Outcomes and possible risk factors associated with axis alignment and rotational stability after implantation of the Toric implantable collamer lens for high myopic astigmatism.

Aim: To assess the visual outcomes and possible risk factors associated with axis alignment and rotational stability after implantation of Toric implantable collamer lens (TICL) for the correction of high myopic astigmatism.

Methods: In this prospective, nonrandomized clinical study, 54 consecutive eyes of 29 patients with high myopic astigmatism received TICL implantation. To evaluate postoperative axis deviation from the intended axis, a digital anterior segment photograph was taken. The ultrasound biomicroscopy(UBM) was used to observe footplate-position.

Results: After mean follow-up of 8.6 months, mean manifest refractive cylinder (MRC) decreased 79.3% from (-1.88±1.49)D preoperatively to (0.39±0.61)D postoperatively. MRC within 1.00 D occurred in 68.5% (37/54) of eyes, whereas 48.1% (26/54) had MRC within 0.50 D. Mean manifest refraction spherical equivalent (MRSE) changed from (-12.08±4.22)D preoperatively to (-0.41±0.61)D postoperatively. Uncorrected binocular vision of 20/20 or better occurred in 72.2% (39/54) of patients compared with binocular best-corrected visual acuity (BCVA) of 20/20 or better in 44.4% (24/54) preoperatively. The mean difference between intended and achieved TICL axes was (6.96±8.37)°. Footplates of TICLs were in the ciliary sulcus in 22 eyes (46.3%), below the ciliary sulcus in 32 eyes (53.7%). The angle of TICL rotation had significant correlation with the footplates-position (t=2.127; P=0.045) and the postoperative TICL vaulting (r=-0.516; P=0.000).

Conclusion: The results of our study further support the safety, efficacy and predictability of TICL for the correct high myopic astigmatism. The footplate-position of TICL and vault value should be taken into consideration as two possible risks factors for TICL rotation.