[Primary hyperoxaluria-induced bilateral oxalate retinopathy: a case report]

A 35-year-old male patient presented with decreased visual acuity in both eyes for 4 years. His medical history included hypertension, type 2 diabetes mellitus, renal failure, and kidney transplantation. In 2021, he was diagnosed with primary hyperoxaluria based on genetic testing, which revealed a homozygous variant of the AGXT gene (c.32C>G). During this ophthalmic examination, decreased corrected visual acuity was noted in both eyes; fundus examination showed crystalline deposits in the retina and perimacular ring-shaped pigment deposition. Optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) indicated abnormalities in retinal structure and blood vessels. Systemic examination revealed elevated 24-hour urinary oxalic acid. His second eldest sister carried the same homozygous variant of the AGXT gene with renal symptoms. The final diagnoses were: bilateral oxalate retinopathy, bilateral diabetic retinopathy, primary hyperoxaluria, and type 2 diabetes mellitus. The patient refused laser treatment, and no significant changes in the lesions were observed during the 3-month follow-up. This case suggests that primary hyperoxaluria caused by AGXT gene variation can lead to ocular oxalate deposition, and diagnosis should be made by combining genetic testing and imaging examinations, with long-term follow-up required.