Posters

A progressive-toric IOL design that accounts for the decrease of corneal astigmatism with pupil size: ray-tracing simulations using corneal topography data

Poster Details

First Author: G.Labuz GERMANY

Co Author(s):    D. Varadi   R. Khoramnia   G. Auffarth              

Abstract Details

Purpose:

A recent population study on corneal astigmatism has shown that the astigmatism magnitude is higher in the center than at the periphery. A standard toric intraocular lens (IOL), which has a constant cylinder power, cannot account for those differences. A new design with progressively changing cylinder power has the potential to lower residual astigmatism after implantation of a toric IOL. However, this concept has yet to be tested. This study aimed to assess and compare the image quality metrics after correction of corneal astigmatism using the progressive- and standard-toric IOL in a personalized eye model.

Setting:

David J Apple Center for Vision Research, Department of Ophthalmology, University of Heidelberg, Germany.

Methods:

A physiological model eye was built in OpticStudio (Zemax) based on corneal topography data obtained with Pentacam HR (Oculus). The study population consisted of 42 healthy patients. In this customized model, we tested the optical quality (by means of the Strehl ratio) and residual astigmatism after simulated implantation of two types of toric IOLs. One was a progressive Avansee Toric (Kowa) with gradually decreasing cylinder power from the center to the periphery. Its performance was compared against a lens having identical design parameters but featuring conventional astigmatism correction. The simulation was performed under a 3- and 5-mm pupil.

Results:

The mean (±SD) age of the study population was 69.5 ±6.0 years. Corneal astigmatism ranged from 0.8 to 3.8D with a mean value of 2.03 ±0.74D and. At 3 mm, slightly lower residual astigmatism was obtained with the progressive lens by 0.02 ±0.07D (P=.14), but the Strehl ratio was identical in both cases, and that was 0.53 ±0.15 (P=.94). At 5 mm, the progressive IOL yielded significantly lower residual astigmatism by 0.10 ±0.2D (P=.001). The Strehl ratio was 0.30 ±0.08 and 0.29 ±0.08 with the progressive and the standard lens, respectively (P=.002).

Conclusions:

The optical performance of the two IOL types was comparable at 3 mm. However, at 5 mm, the progressive toric design was more effective in correcting corneal astigmatism than using a standard approach, which resulted in reduced residual astigmatism. We found that the optical quality was (minimally) better in the progressive-lens group; thus, this new technology may contribute to the continuous effort to improve the visual quality of toric-IOL patients.

Financial Disclosure:

receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented, research is funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, receives consulting fees, retainer, or contract payments from a competing company