Three patients with typical features of mannosidosis and deficiency of alpha-mannosidase activity, who were examined ophthalmologically, had similar lenticular opacities. Corneal opacities were absent. Chamber angle and striking ophthalmoscopic anomalies occurred in two young patients who had normal electroretinograms. Two patients had strabismus. Conjunctival biopsy specimens morphologically confirmed the lysosomal nature of this disorder.