The measurement of corneal epithelial thickness in response to hypoxia using optical coherence tomography.
OBJECTIVE
To determine if corneal epithelial thickness increases in association with corneal edema induced by wearing soft contact lenses during eye closure.


METHODS
Experimental study.


METHODS
One eye (randomly selected) of twenty noncontact lens wearers (10 males and 10 females, age 35.6 +/- 9.6 years) was patched during 3 hours of soft contact lens (SCL) wear and the contralateral eye acted as a control. Corneal and epithelial thickness of both eyes was measured before and after SCL wear using optical coherence tomography (OCT).


RESULTS
Immediately after contact lens removal, total corneal thickness was increased significantly by 13.8 +/- 2.3% (mean +/- SD) compared with baseline (P <.0001, paired t test) and after 100 minutes was still 4.5 +/- 2.3% thicker than baseline (P <.0001, paired t test). The control eyes showed no change in total corneal thickness (P >.05, paired t test). Immediately after contact lens removal, corneal epithelial thickness was increased by 1.7 +/- 4.8%, but this change was not statistically significant (P >.05, paired t test). Following contact lens removal, epithelial thickness changed significantly (Repeated measure analysis of variance [Re-ANOVA]: F((7,133)) = 4.91, p(H-F) < 0.001) over the next 100 minutes with thinning recorded at 60, 80, and 100 minutes (P <.05, paired t test). There was no significant change over time in epithelial thickness of the control eyes (Re-ANOVA: F(4, 76) = 0.91, p(H-F) = 0.464).


CONCLUSIONS
OCT demonstrated that corneal epithelial thickness does not increase in response to hypoxia from SCL wear and eye closure, in contrast to a significant increase in total corneal thickness.
Wang
Jianhua
J
Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada.
Fonn
Desmond
D
Simpson
Trefford L
TL
Jones
Lyndon
L
D000328:Adult; D003263:Contact Lenses, Hydrophilic; D003316:Corneal Diseases / Q000175:diagnosis / Q000209:etiology*; D019573:Epithelium, Corneal / Q000473:pathology*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000150:complications*; D007368:Interferometry; D008027:Light; D008297:Male; D014054:Tomography