Effect of peripheral refractive errors on driving performance

Impact of Peripheral Refractive Errors in Mobility Performance

Purpose

The purpose of this study was to investigate the functional effects of peripheral refractive errors on mobility performance through a stair negotiation task.

Methods

Twenty-one young, normal sighted subjects navigated through an obstacle with steps, wearing spectacles that altered only their peripheral refraction. Lenses were used to induce positive defocus (+2 diopters [D] and +4 D), negative defocus (-2 D and -4 D), or astigmatism (+1.75 D and -3.75 D, axis 45 degrees) in the periphery. Feet trajectories were analyzed, and several gait assessment parameters were obtained. Statistical tests were conducted to determine significant performance differences between the lenses. Peripheral refraction in each subject was measured using a scanning Hartmann-Shack wavefront sensor to assess the impact of intrinsic peripheral refraction on the experiment.

Results

Statistically significant differences in performance appeared when peripheral errors were superimposed. Crossing time with respect to plano lenses increased by 6.2%, 7.6%, 19.2%, and 29.6% for the -2 D, +2 D, -4 D, and +4 D lenses, respectively (P < 0.05 in the last 3 cases). Subjects exhibited slower walking speeds, increased step count, and adopted precautionary measures. High-power positive defocus lenses had the biggest impact on performance, and differences were observed in distance to steps between induced positive and negative defocus.

Conclusions

In this laboratory-based study without an adaptation period, peripheral refractive errors affected stair negotiation, causing cautious behavior in subjects. Performance differences among types of peripheral defocus may result from magnification effects and intrinsic peripheral refraction. These results highlight the importance of understanding the effects of induced peripheral errors by myopia control and intraocular lenses.

Peripheral defocus of monofocal intraocular lenses

PURPOSE

To quantify the angular dependence of monofocal intraocular lens (IOL) power.

SETTING

Ophthalmic Biophysics Laboratory, Kallam Anji Reddy campus, L V Prasad Eye Institute, Hyderabad, India.

DESIGN

Laboratory study.

METHODS

Experiments were performed on IOLs from 2 different manufacturers (APPALENS 207, Appasamy Associates and SN60WF, Alcon Laboratories, Inc.). IOL powers ranged from 17 to 25 diopters (D). The IOLs were mounted in a fluid-filled chamber, and the on-axis and off-axis powers were measured using a laser ray tracing system over the central 3 mm zone with delivery angles ranging from -30 to +30 degrees in 5-degree increments. The position of the best focus was calculated for each IOL at each angle. The angular dependence of IOL power was compared with theoretical predictions.

RESULTS

Peripheral defocus increased significantly with increasing incidence angle and power. The peripheral defocus at ±30 degrees increased from 5.8 to 8.5 D when the power increased from 17.5 to 24.5 D for APPALENS 207 and from 4.9 to 7.4 D when the power increased from 17 to 25 D for SN60WF. The mean difference between the measured and theoretical tangential power at ±30 degrees was 0.50 ± 0.16 D for the APPALENS 207 and -0.40 ± 0.10 D for the SN60WF, independent of IOL power.

CONCLUSIONS

IOLs introduce a significant amount of peripheral defocus which varies significantly with IOL power and design. Given that peripheral defocus is related to lens power, replacement of the crystalline lens (approximately 24 D) with an IOL will produce a significant difference in peripheral defocus profile after surgery.

Peripheral Choroidal Response to Localized Defocus Blur: Influence of Native Peripheral Aberrations

Purpose

This study aims to examine the short-term peripheral choroidal thickness (PChT) response to signed defocus blur, both with and without native peripheral aberrations. This examination will provide insights into the role of peripheral aberration in detecting signs of defocus.

Methods

The peripheral retina (temporal 15°) of the right eye was exposed to a localized video stimulus in 11 young adults. An adaptive optics system induced 2D myopic or hyperopic defocus onto the stimulus, with or without correcting native peripheral ocular aberrations (adaptive optics [AO] or NoAO defocus conditions). Choroidal scans were captured using Heidelberg Spectralis OCT at baseline, exposure (10, 20, and 30 minutes), and recovery phases (4, 8, and 15 minutes). Neural network-based automated MATLAB segmentation program measured PChT changes from OCT scans, and statistical analysis evaluated the effects of different optical conditions over time.

Results

During the exposure phase, NoAO myopic and hyperopic defocus conditions exhibited distinct bidirectional PChT alterations, showing average thickening (10.0 ± 5.3 µm) and thinning (-9.1 ± 5.5 µm), respectively. In contrast, induced AO defocus conditions did not demonstrate a significant change from baseline. PChT recovery to baseline occurred for all conditions. The unexposed fovea did not show any significant ChT change, indicating a localized ChT response to retinal blur.

Conclusions

We discovered that the PChT response serves as a marker for detecting peripheral retinal myopic and hyperopic defocus blur, especially in the presence of peripheral aberrations. These findings highlight the significant role of peripheral oriented blur in cueing peripheral defocus sign detection.

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.].

Widefield wavefront sensor for multidirectional peripheral retinal scanning

The quantitative evaluation of peripheral ocular optics is essential in both myopia research and the investigation of visual performance in people with normal and compromised central vision. We have developed a widefield scanning wavefront sensor (WSWS) capable of multidirectional scanning while maintaining natural central fixation at the primary gaze. This Shack-Hartmann-based WSWS scans along any retinal meridian by using a unique scanning method that involves the concurrent operation of a motorized rotary stage (horizontal scan) and a goniometer (vertical scan). To showcase the capability of the WSWS, we tested scanning along four meridians including a 60° horizontal, 36° vertical, and two 36° diagonal scans, each completed within a time frame of 5 seconds.

Central and peripheral refraction measured by a novel double-pass instrument

A novel double-pass instrument and its data analysis method for the measurement of central and peripheral refraction is presented and validated in a group of healthy subjects. The instrument acquires in-vivo, non-cycloplegic, double-pass, through-focus images of the eye's central and peripheral point-spread function (PSF) using an infrared laser source, a tunable lens and a CMOS camera. The through-focus images were analyzed to determine defocus and astigmatism at 0° and 30° visual field. These values were compared to those obtained with a lab-based Hartmann-Shack wavefront sensor. The two instruments provided data showing good correlation at both eccentricities, particularly in the estimation of defocus.

Inverted meniscus intraocular lens as a better optical surrogate of the crystalline lens

Current intraocular lenses (IOLs) are designed to substitute the cataractous crystalline lens, optimizing focus at the fovea. However, the common biconvex design overlooks off-axis performance, leading to a reduced optical quality in the periphery of the retina in pseudophakic patients compared to the normal phakic eye. In this work, we designed an IOL to provide better peripheral optical quality, closer in that respect to the natural lens, using ray-tracing simulations in eye models. The resulting design was a concave-convex inverted meniscus IOL with aspheric surfaces. The curvature radius of the posterior surface was smaller than that of the anterior surface by a factor that depended on the IOL power. The lenses were manufactured and evaluated in a custom-built artificial eye. Images of a point source and of extended targets were directly recorded at various field angles with both standard and the new IOLs. This type of IOL produces superior image quality in the whole visual field, being a better surrogate for the crystalline lens than the commonly used thin biconvex intraocular lenses.