The study reveals that the implemented spatial light modulators (SLMs) can be used reliably to simulate multifocal contact lenses and thus provide patients with the experience of multifocal vision before physically fitting the lenses on the eye. The simulation replicates the visual quality provided by real multifocal contact lenses at various distances

What is a spatial light modulator?

Spatial Light Modulators are pixelated liquid crystal devices capable of changing the refractive index of each pixel in response to a digital signal.

The possibility of performing visual simulations with different designs of multifocal contact lenses (MCL) programmed into an SLM is very promising both in clinical practice of contactology and even before the manufacture of new lenses because it allows patients to experiment with different designs of lenses. multifocal contact lenses quickly and in a totally non-invasive way.

Multifocal contact lenses

multifocal contact lenses are solutions increasingly used in the correction of presbyopia, an age-related eye condition in which the lens loses its ability to focus dynamically. Furthermore, multifocal contact lenses have shown promising results in controlling the progression of myopia.

These lenses work on the principle of simultaneous vision, that is, the simultaneous projection of a far-focused image and a near-focused image. Presbyopes obtain better near-intermediate vision at the expense of some optical degradation in the distance. There are designs on the presbyopia market that vary in the magnitude of the near addition and the distribution of far and near zones in the pupil. How multifocal contact lenses work in myopic patients to slow eye growth is not well understood and may depend on reducing hyperopic blur in the periphery or decreasing accommodative delay. Carrying out systematic studies with simulated lenses will allow a better understanding of the visual quality with these lenses in presbyopes and myopics.

Adaptive optics visual simulators

Adaptive Optics (AO) visual simulators are used to test vision in patients with different designs before fitting the lens into the eye.
The simulation of new multifocal corrections using AO thus makes it possible to investigate the interactions between the patient's optics and a given correction, evaluate the differences between the corrections and, finally, select the correction that optimizes perceived visual quality and visual performance in patients. .

An alternative to visual spatial simulators is the Simultaneous Vision Simulator - Sim + Vis technology, SimVis, a compact device with a large field of vision that works under the principle of time multiplexing with an optimizable lens driven at high speed. The commercial SimVis Gekko system (2EyesVision, Madrid, Spain) based on this technology is portable, binocular and transparent. As far as we know, among all the visual simulators available, only SimVis has been reported to be able to mimic existing multifocal contact lenses on the market.

In this study, we tested, for the first time to our knowledge, the precision of a commercially available multifocal contact lens design using a spatial light modulator (PLUTO-VIS; Holoeye Photonics AG, Germany) on an AO visual simulator. This spatial light modulator is the core technology of various laboratory visual simulators, and as far as we know, a commercial visual simulator.

Given the results, the study supports the use of simulators based on a spatial light modulator to mimic multifocal contact lenses (at least with monochromatic stimuli) and the representation of the phase map of multifocal contact lenses, also used as an intermediate step in the programming of other types of simulators that are very compact and adapted to clinical use, such as SimVis.