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WW Haw, E Manche; Prospective Multivariable Analysis of Regression following LASIK for Compound Hyperopic Astigmatism-Phase III US FDA Trial . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2071.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To prospectively assess variables influencing "early" onset and "late" onset regression following LASIK for compound hyperopic astigmatism. Methods: As part of a U.S. phase III Food and Drug Administration trial, 124 eyes of 80 patients underwent LASIK for +1.0 to +6.0 D of sphere and +1.0 to +4.0 D of astigmatism using the VISX S2 Smoothscan excimer laser. Patients were prospectively evaluated at 1 day, 1, 3, 6, and 12 months. A linear regression model was performed to determine the effect of age, preoperative spherical equivalent, astigmatism, sphere, and mean keratometry on the regression of refractive effect at each interval. Results: A mean hyperopic regression of +0.42 D occurred between the first postoperative day and the third postoperative month. The level of preoperative spherical equivalent demonstrated a positive correlation with the amount of "early" onset (<3mo) hyperopic regression (P=0.016, r2=0.10) and a weak correlation with preoperative astigmatism (P=0.13). Preoperative mean keratometry (p=0.62) and age (p=0.38) were not statistically correlated with the amount of "early" hyperopic regression. "Late" (≷3-6 mo) onset hyperopic regression ≷1.0 D occurred in 3.4% and ≷0.75 D occurred in 15.5% of eyes. "Late" hyperopic regression occurred in eyes independent of their preoperative spherical equivalent, sphere, astigmatism, mean keratometry and age. (P≷0.05) Conclusion: "Early" and "late" hyperopic regression following LASIK for compound hyperopic astigmatism may be influenced by different dependent variables. Early hyperopic regression is primarily correlated with preoperative level of correction while "late" hyperopic regression is most likely dependent upon multiple individual factors.
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