Abstract
Purpose: :
To determine if the Bausch & Lomb Zyoptix XP Microkeratome produced equivalent clinical outcomes compared to the Intralase FS Laser when used to create a lamellar resection of the cornea during LASIK surgery.
Methods: :
This randomized study involved 50 patients where one eye of each subject was treated with the Zyoptix XP and the fellow eye was treated with the Intralase FS. The Zyoptix XP used a 120um head, with 19mm or 20mm suction rings with 8.5mm flap diameter. The Intralase was programmed for a flap thickness of 120um; a flap diameter 8.5mm with a 5.0mm hinge; laser pulse size of 12um and pulse separation of 10um. Flap thickness was calculated by subtraction pachymetry. Pachymetry was measured with an OCT and ultrasound pachymeter. Manifest subjective refraction and visual acuity was measured using high and low contrast logMAR charts.
Results: :
Ultrasound mean flap thickness was 116.0±16.1um for the Zyoptix XP and 152.1±16.2um for the Intralase. OCT mean flap thickness was 108.7±14.4um for the Zyoptix XP and 137.3±15.9um for the Intralase. The difference between the Zyoptix XP and Intralase mean flap thickness was significantly different for both measurement methods (t–test, p<0.001), but the variance was not statistically significantly different (Pitman t–test, p>0.470). The mean high contrast BCVA at the 1 month postop visit was –0.08±0.07 logMAR for the Zyoptix XP and –0.09±0.07 logMAR for the Intralase. The mean low contrast BCVA at the 1 month postop visit was +0.14±0.09 logMAR for the Zyoptix XP and the Intralase. There was no clinically or statistically significant difference between the Zyoptix XP and the Intralase at 1 month postop for either high or low contrast BCVA (p=0.763 and p=0.942, ANOVA). The mean high contrast UCVA at the 1 month postop visit was –0.05±0.09 logMAR for the Zyoptix XP and –0.07±0.08 logMAR for the Intralase. There was no clinically or statistically significant difference between the Zyoptix XP and the Intralase at 1 month postop for high contrast UCVA (p=0.169, ANOVA). The mean SE at 1 month postop was –0.16±0.34DS for the Zyoptix XP and –0.20±0.35DS for the Intralase. There was no clinically or statistically significant difference between the Zyoptix XP and the Intralase at 1 month postop for SE (p=0.524, ANOVA).
Conclusions: :
The Zyoptix XP microkeratome was more accurate than the Intralase. Flap thickness standard deviation was equivalent between the Zyoptix XP microkeratome and the Intralase. There were no clinically or statistically significant differences between the Zyoptix XP and Intralase for SE and visual acuity (high and low contrast logMAR).
Keywords: refractive surgery • refractive surgery: comparative studies • refractive surgery: LASIK