Abstract
Abstract: :
Purpose: Type 1 occult choroidal neovascularization (CNV) (associated with an exudative pigment epithelium detachment) and type 2 occult CNV (fibrovascular RPE detachment) have different clinical features and functional prognosis. Usually they can be easily differentiated on the fluorescein angiographic frames, but sometimes they present borderline characteristics that make the diagnosis difficult. In order to ascertain how many angiographically pure type 2 CNV belongs actually to the type 1 form, and if this difference is relevant or not for the visual prognosis after photodynamic therapy with Visudyne, OCT scans were performed on consecutive patients with angiographically pure type 2 CNV. Patients and methods: 30 angiographically pure type 2 CNV (30 eyes for 29 patients) underwent radial OCT scans centred on the foveola before being treated by PDT with Visudyne. The CNV on the OCT scans were classified in: 1. RPE neovascularized detachment (type 1 CNV) if the RPE /choriocapillaris (CC) complex was detached by a liquid layer and possibly thickened. 2. Pure type 2 CNV if the complex RPE/CC was thickened or slightly elevated due to a solid mildly–reflective layer. 3. Doubtful occult CNV if scans could not be classified. ETDRS best–corrected visual acuity (VA) and Pelli–Robson contrast sensitivity before and after treatment were recorded at each follow–up time and correlated with the OCT classification. Results: In our series of 29 patients (30 eyes), there were 9 men and 20 women (mean age 74.2 ± 5.6 years). On OCT scans, 12 eyes were type 1 CNV(40%), 16 type 2 CNV (53.3%) and 2 doubtful CNV (6.7%). All patients were treated by PDT, but only for 25 patients (26 eyes) data were available for at least 6 months of follow–up. Ten of these eyes were of group 1 on OCT (38.5%), 14 of group 2 (53.8%) and 2 of group 3 (7.7 %). Age, sex, mean initial VA (0.37 ± 0.18), contrast sensitivity (1.25 ± 0.24) and number of PDT treatments were not statistically different in the 3 OCT groups. The mean follow–up was of 7.8 months. At the final visit, VA was decreased in 38.5% of eyes (mean final VA 0.2), stable in 23.1% (mean final 0.4) and improved in 38.4% (mean final 0.4). PR contrast sensitivity was deteriorated in 34.6% (mean final PR 0.85), stable in 38.5% (mean final PR 1.27) and improved in 26.9% of eyes(mean final PR 1.30). Final VA and PR scores were significatively better in the OCT group 2 CNV (p = 0.031 and 0.048 repectively). Conclusion: OCT scans allow to visualize unsuspected RPE detachments in case of angiographically pure occult CNV. This OCT features can help for the exact diagnosis and give useful prognostic clues.
Keywords: age–related macular degeneration • choroid: neovascularization • imaging/image analysis: clinical