Spherical Aberration Customization to Extend the Depth of Focus With a Clinical Adaptive Optics Visual Simulator

Multi-toric optical element to compensate ocular astigmatism with increased tolerance under rotation

A new, to the best of our knowledge, optical element designed to compensate regular astigmatism while exhibiting increased tolerance to rotational misalignment is introduced. The element incorporates an optical design based on concentric annular regions with slightly different cylindrical axis angular positions. To assess visual quality performance as a function of rotation, retinal image simulation and clinical assessments with an adaptive optics visual simulator were carried out. The results demonstrate the superior performance of the newly proposed element in the presence of rotational errors when compared to traditional solutions.

Effects of Neural Adaptation to Habitual Spherical Aberration on Depth of Focus

We investigated how long-term visual experience with habitual spherical aberration (SA) influences subjective depth of focus (DoF). Nine healthy cycloplegic eyes with habitual SAs of different signs and magnitudes were enrolled. An adaptive optics (AO) visual simulator was used to measure through-focus high-contrast visual acuity after correcting all monochromatic aberrations and imposing +0.5 μm and -0.5 μm SAs for a 6-mm pupil. The positive (n=6) and negative (n=3) SA groups ranged from 0.17 to 0.8 μm and from -1.2 to -0.12 μm for a 6-mm pupil, respectively. For the positive habitual SA group, the median DoF with positive AO-induced SA (2.18D) was larger than that with negative AO-induced SA (1.91D); for the negative habitual SA group, a smaller DoF was measured with positive AO-induced SA (1.81D) than that with negative AO-induced SA (2.09D). The difference in the DoF of individual participants between the induced positive and negative SA groups showed a quadratic relationship with the habitual SA. Subjective DoF tended to be larger when the induced SA in terms of the sign and magnitude was closer to the participant's habitual SA, suggesting the importance of considering the habitual SA when applying the extended DoF method using optical or surgical procedures.

Head-mounted adaptive optics visual simulator

Adaptive optics visual simulation is a powerful tool for vision testing and evaluation. However, the existing instruments either have fixed tabletop configurations or, being wearable, only offer the correction of defocus. This paper proposes a novel head-mounted adaptive optics visual simulator that can measure and modify complex ocular aberrations in real-time. The prototype is composed of two optical modules, one for the objective assessment of aberrations and the second for wavefront modulation, all of which are integrated into a wearable headset. The device incorporates a microdisplay for stimulus generation, a liquid crystal on silicon (LCoS) spatial light modulator for wavefront manipulation, and a Hartmann-Shack wavefront sensor. Miniature optical components and optical path folding structures, together with in-house 3D printed mounts and housing, were adapted to realize the compact size. The system was calibrated by characterizing and compensating the internal aberrations of the visual relay. The performance of the prototype was analyzed by evaluating the measurement and compensation of low-order and higher-order aberrations induced through trial lenses and phase masks in an artificial eye. The defocus curves for a simulated bifocal diffractive lens were evaluated in real eyes. The results show high accuracy while measuring and compensating for the induced defocus, astigmatism, and higher-order aberrations, whereas the MTF analysis shows post-correction resolution of up to 37.5 cycles/degree (VA 1.25). Moreover, the subjective test results show the defocus curves closely matched to a commercial desktop visual simulator.

Effect of spherical aberration on visual acuity and depth of focus in pseudophakic eyes

PURPOSE

To assess the performance of 4 intraocular lenses (IOLs) in various spherical aberration (SA) conditions, using the VAO adaptive optics simulator.

SETTING

Cullen Eye Institute, Baylor College of Medicine, Houston, Texas.

DESIGN

Prospective case series.

METHODS

Distance-corrected visual acuities at distance (CDVA), intermediate (DCIVA), and near (DCNVA) were measured in 42 dilated pseudophakic eyes at baseline and with ocular SA ranging from -0.4 to +0.4 μm in increments of 0.2 μm (6.0-mm pupil). 4 IOL types were assessed: monofocal IOLs with zero-SA, enhanced-monofocal, extended depth-of-focus (EDOF), and continuous range-of-vision.

RESULTS

Compared with SA = 0 μm, significant changes (all P < .05) were: (1) zero-SA monofocal IOLs' DCNVA at high contrast improved by 0.13 logMAR with SA = -0.4 μm and worsened by 0.09 and 0.10 logMAR with SA = +0.2 and +0.4 μm, respectively. DCNVA at low contrast worsened by 0.09 logMAR with SA = +0.4 μm; and (2) with SA = -0.4 μm, the enhanced monofocal IOL lost 0.06 logMAR of CDVA at high contrast and gained 0.09 logMAR of DCNVA at low contrast. There were no significant changes from SA = 0 μm for EDOF and continuous range-of-vision IOLs.

CONCLUSIONS

Zero-SA and EDOF IOLs were the most and least sensitive to SA modulation, respectively. In perfect optical systems where all the optical elements are aligned, induction of targeted amounts of negative SA improved the depth of focus of some IOL types. No benefit was found with positive SA.

Using adaptive optics to optimize the spherical aberration of eyes implanted with EDOF and enhanced monofocal intraocular lenses

PURPOSE

To assess the effect of change in ocular spherical aberration (SA) with adaptive optics on visual acuity (VA) at different defocus after implantation of extended depth-of-focus (EDOF) and enhanced monofocal intraocular lenses (IOLs).

SETTINGS

Narayana Nethralaya Eye Hospital, Bangalore, India.

DESIGN

Prospective, longitudinal, observational.

METHODS

80 eyes (40 patients) that had cataract surgery were included in the study. 40 eyes were implanted with Eyhance EDOF IOLs and the remaining with Vivity EDOF IOLs. Baseline ocular aberrations were measured with a visual adaptive optics aberrometer, then the optimal SA was determined by increasing it in steps of -0.01 μm up to -0.1 μm until the maximum improvement in near distance VA was observed for a given eye. Then the defocus curve for each eye was measured after modifying the ocular SA by magnitude equal to optimal SA.

RESULTS

Most of the eyes accepted a negative induced SA of -0.05 μm (Eyhance group: 67.6%; Vivity group, 45.2%). In the Eyhance group (dominant eyes), VA improved at -2 diopters (D) ( P < .02) only and degraded at 0 D, +0.5 D, and +1 D defocus ( P < .05). In the Vivity group, the VA remained unchanged at all defocus ( P > .05). In the Eyhance group (nondominant eyes), VA improved at -3.5 D defocus only and degraded at +1.5 D and +2 D defocus ( P < .05). In the Vivity group, VA improved at -2.5 D defocus ( P < .05) only.

CONCLUSIONS

A negative induced SA of -0.05 μm in implanted eyes was optimal for a slight improvement in distance-corrected near and intermediate VA without any significant decrease in baseline distance-corrected VA.

Visual Performance at All Distances and Patient Satisfaction With a New Aspheric Inverted Meniscus Intraocular Lens

PURPOSE

To evaluate visual performance, spectacle independence, and quality of vision of new intraocular lenses (IOLs) for presbyopia correction with an aspheric inverted meniscus optical design (ArtIOLs; Voptica SL) in patients undergoing bilateral cataract surgery.

METHODS

In this prospective study, 60 eyes from 30 patients implanted bilaterally with Art40 and Art70 IOLs were included. These new IOLs were designed with an inverted meniscus shape to improve the peripheral performance and with aspheric surfaces to induce different amounts of negative spherical aberration in each IOL model. Distance-corrected and uncorrected through-focus visual acuities and contrast sensitivity were measured 1 to 3 months after surgery. Twenty-eight patients answered Patient Reported Spectacle Independence (PRSIQ) and Quality of Vision (QoV) questionnaires.

