Incision-related astigmatism on the anterior and total cornea after implantable collamer lens implantation.

Purpose: To evaluate incision-related astigmatism (IRA) on the anterior and total cornea after implantable collamer lens (ICL) implantation through superior and temporal corneal incisions.

Methods: The retrospective study included 141 eyes of 80 consecutive patients who underwent ICL implantation. An ocular examination was performed preoperatively and at 1 and 6 months postoperatively. The magnitude and axis of corneal astigmatism were assessed with keratometry (AstigK) and total corneal refractive power (TCRP, AstigTCRP) using a Scheimpflug camera, while the IRA obtained from keratometry (IRAK) and TCRP (IRATCRP) were evaluated using vector analysis.

Results: At 6 months, AstigK significantly decreased from 1.45 ± 0.72 D to 1.15 ± 0.75 D in the superior incision group, whereas it increased from 1.70 ± 0.74 D to 1.88 ± 0.79 D in the temporal incision group (both P < 0.001). AstigTCRP significantly decreased from 1.32 ± 0.74 D to 1.09 ± 0.80 D in the superior incision group, while it increased from 1.61 ± 0.78 D to 1.83 ± 0.86 D in the temporal incision group (both P < 0.001). IRAK was 0.55 ± 0.30 D and 0.35 ± 0.25 D in the superior and temporal incision groups, respectively, while IRATCRP was 0.50 ± 0.28 D and 0.40 ± 0.26 D in the superior and temporal incision groups, respectively. IRAK was larger in the superior incision group than in the temporal incision group for both low- (P = 0.009) and high-astigmatism (P = 0.017).

Conclusions: Incisions in ICL surgery cause corneal flattening in the meridian of the incision. The superior incision had a greater IRAK compared to the temporal incision.