BCLA CLEAR presbyopia: Mechanism and optics.

With over a billion adults worldwide currently affected, presbyopia remains a ubiquitous, global problem. Despite over a century of study, the precise mechanism of ocular accommodation and presbyopia progression remains a topic of debate. Accordingly, this narrative review outlines the lenticular and extralenticular components of accommodation together with the impact of age on the accommodative apparatus, neural control of accommodation, models of accommodation, the impact of presbyopia on retinal image quality, and both historic and contemporary theories of presbyopia.

The association between participant-reported ratings of comfort, dryness and vision quality in soft contact lens wearers.

INTRODUCTION: Previous literature has indicated an association between participant-reported perceptions (e.g., ratings) of comfort, dryness and vision quality during soft contact lens wear. However, these reports do not account for participant- and lens-specific factors which may impact the interpretation of these results. The purpose of this project was to quantify the association between these participant-reported ratings while accounting for both participant- and lens-specific factors. METHODS: Participant-reported ratings (scale 0-100) of comfort, dryness and quality of vision for 675 soft contact lens wearers (1207 eyes) were aggregated across 31 studies completed at Indiana University. Linear mixed-effects regression modelling was performed on each outcome rating individually. Covariate-adjusted models incorporated both participant- (e.g., age, sex) and lens-related (e.g., lens material, edge and optics) factors. The models were statistically adjusted for the duration of lens wear in hours and cumulative days of exposure. RESULTS: Consistent with estimates from covariate-adjusted regression models, pairwise Spearman correlations [95% CI] between dryness and comfort (rs = 0.71, [0.69, 0.74]), vision quality and comfort (rs = 0.53, [0.49, 0.57]) and vision quality and dryness (rs = 0.49, [0.42, 0.54]) were all positive and had p < 0.001. Average participant-reported ratings of comfort, dryness and vision quality decreased by (bs [95% CI]) = -0.81 [-1.15, -0.46] -0.34 [-0.67, 0.0005] and -0.90 [-1.19, -0.60] rating units, respectively, for each hour of lens wear. CONCLUSIONS: Significant positive associations were found between participant-reported measures of comfort, dryness and vision quality during soft contact lens wear. The associations between these ratings and the participant- and lens-related factors that drive them should be considered by clinicians and manufacturers when fitting and designing soft contact lenses.

Digital device viewing behaviour in children.

INTRODUCTION: Habitual viewing behaviour is widely believed to be an important contributing factor to the onset and progression of myopia and may be task dependent. The purpose of this study was to quantify the habitual viewing distance of children performing five different tasks on a smartphone digital device. METHODS: The real-time viewing distance in 38 children with their habitual correction was measured using software (MyopiaApp) on a handheld (Google Pixel 3) device. Five tasks were performed in a randomised sequence: playing a game, watching video in a light (680 lux) and dark (5.5 lux) environment and reading small (8 pt) and large (16 pt) text. ANCOVA statistical analysis was used to evaluate the effect of task, group (myope vs. non-myope) and arm length on the median relative viewing distance. RESULTS: Arm length was not correlated with viewing distance in any of the tasks, and there was no significant difference in viewing distance between any of the tasks. Specifically, a two-way mixed ANCOVA indicated that task, refractive group (myopic vs. non-myopic), age and arm length, as well as all two-way interactions were not significantly associated with viewing distance. Overall, 60% of the total variance in viewing distance was accounted for by individual differences. CONCLUSIONS: The average handheld viewing distance was similar across a variety of everyday tasks in a representative sample of myopic and emmetropic children. Neither arm length, age nor refractive group were associated with viewing distance in any of the tasks. Importantly, myopic children of a given size did not hold the smartphone digital device at a different distance for any task than their equally sized non-myopic peers. However, both groups exhibited high inter-individual variability in mean viewing distance, indicating some subjects performed all tasks at further distances while other subjects used at nearer distances.

On-eye centration of soft contact lenses.

