Evaluation of treatment with cysteamine eyedrops for cystinosis with confocal microscopy.

Purpose: The purpose of this study was to evaluate the efficacy of cysteamine eyedrops 0.1136% (new formulation, now stable at room temperature without the need for refrigeration for up to 2 months) for the treatment of cystine crystals in the cornea using slit lamp biomicroscopy and confocal microscopy.

Methods: A 20-year-old woman with infantile cystinosis, with a history of kidney transplantation at age 10, was studied. She applied cysteamine eyedrops (0.1136%) 10 times a day (a new formulation, now stable at room temperature without the need for refrigeration for up to 2 months, was prepared for compassionate use). The density of the cystine crystals in the cornea was evaluated using slit lamp biomicroscopy and confocal microscopy (Heidelberg Retina Tomograph 2 equipped with the Rostock Module for the Cornea).

Results: The deposits were absent in the surface epithelium and basal cells of the central cornea before and after treatment. We found crystals mainly in the anterior and medium stroma; they had various shapes; were intracellular, rectangular, or fusiform; and showed hyperreflectivity. The posterior stroma showed lower density of the crystals. No deposits in the endothelium were found. Therapy with cysteamine eyedrops reduced the density of the crystals and lessened the photophobia.

Conclusion: Confocal microscopy is a valuable technique to study cystine crystals of the cornea in vivo. Cysteamine eyedrops appear to be very useful in the treatment of these crystals, especially for photophobic complaints.