The influence of corneal astigmatism on retinal nerve fiber layer thickness and optic nerve head parameter measurements by spectral-domain optical coherence tomography (Diagnostic Pathology)

Background: To evaluate the influence of corneal astigmatism (CA) on retinal nerve fiber layer (RNFL)thickness and optic nerve head(ONH) parameters measured with spectral-domain opticalcoherence tomography (OCT) in high myopes patients before refractive surgery. Methods: Seventy eyes of 35 consecutive refractive surgery candidates were included in this study. Themean age of the subjects was 26.42 +/- 6.95 years, the average CA was 1.17 diopters (D;SD 0.64; range 0.2 to-3.3D), All subjects in this study were WTR CA. 34 eyes were inthe normal CA group with a mean CA was 0.67 +/- 0.28D, 36 eyes were in the high CA groupwith an average CA of 1.65 +/- 0.49D. All subjects underwent ophthalmic examination andimaging with the Cirrus HD OCT. Results: No significant difference was noted in the average cup-to-disk ratio, vertical cup-to-disk ratioand cup volume (all P values > 0.05). Compared with the normal CA group, the high CAgroup had a larger disc area and rim area, thinner RNFL thickness in the temporal quadrant,and the superotemporal and inferotemporal peaks were farther to the temporal horizon (All Pvalues < 0.05). There were no significant differences between the two groups in globalaverage RNFL thickness, as well as superior, nasal and inferior quadrant RNFL thickness (allP values > 0.05). Conclusions: The degree of with-the-rule CA should be considered when interpreting ONH parametersand peripapillary RNFL thickness measured by the Cirrus HD OCT.Virtual slidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1148475676881895