PURPOSE: To evaluate the relative positions of modern soft contact lenses (SCLs) relative to the limbus/cornea and the pupil. METHODS: Sixty images of the anterior eyes of 101 subjects were acquired over 10 s while participants fixated the centre of the camera lens located 33 cm in front of the eye in a well-lit (300 lux) clinic. Custom validated image analysis software was used to locate the boundaries of the contact lenses, pupils and corneas (limbus). Horizontal and vertical relative positions of the contact lens, pupil and limbus were calculated from the fitted boundaries. RESULTS: The mean (standard deviation) pupil and corneal diameters for all subjects were 3.84 mm, (0.83) and 11.97 mm (0.48), respectively. The mean [95% confidence interval] pupil centre was located 0.28 mm [0.26, 0.30] nasally and 0.07 mm [0.05, 0.10] superiorly to the corneal centre. Consistent with clinical observations, the contact lenses centred accurately relative to the corneal centre both nasally 0.04 mm [0.01, 0.07] and inferiorly -0.01 mm [-0.06, 0.03]. However, regardless of the eye, the contact lens was significantly (p < 0.001) decentred relative to the pupil centre both temporally -0.23 mm [-0.26, -0.20] and inferiorly -0.08 mm [-0.12, -0.04]. Decentration magnitudes were significantly correlated between the right and left eyes. CONCLUSIONS: Spherical SCLs centred well on the cornea but temporally and inferiorly from the primary line of sight (pupil centre), due to the differences in the location of the pupil and corneal centres. Contrary to some previous reports, there was no evidence that lens optics or material affected lens centration significantly.

Clinical Comparison of High-resolution and Standard Refractions and Prescriptions.

SIGNIFICANCE: Recently, novel refraction technology allows subjective refractions to be performed with a higher-resolution. It is unclear, however, if these benefits are noticed and appreciated by the patient during the examination and after dispensing. PURPOSE: This study investigated benefits and drawbacks of high-resolution refraction technology over standard, specifically in terms of the refraction, glasses prescription, and participant's perceptions of the technology. METHODS: Sixty progressive-addition-lens wearers (aged 35 to 70 years) and 60 single-vision wearers (18 years or older) were randomized to a high-resolution refraction (Vision-R 800; Essilor Instruments, Dallas, TX; essilorinstrumentsusa.com ) and standard refraction in a 2-week crossover dispensing design. Refractive results were converted to M, J0, and J45 and analyzed using multivariate t tests. Bayesian estimation was used to analyze differences between refraction type and age group for subjective outcomes. RESULTS: Differences in refractive error between the two refractions were small, and none differed statistically ( P > .05) or clinically (e.g., <0.25 D) in either subgroup. Visual acuities at distance and near were better than 0.00 logMAR; none of the mean differences between the refractions reached statistical or clinical (e.g., <0.10 D) significance. Participants significantly preferred the high-resolution refraction for its quickness and efficiency, improved comfort, and less stress. Bayesian analysis indicated a 76% probability that participants had higher confidence in the high-resolution refraction, 93% probability that they would seek it out for their care, and 94% probability that they would recommend an optometrist using this technology. CONCLUSIONS: Refractive and acuity endpoints were similar with the high-resolution and standard refraction. Participants, however, perceived several key benefits of the high-resolution refraction and prescription for their care, the care of their friends/family, and the practice itself.

Impact of zone geometry on the introduction of myopic defocus in young adult eyes wearing multi-zone lenses.

PURPOSE: Multizone contact lenses control myopia progression by proposed introduction of myopic defocus. This project investigated how much of the pupil area and how many dioptres of myopic defocus are introduced by different lens zone geometries with near- and off-axis viewing. METHODS: Ten young myopic adults (18-25 years) binocularly wore four soft contact lenses including a single vision (SV), concentric-ring dual-focus (DF), centre-distance multifocal (MF) and a RingBoost™ (RB) multi-zone design containing a combination of coaxial and non-coaxial zones. A modified aberrometer captured aberrations and pupil sizes at four target vergences between -0.25 and -4.00 D (on-axis) and across the central ±30° of the horizontal retina (off-axis). Defocus was quantified as the difference between the measured refractive state and the target vergence within each zone of a multi-zone design within the pupil and compared with that of equivalent zone areas of the SV lens. The percentage of the pupil containing myopic defocused light for each lens was calculated. RESULTS: Defocus within the distance correction zones of multi-zone lenses was similar to that of the SV lens. When viewing on-axis at -0.25 D target vergence, on average 11% of the pupil was myopic with SV, whereas 62%, 84% and 50% of the pupil was myopic for the DF, MF and RB designs, respectively. At -4.00 D target vergence, all lenses exhibited a systematic decrease in the percentage of pupil area having myopic defocus (SV: 3%; DF: 18%; MF: 5% and RB: 26%). The off-axis proportions were similar across multi-zone lenses; however, multi-zone lenses retained approximately 1.25-3.0× more myopic defocus than the SV lens. CONCLUSIONS: Subjects accommodated using the distance-correction zones of multi-zone lenses. Multi-zone contact lenses introduced significant myopic defocus on-axis and across the central ±30° retina. However, the magnitude and proportion of defocus were influenced by zone geometry, add power and pupil size.

