Purpose:
To compare the optic nerve head parameters measured on Cirrus HD-OCT with similar parameters measured on Stratus OCT in subjects with no known eye disease.
Methods:
Ten volunteer subjects were imaged on both instruments. Two optic disc scans were obtained from each instrument for each eye of the subject on each instrument. The best scan from each eye from each instrument was used to generate quantitative optic nerve summary measurements of Disc Area (mm2), Rim Area (mm2), Cup Volume (mm3) and Vertical cup to disc ratio.
Results:
Table 1 shows the means and standard deviations of the four optic nerve parameters from each instrument, and the mean difference between them. There were substantial differences for Disc Area, Rim Area and Cup Volume. The Rim Area found by Cirrus HD-OCT was 0.41 mm2 smaller than that found by Stratus OCT, on average, though the difference was greater for larger discs. The discrepancy and the trend may be explained by the fact that Cirrus attempts to identify the termination of Bruch’s membrane as the disc boundary, while Stratus in general identifies the termination of the retinal pigment epithelium. Rim Area difference was -0.37 mm2, which is consistent with the Disc Area being smaller on Cirrus. The Cup Volume was larger on Cirrus, and the difference was greater for larger cups. The Vertical cup to disc ratio was not significantly different between the two systems (P = 0.15).
Conclusions:
The disc and rim area measurements are different between the Cirrus HD-OCT and the Stratus OCT. The vertical cup to disc ratio is not significantly different between the two instruments in this small sample of eyes with no known eye disease.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optic nerve • imaging/image analysis: clinical