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R. Angeles, T. Abunto, D. Schanzlin, L.M. Zangwill, C. Bowd, R.N. Weinreb; Corneal Changes After Laser in Situ Keratomileusis: Measurement of Corneal Polarization and Magnitude . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2666.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the effect of LASIK on corneal polarization axis (CPA) and magnitude (CPM). LASIK involves ablation of the corneal stroma, leading to corneal changes, which may induce a change in these parameters. Methods: We measured the change in CPA and CPM before and after LASIK utilizing the Variable Corneal Compensated Scanning Laser Polarimeter (SLP) (GDx-VCC, Laser Diagnostic Technologies, San Diego, CA), Scans were completed on nine (9) subjects prior to and three months after LASIK. Ten (10) normal controls were tested twice at the same time interval. Differences in CPA, CPM, corneal thickness and curvature measurements were compared between LASIK and normal subjects. Results: At baseline, the mean (± SD) CPA was 33.4° ± 20.0°, CPM was 40.7 ± 13.9nm, corneal thickness was 549 ± 26.7µm, and corneal curvature was 7.6 ± 0.3mm. There was no significant difference between normal and LASIK subjects in these baseline values. The mean absolute value of the change in CPA, CPM, corneal thickness and curvature, was significantly greater (P < 0.02) in LASIK subjects (9.6° ± 5.7°, 5.4 ± 3.6nm, 39.1 ± 27.4µm and 0.6 ± 0.3mm respectively), than normal subjects (1.6° ± 0.9°, 2.2 ± 1.61nm, 5.2±3.2µm, 0.03±0.03mm, respectively). Conclusions: LASIK causes a measurable change in the CPA and CPM that may be related to the loss of corneal tissue. This change may have implications in the accuracy of RNFL thickness measurements using the SLP.
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