Efficacy of an aspheric treatment algorithm in decreasing induced spherical aberration after laser in situ keratomileusis.
OBJECTIVE
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.


METHODS
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 microm of spherical aberration, which was significantly higher than the 0.04 microm 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.


CONCLUSIONS
The aspheric algorithm was more effective than the conventional algorithm in reducing induced spherical aberration and maintaining corneal asphericity after myopic LASIK.
Ang
Robert Edward T
RE
Asian Eye Institute, Makati City, Philippines. rtang@asianeyeinstitute.com
Chan
Wing Kwong
WK
Wee
Tze-Lin
TL
Lee
Hung Ming
HM
Bunnapradist
Pattaramon
P
Cox
Ian
I
D000328:Adult; D000465:Algorithms; D001251:Astigmatism / Q000503:physiopathology / Q000601:surgery*; D003315:Cornea / Q000503:physiopathology*; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D012029:Refraction, Ocular / Q000502:physiology*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult