Purpose:
To determine the repeatability of retinal thickness measurements using Cirrus TM HD-OCT, a spectral domain optical coherence tomography instrument (Carl Zeiss Meditec, Dublin, CA).
Methods:
A total of 227 subjects were recruited from 4 sites with various retinal pathologies. Only one eye was chosen as the study eye when both were eligible. Two (2) scans were acquired during a single visit with the CirrusTM HD-OCT using the same scanning protocol. Retinal thicknesses in all subfields was calculated. Analysis of variance was performed for each pathology subgroup, and repeatability standard deviation (SD) was determined by taking the square root of the random variance component. Assuming a normal distribution of random errors, the repeatability 95% limits are expected to be 2.77*SD.
Results:
A few scans were rejected due to algorithm failures, poor placement of scan, or poor quality (5-10%). The repeatability SD of the remaining scans varied by pathology (see Table 1).
Conclusions:
The repeatability of measurements for retinal thicknesses with CirrusTM HD-OCT is excellent for normals. For cases with pathology, it also appears more than adequate for clinical practice in this study. Improvements in repeatability for low vision pathologies likely will be seen when registration between scans is performed.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical