Efficacy of an aspheric treatment algorithm in decreasing induced spherical aberration after laser in situ keratomileusis
Received 24 January 2008; received in revised form 13 February 2009; accepted 12 March 2009.
Purpose
To determine the effectiveness of an aspheric laser in situ keratomileusis (LASIK) algorithm for myopia with and without astigmatism in minimizing postoperative induction of spherical aberration.
Setting
Four sites in Asia.
Methods
Patients with −1.00 to −10.00 diopters (D) of spherical myopia with −4.00 D or less of astigmatism were recruited. Patients randomly had bilateral Zyoptix aspheric algorithm (aspheric group) or bilateral conventional Zyoptix Tissue Saving algorithm (control group). A Technolas 217z100 excimer system was used for LASIK ablation. Visual effectiveness, safety, higher-order aberrations, and corneal asphericity (Q value) were evaluated postoperatively.
Results
The aspheric group comprised 86 eyes and the control group, 84 eyes. At 3 months, the high-contrast uncorrected distance visual acuity was 20/20 or better in 78% of eyes in the aspheric group and 83% of eyes in the control group. The control treatment induced 0.22 μm of spherical aberration, which was significantly higher than the 0.04 μm induced with the aspheric treatment (6.0 mm pupil) (P<.0001). The aspheric treatment induced significantly less vertical coma and trefoil (P = .02). Eyes in the aspheric group had significantly lower Q values (P<.0001). There was no statistically significant difference in the manifest refraction spherical equivalent between the 2 groups (P >.05). Although high- and low-contrast corrected distance visual acuity (CDVA) was similar between the groups, the aspheric group gained more lines of low-contrast CDVA.
Conclusion
The aspheric algorithm was more effective than the conventional algorithm in reducing induced spherical aberration and maintaining corneal asphericity after myopic LASIK.
From the Asian Eye Institute (Ang), Makati City, Philippines; Singapore National Eye Center (Chan, Wee) and the Eye Hospital (Lee), Singapore; Rutnin Eye Hospital (Bunnapradist), Bangkok, Thailand; and Bausch & Lomb (Cox), Rochester, New York, USA
Corresponding author: Robert Edward T. Ang, MD, Asian Eye Institute, Hidalgo Drive Rockwell Center, Makati City 1200, Philippines.
Dr. Cox is an employee of Bausch & Lomb. No author has a financial or proprietary interest in any material or method mentioned.
ABSTRACT