Analysis of the optical performance of intraocular lenses using profilometric measurements

Purpose

The aim of this study was to develop a methodology, based on profilometer measurements to assess the optical behaviour of Intraocular Lenses (IOls). The “Modulation Transfer Function through-object” (MTF through-object) based on vergence object displacement was calculated for different pupil sizes and pseudophakic eyes. Tilt and decentration were also analysed in a realistic cornea eye model.

Methods

For comparison between the different IOLs, an optical quality criterion based on a minimum value the MTF through-object and the recognition of simulated vision optotypes was introduced. Five IOLs were used in this study: Tecnis Eyhance, Mini Well, Tecnis Symfony, Tecnis Synergy and RayOne EMV.

Results

The technique was validated with previous methodologies. A general narrowing of the through-object MTF curve compared to the through-focus MTF curve was shown, resulting in greater distances between near and intermediate points and less depth of field around the far peak. The comparison between the IOLs showed that variations in corneal aberrations, pupil size and decentration caused relevant changes in IOL performance. A decrease of the SA produced a hypermetropic shift of the far focus between + 0.3 D and + 0.4 D. Most of IOLs worsen the optical quality as pupil size increased, even the MTF through-object shape changed. Decentration was an important factor in IOL implantation, causing a significant change in MTF through-object shape in most of IOLs.

Conclusions

This study highlights the need to evaluate pre-operative patients for corneal aberrations and pupillary size to have the best optical success after cataract surgery in multifocal or extended depth of focus IOLs.

Key messages

What is known

• MTF(Modulation Transfer Function) through-focus curves (calculated in image space by moving the detector plane) can be obtained from optical bench assembly or from commercial devices.

• Recently, some studies proposed to characterize the lens surface design based on the profilometric measurements

What is new

• A novel methodology based on profilometer measurements to assess the optical behaviour of Intraocular Lenses (IOls) was shown.

• The “Modulation Transfer Function through-object” based on vergence object displacement was introduced in order to analyse five premium IOLs.

• MTF through-object curve is more appropriate for studying clinical behaviour, as it provides further near and intermediate points distances and lower depth of focus around far peak compare to MTF through-focus curves.

• The optical behaviour of the five IOLs can vary considerably depending on the eye model and pupil size.

• The effect of tilt and decentration on the MTF through-object the IOLs was analysed.