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Case report
A 31-year-old woman of Brazilian ancestry with nephropathic cystinosis presented for a follow-up exam at the eye clinic at the National Institutes of Health Clinical Center with photophobia and decreased vision. She was on oral cysteamine bitartrate capsules 675 mg twice daily but reported irregular use of cysteamine 0.44 % eye drops between one to five times a day. Additionally, the patient reported the development of diabetes mellitus since her last visit 5 years prior. The patient’s blood cystine trough levels were elevated to 3.01 (normal 0.2) nmol half-cystine/mg protein. Best-corrected visual acuities were 20/25 in the right eye and 20/32 in the left eye. Corneal pachymetries were unmeasurable. Examination revealed dense crystal deposition with thickening of the cornea ( Fig. 1 A) and small crystalline deposits bilaterally on the iris ( Fig. 1 B). Additionally, she had crystal deposits in the meibomian glands, bulbar and tarsal conjunctivas ( Fig. 2 ), and retinas of both eyes. The patient’s oral cysteamine bitartrate was increased gradually by the primary team to achieve normal blood cystine levels and compliance with frequent daily application of cysteamine eye drops was stressed.