Myopia Control Dose Delivered to Treated Eyes by a Dual-focus Myopia-control Contact Lens.

PURPOSE: This study examined the optical impact of a DF contact lens during near viewing in a sample of habitual DF lens wearing children. METHODS: Seventeen myopic children aged 14 to 18 years who had completed 3 or 6 years of treatment with a DF contact lens (MiSight 1 Day; CooperVision, Inc., San Ramon, CA) were recruited and fit bilaterally with the DF and a single-vision (Proclear 1 Day; CooperVision, Inc.) contact lens. Right eye wavefronts were measured using a pyramidal aberrometer (Osiris; CSO, Florence, Italy) while children accommodated binocularly to high-contrast letter stimuli at five target vergences. Wavefront error data were used to compute pupil maps of refractive state. RESULTS: During near viewing, children wearing single-vision lenses accommodated on average to achieve approximate focus in the pupil center but, because of combined accommodative lag and negative spherical aberration, experienced up to 2.00 D of hyperopic defocus in the pupil margins. With DF lenses, children accommodated similarly achieving approximate focus in the pupil center. When viewing three near distances (0.48, 0.31, and 0.23 m), the added +2.00 D within the DF lens treatment optics shifted the mean defocus from +0.75 to -1.00 D. The DF lens reduced the percentage of hyperopic defocus (≥+0.75 D) in the retinal image from 52 to 25% over these target distances, leading to an increase in myopic defocus (≤-0.50 D) from 17 to 42%. CONCLUSIONS: The DF contact lens did not alter the accommodative behavior of children. The treatment optics introduced myopic defocus and decreased the amount of hyperopically defocused light in the retinal image.

Retrospective review of the effectiveness of orthokeratology versus soft peripheral defocus contact lenses for myopia management in an academic setting.

PURPOSE: To evaluate the relative efficacy of peripheral defocus contact lenses (PDCLs) and orthokeratology (OK) in a real-world clinical population, and compare these results with previous randomised controlled clinical trials. METHODS: Records from a university practice were reviewed to identify children who were treated with OK or PDCLs. The analysed sample contained 273 visits from 77 patients. Annualised rates of axial length (AL) progression were calculated and used as the response variable in both linear mixed-effects (LME) and nonlinear regression models. RESULTS: On average, children were 10.7 years of age at baseline (p = 0.14 between treatments), and most patients were female. More Asian children wore OK lenses compared with PDCLs (p < 0.01). At baseline, children had ~3.00 D of myopia and 0.75 D of astigmatism in both treatment groups (p > 0.20 between treatments). LME regression models using only baseline covariates showed no evidence that the annualised change in AL differed between treatments, with or without the inclusion of age, race, sex, baseline AL or spherical equivalent refractive error. Across all possible subsets of models, age at baseline was the best predictor of annualised AL change. There was no statistical difference between parameters of an exponential decay model fitted within treatment using follow-up age as a time-varying predictor, indicating that the rate of annualised change in AL was similar for OK and PDCL. CONCLUSIONS: Retrospective analysis of real-world clinical data found no difference in annualised AL growth between PDCL and OK. Importantly, the AL progression from this clinical setting is consistent with that reported in randomised clinical trials. Therefore, continued research of real-world performance is warranted to understand the safety and efficacy of modern myopia control treatments in the broader population.

Optical characterisation of two novel myopia control spectacle lenses.

