In Vivo Confocal Microscopy and Anterior Segment Optical Coherence Tomography Features of Corneal Pseudodendritic Lesions in Hereditary Tyrosinemia Type 1

BACKGROUND Tyrosinemia is a metabolic disorder leading to hepatic, renal, and ocular involvement. Ocular manifestations, such as photophobia and pseudodendritic keratitis, can mimic herpetic keratitis without response to antiviral therapy but improve with metabolic intake and appropriate drugs. Although rare, it poses significant challenges, needing a multidisciplinary approach. CASE REPORT A 14-year-old girl with a diagnosis of type 1 hereditary tyrosinemia was evaluated at our tertiary center for persistent photophobia and bilateral ocular discomfort. Previously, a presumptive diagnosis of recurrent bilateral herpetic keratitis had been made, and the patient was started on repeated cycles of topical and systemic antivirals. Slit-lamp examination revealed bilateral dendritiform epithelial lesions in the central cornea, which stained poorly with fluorescein. In vivo confocal microscopy highlighted multiple hyper-reflective linear crystalline deposits at the level of superficial epithelium. Anterior segment optical coherence tomography demonstrated the presence of focal, highly reflective areas in the epithelial layer. Personal medical history was remarkable for tyrosinemia type 1, diagnosed in the first year of life, with incomplete therapeutic adherence. Antiviral therapy was thus discontinued, and a protein-restricted diet was re-introduced, with net improvement. Importantly, partial regression of corneal epithelial lesions was noted, and a decrease of corneal deposits was confirmed using imaging. CONCLUSIONS Corneal pseudodendritic lesions in hereditary tyrosinemia type I can mimic herpetic keratitis, leading to misdiagnosis and unnecessary antiviral treatments. In vivo confocal microscopy is a valuable tool for disease monitoring. A strict low-protein diet significantly reduces corneal lesions and symptoms in the context of type 1 tyrosinemia.