Optics of spectacle lenses intended to treat myopia progression.

SIGNIFICANCE: This is a review of the optics of various spectacle lenses that have been used in myopia control over the last 60 years, with emphasis on approximately the last 15 years.Myopia has become an increasing health problem worldwide, particularly in some East Asian countries. This has led to many attempts to slow its progression in children and reduce its endpoint value. This review is concerned with the optics of spectacle lenses for use in myopia control, from bifocal lenses to multisegment and diffusion optics lenses. Treatments are based on theories of the onset or progression of myopia. These include the hypotheses that eye growth and myopia in susceptible children may be stimulated by (1) poor accommodation response and the consequent hyperopic defocus with near vision tasks, (2) relative hyperopic peripheral refraction, and (3) high retinal image contrast as occurs in urban environments. Using spectacle lenses to slow myopia progression has a history of about 60 years. The review is laid out in approximately the order in which different types of lenses have been introduced: bifocals, conventional progressive addition lenses, undercorrection with single-vision lenses, specialized progressive addition lenses, defocus-incorporated multiple segments, diffusion optics, and concentric bifocals. In the review, some of the lenses are combined with an eye model to determine refractive errors for peripheral vision for the stationary eye and for foveal vision for the rotating eye. Numbers are provided for the reported success of particular designs in retarding myopia progression, but this is not an epidemiological paper, and there is no critical review of the findings. Some of the recent treatments, such as multiple segments, appear to reduce the eye growth and myopia progression by better than 50% over periods of up to 2 years.

Accommodative response and visual fatigue following a non-congruent visual task in non-asthenopic and asthenopic individuals.

PURPOSE: Asthenopia is related to near vision activities or visual tasks that dissociate accommodation from vergence. Since the results of previous studies using objective measures to diagnose asthenopia are inconsistent, this study compared optometric tests and objective metrics of accommodation in non-asthenopic and asthenopic young adults before and after a visual fatigue task. METHODS: The accommodative response was recorded objectively for 6 min at a 3.33 D accommodative demand using an autorefractor, before and after a 5-min non-congruent visual task. Accommodation was disassociated from vergence with a ±2.00 D accommodative flipper while reading at the same distance. Optometric tests and subjective evaluations of asthenopia were performed before and after the task. Twenty-six non-presbyopic adults (23.15 ± 2.56 years) were included and identified as asthenopic (n = 14) or non-asthenopic (n = 12) based on their score on the Computer Vision Syndrome Questionnaire. RESULTS: A mixed ANOVA found no significant difference between the groups for objective (accommodative response) or subjective metrics (feeling of fatigue, optometric tests), although all participants reported greater visual fatigue after the task. A significant effect of time (before and after the non-congruent task) was identified for the overall sample for mean accommodative lag (+0.10 D, p = 0.01), subjective visual fatigue (+1.18, p < 0.01), negative relative accommodation (-0.20 D, p = 0.02) and near negative fusional reserve (blur: +2.46Δ, p < 0.01; break: +1.89Δ, p < 0.01; recovery: +3.34Δ, p = 0.02). CONCLUSIONS: The task-induced asthenopia, measured both objectively and subjectively, was accompanied by a change in accommodative lag, greater visual fatigue and a decrease in negative relative accommodation. Conversely, near negative fusional reserves seem to adapt to the task. No significant differences were found between the two groups with respect to accommodative metrics (objective) or subjective and optometric tests.

Effects of vision therapy on near exodeviation in children with convergence insufficiency treated during the convergence insufficiency treatment trials.

