Ocular manifestations in children with HIV infection in Dar es Salaam, Tanzania.

A study of ocular lesions among 62 HIV seropositive and 47 HIV seronegative children admitted to the paediatric ward of Muhimbili Medical Centre was conducted. The prevalence of ocular manifestations was 38 per cent among the HIV seropositive children and 25 per cent among HIV seronegative children. While conjunctival lesions were common in both groups, fundus and corneal lesions were more common in HIV seropositive children. The common lesions were macular oedema, haemorrhages and sheathing of retinal vessels. In addition, HIV seropositive children had a 10 per cent prevalence of abnormal visual acuity compared with HIV seronegative children who had a 6 per cent prevalence. This study showed that ocular manifestations of HIV is high in African children and can be confounded by nutritional status. The commonest non-ocular manifestation was pulmonary tuberculosis and malnutrition. Children with HIV infection should have an ocular examination.

Epidemic optic neuropathy in primary school children in Dar es Salaam, Tanzania.

BACKGROUND: An epidemic of bilateral optic neuropathy is affecting large numbers of people aged between 10 and 40 in Dar es Salaam, the capital city of Tanzania. The disease is characterised by acute onset of bilateral visual impairment, bilateral impairment of colour vision, and a characteristic temporal pallor of the optic discs. The disease often occurs in association with peripheral neuropathy and sensorineural hearing loss. This report presents the first data on disease prevalence in adolescents, based on a rapid assessment of schoolchildren. METHODS: Three schools in Dar es Salaam were visited and all children aged between 10 and 16 were screened for the disease. RESULTS: The prevalence of bilateral optic neuropathy among the schoolchildren is estimated to be 1.0% (95% CI 0.5-1.4%). This suggests that 5000 children (95% CI 2600-7300) aged 10-16 in Dar es Salaam may have the disease. CONCLUSION: The results of this rapid assessment indicate this epidemic is a major public health problem. The prevalence of the disease in the community is likely to be far higher than found in this survey because children with the disease may have withdrawn from school. As the disease predominantly affects young adults, resulting in impaired vision and hearing, the economic and social consequences are enormous.

An epidemic of optic neuropathy in Tanzania: characterization of the visual disorder and associated peripheral neuropathy.

An epidemic of subacute bilateral visual failure has affected large numbers of teenagers and young adult Africans in coastal Tanzania since 1988. Previous work had indicated that many patients had sensory symptoms, but the nature of the neurological involvement was uncertain. The primary objective of this study was to characterize the accompanying neurological disorder. Furthermore, the nature of the visual loss was uncertain from previous reports as both retinopathy and optic neuropathy had been suggested. Full ophthalmic and neurological examinations were carried out at the Muhimbili University Hospital in Dar es Salaam. Nerve conduction studies, pattern electro-retinograms and cortical visually evoked responses and colour contrast sensitivity tests were carried out. Thirty eight young Africans and 12 controls were included in the study. The characteristic fundus picture was symmetrical temporal optic atrophy, and thinning of the caeco-central nerve fibre layer. Fluorescein angiography was normal. The electrophysiological and colour contrast sensitivity tests confirmed optic neuropathy in the majority of cases but primary retinal involvement was indicated in some. Neurological examination and nerve conduction measurements showed evidence of a peripheral neuropathy in 47% of the patients. The peripheral neuropathy is likely to have involved large fibres (from the nerve conduction studies) but the symptoms suggest small fibre loss also. 42% had developed hearing loss. Urinary thiocyanate levels were uniformly low. Serum was negative for antibodies to HTLV-1. DNA analysis from three cases was negative for three known mutations associated with Leber's hereditary optic atrophy (11778, 3460 and 14484). This entity, occurring predominantly in a young age group, does not correspond closely to other tropical neurological syndromes previously described from East Africa although it is clinically very similar to Strachan's syndrome (originally described in the Caribbean and more recently in prisoners of war) and also to an epidemic of optic and peripheral neuropathy that has recently occurred in Cuba. The aetiology has not yet been determined. A micronutrient deficiency is likely but has not been established.

Chronic cyanide poisoning in relation to blindness and tropical neuropathy.

Within a group of 20 patients showing optic atrophy and macula degeneration, 14 patients could be examined for neurological and audiometric defects. In 6 patients neurological signs and symptoms were observed. Nine patients reported loss of hearing and in 3 of them a severe perceptive deafness was seen in the audiogram. In 3 of the 14 patients a combination of severe neurologic and audiologic symptoms developed and in two of them a high thiocyanate concentration in serum was observed. The occurrence of perceptive deafness and posterior column sensory loss in the lower extremities in four of the patients made the diagnosis of polyneuropathy the most plausible. Although a similarity to chronic myelopathies caused by nutritional cyanide poisoning cannot be denied, the mean thiocyanate concentration in plasma 24 mumol/L (1.39 mg/L), and the cyanide levels in the blood 0.09 mumol/L (2.3 micrograms/L) were substantially lower than those found in other individuals during periods of extreme drought in which food only consisted of the bitter variety of cassava. The role of cyanide in the etiopathology of this polyneuropathy is unknown.

Congenital adduction palsy and synergistic divergence: a clinical and electro-oculographic study.

We studied two patients with a peculiar congenital disturbance of ocular motility in which the horizontal movements of the left eye were always opposite the normal expected direction. The common features were: (1) congenital monocular adduction palsy and exotropia of the left eye; (2) simultaneous abduction of both eyes (divergence) on attempted dextroversion; (3) ocular torticollis, head turned to the right; and (4) inverse nystagmus of the left eye, occurring spontaneously as well as during optokinetic and vestibular testing. Clinical and electrooculographic findings suggested a close relationship to Duane's retraction syndrome and supported the concept that innervational mechanisms were responsible for the phenomenon.

Optic atrophy in Wolfram syndrome.

The clinical and electrophysiologic findings in 11 cases of Wolfram syndrome are presented. These findings suggest that optic atrophy in Wolfram syndrome is not secondary to retinal pathology, but probably represents part of a generalized degeneration of neural structures. The relationship of diabetes mellitus to this process of neural degeneration remains unclear.

Evaluation of colour vision, mesopic vision, visual evoked potentials and lightness discrimination in adult amblyopes.

This is a study conducted on thirty adult strabismic and anisometropic amblyopes using colour vision tests, the lightness discrimination test, mesopic vision and visual evoked responses, in order to determine the probable site of the amblyopic defect. The results showed that, in its progressed stages, amblyopia is associated with eccentric fixation, abnormal hue discrimination, disturbed lightness discrimination and mesopic vision, and attenuation of the amplitude of the pattern visual evoked response. It is suggested that these abnormalities result from a defect involving the extrastriate higher visual association areas 18 & 19 of Brodmann.

Cryosurgery in vernal catarrh.

Thirty four cases of vernal catarrh were treated with cryosurgery. During a mean follow up of 5 months this resulted in complete relief of symptoms and flattening of papillae in 94% of cases. Significant improvement in vision occurred in three out of six patients with decreased vision. Cryosurgery is recommended as a first line treatment for vernal catarrh.