Clinical Study
Eye (2009) 23, 1282–1287; doi:10.1038/eye.2008.307; published online 10 October 2008
The effect of long-term wear of soft lenses of low and high oxygen transmissibility on the corneal epithelium
This work was supported by the Australian Government through the Cooperative Research Centre scheme and by the Contact Lens Society of Australia. Funding support from CIBA Vision, USA, is acknowledged. The Vision Cooperative Research Centre also has a royalty agreement with CIBA Vision
I Jalbert1, D F Sweeney1,2 and F Stapleton1,2
- 1School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia
- 2The Institute for Eye Research and The Vision Cooperative Research Centre, Sydney, Australia
Correspondence: I Jalbert, OD, PhD, FAAO, School of Optometry and Vision Science, The University of New South Wales, Sydney UNSW NSW 2052, Australia. Tel: +61 2 9385 9816; Fax: +61 2 9313 6243. E-mail: i.jalbert@ unsw.edu.au
Received 8 January 2008; Revised 12 September 2008; Accepted 12 September 2008; Published online 10 October 2008.
Abstract
Purpose
To measure the effects of long-term wear of soft lenses of low and high oxygen transmissibility (Dk) on basal epithelial appearance and epithelial thickness.
Methods
Sixty-three subjects were enroled in a cross-sectional study. Seventeen high Dk lens wearers and 24 low Dk lens wearers who had worn lenses on an extended wear basis for more than 3 years (range: 3–22) were compared to a group of 22 age-matched subjects who had never worn contact lenses. Cell regularity and the intensity of light backscattered by the basal epithelium were assessed using confocal microscopy. Epithelial thickness was measured at the centre and at four peripheral locations using modified optical pachometry.
Results
Epithelial basal cells appeared less regular in low Dk lens wearers than high Dk wearers or controls (Mann–Whitney U-test, P=0.001). The intensity of backscattered light did not differ across groups (Kruskal–Wallis test, P=0.37). Low Dk wearers had the thinnest epithelium (46 (10) 
m), followed by high Dk wearers (54 (14) m) and controls (58 (9) m; ANOVA, P
0.006). Topographical position did not affect epithelial thickness (ANOVA, P=0.10).
Conclusions
Visible alterations to the basal epithelial cells can only be detected in long-term extended wearers of low Dk soft lenses. Extended wear of high Dk soft lenses results in topographically uniform epithelial thinning that is significantly less than the thinning seen with low Dk lenses. Confirmation of these findings using groups with evenly matched duration of lens wear is required.
Keywords:
epithelial thickness, basal epithelium, contact lens wear, hypoxia, in vivo confocal microscopy
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