Causes of severe visual impairment and blindness in children attending schools for the visually handicapped in the Czech Republic

AIMS

To describe the causes of severe visual impairment and blindness in children in schools for the visually handicapped in the Czech Republic in 1998.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Angiotensin-converting enzyme inhibitors and AT1-receptor antagonist restore nitric oxide synthase (NOS) activity and neuronal NOS expression in the adrenal glands of spontaneously hypertensive rats

During development of hypertension in spontaneously hypertensive (SHR) rats, the activity of adrenal nitric oxide synthase (NOS) was investigated. SHR and Wistar-Kyoto (WKY) rats were studied at different ages: 3-4, 7-8 and 12-13 weeks after birth. Basal NOS activity was measured by the ability of homogenate to convert [3H]-L-arginine to [3H]-L-citrulline. At all ages, SHR rats exhibited 50-60% reduction in NOS activity when compared to age-matched WKY rats. In a following study, SHR rats (12-13 weeks) were treated chronically with the angiotensin I-converting enzyme inhibitors (ACE-I) captopril or enalapril, or the AT1-receptor antagonist losartan (2 x 25, 10 and 60 mg/kg per day for 10 days, respectively). The total NOS activity and protein expression of NOS isoenzymes from adrenals were determined. The basal NOS activity and protein expression of neuronal NOS (nNOS) was significantly increased in treated SHR rats when compared to control rats. The isoforms endothelial NOS and inducible NOS were undetectable. We conclude that impaired NO synthesis in the adrenal glands of SHR rats may contribute to the onset and maintenance of hypertension. The upregulation of nNOS protein in the adrenal glands may be one of the mechanisms by which ACE inhibitors and AT1-receptor antagonists by restoring the NO synthesis, mediate their antihypertensive effects.

A method to determine the coverage of ivermectin distribution in onchocerciasis-control programmes

Onchocerciasis is a human filarial infection responsible for an estimated 750,000 blind and severely visually disabled people. In some African countries, this disease represents the main cause of blindness, with considerable socio-economic impact on the affected communities. Since the introduction of ivermectin as a microfilaricidal agent, there is hope that visual loss from onchocerciasis can be eliminated through community-based ivermectin-distribution programmes. The African Programme for Onchocerciasis Control (APOC) has now been initiated, by the World Health Organization and World Bank, to distribute ivermectin in 19 African countries where onchocerciasis is endemic. Estimates of ivermectin coverage in distribution programmes for onchocerciasis control have so far been based on the number of treatments given, in any one year, to a target population. There is a need for a standardized method to evaluate, measure and monitor coverage over time. In April 1996, a cluster random-sampling method was used to calculate coverage with ivermectin in an urban population of 30,000 people in the Central African Republic. The method was adapted from that used to determine coverage by the WHO Expanded Programme on Immunization. It proved to be inexpensive and easy to perform, requiring only local equipment and personnel. The method used and results obtained in Bossangoa and the potential use of the technique in other distribution programmes are discussed.

Blindness and visual impairment in a region endemic for onchocerciasis in the Central African Republic

AIMS

A population based survey of blindness and visual impairment was conducted in the district of Bossangoa, Central African Republic.

METHODS

A total of 48 communities were randomly selected, and 6086 people examined.

RESULTS

The prevalence of blindness (visual acuity in the better eye less than 3/60) was 2.2%, and visual impairment 3.0% (6/24 to 3/60 in the better eye). The major causes of blindness were onchocerciasis (73.1%), cataract (16.4%), trachoma (4.5%), and glaucoma (2.2%).

CONCLUSION

Around 95.5% of all blindness could potentially have been prevented or treated. Ivermectin mass distribution is hoped to prevent 50% of all forms of visual loss in the future.

[Etiology of secondary glaucoma at university clinics in Munich and Nairobi]

Glaucoma is one of the most common blinding diseases worldwide. For early detection and treatment of this insidious ailment investigations of risk factors are necessary, most of which require extensive technically demanding and time consuming procedures. Basic information on risk factors for the development of glaucomatous damage is essential for diagnosis of glaucoma, for the identification of groups at risk, and for the planning of prevention and intervention programs. Epidemiological data on secondary glaucomas is especially scarce, while at the same time the strict distinction between primary and secondary glaucomas has been abandoned with changing pathophysiological rationale. We compared the distribution of the main causes of secondary glaucomas in the university eye clinics in Munich and Nairobi, with the aim of finding possible risk factors and obtaining basic information that might be used in preventive programs. We examined 150 patients in Munich and 132 in Nairobi in 1991 and 1992. In addition to tests of visual acuity and intraocular pressure, gonioscopy, ophthalmoscopic assessment of the optic disc and perimetry were performed. Eyes with intraocular pressures above 22 mmHg and a detectable causative condition were selected for the study. The average age of the patients in Munich was 65 years, and most of them presented with glaucoma caused by iris neovascularization (42%), followed by exfoliation syndrome (14%), intraocular inflammation (11%), trauma (10%) and preceding ocular surgery (9%). In Kenya patients were significantly younger, with an average age of 41 years. Here most glaucomas were posttraumatic (40%); 70% of these patients were aged under 30. Other causes were earlier operations (17%), inflammation (16%), lentogenous changes (10%) and neovascularizations (10%).(ABSTRACT TRUNCATED AT 250 WORDS)