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Current Opinion in Ophthalmology Jan 2017Presbyopia and cataract development are changes that ubiquitously affect the aging population. Considerable effort has been made in the development of intraocular lenses... (Review)
Review
PURPOSE OF REVIEW
Presbyopia and cataract development are changes that ubiquitously affect the aging population. Considerable effort has been made in the development of intraocular lenses (IOLs) that allow correction of presbyopia postoperatively. The purpose of this review is to examine the benefits and barriers of accommodating IOLs, with a focus on emerging technologies.
RECENT FINDINGS
True accommodation of an IOL involves a dynamic increase in dioptric power to affect a shift from distance to intermediate or near focus. The Crystalens (Crystalens Bausch and Lomb, Inc., Rochester, NY, USA) was the first IOL labeled by the FDA as an accommodating IOL. Further studies have suggested that the Crystalens and several other single optic presbyopia-correcting IOLs may be providing improved intermediate or near vision predominantly through pseudoaccommodative mechanisms, in addition to small changes in axial translation. In light of these findings, a more objective demonstration of accommodation is now required for an IOL to have an accommodative label. Newer technology accommodating IOLs in development have embraced design strategies using dual optics, shape-changing optics, and IOLs with dynamic changes in refractive index. Prevention and treatment algorithms for capsular contraction syndromes unique to Crystalens and Trulign IOL designs will be discussed.
SUMMARY
Accommodating IOLs that are in current use are constrained by their low and varied amplitude of accommodation. Such limitations may be circumvented in the future by accommodative design strategies that rely more on shape-related changes in the surfaces of the IOLs or in dynamic changes in refractive index than by forward translation alone.
Topics: Accommodation, Ocular; Cataract Extraction; Humans; Lens Implantation, Intraocular; Lenses, Intraocular; Optics and Photonics; Postoperative Period; Presbyopia; Prosthesis Design
PubMed: 27653608
DOI: 10.1097/ICU.0000000000000323 -
BMC Ophthalmology Mar 2022To assess dynamic visual acuity (DVA) under different defocus statuses and explore the assessment of dynamic vision accommodation.
BACKGROUND
To assess dynamic visual acuity (DVA) under different defocus statuses and explore the assessment of dynamic vision accommodation.
METHODS
Twenty subjects (6 males and 14 females) aged 18 to 35 were recruited. Nonmydriatic subjective refraction (sphere and cylinder) and accommodative tests including negative relative accommodation (NRA), positive relative accommodation (PRA), binocular cross cylinder (BCC) and accommodative facility using a flipper were performed. Binocular static visual acuity (SVA) and DVA at 40 degrees per second (dps) were measured under different defocus statuses (+1.5D to -4D in -0.5D steps) based on the refractive error fully corrected. Static and dynamic defocus curves were plotted. The area under the curve (AUC) and corrected dynamic vision accommodation (CDVAc) were calculated.
RESULTS
The study showed that the dynamic defocus curve fitted the cubic curve properly (p<0.001). DVA was significantly worse than SVA at all defocused statuses (p<0.001), and the difference was more significant at greater defocus diopters. Single factor analysis indicated that CDVAc was significantly correlated with NRA-PRA (p=0.012) and AUC (p<0.001). Significant associations were observed between AUC and PRA (p=0.013) as well as NRA-PRA (p=0.021). Meanwhile, DVA was positively correlated with PRA at 0D, -1.0D, -1.5D, -2.5D and -3.0D (p<0.05) and with NRA-PRA at 0D, -1.0D, -1.5D, -2.0D and -2.5D (p<0.05). Multiple factor regression analysis indicated that CDVAc (0D ~ -3.5D) and SVA (+1.5D ~ +1.0D & -2.5D ~ -4.0D) were significant influential factors for defocused DVA (p<0.05).
CONCLUSIONS
Our study demonstrated that DVA had a defocus curve similar to that of SVA. CDVAc was feasible for the assessment of dynamic vision accommodative function. The dynamic defocus curve test could efficiently be applied in the evaluation of dynamic visual performance under different defocus statuses.
Topics: Accommodation, Ocular; Adolescent; Adult; Female; Humans; Male; Refractive Errors; Vision Tests; Vision, Binocular; Visual Acuity; Young Adult
PubMed: 35248018
DOI: 10.1186/s12886-022-02335-9 -
Ophthalmic & Physiological Optics : the... Jan 2021To examine the pupil and visual impact of a single early morning drop of a low concentration 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.
Topics: Accommodation, Ocular; Adrenergic alpha-2 Receptor Agonists; Adult; Brimonidine Tartrate; Female; Humans; Intraocular Pressure; Male; Middle Aged; Presbyopia; Pupil; Reading; Refraction, Ocular; Time Factors; Visual Acuity
PubMed: 33150654
DOI: 10.1111/opo.12749 -
Journal of Optometry 2022Several studies have suggested that accommodative and non-strabismic binocular dysfunctions are commonly encountered in optometric practice. This study aims to verify...