PURPOSE: To report the change in the magnitude of near exodeviation in children with symptomatic convergence insufficiency successfully treated with office-based vergence/accommodative therapy in the Convergence Insufficiency Treatment Trial-Attention and Reading Trial. METHODS: A total of 131 children 9-14 years of age with symptomatic convergence insufficiency classified as successfully treated with office-based vergence/accommodative therapy at the 16-week outcome visit were included. Masked examiners measured the near ocular deviation by the prism and alternate cover test at baseline, primary outcome and 1-year post-treatment. The mean change in near deviation was calculated from baseline to primary outcome, from primary outcome to 1-year post-treatment and from baseline to 1-year post-treatment. RESULTS: Of the 131 participants successfully treated with vergence/accommodative therapy, 120 completed the 1-year post-treatment visit. A significant change in near exodeviation was observed at baseline to primary outcome (2.6Δ less exo, p < 0.001, moderate effect size d = 0.61) and at baseline to 1-year post-treatment (2.0Δ less exo; p < 0.001, small effect size d = 0.45). The change from primary outcome to 1-year post-treatment (0.6Δ more exo; p = 0.06, small effect size d = 0.11) was not significant. Forty per cent (48/120) of participants had a decrease in near exodeviation >3.5∆ (expected test/retest variability) between baseline and the primary outcome examination. Of the 120 participants, one (1.0%) was esophoric at the primary outcome and was subsequently exophoric at 1-year post-treatment. Four participants (3.3%) who were orthophoric or exophoric at the primary outcome were esophoric (all ≤3∆) at the 1-year post-treatment visit. CONCLUSION: On average, the near exodeviation was smaller in size immediately after the discontinuation of vergence/accommodative therapy (2.6∆, moderate effect size) and 1 year post vergence/accommodative therapy (2.0∆, small effect size) in children with convergence insufficiency who were successfully treated; 40% had a clinically meaningful decrease in exophoria. The development of near esophoria was rare.

Wavefront Changes during a Sustained Reading Task in Presbyopic Eyes.

The objective of this study was to assess the effect of sustained reading on the temporal changes in the wavefront error in the presbyopic eye. The wavefront aberration of the eyes was measured using an IRX3 Shack-Hartmann aberrometer before and after (immediately, 5 min, and 10 min after) a reading task. Temporal changes in C20, C40, and C3-1 coefficient values of the eyes were plotted, showing a predominant number of V-shaped patterns (for C40 and C3-1) and inverse V-shaped patterns (for C20) among the study group, and the percentages (between 27 and 73%) were reported. The median of the total RMS of aberrations and the RMS of HOA (higher-order aberrations), which included comatic (3rd order) and spherical-like aberrations (4th and 6th order), increased immediately after finishing the near-vision reading task and then decreased. The median of RMS of comatic aberrations had a similar pattern of variations, while the median of RMS of spherical-like aberrations displayed an opposite pattern. Simulating the aberration changes due to lens decentration caused by relaxed zonules during 4 D accommodation in an eye model demonstrated that the expected range of changes for the vertical coma and spherical aberrations are in the order of 0.001 and 0.01 µm, respectively, which could justify why the observed changes were not statistically significant. The observed dynamic changes in HOA might be linked to the biomechanical characteristics and alterations in the displacement of the crystalline lens following prolonged near-vision tasks in presbyopic people. Although some predominant patterns under some conditions were shown, they exhibit considerable inter-subject and inter-ocular variability. This might be due to slight misalignments while fixating on the internal extended object in the aberrometer.

Vergence-Accommodation Conflict: Increased Presbyopia in Virtual Reality.

BACKGROUND: Performance and symptoms in completing a visual search task on a PC monitor and using a head-mounted display (HMD) were compared for different viewing conditions and between users of different ages. PATIENTS AND METHODS: Twenty-three young (M = 30 y, SD = 7 y) and 23 older (M = 52 y, SD = 5 y) participants performed a visual search task presented on a PC monitor. The task was repeated using an HMD for a near and a far virtual viewing distance. Reaction times (RT), detection sensitivity (d'), and symptoms were recorded for the three different viewing conditions. RESULTS: RT and d' were not affected by the viewing condition (p > 0.05). In contrast, symptoms significantly depended on the viewing condition but were, in part, not significantly affected by age. It is interesting to note that although not significant, young participants reported more ocular symptoms than older participants in the near vision task carried out using the HMD. DISCUSSION: HMD increases visual symptoms. However, HMD could be, in part, a remedy to problems when using visual aids for near work, in particular for presbyopes.

Active efficient coding explains the development of binocular vision and its failure in amblyopia.

The development of vision during the first months of life is an active process that comprises the learning of appropriate neural representations and the learning of accurate eye movements. While it has long been suspected that the two learning processes are coupled, there is still no widely accepted theoretical framework describing this joint development. Here, we propose a computational model of the development of active binocular vision to fill this gap. The model is based on a formulation of the active efficient coding theory, which proposes that eye movements as well as stimulus encoding are jointly adapted to maximize the overall coding efficiency. Under healthy conditions, the model self-calibrates to perform accurate vergence and accommodation eye movements. It exploits disparity cues to deduce the direction of defocus, which leads to coordinated vergence and accommodation responses. In a simulated anisometropic case, where the refraction power of the two eyes differs, an amblyopia-like state develops in which the foveal region of one eye is suppressed due to inputs from the other eye. After correcting for refractive errors, the model can only reach healthy performance levels if receptive fields are still plastic, in line with findings on a critical period for binocular vision development. Overall, our model offers a unifying conceptual framework for understanding the development of binocular vision.

Polarization enlargement of FOV in Super Multi-view display based on near-eye timing-apertures.

With strip-type timing-apertures attached to each eye of a viewer, more than one perspective views can be guided to either eye sequentially through different timing-apertures, thus implementing VAC-free (vergence-accommodation conflict-free) SMV (Super Multi-view) 3D (three-dimensional) display. To overcome the FOV (field of view) limitation problem due to small size of the timing-apertures along their arrangement direction, novel polarization architectures are designed to the timing-apertures in this paper. Correspondingly, the display screen of the proposed SMV display system is divided into M > 1 sub-screens along the arrangement direction of the timing-apertures, with adjacent sub-screens emitting light of mutually orthogonal polarization. At a time-point of each time period, a group of M timing-apertures, which correspond to the M sub-screens in a one-by-one manner along the arrangement direction, are turned on for creating an M-fold FOV, with each polarized timing-aperture of the group allowing light from the corresponding sub-screen passing through and blocking light from sub-screen(s) adjacent to the corresponding sub-screen. At 2T > 1 time-points of each time period, 2T groups of timing-apertures are turned on sequentially for presenting more than one two-dimensional images of the displayed scene to each eye, to implement SMV display based on persistence of vision. M stands for the FOV magnification number and T stands for the two-dimensional image number for each eye. As proof, a 3-fold FOV of 41° gets implemented experimentally with a currently available timing-aperture array of M = 3, accompanied by an effective noise-free region (ENFR) of 8.34 mm. Furthermore, the promising of freeing FOV from timing-aperture constraint fundamentally by larger M is described, out-of-screen blur along strip direction of the timing-apertures and the problem of limited ENFR are discussed.

Temperature affects the biomechanical response of in vitro non-human primate lenses during lens stretching.

PURPOSE: To determine the effect of temperature on the accommodative response of non-human primate crystalline lenses during simulated accommodation. METHODS: Eight lenses from 7 cynomolgus monkeys (Macaca fascicularis, ages: 4.5-7.3 years; post-mortem time: 17.0 ± 16.4 h) were mounted in a lens stretcher. Stretching experiments were performed on each lens at 24 °C (room temperature), then the tissue was warmed to 35 °C (intraocular temperature) and the stretching experiments were repeated. The lens diameter, thickness, anterior and posterior surface radii of curvature, optical power, and the stretching force (load) were measured at each stretch position and the linear optomechanical relationships were quantified: load-lens diameter, load-thickness, power-load, load-anterior radius, and load-posterior radius. The rate of change for each parameter was quantified by performing a linear regression. The slopes of the linear regressions were compared at the two temperatures using a paired sample t-test. RESULTS: The average changes in the lens with stretching at 24 °C and 35 °C were: 3.07 ± 0.17 and 2.58 ± 0.15 for load-lens diameter (g/mm), -2.38 ± 0.20 and -2.00 ± 0.32 for load-thickness (g/mm), -13.35 ± 1.21 and -13.75 ± 1.26 for power-load (D/g), 0.41 ± 0.10 and 0.34 ± 0.05 for load-anterior radius of curvature (g/mm), and 1.35 ± 0.24 and 1.31 ± 0.35 for load-posterior radius of curvature (g/mm), respectively. The changes in load-diameter and load-thickness with lens stretching were significantly different for the two temperatures. CONCLUSIONS: Temperature influences the change in lens shape observed during simulated accommodation in non-human primate lenses. These results suggest that lens stretching experiments and other optomechanical measurement techniques on ex vivo crystalline lenses be conducted at 35 °C and that the temperature of the tissue sample be documented and maintained constant to ensure repeatability.

Transient reduction in the retinal microvascular network following implantation surgery of implantable collamer lens: An OCT angiography study.

