Spatial extent of pigment epithelial detachments in age-related macular degeneration

Objective: To quantify the spatial extent of pigment epithelial detachment (PED) associated with age-related macular degeneration (AMD) using a rapid, noninvasive method. Design: Prospective, cross-sectional study. Participants: The authors tested 32 eyes of 21 patients (13 women and 8 men ) with AMD 56 to 91 years of age (mean = 72.8 years). The authors retested seven eyes of six patients. Intervention: Three-dimensional imaging and quantification of FED were perf ormed in each subject using confocal infrared imaging (790 nm) with a Topog raphic Scanning System (TopSS), The data consisted of a series of 32 images within a 3-mm-depth range requiring 0.9 second. Three-dimensional calculat ions were made from the series. Main Outcome Measure: Height, diameter, area, volume, and slope of each FED were obtained with two calculation methods. The Ellipse Method used a grap hics tool to draw elliptical borders circumscribing the region of interest in the image. The software automatically calculated the values for all para meters for the region inside the ellipse, with the retinal reference plane adjusted to match the height of the surrounding retina. The User-Defined Re gion Method differed in that the region of interest was drawn manually. Results: PEDs were easily detected in all patients using the TopSS. Maximum height of all PEDs above the reference plane ranged from 0.204 to 1.818 mm (mean = 0.57 mm). The diameter was 0.501 to 5.151 mm (mean = 2.711 mm), ar ea was 0.179 to 20.402 mm(2) (mean = 6.585 mm2), and volume was 0.012 to 13 .981 mm(3) (mean = 2.173 mm(3)). Intraobserver variability was low, with co rrelations between first and second measurements for the first visit rangin g from r = 0.906 to 0.997 for slope and diameter, respectively. Conclusions: Three-dimensional analysis with the TopSS provides objective o utcome measures not obtainable with typical clinical methods such as fundus photography and angiography. Height and volume are crucial in determining whether neovascularization is worsening or persistent after photocoagulatio n. More longitudinal data are needed to determine whether tomographic data reduce the need for angiography. Unique to scanning laser tomography, exuda tive features were imaged at different depths.