Sialidosis (neuraminidase deficiency) types I and II: neuro-ophthalmic manifestations.

The clinical details and ophthalmologic findings of two siblings with neuraminidase deficiency (sialidosis) are presented. One patient is best classified as having sialidosis type I, while the younger sibling has features of type II. Both exhibited classic cherry-red macular abnormalities, and the patient who would permit complete ophthalmologic examination had both corneal and lenticular opacities. Markedly reduced neuraminidase activity was demonstrated in both patients. These two patients, and 48 others from the literature, were reviewed to determine the frequency of various ophthalmologic abnormalities with sialidosis. Macular cherry-red spots were present in all adequately described type I patients and all but three patients with type II disease. Visual field defects, diminished acuity, and optic atrophy, though less well documented, occurred in the majority of both type I and type II patients. Lenticular lesions were present in all but two of the 18 patients with detailed ocular examination, whereas corneal opacities were found more often in type II than type I disease.