Ocular cystinosis is amongst the rarest Autosomal Recessive Lysosomal storage disorder1 with a ratio of 1 in 1–2 lakh live births, involving multiple systems (renal, ocular, and endocrine) of the human body. A hallmark feature is the accumulation of cystine in lysosomes due to CTS gene defective function.1 The most severe phenotype is known as infantile nephropathic cystinosis.2 Various ocular manifestations of ocular cystinosis have been documented in the literature. In this case, we report a rare case of ocular cystinosis with corneal involvement. We would like to emphasize the importance of how eyes can act as a window to guide in timely diagnosis and treatment of various underlying systemic pathologies. A 3-year-old preschool male child presented to the outpatient department with difficulty to open the eyes in bright light, as noticed by the parents for 2 weeks. There was difficulty in the assessment of vision but the child was fixing and following the light. Anterior segment evaluation on the slit lamp revealed crystalline deposits in the anterior corneal stroma Figure 1a. Anterior segment optical coherence tomography (AS-OCT) showed diffuse hyperreflective cysteine deposits in the corneal stroma Figure 1b. Posterior segment evaluation was within normal limits. Cycloplegic refraction showed no refractive error. On systemic evaluation, the child had short stature, Frontal Bossing, Depressed nasal Bridge, pot belly, genu valgum, rachitic rosary, and wrist widening Figure 1c. The patient was also evaluated by the pediatric department for Vitamin D deficiency and blood evaluation suggestive of hypophosphataemic rickets. The child also had polyuria suggestive of nephropathic cystinosis. On gene testing, the child was positive for the CTNS gene variant (Homozygous 107), suggestive of cystinosis nephropathic (OMIM 219800). Elevated levels of leukocyte Cysteine levels found on Leukocyte Cysteine Quantification test (1.90 umol 1/2 Cysteine /g protein). The mainstay of treatment is oral and topical cysteamine but due to non-affordability for the same, the child was given artificial tear substitutes.Figure 1: (a) Slit lamp image of right eye showing diffuse cystine crystal deposits in corneal stroma (marked with asterisk), (b) Anterior-segment optical coherence tomography showing diffuse hyperreflective cysteine deposits in the corneal stroma. (Marked with arrow), (c) Clinical Photograph short stature, Frontal Bossing, Depressed nasal Bridge, pot belly, genu valgum, wrist widening (inset)Cystinosis is a multisystem disorder in which progressive intracellular cystine accumulation leads to significant renal, endocrine, neurological, and ocular morbidity.3 Ocular involvement is almost universal and typically begins with corneal crystal deposition, which progresses from the anterior peripheral stroma toward the central and posterior corneal layers.4 This pattern of deposition accounts for the early development of photophobia, recurrent epithelial erosions, and gradual deterioration of vision. Over time, additional ocular structures – including the conjunctiva, iris, ciliary body, retina, and optic nerve – may also show cystine accumulation, contributing to complications such as pigmentary retinopathy, peripheral corneal neovascularization, and secondary glaucoma.1 Slit-lamp identification of corneal crystals remains a key diagnostic feature and correlates well with systemic disease burden. Adjunctive imaging tools such as AS-OCT and in vivo confocal microscopy provide valuable insights into the depth and density of corneal deposits, offering objective markers to guide monitoring. Cysteamine remains the mainstay of treatment.1 It reacts with lysosomal cystine to form cysteamine-cysteine mixed disulfide, which exits the lysosome via the lysine cationic transport system, consequently lowering intracellular cysteine concentration and significantly improving long-term outcomes by reducing intracellular cystine levels. While systemic cysteamine effectively addresses systemic complications, topical formulations are essential for managing corneal involvement due to the avascular nature of the cornea. Newer viscous formulations such as cystadrops and cystaran have demonstrated enhanced corneal penetration and better crystal clearance compared with conventional eye drops,5 although challenges such as frequent dosing requirements, stability issues, and compliance concerns still exist. Emerging options like cysteamine-loaded contact lenses show promise for sustained drug delivery and reduced treatment burden. Supportive management with lubricants and anti-inflammatory agents is often required, particularly in cases with recurrent erosions or significant ocular discomfort. Keratoplasty is rarely indicated and is reserved for advanced corneal scarring or severe neovascularization, as recurrence of crystal deposition may still occur in the graft. Overall, early diagnosis, regular ophthalmic monitoring, and timely initiation of appropriate topical therapy are crucial for preserving visual function and improving quality of life in patients with cystinosis. Cystinosis is a multisystem disorder with diverse clinical manifestations. In settings where genetic testing is unavailable or not performed, characteristic ocular findings can serve as important diagnostic clues, enabling early initiation of cysteamine therapy, which can slow disease progression and improve overall survival. Data availability statement Data supporting this study are available from the corresponding author upon reasonable request. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Chavhan et al. (Wed,) studied this question.