Analysis of macular thickness in British population using optical coherence tomography (OCT): An emphasis on interocular symmetry

Purpose: To evaluate macular thickness measurements in normal subjects from British origin, to assess interocular asymmetry using optical coherence tomography (OCT) and to establish standard values for macular and foveal thickness. Methods: Two hundred eyes of 100 normal individuals underwent serial scans using fast macular thickness map protocol in the Stratus OCT version 3.51, with foveal fixation. Minimum foveal thickness (MFT), central 1 mm average foveal thickness (AFT), total foveal volume (TFV) and total macular volume (TMV at 6 mm) of both eyes were assessed. The interocular asymmetry was measured and statistically analyzed. Results: The mean +/- SD (N = 200) was 173 +/- 23 mu m for MFT and 203 +/- 24 mu m for AFT. The mean difference +/- SD between the two eyes was (3.5 +/- 14.5 mu m at p = 0.17) for MFT, (6.4 +/- 14.7 mu m at p = 0.06) for AFT, (0.007 mm3 +/- 0.007 at p = 0.06) for TFV and (0.19 +/- 0.35 at p = 0.07) for TMV. Conclusion: Our study provides a normative database for macular thickness and volume parameters in normal British individuals using Stratus OCT. The MFT, AFT, TMV and TFV measurements were not statistically significant between the two eyes. Hence, the interocular symmetry should be considered on interpretation of macular thickness values especially in cases of uniocular or asymmetrical macular involvement.