Comparative evaluation of residual astigmatism between elliptical and circular flap creation in femtosecond laser-assisted LASIK for compound myopic astigmatism

Session Details

Session Title: LASIK II

Session Date/Time: Tuesday 08/09/2015 | 14:00-16:00

Paper Time: 14:00

Venue: Room 10

First Author: : H.Lin TAIWAN

Co Author(s): :    Y. Chuang   C. Lin   P. Lin              

Abstract Details

Purpose:

To compare the residual astigmatism outcome of two flap designs (temporal hinge with elliptical shape versus circular shape) in eyes using femtosecond laser assisted LASIK for the correction of compound myopic astigmatism.

Setting:

Universal Eye Center, Zhong-Li

Methods:

The retrospective study compared residual astigmatism outcomes between two groups of eyes with compound myopic astigmatism with the Intralase femtosecond laser (Abott Medical Optic, Inc.) and EX-500 excimer laser (Alcon Laboratories, Inc.). These eyes were divided into Group I (elliptical flap) and group II (circular flap). Elliptical flaps were created using 4% over-sizing of the horizontal diameter of the LASIK flap. The residual refractive cylinder classified into with-the-rule (0˚~30˚, 151˚ ~180˚), oblique astigmatism (31˚ ~60˚, 121˚ ~150˚), and against-the-rule (61˚ ~120˚). Rest of the surgical procedure remained the same in the all the eyes.

Results:

173 eyes of 88 patients were reviewed. In one month postoperatively, refractive cylinder magnitude were reduced significantly. The mean residual refractive cylinder was -0.19D+-0.29D (with-the-rule), -0.10D+-0.27D (oblique) and -0.50D+-0.45D (against-the-rule) in group I (elliptical flap). The mean residual refractive cylinder was -0.26D +- 0.29D (with-the-rule), -0.55D+-0.97 (oblique) and -0.23D+-0.45 (against-the-rule) in group II (circular flap). The residual refractive cylinder is statistically significant lesser in Group I, especially in oblique astigmatism.

Conclusions:

Femtosecond laser assisted LASIK with an elliptical cut for treating compound myopic astigmatism results in significantly reduced refractive cylinder magnitude than a circular flap especially in oblique astigmatism. This may be due to the geometric optimization provided by the enlargement of the optical and transition zones along the flat meridian.

Financial Interest:

NONE