PURPOSE: To quantify the amount of myopic defocus, contrast modulation and other optical characteristics of two novel spectacle lenses (MiYOSMART by Hoya and Stellest by Essilor) with the inclusion of lenslets in their designs were investigated computationally and experimentally. This paper examined the hypothesis that despite the non-coaxial nature of the optics, image degradation will exist due to the fragmented nature of the base optic when imaging through the lens regions populated by lenslets. METHODS: Optical power was evaluated by computing wavefront vergence and curvature from wavefront slope measured with the Optocraft aberrometer within 1.0 and 6.0 mm apertures across MiYOSMART hexagons and Stellest rings. Point-spread functions (PSFs) were computed using physical (wave) optics and geometrical ray optics principles, and compared with experimental measurements using a 4f optical system. Simulated retinal images and modulation transfer functions (MTFs) were computed from PSF-derived optical transfer functions (OTFs). RESULTS: Mean lenslet power in MiYOSMART was +3.95 ± 0.10 D through the hexagons and +6.00 ± 0.15 D in Stellest in rings 1-5 and decreased by 0.42 D/ring reaching 3.50 D in the final one. Stellest lenslets included up to -0.015 microns of primary spherical aberration. PSFs and retinal images revealed simultaneous contributions of the base optic and lenslets. MTFs showed a decrease in contrast at low (1-10 c/deg) spatial frequencies (SFs) comparable to 0.25 D of defocus, and retention of diminished levels of contrast at higher SFs. CONCLUSIONS: Varying sagittal power and consistent curvature power across the lenslets is an identifying signature of the novel non-coaxial lens design included in both spectacle lenses. Lenslet array structure itself plays a significant role in determining image characteristics. For both lenses, the blur created by the fragmented base optic contributes to the image quality. The reduced MTFs over a wide range of spatial frequencies result in lowered image contrast.

Smart soft contact lenses for continuous 24-hour monitoring of intraocular pressure in glaucoma care.

Continuous monitoring of intraocular pressure, particularly during sleep, remains a grand challenge in glaucoma care. Here we introduce a class of smart soft contact lenses, enabling the continuous 24-hour monitoring of intraocular pressure, even during sleep. Uniquely, the smart soft contact lenses are built upon various commercial brands of soft contact lenses without altering their intrinsic properties such as lens power, biocompatibility, softness, transparency, wettability, oxygen transmissibility, and overnight wearability. We show that the smart soft contact lenses can seamlessly fit across different corneal curvatures and thicknesses in human eyes and therefore accurately measure absolute intraocular pressure under ambulatory conditions. We perform a comprehensive set of in vivo evaluations in rabbit, dog, and human eyes from normal to hypertension to confirm the superior measurement accuracy, within-subject repeatability, and user comfort of the smart soft contact lenses beyond current wearable ocular tonometers. We envision that the smart soft contact lenses will be effective in glaucoma care.

Modelling the refractive and imaging impact of multi-zone lenses utilised for myopia control in children's eyes.

PURPOSE: To develop an optical model of a child's eye to reveal the impact of target distance and accommodative behaviour on retinal image quality when fitted with multi-zone lenses. METHODS: Pupil size, aberration levels and accommodative lag were adjusted for models viewing stimuli at 400, 100, 33 and 20 cm. Distributions of defocus across the pupil and simulated retinal images were obtained. An equivalent 16-point letter was imaged at near viewing distances, while a 0.00 logMAR (6/6) letter was imaged at 400 cm. Multi-zone lenses included those clinically utilised for myopia control (e.g., dual-focus, multi-segmented and aspherical optics). RESULTS: Viewing distance adjustments to model spherical aberration (SA) and pupil radius resulted in a model eye with wider defocus distributions at closer viewing distances, especially at 20 cm. The increasing negative SA at near reduced the effective add power of dual-focus lenses, reducing the amount of myopic defocus introduced by the centre-distance, 2-zone design. The negative SA at near largely compensated for the high positive SA introduced by the aspheric lens, removing most myopic defocus when viewing at near. A 0.50 D accommodative lag had little impact on the legibility of typical text (16-point) at the closer viewing distances. CONCLUSIONS: All four multi-zone lenses successfully generated myopic defocus at greater viewing distances, but two failed to introduce significant amounts of myopic defocus at the nearest viewing distance due to the combined effects of pupil miosis and negative SA. Typical 16-point type is easily legible at near even in presence of the multi-zone optics of lenses utilised for myopia control and accommodative lag.

Retinal defocus in myopes wearing dual-focus zonal contact lenses.

