Radhkrishnan, A. | 2EyesVision

VioBio lab adaptive optics: technology and applications by women vision scientists (2020)

Marcos, S — Sun, 08 Mar 2020 15:33:57 +0000

Citation

Marcos S, Benedí‐García C, Aissati S, Gonzalez‐Ramos AM, Lago CM, Radhkrishnan A, Romero M, Vedhakrishnan S, Sawides L & Vinas M. VioBio lab adaptive optics: technology and applications by women vision scientists. Ophthalmic Physiol Opt 2020; 40: 75-87. For more information, click here.

Abstract

Purpose

Adaptive Optics allows measurement and manipulation of the optical aberrations of the eye. We review two Adaptive Optics set-ups implemented at the Visual Optics and Biophotonics Laboratory, and present examples of their use in better understanding of the role of optical aberrations on visual perception, in normal and treated eyes.

Recent findings

Two systems (AOI and AOII) are described that measure ocular aberrations with a Hartmann-Shack wavefront sensor, which operates in closed-loop with an electromagnetic deformable mirror, and visual stimuli are projected in a visual display for psychophysical measurements. AOI operates in infrared radiation (IR) light. AOII is provided with a supercontiniuum laser source (IR and visible wavelengths), additional elements for simulation (spatial light modulator, temporal multiplexing with optotunable lenses, phase plates, cuvette for intraocular lenses-IOLs), and a double-pass retinal camera. We review several studies undertaken with these AO systems, including the evaluation of the visual benefits of AO correction, vision with simulated multifocal IOLs (MIOLs), optical aberrations in pseudophakic eyes, chromatic aberrations and their visual impact, and neural adaptation to ocular aberrations.

Summary

Monochromatic and chromatic aberrations have been measured in normal and treated eyes. AO systems have allowed understanding the visual benefit of correcting aberrations in normal eyes and the adaptation of the visual system to the eye’s native aberrations. Ocular corrections such as intraocular and contact lenses modify the wave aberrations. AO systems allow simulating vision with these corrections before they are implanted/fitted in the eye, or even before they are manufactured, revealing great potential for industry and the clinical practice. This review paper is part of a special issue of Ophthalmic & Physiological Optics on women in visual optics, and is co-authored by all women scientists of the research team.

Vision with different presbyopia corrections simulated with a portable binocular visual simulator (2019)

Radhkrishnan, A. — Tue, 20 Aug 2019 14:59:46 +0000

Citation

Radhakrishnan A, Pascual D, Marcos S, Dorronsoro C. Vision with different presbyopia corrections simulated with a portable binocular visual simulator. PLoS ONE 14(8): e0221144. For more information, click here.

Abstract

Presbyopes can choose today among different corrections to provide them with functional vision at far and near, and the outcomes and patient satisfaction depend on the selection. In this study, we present a binocular and portable vision simulator, based on temporal multiplexing of two synchronized tunable lenses allowing see-through and programmable visual simulations of presbyopic corrections. Seventeen binocular corrections were tested: 3 Monofocal (Far, Intermediate, Near), 4 Simultaneous Vision (bifocal, trifocal), 2 Monovision (far and near in either eye) and 8 Modified Monovision corrections (Simultaneous vision in one eye, Monofocal in the other eye). Perceived visual quality was assessed through the simulated corrections in 8 cyclopleged subjects who viewed a composite realistic visual scene with high contrast letters and a landscape at far (4 m) and a high contrast text at intermediate (66 cm) and near (33 cm) distances. Perceptual scores were obtained on a scale of 0 to 5 (low to high perceived quality). Perceptual preference was assessed by judging 36 random image pairs (6 repetitions) viewed through 9 binocular presbyopic corrections using two-interval forced choice procedures. The average score, across far and near distances, was the highest for Monovision (4.4±0.3), followed by Modified Monovision (3.4±0.1), Simultaneous Vision (3.0±0.1) and Monofocal corrections (2.9±0.2). However, the mean difference between far and near was lower for Simultaneous Vision and Monovision (0.4±0.1 PS) than Modified Monovision (1.8±0.7) or monofocal corrections (3.3±1.5). A strong significant correlation was found between the perceptual scores and the percentages of energy in focus, for each correction and distance (R = 0.64, p<0.0001). Multivariate ANOVA revealed significant influence of observation distances (p<10–9) and patients (p = 0.01) on Perceptual Score. In conclusion, we have developed a binocular portable vision simulator that can simulate rapidly and non-invasively different combinations of presbyopic corrections. This tool has applications in systematic clinical evaluation of presbyopia corrections.

Testing vision with angular and radial multifocal designs using Adaptive Optics (2017)

Vinas, M. — Tue, 07 Mar 2017 09:09:12 +0000

Citation

Vinas M, Dorronsoro C, Gonzalez V, Cortes D, Radhakrishnan A, Marcos S. Testing vision with angular and radial multifocal designs using Adaptive Optics. Vision Res 2017 Mar;132:85-96. For more information, click here.

Abstract

Multifocal vision corrections are increasingly used solutions for presbyopia. In the current study we have evaluated, optically and psychophysically, the quality provided by multizone radial and angular segmented phase designs. Optical and relative visual quality were evaluated using 8 subjects, testing 6 phase designs. Optical quality was evaluated by means of Visual Strehl-based-metrics (VS). The relative visual quality across designs was obtained through a psychophysical paradigm in which images viewed through 210 pairs of phase patterns were perceptually judged. A custom-developed Adaptive Optics (AO) system, including a Hartmann-Shack sensor and an electromagnetic deformable mirror, to measure and correct the eye’s aberrations, and a phase-only reflective Spatial Light Modulator, to simulate the phase designs, was developed for this study. The multizone segmented phase designs had 2-4 zones of progressive power (0 to +3D) in either radial or angular distributions. The response of an “ideal observer” purely responding on optical grounds to the same psychophysical test performed on subjects was calculated from the VS curves, and compared with the relative visual quality results. Optical and psychophysical pattern-comparison tests showed that while 2-zone segmented designs (angular & radial) provided better performance for far and near vision, 3- and 4-zone segmented angular designs performed better for intermediate vision. AO-correction of natural aberrations of the subjects modified the response for the different subjects but general trends remained. The differences in perceived quality across the different multifocal patterns are, in a large extent, explained by optical factors. AO is an excellent tool to simulate multifocal refractions before they are manufactured or delivered to the patient, and to assess the effects of the native optics to their performance.

Keywords

Adaptive Optics; Multifocal corrections; Presbyopia; Spatial Light Modulators.

Comparison of vision through surface modulated and spatial light modulated multifocal optics (2017)

Vinas, M. — Fri, 03 Mar 2017 09:20:18 +0000

Citation

5. Vinas M, Dorronsoro C, Radhakrishnan A, Benedi-Garcia C, LaVilla EA, Schwiegerling J, et al. Comparison of vision through surface modulated and spatial light modulated multifocal optics. Biomed Opt Express 2017 Mar 3;8(4):2055-2068. For more information, click here.

Abstract

Spatial-light-modulators (SLM) are increasingly used as active elements in adaptive optics (AO) systems to simulate optical corrections, in particular multifocal presbyopic corrections. In this study, we compared vision with lathe-manufactured multi-zone (2-4) multifocal, angularly and radially, segmented surfaces and through the same corrections simulated with a SLM in a custom-developed two-active-element AO visual simulator. We found that perceived visual quality measured through real manufactured surfaces and SLM-simulated phase maps corresponded highly. Optical simulations predicted differences in perceived visual quality across different designs at Far distance, but showed some discrepancies at intermediate and near.

Perceived image quality with simulated segmented bifocal corrections (2016)

Dorronsoro C. — Tue, 01 Nov 2016 12:39:54 +0000

Bifocal contact or intraocular lenses use the principle of simultaneous vision to correct for presbyopia. A modified two-channel simultaneous vision simulator provided with an amplitude transmission spatial light modulator was used to optically simulate 14 segmented bifocal patterns (+ 3 diopters addition) with different far/near pupillary distributions of equal energy. Five subjects with paralyzed accommodation evaluated image quality and subjective preference through the segmented bifocal corrections. There are strong and systematic perceptual differences across the patterns, subjects and observation distances: 48% of the conditions evaluated were significantly preferred or rejected. Optical simulations (in terms of through-focus Strehl ratio from Hartmann-Shack aberrometry) accurately predicted the pattern producing the highest perceived quality in 4 out of 5 patients, both for far and near vision. These perceptual differences found arise primarily from optical grounds, but have an important neural component.

Corrections

Carlos Dorronsoro, Aiswaryah Radhakrishnan, Pablo De Gracia, Lucie Sawides, and Susana Marcos, “Perceived image quality with simulated segmented bifocal corrections” Biomed. Opt. Express 7, 4620-4620 (2016): https://opg.optica.org/boe/abstract.cfm?uri=boe-7-11-4620.

Portable simultaneous vision device to simulate multifocal corrections (2016)

Dorronsoro C. — Tue, 16 Aug 2016 08:28:06 +0000

Citation

3. Dorronsoro C, Radhakrishnan A, Alonso-Sanz J, Pascual D, Velasco-Ocana M, Perez-Merino P, and Marcos S. Portable simultaneous vision device to simulate multifocal corrections. Optica 3, 918-924 (2016). For more information, click here.

Abstract

Multifocal lenses are increasingly used solutions for presbyopia, the age-related loss of crystalline lens focus ability. These lenses work by the principle of simultaneous vision, superimposing focused and defocused images on the retina. Providing the experience of simultaneous vision to a patient before permanent implantation of a multifocal lens is a recognized unmet need to increase the patient’s confidence and optimize the lens selection. We developed a hand-held, see-through multifocal vision simulator based on temporal multiplexing of a tunable lens. The device was calibrated and validated using focimetry and Hartmann–Shack aberrometry revealing high reproducibility of the through-focus multifocal energy distribution and high optical quality. We measured visual acuity and perceptual quality on nine cyclopeged patients with three monofocal, two bifocal, and two trifocal corrections with different far/intermediate/near energy distributions simulated using the device. Visual performance and perceptual quality with multifocal corrections varied across patients, although they were more uniform across distances than monofocal corrections. Among the bifocal and trifocal designs, a trifocal with more energy at far was the most frequently identified as providing better quality. The simultaneous vision simulator proved a promising compact tool to study visual performance with multifocal corrections and to select the lens design best suited for each patient, alternative to costly and bulky adaptive optics based devices.