Childhood blindness in Cyprus

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.

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.

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.

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.

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.

Pattern of childhood blindness and partial sight among Jordanians in two generations

A study of 260 Jordanians who became blind or visually impaired (according to World Health Organization standards) before the age of 15 years showed the dominant effects of genetically determined causes in two generations. Genetic causes were responsible for the visual impairment in 122 (77.7%) of 157 subjects in the group born after 1970 and for 69 (67%) of 103 in the group born before 1970. There was a statistically significant change in the overall pattern (genetic and acquired causes) of blindness between the two generations, and there was also a significant change in the pattern of acquired blindness alone. A decrease in corneal infections leading to blindness or visual disability in the younger generation was accompanied by an increase of trauma in the same age group. Parental consanguinity in those with genetically determined causes of visual impairment was high compared with those with nongenetic causes (79% vs 33.3%, P < .05). The autosomal recessive mode of inheritance was the most common pattern encountered (53.9%).

Clinical reinvestigation and linkage analysis in the family with Episkopi blindness (Norrie disease)

We present the results of a clinical and genetic reinvestigation of the Cypriot family affected by an X chromosomally inherited eye disease originally published by Taylor et al, who coined the term Episkopi blindness. The pedigree was extended to 160 members, including 16 affected males out of 48 males at risk for the disease, most of whom were seen by one of us (PA). Affected males are blind with no associated symptoms and apparently are not mentally retarded. Thirty-nine family members agreed to blood sampling for genetic investigations. RFLP analysis was performed using probes from the region known to be deleted in some Norrie patients and polymorphic markers (DXS77, DXS7, MAOA, DXS255) from the proximal short arm of the X chromosome. There was no deletion for any of the probes in the affected males. Linkage analysis yielded positive lod scores for all informative markers (Z (DXS255, theta = 0) = 6.54, Z (MAOA, theta = 0) = 2.23, Z (DXS7, theta = 0) = 2.13). Thus, the conclusion that Episkopi blindness and Norrie disease (NDP, MIM *310600) are the same entity based on clinical evidence is now reinforced by gene mapping.

Severe visual deficits in infancy in northern Israel: an epidemiological perspective

The characteristics of 193 legally blind children ranging in ages from birth to 4 years were analyzed. The overall incidence was 1/1000 live births; however, the ethnic specific incidence varies. All children were diagnosed before the age of 20 months and the most frequent alerting sign was lack of visual tracking. In 33.3%, the deficit was first suspected by a family member. A genetic etiology accounted for 38% of the cohort. The relative risk for an associated handicap was significant as well as the rate of hospitalizations for apparently unassociated diseases. It appears that both prevention and early detection could be achieved by a risk index.

Juvenile cataract with autosomal recessive inheritance. A study from the Aland Islands, Finland

Juvenile (including congenital and infantile) cataract occurs commonly as part of a more generalized or systematic condition, or as a component of a syndrome. Isolated juvenile cataract is a relatively rare disorder and the mode of inheritance is often autosomal dominant. Autosomal recessive transmission of isolated juvenile cataract is rare. The present paper is a report of 15 cases of juvenile cataract on the Aland Islands (Finland) with about 23,000 inhabitants. Twelve belong to 7 sibships of two different pedigrees and 3 cases are sporadic, of which we have found no genealogical connections in the last 6-10 generations to the two cataracta pedigrees. One of the sporadic cases presented an operated cleft palate and a chromosomal anomaly. In another sporadic case the mother probably had been infected with rubella during early gestation. In the third sporadic case the cataract was combined with partial aniridia, but he has several genealogical connections to one of the cataract pedigrees. Consanguinity between the parents was detected in 5 of the 7 sibships, in some even on various ancestral levels. Apart from the cataracts, all patients were healthy, with normal intellect, behavior, hearing, growth and development. They were neurologically intact and there were no ocular lesions apart from cataract. In the Alandic familial cases the cataracts appear to be an autosomal recessive trait. A family branch originating from southwestern Sweden and south Norway showed transmission of the cataract in three successive generations. The possibility of quasi-dominant inheritance is discussed against the background that autosomal recessive juvenile cataract may not be so rare as the small number of recorded cases would suggest.(ABSTRACT TRUNCATED AT 250 WORDS)

The burden of genetically determined eye disease

We determined the underlying aetiology of blindness for the registered blind population of the Province of Newfoundland and Labrador. In both 1981 and 1984 single-gene disorders accounted for 30% of total blindness and congenital defects for another 10-11%. Genetically determined conditions, diabetes, and senile macular degeneration (SMD) were the three leading causes of registration in each year, 1980-4. We calculated mean ages of registration and mean ages of death over the last four years for five major aetiological groups. Patients with genetic conditions were registered at a much younger age and had a correspondingly longer duration of blindness (21 years as compared with 5 years for either diabetes or SMD). Total 'person-years of blindness' was then calculated from the product of this duration of blindness and the total numbers registered in each group. This index shows that the overall individual and population impact of monogenic blindness is overwhelmingly greater than that of other causes (6849 person-years compared with 270 for diabetes and 430 for SMD). In view of this frequency and duration of monogenic blindness, and also of the substantial hereditary liability to relatively common causes of blindness such as glaucoma, diabetic retinopathy, and high myopia, we suggest that more attention needs to be paid to elucidating the genetic contribution to blindness.

