Is quantitative spectral-domain superior to time-domain optical coherence tomography (OCT) in eyes with age-related macular degeneration?

PURPOSE

The aim of this study was to determine the variability of macular map measurements, for two generations of optical coherence tomography (OCT) instruments, in eyes with wet age related macular degeneration (AMD) and low visual acuity.

METHODS

Patients were examined with Stratus OCT and Cirrus HD-OCT. The macular thickness was assessed with the 'macular thickness map scan' and 'fast protocol' in Stratus and with the 512 × 128 and 200 × 200 cube protocols in Cirrus OCT. Two measurements were taken one directly after the other, at the first visit to analyse repeatability. Approximately 1 week later, a third measurement was taken to analyse reproducibility. In Cirrus OCT, a manual correction of foveal location was also performed. Repeatability and reproducibility were calculated as a coefficient of variance (CoV) and a coefficient of repeatability/reproducibility.

RESULTS

Repeatability for central macular thickness (expressed as CoV) was about three per cent for all protocols, and the coefficient of repeatability between 34 and 54 μm. Reproducibility (also expressed as CoV) was between four to seven per cent and coefficient of repeatability between 64 and 89 μm. After manual adjustment of foveal location in Cirrus OCT, the coefficient of repeatability improved to 12-18 μm, and the coefficient of reproducibility to 44-47 μm.

CONCLUSIONS

In eyes affected by wet AMD, there were small differences in repeatability and reproducibility when comparing quantitative maps in Stratus and Cirrus OCT. However, when the software for manual correction of foveal position in Cirrus OCT was used, the variability decreased markedly, and the repeatability was close to what had been reported in normal eyes, demonstrating a significant, potential advantage of spectral-domain over time-domain OCT.