PURPOSE: To evaluate the refractive impact of dual-focus (DF) myopia control contact lenses (CLs) on accommodating young myopic adults. METHODS: Phase 1: accommodative accuracy was assessed in 40 myopic participants. Phase 2: a subset of four subjects who demonstrated accurate accommodation and six who chronically underaccommodated were fitted with single vision (SV, Proclear 1 day) and centre-distance DF myopia control CLs (MiSight 1 day) with approximately +2.00 D of additional power in two surrounding annular zones. While binocularly viewing high contrast characters at 4.00, 1.00, 0.50, 0.33, 0.25 and 0.20 m, aberrometry data were captured across the central ±30° of the horizontal retina. Local refractive errors were pooled for each area of the pupil covered by the central distance or first annular defocus zone of the DF CLs. RESULTS: In the "good" accommodator group fitted with SV CLs, accommodative lags were generally absent except at the closest viewing distance (mean errors: -0.09 ± 0.22 D, -0.12 ± 0.26 D, -0.05 ± 0.37 D and +0.38 ± 0.54 D for -2.00, -3.00, -4.00 and -5.00 D target vergences, respectively) but significantly larger in the "poor" accommodating participants (+0.81 ± 0.21 D, +0.97 ± 0.27 D, +1.18 ± 0.39 D, +1.47 ± 0.55 D). For most viewing distances, hyperopic defocus observed in the region of the pupil covered by the first annular zone was replaced with myopic defocus when fitted with the DF CLs. Myopic defocus created by the first annular region was present across the central 30° of the retina. CONCLUSIONS: Some young adult myopes chronically experience high levels of hyperopic defocus when viewing near targets, which was replaced by myopic defocus in the annular part of the pupil covered by the treatment zones when fitted with a centre-distance myopia control DF CL.

CLEAR - Contact lens optics.

The most fundamental aspect of a contact lens is its optics; the manner in which the refraction of light is managed to optimise vision to the clinical benefit of the lens wearer. This report presents contemporary information on the optical structure of the eye and the optical models employed to understand the correction of refractive error. The design, measurement and clinical assessment of spherical, aspheric, toric, multifocal and myopia control contact lenses are described. The complexity and variety of multifocal lenses is recognised and detailed information is provided for alternating, simultaneous, diffractive, annular, aspheric and extended depth of field lens designs. In terms of clinical assessment, a contemporary review is provided for the measurement of: visual acuity, contrast sensitivity, through focus curves, reading performance, peripheral refraction, toric displacement realignment and patient reported outcomes. Overall, the paper aims to serve as a resource for the prescribing clinician, who can optimise contact lens corrections for patients by building on the optical rationale of these devices; and also highlights future opportunities for research innovation.

All-printed stretchable corneal sensor on soft contact lenses for noninvasive and painless ocular electrodiagnosis.

Electroretinogram examinations serve as routine clinical procedures in ophthalmology for the diagnosis and management of many ocular diseases. However, the rigid form factor of current corneal sensors produces a mismatch with the soft, curvilinear, and exceptionally sensitive human cornea, which typically requires the use of topical anesthesia and a speculum for pain management and safety. Here we report a design of an all-printed stretchable corneal sensor built on commercially-available disposable soft contact lenses that can intimately and non-invasively interface with the corneal surface of human eyes. The corneal sensor is integrated with soft contact lenses via an electrochemical anchoring mechanism in a seamless manner that ensures its mechanical and chemical reliability. Thus, the resulting device enables the high-fidelity recording of full-field electroretinogram signals in human eyes without the need of topical anesthesia or a speculum. The device, superior to clinical standards in terms of signal quality and comfortability, is expected to address unmet clinical needs in the field of ocular electrodiagnosis.

Time-course of the visual Impact on presbyopes of a low dose miotic.

PURPOSE: To examine the pupil and visual impact of a single early morning drop of a low concentration miotic. METHODS: Pupil size, refraction, visual acuity (VA), near reading performance and intraocular pressure were monitored for 8 h at a wide range of light levels following bilateral instillation of single drops of 0.1% brimonidine tartate in 19 early presbyopes (40-50 years) and 11 mature presbyopes (>50 years). RESULTS: Pupil miosis did not alter distance VA or refraction. Significant pupil miosis peaked at 1-2 h after dosing, which expanded the depth of focus of mature presbyopes with the mean improvement in near logMAR VA of -0.15, -0.07 and -0.03, at 20, 200 and 2000 lux, respectively. One hour after instillation, near reading speed improved by 21, 24 and 5 words per min for text size commonly seen in US newspaper and cellphone text messages, 18, 21 and 19 words per min for text size of grocery labels and 12, 13 and 30 words per min for text size of over-the-counter medications at light levels of 20, 200 and 2000 lux, respectively. No such improvements in near VA and near reading speed were observed in the young presbyopes having some residual accommodation. Most of the pupil miosis remained 8 h after instillation, whereas near VA improvements disappeared after 4 h. CONCLUSION: Low dose miotics can enhance near vision in presbyopic subjects while retaining high quality distance vision over a wide range of light levels. Significant improvements in near vision were observed only during the 1-2 h period after dosing when miosis peaked.

