Starry-like Cornea: A Case of Ocular Cystinosis

Ocular cystinosis is a rare autosomal recessive disorder caused by mutations in the CTNS gene, which encodes a lysosomal cystine transporter protein. This results in the accumulation of cystine crystals in various ocular structures, leading to a range of ocular manifestations. The incidence of cystinosis is estimated to be 1 in 100,000 to 200,000 live births, with a higher prevalence in certain populations such as those of European descent. We report the case of a 5-year-old child with ocular cystinosis. The ophthalmological examination revealed a photophobic child with a visual acuity of 3/10 in both eyes (Pigassou scale), and diffuse stromal crystal deposits over the entire cornea in both eyes. The rest of the examination was unremarkable. The patient was referred to pediatrics for work-up of storage disease and was diagnosed with ocular and nephrological cystinosis. The patient was able to start general treatment with Mercaptamine with improvement in renal function, but was unable to obtain local treatment due to lack of funds. The patient is still being followed in our clinic with stable corneal involvement. Ocular cystinosis is a very rare genetic disorder. There are three main types of cystinosis: nephropathic cystinosis and non-nephropathic cystinosis. Nephropathic cystinosis divides further on infantile and intermediate. The most common ocular manifestation of cystinosis is corneal cystine crystal deposit, which typically presents in the first year of life and can lead to photophobia, tearing, and decreased visual acuity. The corneal crystals can also cause recurrent erosions, which can be very painful. The severity of corneal involvement can range from mild punctate deposition to severe confluent crystal accumulation that can lead to corneal scarring and vision loss. Cysteamine drops, which are a form of cysteamine hydrochloride, can help dissolve the cystine crystals and improve corneal clarity, prevent further vision loss, and reduce the frequency of recurrent erosions.

Early diagnosis and treatment are crucial in preventing further ocular damage in individuals with cystinosis. Regular ophthalmologic examinations should be conducted to monitor for ocular manifestations and initiate treatment as early as possible. A multidisciplinary approach is necessary, involving ophthalmologists, nephrologists, and other specialists, to manage the systemic manifestations of cystinosis.