Changing pattern of childhood blindness in Saudi Arabia

We studied 187 patients attending special educational institutions in Saudi Arabia who were blind before the age of 14. All patients underwent complete ophthalmological evaluation. The visual acuity in 31% of the patients was no light perception and in 58% light perception to counting fingers at 3 feet (1 m). 70% were blind before age 2. Prior to 1962 acquired diseases led to blindness in 75% of the patients. From 1962 onwards genetically determined diseases accounted for 84% of childhood blindness. 56% of this group were the product of consanguineous marriages. On the other hand in the group who acquired blindness only 14% were from consanguineous marriages (p less than 0.0001). We here describe guidelines for the prevention of childhood blindness in Saudi Arabia.

Defective vision among Kuwaiti students

A study, which was intended to find out the main causes of defective vision among Kuwaiti students, yielded the following results: The percentage of defective vision among 139,769 Kuwaiti students is 0.099%. Hereditary and genetic causes are responsible for 75.5% of the cases. Recessive inheritance account for 36.2% Autosomal dominant account for 34.3% Sex linked 9.5% Multifactorial 20.0% Forty-nine cases (of the total number of hereditary and genetic cases), i.e., 46.7% are the product of consanguineous marriages. Inflammatory causes account for 20.9%. The most common cause is neglected cases of muco-purulent and purulent conjunctivitis, becoming corneal ulcers and ensuing complications. This accounts for 62.1% of the total number of inflammatory causes. Traumatic, metabolic, and neoplastic causes account for 3.6%. Comparative data between England and Wales, Australia, Cyprus and Lebanon together with recommendations for improvement are discussed.

Complicated colobomatous microphthalmos in the BW rat: a new form of inherited retinal degeneration

A new model of inherited retinal degeneration has been found in the rat. It is inherited in association with a number of other ocular defects, including microphthalmos, coloboma, retinal dysplasia, optic nerve hypoplasia and/or aplasia, as well as medullation of the nerve fiber layer of the retina. Together, these abnormalities constitute a condition referred to as complicated colobomatous microphthalmos. This condition was originally discovered in the Bmn strain of rats but subsequently transferred to a new genetic background in the Bmn-wys strain of rats (BW). This facilitated the histological evaluation of both the developmental and degenerative ocular defects in the adult animals. A well defined pattern emerged relating eye size, optic nerve size and retinal histology. Normal-sized eyes had normal-sized optic nerves and normal retinal histology while intermediate-sized eyes with no optic nerves had uniformly thin retinas. In contrast, intermediate-sized eyes with small optic nerves had areas of both normal thickness and thin retina. All of these eyes developed retinal degeneration characterized by a late onset and slow progression associated with normal phagocytic activity in the pigment epithelium and a tendency for the rod outer segments to fragment into very thin structures rather than accumulate as lamellar debris. This indicates that the retinal degeneration in the BW model differs in many respects from the well studied RCS model.

Incidence and causes of blindness among the under 5 age group in Malawi

The expected incidence of blindness among children under 5 years of age in Malawi is 34 cases per 100 000 children. Direct ocular infections were responsible for the blindness in 32% of the cases (bacterial infections 20% and measles 12%). The instillation of traditional medicine in these cases worsened the ocular condition and induced in all of the cases a "hopeless" situation of total melting of the cornea and protrusion of the uvea. Congenital factors (excluding retinoblastomas) were responsible for 30-8% of the blind cases. Among these, 11 cases of congenital cataracts were successfully treated and will not appear as blind in future. A high incidence (9-3%) of cortical blindness was recorded. Trauma was implicated in 5-3%, while retinoblastoma was found in 8%. It is believed that adequate preventive measures should be able to lower the incidence of blindness among this age group to 5 cases instead of 34 per 100 000 children.

Causes of blindness among students in blind school institutions in a developing country

Out of 270 students in 17 blind school institutions in Malawi 73 per cent were blind before the age of three. The most common cause for the blindness was ocular infection (75-2 per cent). Meales, as a single cause, was responsible for 43-7 per cent of the cases and smallpox for 5-2 per cent. Bacterial infections were incriminated in 26-3 per cent of the cases. Most of these had received traditional medicine during the acute phase of the disease. Hereditary factors as causes of blindness were found in 7-8 per cent of the cases. These included congenital cataracts (2-6 per cent), optic atorphy of unknown origin (3-0 per cent), microphthalmos (1-5 per cent), and macular degeneration (0-7 per cent). Careful ophthalmological examination showed that in 37 cases an intervention could be attempted in order to improve the vision. In the 11 most favourable cases this was attempted, with the result that nine cases gained a useful vision of 4/60 to 6/18 in the better eye.

Childhood blindness in Lebanon

A survey in the Lebanese schools for the blind revealed that 77% of childhood blindness in the country was genetically determined. Two thirds of the hereditary blindness cases were due to autosomal recessive conditions; the high frequency of consanguineous marriages in Lebanon was the underlying cause of this finding. There is marked similarity in the etiology of childhood blindness in Cyprus and Lebanon, for both countries are somewhere between the highly developed countries.

Norrie's disease--differential diagnosis and treatment

A report on six children with Norrie's disease is presented. It is shown that the diagnosis can be established in sporadic cases if the early retrolental opacities are seen, and dementia or psychosis occurs after a normal infancy. Hearing loss is an important diagnostic sign. Children with Norrie's disease are more sensitive to disruption of family relationship than most other congenitally blind children.