Purpose: To evaluate changes in the retinal microvascular network after posterior chamber phakic implantable collamer lens (ICL) surgery using optical coherence tomography angiography (OCTA) in patients with high myopia. Methods: Patients with high myopia who underwent ICL surgery were enrolled in this study. All patients underwent comprehensive ophthalmologic exams preoperatively and 1 week, 1 month, and 3 months postoperatively. The vascular densities (VDs) in the retina and the superficial and deep capillary plexuses of different annular and quadrantal areas were evaluated from OCTA images (Zeiss Cirrus 5000). Correlations between the variations in microvascular density and possible factors were further analyzed. Results: The study comprised 32 eyes of 32 patients. The mean age of the patients was 26.91±7.610 years (15 men and 17 women). A statistically significant reduction in microvascular density in the retina and the superficial plexus was found 1 week and 1 month postoperatively (p<0.05, repeated-measures ANOVA). Further fractal analysis found that the VD of the outer ring declined statistically significantly (p<0.05). A statistically significant decrease was also found in the inferior nasal sector 1 week postoperatively, with an overall decrease in all four quadrants 1 month postoperatively. The microvascular density recovered toward the baseline level 3 months postoperatively. No correlations were observed between the variation in microvascular density and the spherical equivalent (SE), axial length (AL), intraocular pressure (IOP), amplitude of accommodation (AA), or contrast sensitivity. Conclusions: Retinal microvascular density was decreased postoperatively and then recovered toward the baseline level after 3 months. ICL surgery may have a transient influence on the retinal microvascular network without affecting visual function.

Multifocal and Accommodating Intraocular Lenses for the Treatment of Presbyopia: A Report by the American Academy of Ophthalmology.

PURPOSE: To review the published literature assessing the efficacy and safety of presbyopia-correcting intraocular lenses (IOLs) for the treatment of presbyopia after cataract removal. METHODS: Literature searches were undertaken in January 2018 and September 2020 in the PubMed, Medline, and Cochrane Library databases. This yielded 761 articles, of which 34 met the criteria for inclusion in this assessment and were assigned a level of evidence rating by the panel methodologist. Thirteen studies were rated level I and 21 studies were rated level II. RESULTS: Presbyopia-correcting lenses were effective at improving distance and near visual acuity after cataract surgery. Near acuity at different focal lengths was related directly to the effective add power of multifocal and extended depth-of-focus (EDOF) IOLs. Most multifocal and EDOF lenses that were compared with a control monofocal lens demonstrated that patient-reported spectacle independence was superior to the monofocal lens. All patients who had multifocal and EDOF lenses implanted showed decreased contrast sensitivity and reported more visual phenomena as compared with control participants who received monofocal lenses. CONCLUSIONS: Presbyopia-correcting lenses improve uncorrected near and distance visual acuity and decrease spectacle dependence after cataract surgery. Mesopic contrast sensitivity is decreased compared with monofocal lenses, and patient-reported visual phenomena are more likely in patients receiving multifocal or EDOF lenses.

Home- and Office-Based Vergence and Accommodative Therapies for Treatment of Convergence Insufficiency in Children and Young Adults: A Report by the American Academy of Ophthalmology.

PURPOSE: To review home- and office-based vergence and accommodative therapies for treatment of convergence insufficiency (CI) in children and young adults up to 35 years of age. METHODS: Literature searches were conducted through October 2020 in the PubMed database for English-language studies. The combined searches yielded 359 abstracts, of which 37 were reviewed in full text. Twelve of these were considered appropriate for inclusion in this assessment and assigned a level of evidence rating by the panel methodologist. RESULTS: Of the 12 studies included in this assessment, 8 were graded as level I evidence, 2 were graded as level II evidence, and 2 were graded as level III evidence. Two of the level I studies included older teenagers and young adults; the remainder of the studies exclusively evaluated children. Two randomized controlled trials found that office-based vergence and accommodative therapies were effective in improving motor outcomes in children with symptomatic CI. However, the studies reported conflicting results on the efficacy of office-based therapy for treating symptoms of CI. Data were inconclusive regarding the effectiveness of home-based therapies (including pencil push-ups and home computer therapy) compared with home placebo. In young adults, office-based vergence and accommodative therapies were not superior to placebo in relieving symptoms of CI. CONCLUSIONS: Level I evidence suggests that office-based vergence and accommodative therapies improve motor outcomes in children with symptomatic CI, although data are inconsistent regarding symptomatic relief. Evidence is insufficient to determine whether home-based therapies are effective.

Interaction between sampled rays' defocusing and number on accommodative response in integral imaging near-eye light field displays.

