Nomogram considerations with the Technolas 217A for treatment of myopia.
OBJECTIVE
To determine whether surgeon-specific nomogram adjustments are useful when using the Technolas 217A excimer laser for treating myopia and myopic astigmatism.


METHODS
We conducted a prospective evaluation of 216 consecutive eyes with 6 months follow-up after treatment of myopia or myopic astigmatism with the Technolas 217A laser. Attempted vs. achieved change in refraction was analyzed with a statistical analysis software program. Factors such as age, corneal thickness (pachymetry), preoperative spherical equivalent refraction, preoperative cylinder, and optical zone were studied to evaluate their role in predicting refractive outcome at 6 months after LASIK.


RESULTS
The mean value of attempted spherical equivalent refraction was -5.32 +/- 2.72 D. The mean achieved refractive correction at 6 months was -5.55 +/- 2.78 D, with a mean spherical equivalent of 0.13 +/- 0.54 D. The percent achieved effect at 1 month was 105%, and at 6 months, 103%. Preoperative spherical equivalent refraction and optical zone size were strong predictors of 6-month LASIK outcome. There was a 9% difference in the percent achieved effect between a 4 and 7-mm optical zone. There was no correlation between age, preoperative cylinder, or surgeon and 6-month outcome.


CONCLUSIONS
Surgeons using the planoscan software on the Technolas 217A may experience a small initial overcorrection. There may be a benefit to reducing the treatment given with larger optical zones and smaller corrections.
Anderson
Nicole J
NJ
Minnesota Eye Consultants, PA, Minneapolis, MN 55404, USA.
Hardten
David R
DR
Davis
Elizabeth A
EA
Schneider
Timothy L
TL
Samuelson
Thomas W
TW
Lindstrom
Richard L
RL
D000328:Adult; D001251:Astigmatism / Q000601:surgery*; D003315:Cornea / Q000601:surgery*; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009216:Myopia / Q000601:surgery*; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D016896:Treatment Outcome