Background and objective: To evaluate and compare the intra-session repeatability of retinal thickness measurements from the Topcon 3D OCT 1000 (Topcon Medical Systems; Paramus, NJ), a spectral-domain optical coherence tomography (SD-OCT) system, with the Stratus (Carl Zeiss Meditec, Inc., Dublin, CA), a time-domain OCT (TD-OCT) system, in eyes with retinal diseases.
Patients and methods: Repeated scans with both SD-OCT and TD-OCT were taken. Thickness measurements from high-quality scans were used to assess repeatability and compare measurements between the two instruments.
Results: Paired scans from 127 eyes were evaluated, of which 63 pairs were of high quality. Coefficients of repeatability and variation for the central subfield were 20.1 μm (2.6%) with SD-OCT and 27.4 μm (4%) with TD-OCT (P = .38). The mean difference in central subfield thickness between the two instruments was 24.5 μm (standard deviation = 20.9).
Conclusion: Repeatability of retinal thickness measurements with the Topcon 3D OCT 1000 is comparable to the Stratus. The measurements of the two machines differ significantly and cannot be used interchangeably.
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