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.