RESULTS

Mean monocular (Art40 and Art70) and binocular (Art40/70) corrected distance visual acuities (CDVA) were zero logMAR (20/20). Binocular uncorrected distance visual acuity (UDVA) at far, intermediate (66 cm), and near (40 cm) distances was 0.00 ± 0.01, 0.01 ± 0.03, and 0.09 ± 0.09 logMAR, respectively. Spectacle independence was achieved by 24 (85.7%) patients for far and intermediate vision and 20 patients (71.4%) for near vision. The number of patients never reporting experiencing glare, halos, and starbursts was 28, 27, and 26 (100%, 96.4%, and 92.9%), respectively.

CONCLUSIONS

The binocular combination of two ArtIOLs models (Art40 and Art70) significantly extended the depth of focus up to at least 40 cm. This combination resulted in a full range of vision with a high level of spectacle independence and without the compromise of halos or dysphotopsias. [J Refract Surg. 2023;39(9):582-588.].

Spherical Aberration of Cataractous Eyes and Its Relationship With Age, Ocular Biometry, and Various IOL Platforms

PURPOSE

To determine the median spherical aberration (SA) of the cataractous population, how it relates to biometry, and the theoretical effect of different intraocular lens (IOL) platforms.

METHODS

A retrospective chart review of patients undergoing cataract surgery evaluation with a high quality Pentacam (Oculus Optikgeräte GmbH) were included. Age, gender, Q-value, mean total SA, higher order aberration root mean square wavefront error, and equivalent keratometry were collected from the Holladay report and axial length and anterior chamber depth (ACD) from the IOLMaster 700 (Carl Zeiss Meditec AG).

RESULTS

Data from 1,725 eyes of 999 patients were collected. SA had a median of 0.37 µm (95% confidence interval: 0.36 to 0.38. Age (r = .136, P < .001), Q-factor (r = .743, P < .001), and higher order aberration root mean square wavefront error (r = .307, P < .001) were positively correlated with SA. Average equivalent keratometry (r = -.310, P < .001) was negatively correlated with SA. Axial length (r = -0.037, P = .120) and ACD (r = .004, P = .856) had no association with SA. Up to 1,499 (86.9%) theoretically had SA moved closer to zero with IOLs that had negative SA. Up to 102 (5.9%) had SA theoretically worsened.

CONCLUSIONS

SA is not normally distributed, suggesting that there may be no "average" SA that IOLs should aim to correct. Patients might benefit from tailoring IOL choice to individual SA. Without access to SA data, eyes with steeper average keratometry or younger patients may have less SA, which could influence IOL choice. [J Refract Surg. 2023;39(2):89-94.].

Adaptive optics visual simulators: a review of recent optical designs and applications [Invited]

In their pioneering work demonstrating measurement and full correction of the eye's optical aberrations, Liang, Williams and Miller, [JOSA A14, 2884 (1997)10.1364/JOSAA.14.002884] showed improvement in visual performance using adaptive optics (AO). Since then, AO visual simulators have been developed to explore the spatial limits to human vision and as platforms to test non-invasively optical corrections for presbyopia, myopia, or corneal irregularities. These applications have allowed new psychophysics bypassing the optics of the eye, ranging from studying the impact of the interactions of monochromatic and chromatic aberrations on vision to neural adaptation. Other applications address new paradigms of lens designs and corrections of ocular errors. The current paper describes a series of AO visual simulators developed in laboratories around the world, key applications, and current trends and challenges. As the field moves into its second quarter century, new available technologies and a solid reception by the clinical community promise a vigorous and expanding use of AO simulation in years to come.

Evaluating the effect of ocular aberrations on the simulated performance of a new refractive IOL design using adaptive optics

Adaptive optics (AO) visual simulators are excellent platforms for non-invasive simulation visual performance with new intraocular lens (IOL) designs, in combination with a subject own ocular aberrations and brain. We measured the through focus visual acuity in subjects through a new refractive IOL physically inserted in a cuvette and projected onto the eye's pupil, while aberrations were manipulated (corrected, or positive/negative spherical aberration added) using a deformable mirror (DM) in a custom-developed AO simulator. The IOL increased depth-of-focus (DOF) to 1.53 ± 0.21D, while maintaining high Visual Acuity (VA, -0.07 ± 0.05), averaged across subjects and conditions. Modifying the aberrations did not alter IOL performance on average.

