Abstract
Purpose: :
The comparison of retinal nerve fiber layer (RNFL) and central retinal thickness (CRT) measurements between the Zeiss STRATUS OCT, Optovue RTVue, and Cirrus OCT.
Methods: :
We examined healthy volunteers, glaucoma patients, and patients with macular edema using the 3 different OCT machines. To measure CRT using the STRATUS OCT a fast macular thickness scan was performed. For the Optovue RTVue and Cirrus machines, raster scans were used. The thickness of the central 1 mm of each scan was compared. To measure the RNFL the appropriate scans were obtained from each machine. RNFL thickness was compared in 4 different quadrants: superior, inferior, nasal, and temporal.
Results: :
In the comparison of CRT measurements, the Cirrus OCT averaged 73.8 microns (SD 25.7, n = 8) greater than the STRATUS OCT and 49.2 microns (SD 27.1, n = 6) greater than the RTVue. The average CRT measurement using the RTVue was 22.9 microns (SD 21.5, n = 25) greater than the STRATUS. In the comparison of RNFL thickness, the RTVue appeared to measure greater than the other 2 machines. The differences in the measurements did not vary greatly depending on the quadrant, and for brevity the results for the superior quadrant only will be given here. The average superior RNFL thickness using the RTVue was 22.2 microns (SD 11.2, n = 25) greater than the STRATUS OCT, and 25.9 microns (SD 10.7, n = 18) greater than the Cirrus OCT. The STRATUS OCT RNFL thickness measurements were on average 3.8 microns (SD 9.3, n = 14) greater than those from the Cirrus OCT.
Conclusions: :
Quantitative measurements of central retinal and RNFL thickness differ between the 3 different OCT machines tested. For CRT, the Cirrus appears to generate the thickest measurements, followed by the RTVue and the STRATUS. The differences in measurement of RNFL thickness are not as great, however the Cirrus may generate slightly thinner measurements than the other 2 machines. The differences between the STRATUS and RTVue are minimal, and are not likely clinically relevant. These differences are most likely due to differences in measurement algorithms as well as the anatomic definition retinal boundaries.
Keywords: imaging/image analysis: clinical