Analysis of the optical performance of intraocular lenses using profilometric measurements

Abstract

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.

Keywords: Decentration; Extended Depth of Focus; Modulation Transfer Function; Multifocal Intraocular lenses; Optical quality; Pupil size; Tilt.

Fig. 1

MTF through-focus curves of the Mini Well IOLs implementing the profilometer measurements in the eye model proposed in the (ISO) 11,979–2 standard [12] and for a pupil sizes of 3 mm (blue line) and 4.5 mm (red line) in IOL plane

Fig. 2

Comparison of the MTF through-focus (blue line) and MTF through-object (red line) obtained for the Mini Well and for 3 mm pupil size (left) and 4.5 mm pupil size (right)

Fig. 3

Interpretation of the MTF through-object for the Tecnis Symfony (left) and the Mini Well (right) for 3 mm pupil size. Far, intermediate and near points when MTF (50 cycles/mm) value is 0.1 are shown with the corresponding simulated vision optotypes

Fig. 4

MTF through-object curves of the Mini Well IOL for two eye models and two pupil sizes

Fig. 5

MTF through-object of the Tecnis Eyhance IOL for two eye models and two pupil sizes

Fig. 6

MTF through-object of the Tecnis Symfony IOL for two eye models and two pupil sizes

Fig. 7

MTF through-object of the Tecnis Synergy IOL for two eye models and two pupil sizes

Fig. 8

MTF through-object of the RayOne EMV IOL for two eye models and two pupil sizes

Fig. 9

MTF through-object curves for a 3 mm pupil size of the Mini Well IOL. Model 1 (blue line) with a decentration of 5 mm (green line) and a tilt of 5º (pink line), and Model 3 (orange line)

Fig. 10

MTF through-object curves for a 3 mm pupil size of the Tecnis Eyhance IOL. Model 1 (blue line) with a decentration of 5 mm (green line) and a tilt of 5º (pink line), and Model 3 (orange line)

Fig. 11

MTF through-object curves for a 3 mm pupil size of the Tecnis Symfony IOL. Model 1 (blue line) with a decentration of 5 mm (green line) and a tilt of 5º (pink line), and Model 3 (orange line)

Fig. 12

MTF through-object curves for a 3 mm pupil size of the Tecnis Synergy IOL. Model 1 (blue line) with a decentration of 5 mm (green line) and a tilt of 5º (pink line), and Model 3 (orange line)

Fig. 13

MTF through-object curves for a 3 mm pupil size of the RayOne EMV IOL. Model 1 (blue line) with a decentration of 5 mm (green line) and a tilt of 5º (pink line), and Model 3 (orange line)