In an integral imaging near-eye light field display using a microlens array, a point on a reconstructed depth plane (RDP) is reconstructed by sampled rays. Previous studies respectively suggested the accommodative response may shift from the RDP under two circumstances: (i) the RDP is away from the central depth plane (CDP) to introduce defocusing in sampled rays; (ii) the sampled ray number is too low. However, sampled rays' defocusing and number may interact, and the interaction's influence on the accommodative response has been little revealed. Therefore, this study adopts a proven imaging model providing retinal images to analyze the accommodative response. As a result, when the RDP and the CDP coincide, the accommodative response matches the RDP. When the RDP deviates from the CDP, defocusing is introduced in sampled rays, causing the accommodative response to shift from the RDP towards the CDP. For example, in a system with a CDP of 4 diopters (D) and 45 sampled rays, when the RDP is at 3, 2, 1, and 0 D, the accommodative response shifts to 3.25, 2.75, 2, and 1.75 D, respectively. With fewer rays, the accommodative response tends to further shift to the CDP. Eventually, with fewer than five rays, the eye accommodates to the CDP and loses the 3D display capacity. Moreover, under different RDPs, the ray number influences differently, and vice versa. An x-y polynomial equation containing three interactive terms is finally provided to reveal the interaction between RDP position and ray number. In comparison, in a pinhole-based system with no CDP, the accommodative response always matches the RDP when the sampled ray number is greater than five.

Waveguide-type see-through dual focus near-eye display with a polarization grating.

Waveguide-type near-eye displays have useful properties such as compact form factor, lightweight and see-through capability. Conventional systems, however, support only a single image plane fixed at a certain distance, which may induce eye fatigue due to the vergence-accommodation conflict. In this paper, we propose a waveguide-type near-eye display with two image planes using a polarization grating. Two images with orthogonal polarizations propagate within the waveguide with different total internal reflection angles and form virtual images at different distances. The use of the polarization grating and two pairs of holographic optical elements enables dual image plane formation by a single waveguide with high transparency for the real scene. Optical experiments confirm the principle of the proposed optical system.

Extending eyebox with tunable viewpoints for see-through near-eye display.

The Maxwellian display presents always-focused images to the viewer, alleviating the vergence-accommodation conflict (VAC) in near-eye displays (NEDs). However, the limited eyebox of the typical Maxwellian display prevents it from wider applications. We propose a Maxwellian see-through NED based on a multiplexed holographic optical element (HOE) and polarization gratings (PGs) to extend the eyebox by viewpoint multiplication. The multiplexed HOE functions as multiple convex lenses to form multiple viewpoints, which are copied to different locations by PGs. To mitigate the imaging problem that multiple viewpoints or no viewpoints enter the eye pupil, the viewpoints can be tuned by mechanically moving a PG. We implement our method in a proof-of-concept system. The optical experiments confirm that the proposed display system provides always in-focus images within a 12 mm eyebox in the horizontal direction with a 32.7° diagonal field of view (FOV) and a 16.5 mm eye relief (ERF), and its viewpoints are tunable to match the actual eye pupil size. Compared with other techniques to extend the eyebox of Maxwellian displays, the proposed method shows competitive performances of a large eyebox, adaptability to the eye pupil size, and focus cues within a large depth range.

Design of a near-eye display measurement system using an anthropomorphic vision imaging method.

We developed a new near-eye display measurement system using anthropomorphic vision imaging to measure the key parameters of near-eye displays, including field-of-view (FOV), angular resolution, eye box, and virtual image depth. The characteristics of the human eye, such as pupil position, pupil size variation, accommodation function, and the high resolution of the fovea, are imitated by the proposed measurement system. A FOV scanning structure, together with a non-vignetting image-telecentric lens system, captures the virtual image from the near-eye display by imitating human eye function. As a proof-of-concept, a prototype device was used to obtain large-range, high-resolution measurements for key parameters of near-eye displays.

Relationship of the cornea and globe dimensions to the changes in adult human crystalline lens diameter, thickness and power with age.

