This article is more than 5 years old. Information may no longer be current.
LASIK with cyclotorsion control yields good visual outcomes, predictability
Cornea. 2011;30(9):951-957.
Click Here to Manage Email Alerts
LASIK with advanced cyclotorsion compensation was shown to be safe and predictable, according to a study.
"Refractions and high-order aberrations were reduced to subclinical values without applying additional nomograms, showing the excellent performance of the system," the authors said.
The prospective study included 50 eyes that underwent LASIK with advanced cyclotorsion compensation: 30 aberration-free eyes and 20 eyes that had corneal wavefront assessment.
Mean preoperative spherical equivalent was -4.27 D in the aberration-free group and -2.86 D in the corneal wavefront group. Mean astigmatism was 2.16 D in the aberration-free group and 0.80 D in the corneal wavefront group. Mean root mean square higher-order aberrations were 0.347 um in the aberration-free group and 0.689 um in the corneal wavefront group.
The LDV femtosecond laser (Ziemer) was used to create all LASIK flaps. The Amaris excimer laser with eye registration and tracking (Schwind) was used to perform ablation.
Study results showed successful registration rates of 90% for static cyclotorsion component and 98% for dynamic cyclotorsion component; 64% of static cyclotorsion component measurements were within 5°, and 98% of dynamic cyclotorsion component measurements were within 1°.
Mean postoperative spherical equivalent at 3 months was -0.07 D in the aberration-free group and -0.05 D in the corneal wavefront group; the changes were statistically significant in both groups (both P < .0001). Mean postoperative astigmatism was 0.28 D in the aberration-free group and 0.24 D in the corneal wavefront group. Both changes were statistically significant (P < .0005 and P < .001, respectively).
Mean postoperative root mean square higher-order aberrations were statistically significantly reduced to 0.425 µm in the aberration-free group (P < .01) and 0.591 µm in the corneal wavefront group (P < .05).
The authors evaluated the efficacy of their static and dynamic tracking in a group of patients with higher degrees of astigmatism treated with an aspheric profile and a more normal group treated with customized LASIK. They found excellent repeatability both for the static, which compensates for eye rotation when going from sitting to the supine position, and dynamic system, which compensates for cyclotorsion during the actual procedure.
They found a 90% capture rate with the static registration and 98% with the dynamic system. The 10% of eyes not registered represents an opportunity for improvement, especially in eyes with more than 1 D of astigmatism or greater higher-order aberration. The combination of an accurate predictable static and dynamic tracking system is a powerful tool as evidenced by the reduction of higher-order aberration postoperatively in their customized group. This is an accomplishment that matches precision tracking with a decade-old custom technology that has come of age with improved tracking, wavefront sensors and laser delivery systems.
– Scott M. MacRae, MD
OSN Optics Board
Member
Disclosure: Dr. MacRae is a consultant for Technolas, Bausch + Lomb
and Acufocus.