Figures 1-3. These are high powered views of the corneas of 3 patients with the same condition.
Questions and Answers
1. What is your diagnosis? Answer: Cystinosis.
2. What is the inheritance pattern of this condition? Answer: Autosomal recessive.
3. What is the pathophysiology of this condition? Answer: Defective lysosomal transport of the amino acid cystine with resulting intracellular accumulation of cystine crystals
4. What is the usual presentation for this condition? Answer: Patients may present in infancy, childhood or later adult life. The infantile form has the most severe systemic disease, while the disease presenting in later adulthood may be unaccompanied by systemic findings. Patients generally have good visual acuity, but may have photophobia and superficial keratopathy.
5. What are the systemic findings? Answer: Renal disease is the most important systemic finding and generally leads to renal failure. In addition patients with the more severe form of cystinosis may also develop endocrine gland dysfunction including hypothyroidism, and diabetes mellitus.
6. What are the ocular findings? Answer: Cystine crystals are deposited in all ocular tissues. There are multiple highly refractile crystals deposited in the corneal stroma. Crystal deposition in the iris can increase its thickness and even lead to angle closure. A peripheral pigmentary retinopathy may also be seen.
7. What treatment would you recommend? Answer: Cysteamine (b-mercaptoethylamine) depletes intracellular cystine, and has been used orally to delay onset of renal failure, and topically to decrease the corneal cystine load.