Abstract
Abstract: :
Purpose: To investigate the morphological characteristics of choroidal neovascularisation (CNV), secondary to age–related macular degeneration (AMD) using optical coherence tomography (OCT) and to relate the findings to visual function. Materials and methods:Patients with subfoveal predominantly classic CNV, with or without occult, secondary to AMD were recruited. Observations comprised: full refraction protocol logMAR visual acuity (VA) recorded as letters read on an ETDRS chart at 1 metre, slit lamp biomicroscopy, stereoscopic fluorescein angiography (FA) and OCT. Single horizontal line scan and fast macular OCT3 scans (model 3000, Zeiss–Humphrey, USA) passing through the fovea were analysed using the terminology presented by us at ARVO 2003 (IOVS 2003; 44: E–abstract #4867): neuro–retinal foveal thickness (NFT), bilaminar foveal thickness (BFT) and outer high reflectivity band thickness (OHRBT). Intra retinal fluid (IRF) was defined as well–defined intraretinal hyporeflective spaces separated by reflective septae at the fovea.CNV was classified by OHRBT on OCT as (A) well defined thickening, (B) irregular poorly defined thickening and (C) pigment epithelial detachment (after Hee et al). Linear correlation between variables was analysed using Pearson correlation coefficient. The Independent–Samples t–test was used to compare the means for two groups. P values of ≤0.05 were taken to be significant. Results: 69 eyes were recruited: 60 classic/no occult and 9 predominantly classic with occult. In the classic/no occult group, CNV was type A in 48.3%, type B in 48.3% and type C 3.3%. In the predominantly classic with occult group, CNV was type A in 56% and type B in 44%. VA was significantly better in patients with type A CNV than in type B (p<0.01). There was a statistically significant correlation between the presence of IRF and VA (p<0.01). There was no statistically significant difference in the mean VA in eyes with and without subretinal fluid (SRF) (p>0.2). There was no statistically significant correlation between NFT, BFT, OHRBT respectively and VA (all p>0.05). Conclusions:IRF appears to play a greater role than SRF in contributing to poorer levels of VA in eyes with predominantly classic CNV. VA appears to be worse in patients with a poorly defined CNV/RPE complex. OCT imaging provides information on the CNV that can complement conventional examinations by fundoscopy and FA.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • choroid: neovascularization • age–related macular degeneration