Abstract
Purpose: :
To assess the repeatability and reproducibility of macular measurements in patients with clinically significant diabetic macular edema (CSDME) using the Cirrus HD-OCT, a spectral domain (SD) optical coherence tomography (OCT) system (by Carl Zeiss Meditec, Inc, Dublin, CA).
Methods: :
A cross-sectional study was conducted on 20 patients (29 eyes) with CSDME at Riverside County Regional Medical Center from May 2008 to December 2008. Each eye underwent six consecutive macular cube scans obtained in rapid sequential fashion using the Cirrus HD-OCT. A seventh scan was then performed under recalibrated settings. The first six scans were evaluated for agreement between macular central subfield thickness, total volume, and average thickness measurements based on nine sectoral macular domains. Mean values were calculated for each category. The repeatability analysis yielded intraclass correlation coefficients, coefficients of repeatability, and coefficients of variation. Finally, the mean values of the first six scans were compared with corresponding values from the seventh scan to assess reproducibility.
Results: :
All intraclass correlation coefficients were greater than 0.9444. Repeatability coefficients were all greater than 0.97. The average coefficient of variance among the first six scans for macular central subfield thickness, volume, and average thickness were all less than 3.5%, while the average coefficient of variance between the mean of the first six scans and the seventh scan were all less than 2.3% in all fields of measurement.
Conclusions: :
Due to the high intraclass correlation coefficients (>0.9444), high repeatability coefficients (>0.97), and low variance (<3.5%), the Cirrus HD-OCT appears to be a useful imaging modality for quantifying CSDME. Although all macular areas showed high repeatability and reproducibility, macular average thickness showed a much lower variance (0.64%) than shown by either macular volume or central subfield thickness (2.3% and 0.98% respectively). Our findings suggest that macular average thickness may be the most reliable parameter for objectively assessing CSDME with this imaging system.
Keywords: retina • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • diabetic retinopathy