Abstract
Purpose: :
To compare images obtained with adaptive optics to quantitative measures of visual function and retinal structure within and on the borders of hyperautofluorescent rings in patients with retinitis pigmentosa (RP).
Methods: :
Eleven eyes of 11 patients with RP (autosomal dominant=3, Usher syndrome type II=5, autosomal recessive=3) aged 15-64 years, with visual acuities 20/20 to 20/30, and hyperautofluorescent rings were studied. Cone structure was evaluated with an adaptive optics scanning laser ophthalmoscopic (AOSLO) system (Canon, Inc). Images were obtained in areas 0.5, 1.0 and 1.5 mm from the fovea along the horizontal and vertical midlines. Images of the cone mosaics were evaluated and compared to those from a database of 192 normal eyes. Visual sensitivity along the horizontal and vertical midlines was measured with customized visual fields (Zeiss Inc) and with the MP-1 (Nidek Inc). Total deviation plots were generated from previously collected normative databases. Fundus autofluorescence (FAF) and spectral domain-optical coherence tomography (SD-OCT) horizontal and vertical line scans through the fovea were also obtained (Spectralis HRA+OCT Heidelberg Engineering). The thicknesses of the total receptor layer (R+; Bruch’s membrane to the border between the inner nuclear layer and outer plexiform layer) and outer segment plus RPE layer [OS+; Bruch’s membrane to the inner segment ellipsoid band (ISe)] were measured using a computer-aided manual segmentation technique and values were compared to those for 30 age-similar normals. [1]
Results: :
Within the ring, the ISe was preserved and visual sensitivity was within -6dB of normal.[2] The AOSLO images showed patches in which photoreceptors appeared to be abnormal even in regions with normal sensitivity. Outside and/or on the borders of the ring, the ISe was absent, the R+ layer was significantly decreased, and there was marked sensitivity loss (13 to 35dB). The photoreceptors were clearly abnormal at or beyond the border of the ring. However we also observed isolated patches with what appeared to be photoreceptors.
Conclusions: :
Photoreceptors appeared to be preserved in isolated patches in regions with marked sensitivity loss and there were patches of abnormal photoreceptors in regions with normal sensitivity. Adaptive optics provides additional information about RP that is not apparent on SD-OCT or visual function measures.[3,4] 1. Lazow, Hood, Ramachandran et al. IOVS 2011. 2. Greenstein, Duncker, Holopigian et al. Retina 2011. 3. Duncan, Zhang, Gandhi et al. IOVS 2007. 4. Carroll Arch Ophthalmol 2008.
Keywords: imaging/image analysis: clinical • visual fields • retinal degenerations: hereditary