Vision Improvement through CATaracts by wavefront shaping

Project Information

VICAT

Grant agreement ID: 897300

DOI

10.3030/897300

Project closed

EC signature date 24 March 2020

Start date 1 March 2021

End date 28 February 2023

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 160 932,48

EU contribution

€ 160 932,48

Coordinated by

UNIVERSIDAD DE MURCIA
Spain

Periodic Reporting for period 1 - VICAT (Vision Improvement through CATaracts by wavefront shaping)

Reporting period: 2021-03-01 to 2023-02-28

Summary of the context and overall objectives of the project

Cataracts is a common ocular pathology affecting approximately 70% of people aged over 65, which accounts to approximately 700 million worldwide. If not treated in time, it can cause blindness, being so far responsible for 51% of the cases of blindness all over the world. So far, the only solution available is cataract surgery, an invasive procedure that can cause different side effects as corneal edemas or retinal detachment among others. In addition, this solution is not suitable for every patient, for example if they have other eye conditions or in the case of infants born with cataracts. For these reasons, a non-invasive alternative to surgery is highly desirable, even it can be the preferred option for many people, if they had the opportunity to wear correcting glasses, as most people do for myopia correction for instance, instead of laser surgery.
In this project we studied the feasibility of a non-invasive correction of cataracts, which could benefit many people around the world, not only people that cannot undergo surgery for a medical condition, but also all those that prefer not to undergo surgery if only a non-invasive solution (in the form of wearable glasses) was possible. The goal of this project was to optimize the wavefront shaping technique capable of reverting the effect of cataract’s light scattering and combine it with the optical memory effect of cataracts, for the full optical characterization of cataracts and to improve retinal image formation by shaping and optimizing the incident wavefront, for future wearable devices based on these principles. In addition, we explored the feasibility of miniaturizing this system for wearability.
During this grant we have demonstrated the feasibility of a non-invasive correction of cataracts by performing the PSF optimization in a completely non-invasive manner. We have characterized for the first time the Optical Memory Effect of cataracts, together with a full scattering characterization, which allows us to determine the maximal size of the optimized retinal image by in-vivo scattering measurements in the patients. Using amplitude modulation, we developed an approach for the in-vivo fundus imaging through cataracts. Lastly, we made important advances in the development of a miniaturized and low-cost device for in-vivo cataract correction, testing its capabilities by correcting high-order aberrations in healthy volunteers. All these advances together demonstrate the possibility of a non-invasive, economic and wearable device for the all-optical correction of cataracts, being an excellent potential alternative to cataract’s surgery.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The results of the action have fulfilled very well the originally proposed objectives, demonstrating for the first time the double-pass (or non-invasive) correction of a cataractous PSF in a cataract’s eye model [Paniagua-Díaz, A. M. et al. (2021). Opt. Express, 29(25), 42208-42214]. Here we demonstrated the possibility of an all-optical correction of cataractous vision. We also simulated the potential of the optimized PSF in improving retinal images, however in reality this depends on the scattering properties of cataracts and their Optical Memory Effect.
We fully characterized the scattering properties of cataracts of different grades, measuring their objective straylight parameter (a value that can be measured in vivo in patients), the contrast of the formed images with those lenses and the Optical Memory Effect, finding linear correlations between them, producing a peer-reviewed publication [Paniagua-Diaz, A.M. et al. (2023) Biomed. Opt. Express 14 (2), 693-650]. These results are of great importance when diagnosing cataracts in patients and determining the optimal approach for the PSF optimization leading to the optimal retinal image improvement.
In parallel we also investigated how to improve fundus imaging in a non-invasive manner, avoiding the scattering of cataracts by amplitude modulation. First we explored the manipulation of the wavefront using amplitude masks, demonstrating its potential for improved fundus imaging as well as for improving visual performance [Panezai, S. et al. (2022) Biomed. Opt. Express, 13(4), 2174-2185], that we are pushing forward with a collaboration with the University Jaume I, where we are adding the non-invasive and inexpensive detection of non-homogeneous scattering areas with Spatial Frequency Domain Imaging (SFDI) techniques [Ipus, E. et al. Imaging and Applied Optics Congress 2022 (3D, AOA, COSI, ISA, pcAOP), CM3A.6]. This work will allow the implementation of a non-invasive system for the optical imaging of the eye’s fundus through cataracts in a low-cost approach, which will be very useful for retinal diseases diagnosis before cataract surgery.
We also tested phase correction in subjects, however, due to the current limitation we found in fixing subjects in the bench-based system we decided to correct high-order aberrations as a first step, with phase sections larger than those of cataracts, and therefore more resilient to small head movements. We demonstrated how we could successfully correct high-order aberrations in voluntary subjects, whilst measuring their visual acuity and contrast sensitivity using inexpensive and compact phase modulators [Paniagua-Diaz, A. M. et al. (2022) Optical Engineering, 61(12), 121806]. During the secondment at Voptica S.L. we also moved towards a miniaturization of this system, integrating the bench-based system occupying roughly 1000x500x100mm to 100x50x20mm using commercial elements, still with a large potential for further miniaturization.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Before our work wavefront shaping to improve the PSF through cataracts had been only demonstrated in a single pass through the lens. We advanced the state of the art by doing in the double pass, in a completely non-invasive manner. We are now demonstrating it through real cataractous crystalline lenses.
We also characterized for the first time the objective scattering of cataractous lenses, together with the intrinsic correlations that will allow us to determine the optimal image formation with wavefront shaping, the optical memory effect. In this way, by measuring in vivo the straylight parameter on real subjects, we can estimate the optimal approach for cataract’s correction. This multidisciplinary characterization build bridges between ophthalmology and optics.
We demonstrated that we can use VA-LCoS for economic and compact phase modulation, enabling the use of this technology for future affordable wearable phase modulation devices for ocular phase correction, which not only advances the state of the art in this case, where such devices have been traditionally bench-based due to the high prices and large dimensions of the SLMs. It also paves the way for the use of phase modulation in wearable devices in the future.
The expected socio-economic impact of this project is very high, since it opens new ways to the development of an all-optical correction of cataracts in a non-invasive manner, in the form of a wearable and potentially low-cost device. Since cataracts is a problem affecting approximately 700.000 million people worldwide where only an invasive solution is available, being the only alternative to it, presents a great advantage of a very high impact in the lives of many people.

Illuminated crystalline lens