were responsible for 28%, thorn injuries for 21%, and firecrackers for 5%.

CONCLUSION

Nearly half of non-traumatic cataract in south India is due to potentially preventable causes (CRS and autosomal dominant disease). There is need for further work to identify the factors leading to childhood cataract in at least half of the cases for which no definite cause can as yet be determined.

Infantile cataracts

Cataracts are one of the most treatable causes of visual impairment during infancy. Recent epidemiological studies have shown that they have a prevalence of 1.2 to 6.0 cases per 10,000 infants. The morphology of infantile cataracts can be helpful in establishing their etiology and prognosis. Early surgery and optical correction have resulted in an improved outcome for infants with either unilateral or bilateral cataracts. While contact lenses continue to be the standard means of optically correcting an infant's eyes after cataract surgery, intraocular lenses are gaining in popularity as an alternative means of optically correcting these eyes. Post-operative complications occur more commonly after infantile than adult cataract surgery and many of these complications do not develop until years later. As a result, it is critical that children be followed closely on a long term basis after infantile cataract surgery.

Causes of childhood blindness in Sri Lanka: results from children attending six schools for the blind

AIM

The survey aimed to identify the major treatable or preventable causes of visual loss in children attending blind schools in Sri Lanka so that appropriate control measures can be implemented.

METHOD

A total of 226 children with blindness (BL) or severe visual impairment (SVI) attending six schools for the blind were examined and details recorded using the WHO standard reporting form.

RESULTS

Cataract was responsible for 17% of BL/SVI and was the commonest 'avoidable' cause of childhood blindness. Bilateral microphthalmos accounted for one quarter of BL/SVI. Vitamin A deficiency was not a significant cause of visual morbidity.

CONCLUSION

The pattern of childhood blindness seen in this study is typical of a growing number of south east Asian countries which are developing rapidly. Childhood cataract is a major avoidable cause that can benefit from future intervention strategies.

Hereditary disease as a cause of childhood blindness: regional variation. Results of blind school studies undertaken in countries of Latin America, Asia and Africa

There is evidence from developed countries that genetic disease is the major cause of childhood blindness. Little data are available from most developing and newly industrialised countries concerning the relative importance of hereditary diseases as a cause of childhood blindness. Children in schools for the blind in 13 countries of Africa, Latin America and Asia were examined between 1990 and 1994 using a standardised method The anatomical site of abnormality and underlying aetiology were analysed for children with a corrected acuity in the better eye of less than 6/60 (severe visual impairment and blindness, svi/BL). In these countries II-39% of svi/BL was attributed to genetic disease. Genetic diseases were responsible for a higher proportion of childhood visual loss in countries with higher levels of socio-economic development. An autosomal recessive mode of inheritance was reported in 22-52% of children with genetic disease. Retinal dystrophies were the commonest form of genetic eye disease (49-80%) in all countries apart from Thailand and the Philippines where cataract was the commonest (43.9%). The role of consanguinity, and opportunities for further research are discussed.