Ocular symptoms associated with digital device use in contact lens and non-contact lens groups.

PURPOSE: Previous reports indicate that "eye fatigue" occurs in roughly 60 % of the adult population using digital devices and may negatively impact quality of life. However, the construct of eye fatigue remains poorly understood. The goal of this study was to quantify the relationship among symptoms most frequently associated with eye fatigue in those using digital devices. METHODS: Six hundred and two soft contact lens (SCL) wearers and 127 non-contact lens (non-CL) wearers who reported using digital devices at least 4 hours per day completed a questionnaire assessing the frequency and severity of ten symptoms commonly associated with digital device-related eye fatigue. Subjective ratings were made separately for each symptom using unipolar, five-point Likert scales. RESULTS: From the initial pool of respondents, 89 % of the SCL wearers reported experiencing eye fatigue more than once per month, while over 60 % reported more than once per week. Notably, eye fatigue frequency did not differ between the soft contact and non-contact lens groups. Although eye strain/pain, dryness, and tired eyes were the most frequently endorsed symptoms by both groups, only dryness and eye irritation were significant factors that discriminated the SCL from the non-CL wearers on the basis of frequency and severity. Principal component analysis indicated that eye strain/pain, soreness, tired eyes, and headaches may comprise a "primary sensations" factor, whereas burning, eye irritation, tearing and dryness comprise a "secondary or surface sensations" factor, and blurred/double vision and words move/float comprise a "visual sensations" factor. Confirmatory factor analysis (CFA) of frequency and severity ratings for SCL wearers yielded excellent fits (RMSEA = 0.046 and 0.050, respectively) with construct reliabilities ranging from 0.729 to 0.824. CONCLUSION: Frequent and severe eye fatigue is highly prevalent among both soft contact lens and non-contact lens wearers. Those utilizing SCL do not experience symptoms at higher frequency or severity. Key descriptors of digital eye fatigue have been identified and may then be used to help identify and evaluate specific causative, palliative, or ameliorating factors.

Accommodative Behavior, Hyperopic Defocus, and Retinal Image Quality in Children Viewing Electronic Displays.

SIGNIFICANCE: The prevalence of myopia and use of electronic displays by children has grown rapidly in recent years. We found that children viewing electronic displays, however, experience hyperopic defocus levels similar to those previously reported for other stimuli. PURPOSE: This study aimed to compare accommodative behavior of nonmyopic and myopic children viewing a computer screen or mobile phone. METHODS: Accommodative behavior was examined in 11 nonmyopic and 8 myopic children (11.32 ± 2.90 and 14.13 ± 2.30 years, respectively; P = .04; refractions, +0.51 ± 0.51 and -2.54 ± 1.29, respectively) using an open-field autorefractor (Grand Seiko) at target vergences from -0.25 to -5.00 D. Different size (scaled or nonscaled) and type (text or movie) stimuli were presented on an LCD monitor (distant) or an iPhone (near), with subjects viewing monocularly or binocularly in an illuminated or dark room. RESULTS: At the typical reading distances (20 and 33 cm), all 19 children exhibited some amount of accommodative lag. Stimulus type had little impact on accommodation. However, slightly but statistically significant lower slopes were observed (Bonferroni-corrected significance level of P ≤ .01) for low room lighting (0.96 vs. 0.91; t test, t = 3.88; P = .003), nonscaled targets (0.99 vs. 0.92; t test, t = 4.28; P = .001), and monocular viewing (0.99 vs. 0.90; t test, t = 4.0; P = .002) in the nonmyopic group only. When viewing nonscaled stimuli binocularly (natural viewing), the means and standard deviations of accommodative lags (averaged across room lights on and off, and text and movie) were generally larger for the nonmyopes at all distances and were largest at 33 cm (0.73 ± 0.18 D for the nonmyopes and 0.49 ± 0.23 for the myopes; t test, t = 2.62; P = .01). CONCLUSIONS: Generally small (≤0.50 D) amounts of hyperopic defocus are present in children binocularly viewing handheld electronic devices (nonmyopes slightly more than myopes). Modern electronic devices do not expose children to unusually high levels of hyperopic defocus.

