 Also known as ocular or benign cystinosis, this form usually affects adults during middle age; it was once called adult cystinosis. Kidney disease does not occur in these individuals. The disorder appears to only affect the eyes. Untreated individuals with non-nephropathic cystinosis eventually develop photophobia due to cystine crystal accumulation in the eyes.New methods, like mass-spectrometry give a good chance to characterize specific metabolic alterations in the blood plasma of affected patients that allow diagnosing in the future the disease earlier, with a higher sensitivity and specificity. Therefore it is the goal of the study to identify and validate a new biochemical marker from the plasma of the affected patients helping to benefit other patients by an early diagnose and thereby with an earlier treatment. 