Purpose: Surprisingly, a significant reduction (18.4%) in epithelial thickness was found after 15 seconds of eye rubbing measured using Holden-Payor optical pachometer reported in the literature. Hence, we aimed at studying the effects of compressive and shearing pressure associated with eye rubbing on total corneal, epithelial and Bowman's membrane thickness using spectral domain OCT (SD-OCT).
Methods: SD-OCT (Spectralis; Heidelberg Engineering) was used to acquire cross-sectional images of the cornea. Central total-corneal thickness (TCT), epithelial thickness (ET) and Bowman's membrane thickness (BMT) was measured on 20 eyes of 10 subjects with normal corneas without any ocular pathology using in-house developed MATLAB (Mathworks, Inc.) program. Two different measurement methods (distance between inflection points and peak to peak distance) were performed on luminance graph to obtain thickness profile of the corneas. Baseline measurements were compared with the measurements obtained immediately after 30 seconds of circular eye rubbing over the closed eye lid with contra lateral eye at a primary gaze position.
Results: We have found that the mean difference in TCT, ET and BMT to be 0.44 ± 6.00 µm, 0.28 ± 1.72 µm, and 0.01 ± 0.77 µm with first method of measurement, respectively, and the mean difference in TCT and ET were -0.26 ± 5.75 µm, and 0.37 ± 1.38 µm with second method of measurement respectively before and after eye rubbing. These differences were statistically insignificant (all p > 0.05) using both measuring methods.
Conclusion: Thirty seconds of circular pattern rubbing over closed eye lids using index finger produce no significant changes on total corneal, epithelial and Bowman's membrane thickness.