Technical improvements in photorefractive keratectomy for correction of high myopia.
OBJECTIVE
To evaluate the effects of hardware and software improvements in photorefractive keratectomy (PRK) for the treatment of highly myopic eyes.


METHODS
A retrospective study was carried out in 554 patients (582 eyes) with myopia between -7.00 and -17.00 D (mean -11.20 +/- 3.60 D) who had undergone PRK using the Aesculap Meditec laser. Group 1 with a 5-mm-diameter single ablation zone; Group 2 with a 5-mm-diameter single zone surrounded by a 2-mm tapered transitional zone; Group 3 and Group 4, same as Group 2 but with the laser upgraded with a smoke aspiration control system (Group 3), and with a computer-controlled fluence (Group 4).


RESULTS
In Group 1 at 2 years after PRK (50 eyes), 10 eyes (20%) were within +/-1.00 D of attempted correction and 13 eyes (26%) were within +/-2.00 D. In Group 2 at 2 years (118 eyes), 42 eyes (36%) were within +/-1.00 D of attempted correction and 65 eyes (55%) were within +/-2.00 D. In Group 3 at 2 years (43 eyes), 18 eyes (42%) were within +/-1.00 D of attempted correction and 28 eyes (65%) were within +/-2.00 D. In Group 4 at 2 years (47 eyes), 25 eyes (53%) were within +/-1.00 D of attempted correction and 29 eyes (62%) were within +/-2.00 D.


CONCLUSIONS
Software and hardware improvements facilitated PRK correction of high myopia with reasonable predictability, especially if a tapered transition zone was used. At 12 and 24-month follow-up, only the use of a tapered transition zone was associated with a statistically significant improvement in predictability.
Cennamo
Giovanni
G
Eye Department, University of Naples Federico II, Naples, Italy.
Rosa
Nicola
N
Breve
Maria Angelica
MA
di Grazia
Maria
M
D000293:Adolescent; D000328:Adult; D003315:Cornea / Q000601:surgery*; D006801:Humans; D054018:Lasers, Excimer; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000295:instrumentation / Q000379:methods*; D012189:Retrospective Studies; D012985:Software Design; D016896:Treatment Outcome; D014792:Visual Acuity