Cysteamine eye drops deliver limited efficacy in nephropathic cystinosis
The use of topical 0.55% cysteamine eye drops appears to have limited effects in reducing the corneal cystine deposits in patients with severe forms of nephropathic cystinosis, according to a recent study.
A total of 32 patients (mean age 8 years; range, 8 months to 19 years; 19 female) with nephropathic cystinosis were prospectively included in the study, with a mean follow-up period of 4.1 years (range, 2 to 8 years).
There was no clinically significant improvement of photophobia among symptomatic patients. During the follow-up period, participants demonstrated statistically significant worsening of corneal cystine deposits.
In this study that investigated the efficacy of topical cysteamine 0.55% eye drops in the treatment of corneal cystine crystal deposits in patients with nephropathic cystinosis, patients were administered the said medication. They were examined prior to treatment, on each monthly visit and after treatment at the last follow-up.
The main outcome was evaluation of photophobia and resolution of corneal cystine crystals.
Photophobia was classified as grade 0 (none) for no photophobia, grade 1 (mild) for photophobia in bright light, grade 2 (moderate) for photophobia in room light and grade 3 (severe) for photophobia in dim light. Corneal cystine crystals were classified as grade 0 for none, grade 1 for 1 to 10 crystals/mm2, grade 2 for 11 to 50 crystals/mm2, grade 3 for more than 50 crystals/mm2.
Nephropathic cystinosis is a rare genetic disease characterized by defective lysosomal cystine transport and increased lysosomal cystine. [Saudi J Kidney Dis Transpl 2009;20:436-42]