Improved repeatability of retinal thickness measurements using line-scan ophthalmoscope image-based retinal tracking.

Abstract

To assess repeatability and speed of a line-scan ophthalmoscope (LSO) image-based tracking system and compare to the point-scanning approach. Thirty-five eyes with retinal diseases underwent volume scans using two spectral-domain optical coherence tomography (OCT) devices: a line-scan tracking Cirrus HD-OCT (Carl Zeiss Meditec; Dublin, CA) and point-scan tracking Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany). Eyes were also imaged on the Cirrus HD-OCT with tracking disabled. Mean difference in central subfield thickness (CST) between consecutive scans was 2.6 µm for the Cirrus without tracking, 1.7 µm with tracking, and 3.6 µm for the Spectralis. The repeatability standard deviation was 3.0 µm for the Cirrus without tracking, 1.5 µm with tracking, and 4.0 µm for the Spectralis. Coefficient of variation for the CST was 1.1% for the Cirrus without tracking, 0.5% with tracking, and 1.4% for the Spectralis. Mean scan acquisition time was 12.3 ± 6.2 seconds for the Spectralis, 7.8 ± 6.7 for the Cirrus with tracking, and 4.3 ± 0.6 for the Cirrus without tracking. Real-time LSO image-based retinal tracking appears to improve repeatability of OCT retinal thickness measurements.