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

Area of Science:

• Ophthalmology
• Genetics
• Retinal Diseases

Background:

• Optic nerve head appearance in retinitis pigmentosa (RP) typically involves pallor or pseudo-swelling from optic nerve drusen.
• True optic disc edema is an uncommon finding in RP and its mechanisms are not well understood.
• This report focuses on a unique case of bilateral disc swelling in non-syndromic RP associated with a TULP1 mutation.

Purpose of the Study:

• To describe a rare case of bilateral optic disc swelling in a patient with retinitis pigmentosa (RP).
• To investigate the genetic basis and clinical course of this unusual presentation.
• To expand the understanding of the phenotypic spectrum of RP, particularly in relation to TULP1 mutations.

Main Methods:

• Clinical presentation and fundoscopic examination of an 8-year-old boy with nyctalopia and visual field constriction.
• Multimodal imaging including fundus autofluorescence, fluorescein angiography, optical coherence tomography, and ocular ultrasonography to assess optic disc edema.
• Advanced diagnostics including MRI, arteriography/venography, lumbar puncture, electroretinography, and whole-exome sequencing to confirm diagnosis and rule out other causes.

Main Results:

• The patient exhibited widespread retinal changes and bilateral hyperemic optic nerve swelling confirmed by multimodal imaging.
• Imaging studies ruled out intracranial hypertension, and cerebrospinal fluid analysis was normal.
• Whole-exome sequencing identified a homozygous TULP1 gene mutation (c.1256G>A p.(Arg419GIn)).
• The optic disc swelling remained stable for a 2-year follow-up period without intervention.

Conclusions:

• This case presents a rare instance of persistent bilateral true disc swelling in non-syndromic retinitis pigmentosa linked to a TULP1 mutation.
• The observed stable disc swelling over two years, without treatment, broadens the known clinical spectrum of RP.
• This finding suggests that non-progressive optic disc swelling may be a feature of specific genetic subtypes of RP, such as those involving TULP1.