Testing vision with angular and radial multifocal designs using Adaptive Optics

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.

Evaluation of the True Wavefront Aberrations in Eyes Implanted With a Rotationally Asymmetric Multifocal Intraocular Lens

“…It is straightforward to apply the method to other angularly segmented refractive designs 22,23 and to radially segmented IOLs, provided that the wavefront slope sampling is sufficiently high to map each zone.…”

Vision science and adaptive optics, the state of the field

“…We have also investigated the effects of aberrations on subjective focus (Marcos et al 2015) and of specific combinations of astigmatism and coma on increasing the depth-of-focus (de Gracia et al 2011b). With our most recent polychromatic AO system (which is equipped with a supercontinuum laser source and both deformable mirror and a spatial light modulator) we have tested the impact of monochromatic aberrations on psychophysical and objective measurements of transverse chromatic aberration (Vinas et al 2015a), as well as visual perception and visual performance with different multifocal corrections such as segmented lenses (rotationally symmetric and asymetric) with 2, 3 and 4 zones (Vinas et al 2016). …”

“…This is particularly relevant, as multiple IOL designs can be compared by the same subject (i.e., same brain) potentially significantly reducing costs of clinical trials (allowing only one IOL implanted per patient). In addition, the ability to perform measurements with and without the natural aberrations gives insight into the needs for the correction to be selected on an individual basis or alternatively whether the same correction works similarly across a larger population (Vinas et al 2015b, Vinas et al 2016). AO systems are able to predict both visual performance and short-term adaptation to new corrections before these are implanted in the eye or even manufactured (Radhakrishnan et al 2014)…”

Introduction to special issue on adaptive optics for vision

“…Simulated aberrations have also proven important for studying the optimal design of single or multi-focal lenses for intraocular implant or for contact lenses fitted to the cornea for correction of normal aberrations, presbyopia or aberrant optical systems such as those due to keratoconus. In this special issue adaptive optics is used to investigate neural adaptation in the periphery in myopes and emmetropes (Ghosh, Zheleznyak, Barbot, Jung, & Yoon, 2017), to test the visual improvements following perceptual training in highly aberrated eyes (Sabesan, Barbot, & Yoon, 2017), and to simulate multifocal patterns to investigate differences in visual perception that arise from different lens designs (Vinas et al, 2017).…”

“…Adaptive optics instruments are rapidly evolving into more practical devices that can be routinely used in clinics, either as compact visual simulators for determining optimal optical corrections in patients, for the early diagnosis of retinal disease and monitoring of cell rescue therapies and as fundamental tools for understanding how the eye works (Marcos et al, 2017). This special issue gives a flavor of current research investigations using adaptive optics, improvements to these devices being tested in many laboratories, and insight into what the future can provide.…”