Serial Imaging And Structure-function Correlates Of Abnormal Fundus Autofluorescence In Retinitis Pigmentosa: 4- To 8-year Follow-up

Abstract

Purpose: : To assess the significance and evolution of parafoveal rings of high density fundus autofluorescence (AF) in 11 patients with retinitis pigmentosa (RP).

Methods: : Six patients with autosomal recessive RP and 5 with Usher syndrome type 2 (USH2A confirmed in 4) were ascertained who had a parafoveal ring of high density AF and a visual acuity (VA) of 20/30 or better at baseline. Fine matrix mapping (FMM) was used to test photopic and scotopic sensitivity across the macula at 1-degree intervals over 9-degree x 9-degree area. AF imaging and FMM were repeated after 4 to 8 years (median 8 years). Spectral-domain optical coherence tomography (OCT) was used to measure the lateral extent of the photoreceptor IS/OS band.

Results: : Mild VA reduction occurred due to CMO in 1 case; severe VA and central sensitivity reduction was associated with loss of the ring and patchy RPE atrophy in 1 patient. Progressive ring radius reduction varied between 10 and 50% (median 35%) at a mean rate of between 1 and 12% per year in the 9 patients with stable VA, including the 5 with Usher syndrome. Serial FMM showed progressive photopic sensitivity loss associated with ring constriction; scotopic losses were more severe and encroached upon central areas. The lateral extent of the IS/OS lamina correlated with the ring width along the same OCT scan plane (Slope =0.9, R= 0.95, p<0.005, N=9).

Conclusions: : Rings of increased AF surround areas of preserved photopic function and preserved outer retinal structure. Progressive ring constriction is associated with outer retinal disruption and progressive centripetal sensitivity loss. Rings constrict at different rates and may reach a critical minimum before giving way to patchy atrophy and severe central visual loss.

Keywords: retinal degenerations: hereditary • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)