Abstract
Abstract: :
Purpose:Pigmented paravenous retinochoroidal atrophy (PPRCA), sometimes referred to as paravenous retinitis pigmentosa, is a rare condition with fewer than 100 cases reported. Previous studies have presented conflicting conclusions as to whether PPRCA shows progression and, if so, to what extent. In addition, the natural course of ocular function has not been extensively reviewed. The present study estimates the long–term rates of decline of visual acuity, visual field area, and electroretinogram (ERG) amplitude in this condition. Methods: A retrospective review identified 11 patients (4 males and 7 females, ages 8 to 67 years) with a diagnosis of PPRCA who had a follow–up of 3 to 35 years (average follow–up 13 years). All patients had atrophy of the retinal pigment epithelium and choroid with intraretinal pigment in a paravenous distribution. At each visit, best–corrected Snellen visual acuities were recorded. Full–field ERGs were elicited with 0.5 Hz flashes of white light to record mixed cone/rod responses and with 30 Hz flashes of the same white light to record cone–isolated responses. Goldmann kinetic visual fields were obtained to the V4e white stimulus, digitized, and converted to areas. In each case values were converted to natural logarithms and averaged for both eyes where data were available. Longitudinal regression analyses were performed with log visual acuity, log visual field area, or log ERG amplitude as the dependent variable and age as the independent variable using PROC MIXED of SAS to estimate mean rates of decline and to determine whether rates of decline were significantly different from zero. Results: Mean annual exponential rates of decline were 5.0% for visual acuity (p = 0.007), 2.2% for visual field area (p = 0.06), and 2.7% and 3.1%, respectively, for ERG amplitude to 0.5 Hz flashes (p = 0.008) and 30 Hz flashes (p = 0.005). Conclusions: Patients with PPRCA show, on average, significant decline in ocular function over the long term. The mean annual rate of loss of visual acuity appears comparable to what has been reported for patients with the common forms of retinitis pigmentosa (1.0 – 8.6%). The rates of loss of visual field and 30 Hz ERG appear to be slower than those of typical retinitis pigmentosa (4.6 – 13.5% and 13.3 – 18.5%, respectively).
Keywords: retinal degenerations: hereditary • retina • electroretinography: clinical