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.