MedGen

Blindness is the condition of lacking visual perception defined as a profound reduction in visual perception. On the 6m visual acuity scale, blindness is defined as less than 3/60. On the 20ft visual acuity scale, blindness is defined as less than 20/400. On the decimal visual acuity scale, blindness is defined as less than 0.05. Blindness is typically characterized by a visual field of no greater than 10 degrees in radius around central fixation. [from HPO]

A form of filariasis, caused by the parasitic worm <i> Onchocerca volvulus</i>, transmitted by the black fly. The infection can either be asymptomatic or manifest as an ocular disease (river blindness) with itchy eyes, erythema, photophobia, onchodermatitis or onchocercal skin disease (classified into acute papular, chronic papular, lichenified, atrophic, and depigmentated) and onchocercomas (over bony prominences). Other classic clinical manifestations are ichthyosis-like lesions (''lizard skin'') and ''hanging groin'', which may be associated with lymphadenopathy. [from ORDO]

A disease of the lymphatic vessels of the lower extremities that is caused by chronic exposure to irritant soils. [from MONDO]