Noncontact measurements of central corneal epithelial and flap thickness after laser in situ keratomileusis.
OBJECTIVE
To investigate the changes in the epithelium and flap after laser in situ keratomileusis (LASIK), when measured with optical coherence tomography (OCT).


METHODS
Twenty-eight eyes of 14 patients (age: 39.9 +/- 8.6 years) underwent LASIK. The central thickness of corneal epithelium and flap were measured with a real-time 1310 nm OCT 1 day, 1 week, and 1 month after surgery. A custom software program was used to process multiple images of each eye on each visit.


RESULTS
After surgery, the corneal epithelium changed significantly (ANOVA: F((3, 81)) = 12.3, P = 0.000) with not statistically significant thinning at one day (mean +/- SD: 57.8 +/- 5.9 micro m, P = 0.26, compared with baseline: 59.9 +/- 5.9 micro m) and statistically significant thickening at 1 week (60.8 +/- 5.8 micro m, P = 0.04, compared with 1 day) and 1 month (64.6 +/- 6.1 micro m, P = 0.008 compared with all others). There were statistically significant changes in the corneal flap thickness (ANOVA: F((2, 54)) = 4.59, P = 0.01) with thickening in the intervals between 1 day (143.3 +/- 20.6 micro m) and 1 week (149.7 +/- 24.6 micro m, P = 0.12), and between 1 week and 1 month (152.7 +/- 19.3 micro m, P = 0.01). There was a strong correlation (r = 0.898) between the difference of corneal thickness before and after surgery and predicted laser ablation depth.


CONCLUSIONS
OCT is a useful noncontact tool for thickness measurements of the epithelium, flap, and total cornea. After LASIK, the epithelium and flap showed thickening during the study period.
Wang
Jianhua
J
School of Optometry, University of Waterloo, Waterloo, Ontario, Canada. jianhua_wang@urmc.rochester.edu
Thomas
Joseph
J
Cox
Ian
I
Rollins
Andrew
A
D000328:Adult; D003319:Corneal Stroma / Q000473:pathology*; D003941:Diagnostic Techniques, Ophthalmological; D019573:Epithelium, Corneal / Q000473:pathology*; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D008297:Male; D011184:Postoperative Period; D013524:Surgical Flaps / Q000473:pathology*; D041623:Tomography, Optical Coherence / Q000379:methods*