THE RELATIONSHIP BETWEEN AN INDIVIDUAL’S OVERNIGHT CORNEAL SWELLING AND THE MICROCYST RESPONSE FOR A LOW DK CONTACT LENS WORN IN EXTENDED WEAR

Andrew Jaworski

Abstract

PURPOSE. To investigate whether an individual’s overnight corneal swelling correlates with the subsequent microcyst response to a low Dk contact lens worn in extended wear.
METHOD. 37 subjects new to contact lens wear or who had not worn lenses for at least 12 months had baseline biomicroscopy and corneal swelling measurements taken before commencing 3 months EW of a low Dk hydrogel contact lens. Corneal swelling was assessed with the Orbscan instrument using lenses of the power worn during the wearing trial. Microcyst counts were recorded at the 3 month visit.
RESULTS. For the 29 subjects who completed the 3 month trial, baseline central corneal swelling (±SD) was 12.1 (± 3.1)%. The microcyst count (±SD) averaged 15 (±14) at the final 3 month visit, with a median number of 11. There were no statistically significant correlations between the individual’s overnight corneal swelling and the number of microcysts observed at the 3 month visit (r=0.26, p=0.17). Lens power did not correlate with either corneal swelling or microcyst count.

CONCLUSIONS. It is apparent that overnight corneal swelling and the microcyst response to EW across the spectrum of lens types is linked. However, within a given low Dk lens type worn in extended wear, an individual’s overnight corneal swelling is unlikely to be a useful predictive test of their microcyst response. Although both responses have been clearly linked to hypoxia, it is possible that a different mechanism operates to produce the observed changes. Both indices may be required to obtain useful short and long-term information about the physiological compromise that extended wear of a contact lens produces.

Details

Year: 2001

Program Number: Poster 123

Author Affiliation: Brennan Consultants

Co-Authors: Ruth Cornish, Noel Brennan

Co-Author Affiliation: Brennan Consultants, Brennan Consultants

Room: Poster 123