Abstract
Purpose: :
to compare the intrasession riproducibility of macular thickness measurements by 4 optical coherence tomography (OCT) systems: the Stratus, a time domain system and three spectral domain systems as the Cirrus HD-OCT (Carl Zeiss Meditec, Inc., Dublin CA), the Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany) and OTI spectral OCT/SLO (Opko Health Inc, AMEX: OPK, Miami, FL) in normal subjects.
Methods: :
Consecutive subjects without any retinal disease were considered in this study. Macular thickness measurements of nine standard ETDRS macular subfields were obtained and analyzed. Bland and Altman plots were constructed to assess intrasession repeatability. Precision (repeatability coefficient) was defined as mean difference ±1.96 the standard deviation (SD) of the differences. Coefficients of variation (CV) were also calculated for the nine ETDRS macular subfields for the different OCT systems. Pair-wise comparisons of CV between the 4 different OCT systems were performed with paired t-test
Results: :
twenty-six eyes of 26 normal subjects (mean age 40.4±10.9 years) were considered. The mean difference of test-retest measurements of central retinal thickness (CRT) was 2.16 µm (22.0/-17.7, upper and lower SD level respectively) for the Stratus OCT, -1.53 µm (13.1/-16.1) for the Cirrus HD-OCT, -0.9 µm (12.73/-14.6) for the Spectralis OCT, -0.4 µm (19.6/-20.33) for the OTI OCT. CV of mean central retinal thickness measurements was 1.4% for both the Stratus and Cirrus OCT, 1.1% for the Spectralis and 2.18% for the OTI and the difference between the OCT systems was not statistically significant (p<0.05%). Considering the ETDRS macular subfields the highest CV was found for the nasal internal area for Cirrus and OTI (1.5% and 3.69% respectively), for the nasal external area for the Stratus (1.08%) and for the temporal internal area for the Spectralis (1.35%).
Conclusions: :
macular thickness measurements is highly and similarly reproducible in healthy eyes with different OCT systems evaluated in this study.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • macula/fovea