Visual quality analysis using the Chinese Catquest-9SF scale following different spherical aberration IOL implantation

Purpose

Based on the Chinese version of the Catquest-9SF scale, the contrast sensitivity meter and wavefront aberrometer were used to evaluate the visual quality of cataract patients implanted with different spherical aberrations IOL.

Design

Retrospective Observational Study.

Methods

Patients who had the lens implantation in our department from January 2020 to December 2021 were enrolled. All patients underwent uncorrected visual acuity, best corrected visual acuity and slit lamp microscope, high-order aberrations and contrast sensitivity test. The KR-1W wavefront analyzer (Topcon Medical System, Tokyo, Japan) was used to measure wavefront aberrations post-operation. The Chinese Catquest-9SF scale was used to score the postoperative visual satisfaction of the patients.

Results

145 patients were screened according to the exclusion criteria, including 51 patients in the zero aspherical IOL (SOFTEC HD) group, 42 patients in the negative aspherical IOL (ZCB00) group, and a total of 52 patients in the spherical IOL (HQ-201HEP) group. The score was the highest in the zero spherical aberration group, followed by the negative spherical aberration group with the lowest scores in the spherical IOL group. Higher-order aberrations are relatively low in eyes implanted with the zero spherical aberration group. Contrast sensitivity with spherical lenses under glare-free and glare conditions was lower than those with aspheric lenses, and at higher frequencies the zero-aberration aspheric lens performed the best.

Conclusion

The Chinese Catquest-9SF scale provides an indication of visual quality after aspheric IOL implantation.

Assessment of a New Trifocal Diffractive Corneal Inlay for Presbyopia Correction Using an Adaptive Optics Visual Simulator

In this work, we analyze a proposal of a new intracorneal diffractive lens for presbyopia correction that could allow good, distance, intermediate and near vision. By using an adaptive optics visual simulator, we study the influence of two factors in the inlay performance: the spherical aberration (SA) and the potential errors of in thickness, induced in the manufacturing process. We show that the inlay through-the-focus imaging performance can be customized with the SA value, favoring either distance–intermediate or intermediate–near vision. Moreover, we found that with thickness variations of 10%, the inlay still maintains its trifocal nature.

Spherical aberration for expanding depth of focus

The increase in the depth of focus (DoF) for the treatment of presbyopia or cataracts is a topic of great interest for anterior segment surgeons who have seen how new surgical possibilities to achieve DoF enlargement have emerged. Nowadays, several technologies to extend the DoF are available, from corneal laser refractive surgery procedures in presbyopia to intraocular lens (IOL) implantation in cataract or refractive lens exchange. Some of these procedures are based on aspheric profiles, either in the cornea or in the IOL, which modulate the spherical aberration (SA) and, therefore, extend the light energy on different focal planes. The aim of this narrative review was to give an overall picture about the reasons why there is not a general solution persistent along time of SA induction to extend DoF, especially considering that SA depends on pupil diameter and this decreases with age.

Optical and visual quality of real intraocular lenses physically projected on the patient's eye

Visual simulators aim at evaluating vision with ophthalmic corrections prior to prescription or implantation of intraocular lenses (IOLs) in the patient's eye. In the present study, we present the design, implementation, and validation of a new IOL-in-cuvette channel in an Adaptive Optics visual simulator, which provides an alternative channel for pre-operative simulation of vision with IOLs. The IOL is projected on the pupil's plane of the subject by using a Rassow system. A second lens, the Rassow lens, compensates for an IOL of 20 D while other powers can be corrected with a Badal system within a 5 D range. The new channel was evaluated by through-focus (TF) optical quality in an artificial eye on bench, and by TF visual acuity in patients, with various IOL designs (monofocal, diffractive trifocal, and refractive extended depth of focus).

