Abstract
Purpose :
Scleral contact lenses are increasing in clinical popularity. As a result it is important to fully characterize and understand the normal ocular and visual changes that are expected in a normal, young, healthy population. This study seeks to quantify changes in corneal thickness over the course of a day of wear and investigate changes in corneal and/or ocular aberration measurements, contrast sensitivity, and visual acuity.
Methods :
32 eyes from healthy subjects between the ages of 18 and 40 who were not current gas permeable contact lens wearers and had no ocular disease or prior refractive surgery were included in this study. Subjects were fit for scleral lenses using normal clinical procedures and returned on a separate day for testing. Baseline and end of day measurements were obtained without any lenses in place and 4 measurements were made with the lenses in place, approximately every 2 hours. Measurements included Optovue Anterior Segment Optical Coherence Tomography (OCT), ocular and corneal aberrometry with the i.Profilerplus by Zeiss, visual acuity (VA), and contrast sensitivity (CS).
Results :
There was a significant increase of 4.8 microns or 0.9% in corneal thickness measured with the OCT for 28 eyes (p<0.01). Average corneal thickness increased steadily over the course of wear and correlated with average minutes of wear (p<0.01). Total wear time averaged 422 min (range 342-496 min) and was related to changes in corneal thickness, but the correlation did not reach significance. Ocular aberration measurements showed a significant decrease from the first to last measurements with the lenses in place over a 5mm pupil for spherical aberration, high-order RMS, and vertical coma (p<0.01). The change in thickness was correlated with the change in high-order RMS (p=0.02). No significant changes were seen in corneal aberration measurements. VA and CS measurements were correlated (p<0.0001).
Conclusions :
There were significant differences noted in corneal thickness and ocular aberration measurements for normal subjects wearing scleral contact lenses. High-order RMS for the eye as a whole decreased with scleral lens wear and this change was correlated with changes in corneal thickness. Ocular aberration measurement of spherical aberration and vertical coma also decreased with scleral lens wear.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.