A new manual retinal thickness measurement protocol to evaluate high myopia patients

Abstract

Purpose: To validate a manual measurement protocol for quantifying retinal thickness (RT) using an optical coherence tomography (OCT) device in pathologic myopia patients. Methods: The macular Cross Hair protocol of Stratus OCT3 (Carl Zeiss Meditec, Inc., Dublin, Calif., USA) was applied and manual RT gauging was performed using the caliper tool. Foveal and paramacular RT, located at 1 and 2 mm distances from the fovea in both vertical and horizontal scans, were measured. Three consecutive RT measurements were taken to assess measurement reliability. The within-subject coefficient of variation (CVw) and intraclass correlation coefficients (ICC) were calculated to validate the manual method. Results: The mean axial length of the 29 eyes assessed was 28.28 ± 2.72 mm and the mean spherical refraction was -13.61 ± 6.68 diopters. CVw ranged from 0.86 to 8.73% and ICC varied from 0.81 to 0.98. Conclusion: A manual RT measurement protocol could reliably be used in the daily clinic for assessing pathologic myopic patients when OCT software segmentation fails.