Objective: This study aimed to develop a protocol to screen and monitor patients with diabetic macular thickening using optical coherence tomography (OCT), a technique for high-resolution cross-sectional imaging of the retina. Design: A cross-sectional pilot study was conducted. Participants: A total of 182 eyes of 107 patients with diabetic retinopathy, 55 eyes from 31 patients with diabetes but no ophthalmoscopic evidence of retinopathy, and 73 eyes from 41 healthy volunteers were studied. Intervention: Six optical coherence tomograms were obtained in a radial spoke pattern centered on the fovea. Retinal thickness was computed automatically from each tomogram at a total of 600 locations throughout the macula. Macular thickness was displayed geographically as a false-color topographic map and was reported numerically as averages in each of nine regions. Main Outcome Measures: Correlation of OCT with slit-lamp biomicroscopy, fluorescein angiography, and visual acuity was measured. Results: Optical coherence tomography was able to quantify the development and resolution of both foveal and extrafoveal macular thickening. The mean ± standard deviation foveal thickness was 174 ± 18 μm in normal eyes, 179 ± 17 μm in diabetic eyes without retinopathy, and 256 ± 114 μm in eyes with nonproliferative diabetic retinopathy. Foveal thickness was highly correlated among left and right eyes of normal eyes (mean ± standard deviation difference of 6 ± 9 μm). Foveal thickness measured by OCT correlated with visual acuity (r2 = 0.79). A single diabetic eye with no slit-lamp evidence of retinopathy showed abnormal foveal thickening on OCT. Conclusions: Optical coherence tomography was a useful technique for quantifying macular thickness in patients with diabetic macular edema. The topographic mapping protocol provided geographic information on macular thickness that was intuitive and objective.
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