Ocular onchocerciasis was studied within the framework of a comprehensive multidisciplinary epidemiological investigation in an area of the Republic of Chad, Africa, where onchocerciasis was known to be highly endemic. The total population of a village was screened ophthalmologically, and 20% of that population was selected for a detailed ophthalmological examination. The two major eye conditions, blindness and corneal opacities, are examined for association with indices for onchocercal infection, ie, presence of subcutaneous nodules and recovery of microfilariae from skin snips. Blindness in the majority of the cases was due to onchocercal lesions of the anterior segment of the eye and amounted to 39% in persons over 40. The infrequency of posterior ocular lesions among those with ocular onchocerciasis contrasts with previous reports listing such lesions as a regular feature of ocular onchocerciasis.