Rotational stability of a toric intraocular lens: influence of axial length and alignment in the capsular bag.

Purpose: To evaluate the rotational stability of a toric intraocular lens (IOL) using purpose-designed software and to determine the influence of axial length (AL) and in-the-bag IOL alignment on IOL rotation.

Setting: Iladevi Cataract & IOL Research Centre, Ahmedabad, India.

Design: Prospective observational case series.

Methods: This study enrolled eyes that had AcrySof toric IOL implantation. The AL was measured using optical coherence biometry or immersion A-scan biometry. Corneal astigmatism was determined by manual keratometry and topography. The IOL alignment was vertical, horizontal, or oblique. Rotational stability was measured using the purpose-designed software, and the mean absolute difference was determined. The effect of AL and IOL alignment on rotational stability was determined 6 months postoperatively.

Results: The study evaluated 168 eyes (168 patients). The mean AL was 23.86 mm ± 1.63 (SD), (range 19.50 to 29.03 mm). The median IOL rotation was 0.3 degree from baseline to 1 week, 1.0 degree from 1 week to 1 month, 0.2 degree from 1 to 3 months, and 0.1 degree from 3 to 6 months. The maximum rotation occurred between 1 week and 1 month. There was a strong correlation between AL and IOL rotation at 6 months (r = 0.93, P<.001). The mean absolute difference at 6 months was not significantly different between the 3 axis placement categories when correlated with the rotation (P=.102, analysis of variance).

Conclusions: Toric IOL rotation was greater in eyes with a longer AL. Alignment of the IOL in the capsular bag had no influence on rotation.