Rates of decline in regions of the visual field defined by frequency-domain optical coherence tomography in patients with RPGR-mediated X-linked retinitis pigmentosa

Abstract

Purpose: To determine whether annual decline in visual field sensitivity is greater in the transition zone at the edge of the frequency-domain optical coherence tomography (fdOCT) inner segment ellipsoid zone (EZ) than at other locations in the visual field.

Design: Prospective, longitudinal, observational study.

Participants: Forty-four patients with X-linked retinitis pigmentosa (XLRP) resulting from a mutation in the RPGR gene.

Methods: Static perimetric fields (Humphrey 30-2; Carl Zeiss Meditec, Dublin, CA) were obtained annually for 4 years. Beginning with year 2, fdOCT scans were obtained annually with a Heidelberg Spectralis HRA + OCT (Heidelberg Engineering, Heidelberg, Germany).

Main outcome measures: The rate of visual field decline at locations near the edge of the EZ compared with the rates for the macula and in the mid periphery.

Results: Sensitivity just inside and outside the edge of the EZ declined at rates of 0.84 and 0.92 dB/year, respectively. By comparison, average sensitivity in the macula and mid periphery declined by 0.38 and 0.61 dB/year, respectively.

Conclusions: The edge of the EZ in each patient with XLRP indicates a transition zone between relatively healthy and relatively degenerate retina. The annual loss of sensitivity in the transition zone is more rapid than it is elsewhere in the retina.