Serial Imaging and Functional and Structural Correlates of High Density Rings of Fundus Autofluorescence in Retinitis Pigmentosa

Abstract

Purpose: : To examine the evolution and functional and structural significance of parafoveal rings of high density fundus autofluorescence (AF) in patients with retinitis pigmentosa and preserved visual acuity.

Methods: : Eighty five individuals with retinitis pigmentosa or Usher syndrome were ascertained who had a parafoveal ring of high density AF and a visual acuity of 20/30 or better. Twenty five had repeat AF imaging after periods of up to 7 years. International-standard full-field and pattern ERG (PERG) testing were performed. Some underwent fine matrix mapping (FMM) and ocular coherence tomography (OCT).

Results: : The AF ring radius correlated positively with PERG P50 in RP (R=0.75, p<0.0005, N=85). The ring encircled areas of preserved photopic function. There was high correlation between ring diameter and areas over which the OCT outer retinal layer was preserved. Serial AF revealed progressive ring radius reduction in 14 of 25 cases at rates of 1.5-15% per year.

Conclusions: : High density AF rings progressively constrict in a high proportion of individuals with RP and normal visual acuity. The rate of ring constriction varies between patients. The rings correlate with measures of macular function, encircle areas of preserved outer retina and may be of prognostic value in predicting retention of good central vision.

Keywords: degenerations/dystrophies • electroretinography: clinical • imaging/image analysis: clinical