Astigmatic eyes at higher risk of post-LASIK residual aberrations due to cyclotorsion

Invest Ophthalmol Vis Sci. 2008;49(11):4828-4836.

Patients with higher degrees of astigmatism showed an elevated risk of residual aberrations resulting from cyclotorsion in LASIK surgery.

Investigators developed a method to determine the average cyclotorsion during refractive surgery without a cyclotorsion tracker. They simulated mathematical conditions to determine optical, visual and absolute benefits in 76 eyes.

The percentage of treatments that were predicted to yield global success (optical, visual and absolute benefits) was markedly higher than the portion of treatments that reduced cylinder, stabilized or improved best corrected visual acuity, and reduced postoperative astigmatism to an absolute residual error of less than 0.5 D.

"This confirms that cyclotorsion is not the only reason for differences between theory and practice," the study authors said. "Wound healing and surgical variation are also key factors in the outcome."

The authors said there is a need for a more reliable method of predicting refractive outcomes.

"The leap from the mathematical model to the real-world outcome cannot be extrapolated without further study," they said.