Abstract
Purpose: :
To compare high-definition (HD) CirrusTM optical coherence tomography (OCT) (Carl Zeiss Meditec USA) with standard-resolution (SR) StratusTM OCT (Carl Zeiss Meditec USA) for imaging retinal diseases and analyze differences in quantitative measurement of central macular thickness (CMT) in eyes with and without macular edema (ME).
Methods: :
A prospective head-to-head comparison of 106 eyes of 53 patients with and without ME between the 2 OCT systems: 3-D imaging HD-OCT with an axial resolution of 5 µm and a scan velocity of 27,000 axial scans / second and 2-D imaging SR-OCT with a 10 µm resolution and a scan velocity of 400 axial scans / second. The HD-OCT platform provided quantification of a 1 mm central zone and average macular thickness (AMT) of nine zones including a 1 mm central zone over a 6 mm scan diameter; these were compared with a SR-OCT 1 mm central zone.
Results: :
In all eyes mean CMT was significantly greater when measured with HD-OCT than with SR-OCT (310 µm vs 262 µm; p= 1.38 x 10-13) In eyes without ME (n= 72) mean CMT was significantly greater with HD-OCT than with SR-OCT (259 µm vs 215 µm; p= 1.07 x 10-13) In this group HD-AMT was significantly greater than SR-CMT (282 µm vs 215 µm; p= 9.36 x 10-14) and HD-AMT was greater compared with mean HD-CMT, though this difference was not statistically significant (p= 0.256) In eyes with ME (n=34) mean CMT was significantly greater with HD-CMT compared with SR-CMT (419 µm vs 361 µm, p= 0.0003) In this group mean HD-CMT was significantly greater than HD-AMT (419 µm vs 332 µm, p= 1.68 x 10-7) and mean SR-CMT was greater than mean HD-AMT, though this was not statistically significant (361 µm vs 332 µm, p= 0.097.)
Conclusions: :
In all eyes HD-OCT demonstrated significantly increased CMT compared to SR-OCT. This is likely due to HD-OCT detection of the outer band of the RPE versus SR-OCT detection of the inner boundary of the RPE complex. In eyes without ME, HD-CMT showed no significant difference compared with HD-AMT, indicating high test reproducibility in eyes with homogenous CMT. In eyes with ME, HD-CMT was significantly greater compared to HD-AMT, though SR-CMT showed no significant difference in measurement compared with HD-AMT. This indicates that SR-OCT did not accurately quantify CMT in eyes with ME, whereas HD-OCT was more precisely able to measure central and surrounding macular zones of varying thicknesses.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical • retina