Nephropathic Cystinosis

Purpose Cystinosis is a rare autosomal recessive lysosomal storage disorder characterized by the intracellular accumulation of cystine. Treatment involves intracellular cystine depletion with oral cysteamine. A wide spectrum of ocular pathologic features has been associated with nephropathic cystinosis. We used the largest documented cohort of patients in the world to study the posterior segment manifestations associated with infantile nephropathic cystinosis and to determine retrospectively the effect of chronic oral cysteamine therapy on the frequency of these abnormalities. Design Cross-sectional study of a series of patients. Participants Two hundred eight patients with infantile nephropathic cystinosis were studied at the National Institutes of Health between 1976 and 2004. Methods All patients underwent an ophthalmic evaluation. Patients older than 11 years also underwent Humphrey static perimetry, and electrophysiological testing was performed when possible. Main Outcome Measures Visual acuity, retina findings, visual fields, and electroretinographic (ERG) findings. Results Pigmentary changes with retinal pigment epithelial mottling, seen as early as infancy, were the most common posterior segment manifestations. Moderate to severe constriction of the visual fields, as well as moderate to severe reduction of rod- and cone-mediated ERG responses, was seen in older patients. The frequency of retinopathy correlated directly with time not receiving oral cysteamine therapy and inversely with time receiving oral cysteamine therapy. Conclusions Infantile nephropathic cystinosis has posterior segment complications that can contribute to significant visual handicap. Early initiation of oral cysteamine therapy can reduce the frequency of posterior segment complications in cystinosis patients.