Cystinosis, or the Lignac-Fanconi syndrome, is a disease of childhood that is characterized by dwarfism and by the accumulation of cystine crystals within many tissues of the body. Investigation reveals a generalized aminoaciduria and renal tubular dysfunction, which is usually manifest by acidosis, hypokalemia, and impaired water reabsorption. Renal rickets and uremia are frequent late sequelae.While the disturbance is believed to be a hereditary defect in the utilization of many amino acids, cystine precipitates out, presumably because of its low solubility. The condition is not to be confused with the relatively benign cystinuria which appears to result from a lowered renal threshold (for cystine, lysine, and arginine) and which does not reflect a general disturbance of amino acid metabolism, such as is the case with the cystinosis of children.The ophthalmologic importance of cystinosis is due to the fact that the crystals of cystine can be frequently seen in