Prospective Comparison of Cirrus and Stratus Optical Coherence Tomography for Quantifying Retinal Thickness

PURPOSE: To compare Cirrus Fourier-domain optical coherence tomography (OCT) with Stratus time-domain OCT for imaging retinal diseases and quantifying retinal thickness (RT) of all nine OCT zones, central macular thickness, and average macular thickness in eyes with and without macular edema. DESIGN: Prospective comparison between two OCT systems. METHODS: RT measurements were performed in 120 eyes of 60 patients suspected of having increased retina thickness using both Stratus and Cirrus OCT on the same day. Twenty-one eyes had both 512 x 128 and 200 x 200 Cirrus cube scans done. RESULTS: Data from 101 eyes (53 patients) were analyzed; 46 eyes (45.5%) had macular edema on clinical examination (Group 1), whereas 55 eyes (54.4%) had no clinical evidence of macular edema (Group 2). There was modest correlation between all thickness measurements in 909 zones and each group (range of Pearson correlation, 0.51 to 0.89) and average value was significantly greater when measured with Cirrus OCT for all eyes (mean difference, 43.2 mu m; P < .0001). There were few measurement differences between different resolution Cirrus cube scans. CONCLUSIONS: Cirrus OCT measures RT similar to 43 mu m greater than Stratus OCT, which is likely attributable to Cirrus OCT detection of the outer band of the retinal pigment epithelium vs Stratus OCT detection of the inner/outer segment photoreceptor junction. All zones showed a wide degree of variability in correlation. Both Cirrus cube scans provide similar data. Future studies comparing these systems might consider utilizing average macular thickness values, which reflect macular volume and may provide more consistent measurements. (Am J Ophthalmol 2009;147:267-275. (C) 2009 by Elsevier Inc. All rights reserved.)