Abstract
Purpose: :
To present a series of patients with PPRCA with a unique visual field pattern using HOV modeling and Mercator projection plots.
Methods: :
Patients with PPRCA presenting to the Casey Eye Institute undergoing full-field static visual field testing were identified. Inclusion criteria required intact central vision, characteristic electroretinogram findings, and bilateral chorioretinal atrophy with pigmentary changes in a perivenular distribution. An additional patient with a unique acute bilateral perivenular herpetic (HSV2) retinitis was also evaluated. Static fields were performed to 56° nasally and 80° temporally using the Octopus 101 perimeter, radially-oriented, centrally-condensed grids of 187 test locations, and the German Adaptive Threshold Estimation (GATE) strategy. The HOV was modeled with a flexible spline using the differential luminance sensitivity values and was quantified using the unit decibel-steradian. Mercator projection plots mapped the distribution and extent of field loss.
Results: :
Three characteristic PPRCA cases were identified. Visual field analysis disclosed a unique pattern of sensitivity loss that mirrored the perivenular distribution of chorioretinal atrophy and pigment accumulation. Mercator plots revealed a distinctive pattern of sensitivity loss with bands of marked HOV loss directly abutting bands of normal HOV, which appears characteristic of PPRCA. Analysis of the HOV and mercator projections of the additional patient with acute perivenular herpetic retinitis matched those seen in patients with PPRCA. After resolution of the acute retinitis, spectral domain OCT line scans demonstrated loss of typical outer retinal morphology adjacent to venules (with normal-appearing periarteriolar retinal architecture) accounting for the visual field loss.
Conclusions: :
PPRCA is a rare entity of unknown etiology. The distinctive pattern of sensitivity loss found on HOV modeling and Mercator plots may prove useful in the diagnosis and monitoring of this unusual disease process. This perivenular pattern of sensitivity loss was found in a unique case of herpetic retinitis, suggesting a herpetic infectious process in the etiology of PPRCA.
Keywords: herpes simplex virus • retinal degenerations: hereditary • perimetry