Irregular Astigmatism

Cataract surgery in patients with irregular corneas presents unique challenges, primarily due to the high variability in keratometry and corneal tomography measurements, which complicates accurate intraocular lens (IOL) calculations. In these patients, therapeutic options are currently limited to either non-toric IOLs and rigid contact lenses postoperatively or conventional toric IOLs for the reduction of total astigmatism within cataract surgery. While conventional toric IOLs may be beneficial in selected cases with a stable astigmatic pattern and clear axis, their effectiveness is largely limited, as significant irregularity and higher order aberrations reduce predictability, accuracy of formulae, and refractive outcomes. Therefore, the development of a reliable method to reduce total astigmatism - including irregular components - would represent a major advancement, potentially improving both visual function and patient quality of life. The aim of this exploratory study is to evaluate the effectiveness of customized toric intraocular lenses (AMILens Individual, AMIPLANT GmbH, Germany) in reducing total corneal astigmatism in patients with a significant irregular astigmatic component. These lenses are designed to address corneal aberrations up to the 6th Zernike order, thereby extending correction beyond the capabilities of conventional toric IOLs. To our knowledge, no clinical study has yet investigated this novel approach.

This study aims to compare the ocular health and visual quality of corneal rigid gas permeable lenses (CRGPL) and scleral rigid gas permeable lenses (SRGPL) for patients with keratoconus in a crossover clinical trial. The study will analyze subjective and objective outcomes, including best corrected visual acuity, contrast sensitivity, higher-order aberrations and subjective perception of visual function and comfort. It will also investigate the impact of both lens types on the health of the ocular surface, including evaluation of corneal, conjunctival, and scleral tissues, and tear film. Only one randomized controlled trial has compared the effect of CRGPL and SRGPL wear for patients with an ectatic corneal disorder. With the increasing popularity of SRGPL, examining the differences in efficacy, safety, and patient-reported outcomes between the two types of lenses is increasingly relevant.