Intraoperative angle kappa adjustments during SMILE may limit higher order aberrations

Investigators compared higher-order aberrations (HOAs) after small incision lenticule extraction (SMILE) in patients with and without intraoperative angle kappa adjustments.

Study design

This retrospective case series investigated higher-order aberrations (HOAs) in 106 patients who underwent SMILE at Tianjin Eye Hospital, with and without intraoperative angle kappa adjustments. One eye from each patient underwent correction of myopia and myopic astigmatism. Forty eyes were included in angle kappa-adjusted group, and the remaining 66 eyes were in the nonadjusted group. Preoperative and postoperative visual outcome, refraction and HOA measurements were evaluated at 1 and 3 months postop.

Outcomes

Within the adjusted group, vertical coma was 0.153 μm at 1 month and 0.157 μm at 3 months post-SMILE, which was significantly lower than in the nonadjusted group at 0.204 μm at 1 month and 0.203 μm at 3 months. The increase in vertical coma between preoperative and postoperative measurements was 0.011 μm at 1 month and 0.023 μm at 3 months postoperatively for the angle kappa-adjusted group, and 0.082 μm at 1 month and 0.085 μm at 3 months in the nonadjusted group.

There was no statistical difference in spherical aberration, horizontal coma, trefoil, total HOA, and other aberrations between the groups at both time points at various pupil sizes. There were no differences in the UDVA and refraction between both groups at postop months 1 and 3 (all P>0.05).

Limitations

This study’s limitations include its retrospective design and small sample size. Correlation between measured outcomes and subjective visual quality and symptoms was not assessed.

Clinical significance

Intraoperative angle kappa adjustment resulted in better centration of treatment closer to the visual axis, thereby helping reduce the magnitude of induced coma.