Optical and imaging properties of a novel multi-segment spectacle lens designed to slow myopia progression.

PURPOSE: High sampling density optical metrology combined with pupil- and image-plane numerical analyses were applied to evaluate a novel spectacle lens containing multiple small zones designed to slow myopia progression. METHODS: High-resolution aberrometry (ClearWave, www.lumetrics.com) was used to sample wavefront slopes of a novel spectacle lens, Defocus Incorporated Multiple Segments (DIMS) (www.hoya.com), incorporating many small, positive-powered lenslets in its periphery. Using wavefront slope and error maps, custom MATLAB software ('Indiana Wavefront Analyzer') was used to compute image-plane point-spread functions (PSF), modulation transfer functions (MTF), simulated images and power distributions created by the dual-focus optic for different pupil sizes and target vergences. RESULTS: Outside of a central 10 mm zone containing single distance optical power, a hexagonal array of small 1 mm lenslets with nearest-neighbour separations of 0.5 mm were distributed over the lens periphery. Sagittal and curvature-based measures of optical power imperfectly captured the consistent +3.50 D add produced by the lenslets. Image plane simulations revealed multiple PSFs and poor image quality at the lenslet focal plane. Blur at the distance optic focal plane was consistent with a combination of diffraction blur from the distance optic and the approximately +3.50 D of defocus from the 1 mm diameter near optic zones. CONCLUSION: Converging the defocused beams generated by the multiple small (1 mm diameter) lenslets to a blurred image at the distance focal plane produced a blur magnitude determined by the small lenslet diameter and not the overall pupil diameter. The distance optic located in between the near-add lenslets determines the limits of the optical quality achievable by the lens. When compared to the optics of a traditional concentric-zone dual-focus contact lens, the optics of the DIMS lens generates higher-contrast images at low spatial frequencies (<7 cycles per degree), but lower-contrast at high spatial frequencies.

Experimental Model of Far Temporal Field Negative Dysphotopsia Generated in Phakic Eyes.

Purpose: The axial separation between the iris and the intraocular lens (IOL) in pseudophakic eyes can cause rays originating from the far temporal field to miss the IOL, resulting in negative dysphotopsia (ND). We developed an experimental model to test the hypothesis that obstruction of rays from the far temporal field can generate ND and an accompanying loss of visual sensitivity in the far temporal field. Methods: The right eyes of 10 phakic subjects were fitted with soft contact lenses containing a 5.50-mm central clear zone and a 12-mm outer diameter opaque annulus. In three of the subjects, eyes were dilated with 1% tropicamide solution, and effective aperture diameters were determined optically (pupil camera) and psychophysically (narrow beam detection). Visual field extent (Goldmann bowl) and temporal and inferotemporal meridian sensitivities (Octopus perimeter) were measured. A wide-angle model was constructed to quantify the impact of the annular opacity on retinal illuminance. Results: All 10 subjects observed a dark crescent in the far temporal and inferotemporal fields. The opaque annulus reduced effective horizontal pupil diameters from 8 mm to 5.5 mm on-axis and from >2 mm to <1 mm at 90°. Perimetry revealed a 10° reduction in temporal and inferotemporal field extent and increasing loss of sensitivity beyond 70°. The wide-angle model confirmed significant vignetting (>50% beyond 70°), approaching zero retinal illuminance beyond 85°. Conclusions: Vignetting of rays originating from the far temporal field by axially separated apertures can create symptoms mirroring perceptual reports of negative dysphotopsia in symptomatic pseudophakic patients.

Nasal-temporal asymmetry in peripheral refraction with an aspheric myopia control contact lens.

A combination of human subject data and optical modelling was used to investigate unexpected nasal-temporal asymmetry in peripheral refraction with an aspheric myopia control lens. Peripheral refraction was measured with an auto-refractor and an aberrometer. Peripheral refraction with the lens was highly dependent upon instrument and method (e.g. pupil size and the number of aberration orders). A model that did not account for on-eye conformation did not mirror the clinical results, but a model assuming complete lens conformation to the anterior corneal topography accounted for the positive shift in clinically measured refraction at larger nasal field angles. The findings indicate that peripheral refraction of highly aspheric contact lenses is dependent on lens conformation and the method of measurement. These measurement methods must be reported, and care must be used in interpreting results.