Volumetric High Resolution Optical Coherence Tomography in Retinitis Pigmentosa

Abstract

Purpose: : To examine the intraretinal changes in the central macula in retinitis pigmentosa by volumetric high resolution optical coherence tomography (HR–OCT) with reference to the retinal layers in the healthy macula.

Methods: : Three dimensional retinal imaging is performed using a second generation frequency domain HR–OCT system with a high axial resolution of 6 µm and up to 20 k A–scans/second resulting in 256x256x1024 or 128x512x1024 voxels per volume. Raster scanning of an approximately 5.8 by 5.8 mm wide field within 2 mm depth range was performed to cover all locations and provide a realistic three dimensional imaging of the retinal architecture. Visual acuity and fundus–photography were recorded.

Results: : High speed frequency–domain HR–OCT imaging enables unprecedented in–vivo three–dimensional identification of all major retinal layers including inner and outer photoreceptors and the retinal pigment epithelium. In retinitis pigmentosa, there is progressive thinning of the inner and outer segments of the photoreceptors in the parafoveal region. The outer nuclear layer becomes abnormally thin in the periphery of the macula. The inner nuclear layer and the inner and outer plexiform layer appear normal throughout the HR–OCT images.

Conclusions: : Volumetric HR–OCT has the potential to enhance visualisation, evaluation and follow–up of affected retinal layers in retinitis pigmentosa. Detectable morphologic alterations include the marked atrophy of the photoreceptor inner and outer segments and the outer nuclear layer.

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