Abstract
Purpose: :
To quantify the structural changes in patients with early age-related macular degeneration (AMD), associated with visual field (VF) defects, using spectral domain optical coherence tomography (SD-OCT).
Methods: :
Twenty-one eyes of 21 patients with soft drusen, with or without pigmentary changes were examined. BCVAs ranged from 20/20 to 20/40 and all eyes had foveal fixation. Nidek MP-1 10-2 VFs were obtained and total deviation defects were derived from a normative database [1]. The following SD-OCT (Heidelberg Spectralis HRA+OCT) scans were acquired: 9mm horizontal foveal line scans and detail volume scans (4.5 x 3mm; 25 to 49 B-scans). The thicknesses of the outer segment (OS) and retinal pigment epithelium (RPE) layers and elevation of the RPE from Bruch’s membrane were measured with a computer aided manual segmentation technique [2]. Thickness values for foveal line scans were compared to data for 10 age-similar controls and values at locations with VF defects were compared to non-defect locations at equivalent eccentricities.
Results: :
All 21 eyes showed RPE elevations in drusen areas and disruptions of the inner segment ellipsoid band (aka IS/OS junction). Hyper-reflective foci were seen in 11 eyes. However these characteristics were not exclusively associated with VF defects. Sixteen eyes had MP-1 VF defects. The foveal line scans of these eyes showed a significant thinning of the OS layer (p<0.001) and a thickening and elevation of the RPE (p<0.001, p<0.001) compared to normal subjects. In addition, the OS layer was significantly thinner in locations with VF defects compared to non-defect locations. In 5 eyes with AMD, the VF and the retinal layer thicknesses were essentially the same as those from normal controls.
Conclusions: :
In early AMD, significant thinning of the OS layer and a thickening and elevation of the RPE were observed. OS layer thinning was significantly associated with decreased visual sensitivity, consistent with known photoreceptor loss in early AMD [3]. For patients without VF defects, OS and RPE thickness values were normal. The results highlight the clinical utility of both SD-OCT retinal layer quantification and VF testing for following disease progression in early AMD.1. Acton et al.(2011) Optom Vis Sci;88:1288-972. Hood et al.(2009)IOVS;50:2328-363. Curcio et al.(1996) IOVS;37:1236-49
Keywords: age-related macular degeneration • imaging/image analysis: clinical • visual fields