Ophthalmic Outcome in a Belgian Cohort of Cystinosis Patients Treated with a Compounded Preparation of Cysteamine Eye Drops: Retrospective Analysis

INTRODUCTION: Treatment of the anterior segment problems in cystinosis is challenging as oral cysteamine is ineffective in the treatment of corneal problems because of its avascular structure. Although cysteamine eye drops have been formulated to counter this issue, the stability of cysteamine in these off-licensed formulations and treatment compliance are major problems. The aim of this retrospective study was to determine the efficacy of a compounded preparation of aqueous 0.5% cysteamine eye drops in the management of corneal complications of cystinosis. METHODS: Data of patients attending the multidisciplinary cystinosis clinic at the University Hospitals Leuven, Belgium between January 2015 and December 2018 were analyzed. All cystinosis patients were treated with the compounded preparation of aqueous 0.5% cysteamine eye drops and oral cysteamine. RESULTS: A total of 12 patients were treated with the compounded preparation of aqueous 0.5% cysteamine eye drops, of whom 75% were aged > 18 years (n = 9). The mean instillation frequency of the cysteamine eye drops was 3.3 drops/eye per day, and the mean number of hospital visits was two per year. All patients showed photophobia, > 30% corneal infiltration, blepharospasm, eye pain and conjunctival hyperemia during the study period. None of these symptoms improved with treatment with aqueous compounded 0.5% cysteamine eye drops. The corneal cystine crystal score was ≥ 2 in all patients at the last visit. CONCLUSION: Treatment with the compounded preparation of aqueous 0.5% cysteamine eye drops, combined with oral cysteamine, was not effective in reducing corneal cystine crystal deposition and other ocular symptoms in these patients with cystinosis. FUNDING: Recordati Rare Diseases.