Abstract
Purpose :
Purpose: To compare the effect of eye rubbing on Scheimpflug imaging parameters and corneal biomechanics on keratoconus and normal eyes.
Methods :
Methods: Prospective cohort study including 31 normal eyes and 31 keratoconus eyes that attend to the Institution between January 2017 and November 2017. Patients performed standardized eye rubbing during 2 minutes; pre and immediately after eye rubbing, the tests were taken in minute 1, 7 and 14. More than 25 parameters from the Pentacam HR (Oculus GmBH, Wetzlar, Germany) derivatives of the curvature, elevation and pachymetry maps and 6 parameters from the Ocular Response Analyzer (ORA, Reichert Ophthalmic Instruments, Depew, NY) were measured and compared between normal and keratoconus eyes. Statistical analysis was performed using Stata 13.
Results :
Results: In the normal group pre versus 7 minutes post of eye rubbing mean change on Maximum keratometry (Kmax), Posterior elevation at the thinnest point (PE), Central Corneal Thickness (CCT), corneal hysteresis (CH) and corneal resistance factor (CRF), Goldman-correlated intraocular pressure (IOPG), corneal compensated intraocular pressure (IOPCC) were 0.04 +/-0.36 Diopters (D), -0.07 +/- 2.83 um, 0.10 +/- 9.01 um, -0.22 +/-1.27 seg, -0.83 +/-2.59 mmHg and -0.62 +/-2.60 mmHg respectively. In the keratoconus group pre versus post 7 minutes after eye rubbing mean change on Kmax, PE, CCT, CH and CRF, IOPG, IOPCC were -0.23 +/- 0.44, -2.36 +/- 12.89 um, -3.84 +/-11.26 um, -0.02 +/- 1.01, -0.23 +/- 1.09, -1.33 +/- 1.40 mmHg, -1.08 +/- 1.60 mmHg. There was statistical significant difference on the change after 1 min of eye rubbing in normal eyes on the IOPG (p= 0.03) and in keratoconus eyes on IOPG, IOPCC and CCT (p <.001, p<.001, p=0.002 respectively).
Conclusions :
Conclusions: Both normal and keratoconus group had significant changes in corneal hysteresis parameters after eye rubbing. However keratoconus group experienced greater variability on the changes in the keratometry and elevation parameters when compared with normal eyes.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.