It is well known that human crystalline lens shape, dimensions and optical properties change throughout life and influence whole eye refraction. However, it is not clear if lens properties are associated with other ocular parameters. The purpose of the present study was to investigate the relationship of corneal and external globe dimensions with adult lens diameter (LD), lens thickness (LT) and lens power (LP) in order to determine if external factors influence lens properties. Postmortem human eyes (n = 66, age = 20-78 years) were obtained from the Ramayamma International Eye Bank, Hyderabad, India. Globe antero-posterior length (GAPL) and mean (average of horizontal and vertical) diameters of cornea (MCD) and globe (MGD) were measured using digital calipers. Eyes were dissected to produce ocular structures that contain the lens maintained in its accommodating framework, including intact zonules, ciliary body and sections of sclera. Specimens were mounted in a mechanical lens stretching system. LD, LT and LP were measured using high magnification retro-illumination photography, slit illumination photography and Scheiner principle-based optical system respectively in the unstretched (accommodated) state. Relationships between external globe and corneal dimensions and LD, LT or LP were assessed by multiple regression analysis. Age (0.012 ± 0.003 mm/year; p<0.001) and GAPL (0.185 ± 0.045 mm/mm; p<0.001) were significant (p<0.0001) predictors of LD. After adjusting for age-related increases, LD appears to be positively correlated with GAPL. Age (0.010 ± 0.004 mm/year; p = 0.009) and GAPL (-0.143 ± 0.060 mm/mm; p = 0.02) were significant (p = 0.001) predictors of LT. After adjusting for the age-related increase, LT appears to be negatively correlated with GAPL. Only age was a significant predictor of LP (-0.26 ± 0.04 D/year; p<0.001). The results suggest that, apart from aging, lens diameter and thickness are dependent on the anteroposterior length of the eye globe. Lens power is not influenced by globe dimensions.

Morphometric analysis of in vitro human crystalline lenses using digital shadow photogrammetry.

There is a great need for accurate biometric data on human lenses. To meet this, a compact tabletop optical comparator, the minishadowgraph, was built for measuring isolated eye lens shape and dimensions while the lens was fully immersed in supporting medium. The instrument was based around a specially designed cell and an illumination system which permitted image recording in both sagittal and equatorial (coronal) directions. Data were acquired with a digital camera and analyzed using a specially written MATLAB program as well as by manual measurements in image analysis software. The possible effect of lens orientation and gravity on the dimensions was examined by measuring dimensions with anterior or posterior surfaces up and by measuring lenses with calipers after removal from the minishadowgraph cell. Dimensions, curvatures and shape factors were obtained for 134 fully accommodated lenses ranging in age from birth to 88 years postnatal. Of these, 41 were from donors aged under 20 years, ages which are generally of limited availability. Thickness and diameter showed the same age-related trends described in previous studies but, for the lenses measured in air, age-dependent differences were observed in thickness (-5 to 0%) and diameter (+5 to 0%), consistent with gravitational sag. Anterior and posterior radii of curvature of the central 3 or 6 mm, depending on lens diameter, increase with age, with the anterior increase greater than the posterior. The anterior surface shape of the neonatal lens is that of a prolate ellipse and the posterior, an oblate ellipse. Both surfaces become hyperbolic after age 20. The data presented here on dimensions, shape and sagging will be of great value in assessing age-related changes in the optical and mechanical performance of the lens. In particular, the comprehensive data set from donors aged under 20 years provides a unique and valuable insight to the changes in size and shape during the early dynamic growth period of the lens.

Negative Fusional Vergence Is Abnormal in Children with Symptomatic Convergence Insufficiency.

SIGNIFICANCE: Deficits of disparity divergence found with objective eye movement recordings may not be apparent with standard clinical measures of negative fusional vergence (NFV) in children with symptomatic convergence insufficiency. PURPOSE: This study aimed to determine whether NFV is normal in untreated children with symptomatic convergence insufficiency and whether NFV improves after vergence/accommodative therapy. METHODS: This secondary analysis of NFV measures before and after office-based vergence/accommodative therapy reports changes in (1) objective eye movement recording responses to 4° disparity divergence step stimuli from 12 children with symptomatic convergence insufficiency compared with 10 children with normal binocular vision (NBV) and (2) clinical NFV measures in 580 children successfully treated in three Convergence Insufficiency Treatment Trial studies. RESULTS: At baseline, the Convergence Insufficiency Treatment Trial cohort's mean NFV break (14.6 ± 4.8Δ) and recovery (10.6 ± 4.2Δ) values were significantly greater (P < .001) than normative values. The post-therapy mean improvements for blur, break, and recovery of 5.2, 7.2, and 1.3Δ, respectively, were statistically significant (P < .0001). Mean pre-therapy responses to 4° disparity divergence step stimuli were worse in the convergence insufficiency group compared with the NBV group for peak velocity (P < .001), time to peak velocity (P = .01), and response amplitude (P < .001). After therapy, the convergence insufficiency group showed statistically significant improvements in mean peak velocity (11.63°/s; 95% confidence interval [CI], 6.6 to 16.62°/s), time to peak velocity (-0.12 seconds; 95% CI, -0.19 to -0.05 seconds), and response amplitude (1.47°; 95% CI, 0.83 to 2.11°), with measures no longer statistically different from the NBV cohort (P > .05). CONCLUSIONS: Despite clinical NFV measurements that seem greater than normal, children with symptomatic convergence insufficiency may have deficient NFV when measured with objective eye movement recordings. Both objective and clinical measures of NFV can be improved with vergence/accommodative therapy.

