Bilateral disc edema in retinitis pigmentosa

Retinitis pigmentosa (RP), one of the most common forms of hereditary retinal degeneration, is characterized by night blindness and constricted visual fields. In addition to bone spicule pigmentation, other ocular findings may include posterior subcapsular cataracts, cystoid macular edema, and hyaline bodies or drusen of the optic nerve. Rarely, optic nerve head (ONH) edema has been reported to be associated with RP. A 44-year-old white male with RP and neurosensory hearing loss (Usher's syndrome type II) presented to our clinic for routine examination. A dilated fundus examination revealed bone spicule pigmentation, vessel attenuation, several flame hemorrhages on or adjacent to the nerves, and ONH edema in the right eye. B-scan ultrasonography revealed drusen of the right ONH but not of the left. Late stage fluorescein angiography showed hyperfluorescence and dye leakage from both optic discs which was more pronounced in the right eye than the left. Computed tomography (CT) of the head and orbits and cerebrospinal fluid (CSF) examination by lumbar puncture were normal. The differential diagnosis of bilateral ONH edema in this case included ONH drusen or papilledema secondary to increased intracranial pressure. This patient was found to have RP with asymmetric, bilateral ONH edema of unknown cause. One theory regarding the cause of the ONH edema is disc vessel leakage secondary to an inflammatory reaction caused by rapid photoreceptor and retinal pigment epithelium (RPE) degeneration.