Persistent Bilateral Optic Disc Swelling in Non-Syndromic Retinitis Pigmentosa: A Case Report

BACKGROUND In retinitis pigmentosa (RP), the optic nerve head typically exhibits a pale, waxy appearance and may demonstrates pseudo-swelling due to optic nerve drusen. However, true optic disc edema is rare and remains poorly understood. We present a case with unusual findings of bilateral disc swelling in non-syndromic RP caused by TULP1 mutation. CASE REPORT An 8-year-old boy initially presented to the vitreoretinal division at King Khaled Eye Specialist Hospital with nyctalopia and constricted visual fields in both eyes. Fundoscopic examination revealed widespread retinal pigment epithelial mottling, attenuated retinal blood vessels, and bilateral hyperemic optic nerve swelling. Multimodal imaging, including fundus autofluorescence, fluorescein angiography, optical coherence tomography, and ocular ultrasonography, confirmed true optic disc edema. Magnetic resonance imaging and arteriography/venography showed bilateral optic nerve head swelling without enhancement or radiographic signs of intracranial hypertension. Lumbar puncture revealed normal opening pressure and unremarkable cerebrospinal fluid analysis. The patient was diagnosed with RP, which was confirmed using electroretinography. Whole-exome sequencing revealed a homozygous c.1256G>A p.(Arg419GIn) variant in the tubby-line protein 1 gene (TULP1). The patient was followed for 2 years, during which visual function and optic disc appearance remained stable without treatment. CONCLUSIONS This case highlights a rare presentation of persistent bilateral true disc swelling in a patient with non-syndromic RP due to TULP1 mutation. Unlike previously reported cases, our patient showed persistent disc swelling that remained stable for over 2 years without treatment. This observation expands the phenotypic spectrum of RP and suggests that a non-progressive disc swelling may be part of the disease presentation in certain genetic subtypes such as TULP1.