Repeatability and Reproducibility of Retinal Thickness Measurements by Optical Coherence Tomography in Age-Related Macular Degeneration

Purpose: To evaluate the repeatability and reproducibility of retinal thickness measurements in exudative age-related macular degeneration (AMD) using Stratus optical coherence tomography (OCT) (Carl Zeiss Meditec, Inc., Dublin, CA). Design: Prospective, observational case series. Participants: A total of 200 eyes of 200 subjects with exudative AMD. Methods: Macular thickness and fast macular thickness programs of Stratus OCT were performed twice by the same examiners or 2 different examiners. The sequence of examiners was randomized 1:1:1:1. The variability of 1-mm subfield central retinal thickness (CRT), center point thickness (CPT), and retinal volume (RV) was calculated. Main Outcome Measures: Interobserver and intraobserver variability of retinal thickness measurements. Results: Ninety-nine patients/eyes were enrolled in study arm 1 (repeated by the same examiner), and 101 patients/eyes were enrolled in study arm 2 (repeated by different examiners). Values of CPT, CRT, and RV were well correlated (interclass correlation coefficient, 0.71-0.93) in both study arms, revealing better results for the macular thickness program than for the fast macular thickness program. Threshold algorithm line failures were significantly correlated to the absolute differences of 2 repeated measurements for CPT, CRT, and RV but not with manually corrected maximum retinal thickness (MRT). Maximum retinal thickness was significantly influenced by the examiner performing the measurement. Age, lesion composition, examiner performing OCT examination, and sequence of examination had no significant influence. Conclusions: The repeatability and reproducibility of retinal thickness measurements were high, presenting better results for CRT and RV versus CPT, and for the macular thickness program versus the fast macular thickness program. The reliability of retinal thickness measurement was most frequently affected by algorithm line failures and fixation problems. A possible solution may be manually corrected measurement, such as MRT. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. Ophthalmology 2010; 117: 1577-1584 (C) 2010 by the American Academy of Ophthalmology.