Visual Field Measurement with Motion Sensitivity Screening Test in an Onchoendemic Area after Ivermectin Treatment

Abstract

Eye disease is a frequent complication of onchocerciasis in countrise where the disease is highly endemic. It has been shown that early ocular lesions which manifest as visual field defects or reduction in visual acuity can be reversed following treatment with ivermectin. At the community level, it is important to detect populations with eye disease early and also follow their progress during mass treatment. The Motion Sensitivity Screening Test (MSST) has been suggested as a potential useful method for monitoring visual field in onchocerciasis endemic communities. In this study the aim was to determine the usefulness of this test as a quick and simple method for monitoring visual field changes in an onchocerciasis endemic forest-savanna area following mass treatment with ivermectin. The method was evaluated in four villages over a two-year period. A total of 439 individuals had computerized visual field measurements yearly for up to two years after mass treatment with ivermectin and the results was compared with the pre-treatment values. The results showed an overall significant improvement in the motion sensitivity of the sample population after treatment with ivermectin. Lower percentages of the sample population than at baseline had abnormal teat within a year of treatment with ivermectin. By contrast the visual field tested by confrontation in all the subjects did not show any change over the same period. In conclusion, MSST was found to be a quick and easy-to-understand computer perimeter that could be useful in monitoring visual field changes in onchocerciasis endemic rural community during mass treatment with ivermectin.

Nigerian Journal of Ophthalmology Vol. 9, No.1 (August 2001): pp 40-45

KEY WORDS: Onchocerciasis, ivermectin, visual field, motion sensitivity screening test, monitory.