Subjective Evaluation of Defocus and Astigmatism Combinations Using Image Simulation in Presbyopes.

SIGNIFICANCE: Image simulation is a useful and efficient tool to explore the impact of defocus and astigmatism combinations on visual acuity and image quality score when accommodation is taken into account. PURPOSE: The goal of this experiment was to determine if a simulation is able to predict visual acuity and image quality score (IQS) with defocus and astigmatism combinations in presbyopes. METHODS: We measured visual acuity and IQS in five defocus and astigmatism combinations in either real or simulated conditions. In real conditions, the subjects viewed a stimulus through an ophthalmic lens or a deformable mirror. In simulated conditions, subjects viewed images of the same stimulus with simulated blur. The amounts of defocus and astigmatism combinations of a progressive addition lens in near vision were generated through a static correction of the subject's aberrations. We simulated three levels of accommodation: subject could not accommodate (FOC0), subject could accommodate to the less hyperopic focal point (FOC1), or subject could accommodate to the circle of least confusion (FOC2). RESULTS: Visual acuity or IQS did not differ between mirror and progressive addition lens conditions. Visual acuity measured in real blur conditions differed significantly from that in FOC0 simulated blur condition but were similar to that in FOC1 and FOC2 simulated blur conditions. Image quality score obtained in real conditions were between scores measured with the FOC0 and FOC1 simulated conditions, suggesting that the subjects were able to produce a low level of accommodation. CONCLUSIONS: Accommodation may play a role when comparing optical and simulated defocus and astigmatism combinations. Presbyopic subjects are able to produce a low level of accommodation that may counterbalance a part of the deleterious effect of the astigmatism on image quality. Simulation remains a useful tool if the correct accommodation state is taken into account.

Ocular Anatomical and Functional Characteristics in Anisometropic Chinese Children.

SIGNIFICANCE: This research found that anterior and posterior biometrics differ in many aspects between fellow eyes of anisometropic children. This might shed light on the mechanisms underlying the onset and progression of anisometropia and myopia. PURPOSE: This study aimed to investigate the ocular biometric parameters, peripheral refraction, and accommodative lag of fellow eyes in anisometropic children. METHODS: Anisometropic children were recruited. Axial length (AL), vitreous chamber depth (VCD), central corneal thickness, anterior chamber depth (ACD), lens thickness (LT), simulated K readings, central and peripheral refractive errors, and accommodative lag were measured in both eyes. The subfoveal choroidal thickness, average choroidal thickness, and choroid vessel density of the 6 × 6-mm macular area were measured by optical coherence tomography. RESULTS: Thirty-two children aged 11.1 ± 1.7 years were enrolled. The average degree of anisometropia was 2.49 ± 0.88 D. The AL, VCD, ACD, and simulated K reading values were significantly larger in the more myopic eyes, whereas the LT value was significantly smaller. Subfoveal choroidal thickness (P = .001) and average choroidal thickness (P = .02) were smaller in the more myopic eyes than in the contralateral eyes, whereas choroid vessel density (P = .03) was larger. The amount of anisometropia had a significant positive correlation with the difference in AL (r = 0.869, P < .001), VCD (r = 0.853, P < .001), and ACD (r = 0.591, P < .001) and a negative correlation with the difference in LT (r = -0.457, P = .009). CONCLUSIONS: Ocular biometrics differ in many aspects between the fellow eyes of anisometropic Chinese children, and the difference is correlated with the degree of anisometropia.