Optimization of toric IOL performance

June 1, 2014

In this article, the authors discuss their study that was aimed at evaluating the rotational stability and patient visual quality of a toric IOL with a novel haptic design.

The stability of a toric IOL within the capsular bag can be maximized by means of stable haptic designs. Capsule shrinkage due to the fibrotic contraction of the capsular bag during the postoperative period induces IOL rotation. This can be minimized with haptics counteracting the rotational effect of compression of the shrinking bag, such as plate or special Z-haptic–shaped open-loop haptics.6,7 However, these haptic designs are associated with some disadvantages, such as the increased risk of posterior capsule opacification and immediate rotation after implantation for the plate haptic IOLs, or the more difficult procedure of implantation of Z-haptic IOLs. Aim of this study was to evaluate the rotational stability and patient's visual quality of a toric IOL with a novel haptic design.

Methods of the study

Preoperatively, patients underwent a full ophthalmic examination, including optical biometry performed using the IOLMaster 500 (Carl Zeiss Meditec, Jena, Germany). Additionally, corneal topography using a Placido system (Atlas; Carl Zeiss Meditec) and corneal tomography using Scheimpflug technology (Galilei; Ziemer Ophthalmic Systems, Port, Switzerland) were performed. Toric power calculation software (Abbott Medical Optics, USA; available at http://www.tecnistoriccalc.com/) was used for calculating the toric power and the meridian for IOL alignment. Postoperatively, IOL rotation was evaluated at 1 hour and at 3 months after surgery by analysing photographs obtained with a high-resolution digital retroillumination imaging system.9 Similarly, autorefraction in IOL mode, subjective refraction, IOLMaster 500 keratometry, unaided and corrected distance visual acuity testing, wavefront measurements using a Hartmann-Shack sensor (WASCA; Zeiss Meditec), corneal topography, and a full slit-lamp examination were also performed at 3 months after surgery.

Before surgery, the horizontal meridian was marked with the patient in sitting position at the slit lamp. It was ensured that the patient's head was straight in the chin rest by focusing the horizontally oriented slit of the slit lamp at the first Purkinjemeter reflex of the fellow eye, then moving the slit beam to the study eye without changing the vertical position of the slit lamp.