Abstract
Purpose:
The purpose of this study was to evaluate the inter-ocular characteristics of the ocular surface aberrations using surface aberrometry.
Methods:
The sample comprised ten participants with non-invasive tear breakup time (TBUT) between 5.38s and 7.82s (mean OD 6.94s; mean OS 6.24s). Measurements of dynamic anterior surface aberrations and corneal topography were obtained in both eyes of all participants using the Topcon CA200F corneal analyzer (25 fps). Anterior surface aberration measurements were obtained for two, 15 second open eye intervals. Surface aberrations coefficients were obtained for a 6mm pupil diameter. Analysis of the data was done using the R statistical program and Statistica. The raw RMS and the coefficient for vertical prism were smoothed using a running mean procedure (R: CATools; k=11). A segmented linear regression (R: Segmented) was fitted to the smooth data. The highest positive slope for the linear segments and the times after the start of the blink epoch at which this occurred (the breakpoint) were determined. The breakpoint is assumed to correspond with the timepoint at which the ocular surface starts to lose regularity.
Results:
The highest positive slope for the RMS was, on average, higher in the second eye measured (p<0.01) and occurred later after the blink (p<0.01). The mean (±SE) highest positive slope for RMS across blink epochs was +0.064±0.03 for the right eye and +0.180±0.13 for the left eye. For vertical prism there was no difference between the two eyes for the slope or the location of the breakpoint (both p>0.05).
Conclusions:
The rate of increased RMS of the ocular surface is higher when the loss of regularity of the ocular surface occurs longer after a blink. In this sample, this occurred more often with the second eye measured. These findings will impact the interpretation of between-eye analysis of ocular surface aberrations.
Keywords: 550 imaging/image analysis: clinical •
421 anterior segment •
626 aberrations