Nephropathic Cystinosis with Ocular Involvement: Diagnostic Challenges and Management in a Resource-limited Setting

Abstract

Cystinosis is a rare autosomal recessive lysosomal storage disorder caused by CTNS gene mutations leading to cystine accumulation. We report a genetically confirmed case of nephropathic cystinosis in a 6-year-old Nepali boy with ocular involvement. He presented with photophobia and ocular discomfort. Slit-lamp bio microscopy revealed bilateral corneal crystalline deposits. Visual acuity was 6/9P, improving to 6/6 with refractive correction despite corneal crystals. Systemic evaluation showed electrolyte imbalance and hypothyroidism. Genetic analysis identified a likely pathogenic nonsense variant in the CTNS gene confirming the diagnosis. As cysteamine therapy was unavailable he received symptomatic management and multidisciplinary care resulting in symptomatic improvement at 1 month. This case highlights preserved vision despite corneal crystals, the importance of clinical suspicion and the need to improve access to disease-specific therapy in resource limited settings.