Utility and Effectiveness of Computerised Motion Sensitivity Screening Tests in Rural Onchocercal Community Survey

BACKGROUND: Non-invasive tool of community diagnosis for onchocercal endemicity needs to be identified and ascertained for their utility and effectivity in order to facilitate the control of onchocerciacis in sub-Saharan Africa OBJECTIVE: To determine the utility and effectiveness of the Wu-Jones Motion Sensitivity Screening Test (MSST) in detecting optic nerve diseases in onchocercal-endemic rural Africa. METHODS: MSST was applied to sampled subjects in the selected communities of Raja in Sudan; Bushenyi in Uganda; Morogoro in Tanzania; and of Ikom; Olamaboro and Gashaka in Nigeria. Basically; six points within the central field of vision were repeatedly tested at 1/3 meter from the screen of a laptop computer in a room darkened. Motion sensitivity was expressed as a percentage of motion detected in the individual eye and this was averaged for the community. RESULTS: A total of 3;858 eyes of 2;072 patients were examined. Seventy-six percent of the subjects completed the test; at an average test time of 120.4 (66.7) seconds. The overall mean motion sensitivity of all eyes tested was 88.49 (17.49). At a cut-off point of 50; 6.4of all subjects tested were subnormal; while at 70cutoff; 13.3were subnormal. The highest proportion of 50cutoff sub-normality was recorded at Morogoro at 12.7. CONCLUSION: Motion Sensitivity Screening Test was widely accepted and easily administered to the rural and largely illiterate subjects studied. Our data suggest that the proportion of severe field defects by MSST in a community; with cutoff at 33; best correlates with optic nerve disease prevalence; while proportion of defect from a higher cut-off level at about 50; best correlates with overall ocular morbidity

Apoc impact assessment study: baseline prevalence and distribution of ocular Onchocerciasis in three ecological zones in Nigeria

During the APOC/WHO Impact Assessment studies in Nigeria held in 1998 and 1999, one thousand and sixty four randomly selected subjects underwent detailed eye examination in three selected sites namely, Cross River State (rain forest ecological zone), Taraba State (savanna ecological zone) and Kogi State (forest- savanna ecological zone). The general objective of the impact assessment studies was to evaluate the ophthalmological impact of onchocerciasis control (CDTI) in Nigeria, this paper highlights the public health significance of ocular onchocerciasis in three different ecological zones in Nigeria. The presence of ocular onchocerciasis was established in all the study sites, with a predominance of posterior segment manifestations, in the rain forest zone. A blindness prevalenc e of 2.4o/o was recorded in the study, with onchocerciasis being responsible for 13 out of the 43 (30.2%) bilaterally blind subjects identified. Onchocerciasis-induced blindness prevalence was relatively high in the rain forest and forest savanna zones of Cross River and Kogi States with Cross River State having the highest site-specific- prevalence (5/10) 50.0% of onchocercal blindness followed by Kogr with (5/12) 41.7%. Taraba site recorded only 27.3% (3121). Other conditions identified included glaucoma, optic nerve disease and cataract rates of which were also found to be high among the population (6.90/o,6.5 % and8.9oh respectively). Anterior segment onchocercal lesions, punctate and sclerosing keratitis were the predominant features of the infection in Taraba site (14.1o/o and 6.3% respectively), a savanna zone while posterior segment lesions were much more common in the forest zone of Cross-River site. Visual field measurements reflected the predominant posterior segment disease. The need to sustain the present efforts aimed at controlling onchocerciasis through mass ivermectin distribution is fuither highlighted. Integration of other Eye Care Programme for the conffol of glaucoma and cataract, into the community directed treatment initiative of APOC for onchocerciasis control should also be strongly considered, in order to drastically reduce the prevalence and incidence of ocular morbidity and blindness, in Nigeria, especially in the onchocerciasis endemic areas.