A rare case of unifocal, unilateral pigmented paravenous retinochoroidal atrophy (PPRCA)

Purpose: To report an atypical case of unifocal, unilateral pigmented paravenous retinochoroidal atrophy (PPRCA) characterized by thickening and cystic degeneration of the retinal nerve fiber layer (RNFL). Observations: A 79-year old Asian woman presented with a large area of atrophic, pigmented change along the inferior arcade of her right eye. She denied nyctalopia and any other visual complaints. Visual acuity was 20/40 in both eyes and visual fields were significant for a large absolute peripheral scotoma superiorly in the affected eye corresponding to the atrophic area. Spectral domain optical coherence tomography through the lesion showed loss of choroid except for largest Haller's layer vessels, significant retinal pigment epithelium atrophy with migration and pigment clumping, outer retinal layer loss and RNFL thickening with cystic degeneration. Fundus autofluorescence imaging showed a large area of hypoautofluorescence corresponding to the area of atrophy. Full field electroretinogram demonstrated normal scotopic response and reduced photopic response in the right eye. Conclusions and importance: PPRCA is typically bilateral and symmetric, affecting primarily the outer retina and choroid. However, in rare cases, this disease can present unilaterally and/or unifocally, with degeneration extending to the inner retinal layers.