Purpose:
To compare macula and retinal nerve fiber layer (RNFL) thicknessmeasurements from two models of the Cirrus HD-OCT. The originalCirrus HD-OCT (Model 4000) uses a line-scanning ophthalmoscope(LSO) to generate an image of the fundus for alignment and reference.The newer Model 400 does not use an LSO but utilizes the OCTscanning beam to generate the fundus image in addition to creatingthe B-scan OCT images.
Methods:
The same Cirrus HD-OCT was used for all measurements. Changingthe software allowed the study to be conducted utilizing theLSO (as a Model 4000) and without the LSO (as a Model 400).Sixteen volunteer subjects were scanned twice with the Macula512 x 128 Cube scan (right eye) and twice with the Optic Nerve200 x 200 Cube scan (left eye) on the same day.
Results:
All mean differences were less than one micron. No statisticallysignificant differences were found by paired t-test analysis(P < 0.05) for any of the compared macula or RNFL thicknessmeasurements. The distribution of differences and the repeatabilityof each system were consistent with the previously reportedrepeatability of Cirrus. See Table 1 and Table 2.
Conclusions:
The new Cirrus HD-OCT Model 400 measures macula and RNFL thicknesseson average within 1 micron of the original Cirrus HD-OCT Model4000.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • macula/fovea • nerve fiber layer