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Phillip Rubin, Matthew Gorski, Carolyn Shih; Keratometric outcomes for femtosecond laser-assisted limbal relaxing incisions. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3919.
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© ARVO (1962-2015); The Authors (2016-present)
Limbal relaxing incisions (LRI) are commonly used to reduce astigmatism. In recent years, the femtosecond laser has emerged as an alternative to manual incisional techniques due to greater perceived accuracy, precision, and safety. We performed a retrospective study to assess the keratometric results of femtosecond laser-assisted arcuate keratotomy in the treatment of corneal astigmatism.
Preoperative and postoperative corneal topographic astigmatism measured with an Orbscan II (Bausch + Lomb) were retrospectively analyzed in consecutive patients who underwent fsLRI between March 2011 and June 2014. A single surgeon performed all procedures using an IntraLase Femtosecond Laser (Abbott Medical Optics Inc.) Incisional depth was set at 90% of central corneal thickness. Changes in topographic astigmatism were calculated and significance was determined by paired student’s t-test. Regression methods were used to analyze the relationship between patient and surgical variables and changes in topographic astigmatism.
The study included 25 eyes of 20 patients (16 females, 4 males) with a mean age of 68.1 ± 10.3. Mean preoperative astigmatism was 2.0 ± 1.1D (0.7-4.7D). Postoperatively, astigmatism was reduced by a mean of 0.8 ± 0.6D (p<0.00001). Univariate linear regression analysis of astigmatic reduction as a function of arc length showed a moderate positive correlation R=0.69 (p<0.001). No significant correlation was found from separate univariate regression models of astigmatic reduction as a function of central corneal thickness (R=0.09, p=0.7) or diameter of LRI placement (R=0.01, p=0.9). A multivariable regression model of postoperative astigmatic reduction as a function of central corneal thickness, arc length, and diameter gave a positive correlation R=0.74 (p<0.001). In this model, arc length was a significant predictor of astigmatic reduction (p<0.0001) but corneal thickness (p=0.28) and diameter (p=0.07) were not significant.
FSLRI was effective in reducing corneal topographic astigmatism although responses were variable. There was no association between reduction in topographic astigmatism and central corneal thickness or diameter of incision placement. The degree of astigmatic reduction was positively correlated with arc length but only moderately.
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