EFFECT OF DECENTRATION ON THE QUALITY OF VISION: A COMPARISON BETWEEN ASPHERIC BALANCE CURVE DESIGN AND POSTERIOR ASPHERIC DESIGN INTRAOCULAR LENSES

PURPOSE

To study the effect of decentration on the quality of vision in two aspheric intraocular lenses (IOLs): aspheric balance curve(ABC) design Vivinex iSert XY1(Hoya Surgical Opticals, Inc.) and posterior aspheric design AcrySof IQ SN60WF (Alcon Laboratories, Inc.).

SETTING

Advanced Eye Centre, PGIMER, Chandigarh, India.

DESIGN

Randomised Prospective Trial using Random number table.

METHODS

Eighty-five eyes were randomized to Group 1 (Vivinex XY1) and Group 2 (Acrysof IQ) with 40 and 45 eyes respectively. The HOA profile, Strehl's ratio, decentration of IOL from the visual axis (DVA) and the geometric axis (DGA), angle Alpha and Kappa were recorded on the iTrace aberrometer and contrast sensitivity was measured using the Functional Acuity Contrast Test at 12 weeks post-surgery.

RESULTS

The mean values of the Strehl's ratio (p=0.48) and the HOA's (p=0.12) of both IOLs were comparable. The HOA's gradually increased with increasing DVA for both lenses at 3, 4 and 5mm pupil sizes. On comparing the HOA's with the DGA a statistically insignificant positive correlation was observed. The Strehl's ratio did not deteriorate with increasing angle alpha in the Vivinex XY1 group, however worsened in the Acrysof IQ group. The contrast sensitivity was comparable in both the IOLs except at 1.5cpd under photopic conditions where Acrysof IQ was better.

CONCLUSIONS

Decentration of the lens is best measured with respect to the visual axis. In eyes with a large alpha, the ABC design induced lesser HOA's and maintained a better Strehl's ratio.

Simulating Outcomes of Cataract Surgery: Important Advances in Ophthalmology

As the human eye ages, the crystalline lens stiffens (presbyopia) and opacifies (cataract), requiring its replacement with an artificial lens [intraocular lens (IOL)]. Cataract surgery is the most frequently performed surgical procedure in the world. The increase in IOL designs has not been paralleled in practice by a sophistication in IOL selection methods, which rely on limited anatomical measurements of the eye and the surgeon's interpretation of the patient's needs and expectations. We propose that the future of IOL selection will be guided by 3D quantitative imaging of the crystalline lens to map lens opacities, anticipate IOL position, and develop fully customized eye models for ray-tracing-based IOL selection. Conversely, visual simulators (in which IOL designs are programmed in active elements) allow patients to experience prospective vision before surgery and to make more informed decisions about which IOL to choose. Quantitative imaging and optical and visual simulations of postsurgery outcomes will allow optimal treatments to be selected for a patient undergoing modern cataract surgery.

A new trifocal corneal inlay for presbyopia

Corneal inlays (CIs) are the most recent surgical procedure for the treatment of presbyopia in patients who want complete independence from the use of glasses or contact lenses. Although refractive surgery in presbyopic patients is mostly performed in combination with cataract surgery, when the implantation of an intraocular lens is not necessary, the option of CIs has the advantage of being minimally invasive. Current designs of CIs are, either: small aperture devices, or refractive devices, however, both methods do not have good performance simultaneously at intermediate and near distances in eyes that are unable to accommodate. In the present study, we propose the first design of a trifocal CI, allowing good vision, at the same time, at far, intermediate and near vision in presbyopic eyes. We first demonstrate the good performance of the new inlay in comparison with a commercially available CI by using optical design software. We next confirm experimentally the image forming capabilities of our proposal employing an adaptive optics based optical simulator. This new design also has a number of parameters that can be varied to make personalized trifocal CI, opening up a new avenue for the treatment of presbyopia.