BACKGROUND
Several studies have suggested that accommodative and non-strabismic binocular dysfunctions are commonly encountered in optometric practice. This study aims to verify whether these findings apply to a Portuguese clinical population.
METHODS
This study included consecutive nonpresbyopic subjects that came to two Portuguese optometric clinics over a period of six months. A complete visual exam was conducted and included the measurement of visual acuity (VA), refraction, near point of convergence (NPC), distance and near phoria, near and distance fusional vergences, amplitude of accommodation (AA), monocular accommodative facility (MAF), relative accommodation and lag of accommodation.
RESULTS
156 subjects with a mean age of 24.9 ± 5.3 years (from 18 to 35 years old) participated in the study. Of all subjects, 32 % presented binocular vision and/or accommodative disorders accompanied or not by refractive errors. Moreover, 21.1 % had accommodative disorders, and 10.9 % had a binocular vision dysfunction. Accommodative insufficiency (11.5 %) was the most prevalent disorder, followed by convergence insufficiency (7.1 %) and accommodative infacility (5. 8 %).
CONCLUSIONS
Clinicians should be aware that about one third of the optometric clinical population could have accommodative and/or non-strabismic binocular disorders. Accommodative insufficiency was the most prevalent dysfunction presented in the studied population, followed by accommodative infacility and convergence insufficiency.
Topics: Accommodation, Ocular; Adolescent; Adult; Humans; Ocular Motility Disorders; Portugal; Presbyopia; Vision Disorders; Vision Tests; Vision, Binocular; Young Adult
PubMed: 34852966
DOI: 10.1016/j.optom.2021.10.002 -
Ethiopian Journal of Health Sciences May 2023Accommodation and Vergence disorder are diverse visual anomalies which can interfere with a child's school performance and impair one's ability to function efficiently....
BACKGROUND
Accommodation and Vergence disorder are diverse visual anomalies which can interfere with a child's school performance and impair one's ability to function efficiently. Its association with refractive error and its intervention were studied less in Indian myopia children; hence, there is a need for research in such setting.
METHOD
One hundred and fifty Indian adolescents aged 10 to 17 years were divided into three refractive error groups (high, moderate, and low myopia). Baseline vision examination and a comprehensive binocular vision assessment were performed on all eligible adolescents. Vision therapy was provided to participants whose parents gave consent on behalf of the children. Chi-square analysis was utilized to look at the association between the groups of refractive errors. To compare the mean constants of the experimental and control groups, a two-way RM ANOVA was performed.
RESULTS
The most common dysfunction found in low myopia (75.3%), and moderate myopia (54%) was convergence insufficiency. High myopes (62.8%) were found to have combined convergence and accommodative insufficiency followed by accommodative dysfunction (14%) and basic exophoria (6%). In moderate myopia, a significant relationship was found between this dysfunction and refractive error. The experimental group in the overall sample showed statistically significant improvement after vision therapy (P<0.001), in comparison to the control group.
CONCLUSION
Refractive error is linked to accommodative and convergence insufficiency. Thus, vergence and accommodative impairment must be tested for all myopic children, and vision therapy should be advised along with spectacle prescription for efficient binocular vision.
Topics: Child; Humans; Adolescent; Convergence, Ocular; Myopia; Accommodation, Ocular; Refractive Errors; Ocular Motility Disorders
PubMed: 37576169
DOI: 10.4314/ejhs.v33i3.16 -
Investigative Ophthalmology & Visual... Nov 2021Peripheral refraction and accommodation are intrinsic factors that were once hypothesized to trigger myopia but are now controversial. Previously, home nearwork...
PURPOSE
Peripheral refraction and accommodation are intrinsic factors that were once hypothesized to trigger myopia but are now controversial. Previously, home nearwork environment (i.e., extrinsic factor) was reported to be associated with myopia progression. In this study, we aimed to evaluate the potential interaction between extrinsic and intrinsic factors with juvenile refractive development.
METHODS
Nearwork environmental parameters were measured for 50 children (aged 9.3 ± 1.2 years), including net amount and dispersion of defocus. Refraction was measured at near distances and in central field (±30° horizontal) at 3m. The relative peripheral refraction (RPRE) was obtained and presented in a vectoral approach. The linear regression coefficient was extracted (mAcc) from the accommodative stimulus-response curve. RPRE was quadratically regressed against field eccentricity, and the first coefficients (aM, aJ0, aP90, and aP180) were extracted. Relationships between RPRE, baseline accommodation, and 1-year myopia progression (∆M), controlled for the nearwork environment, were evaluated.
RESULTS
Coefficients of RPRE were independent of ∆M. However, additional nearwork environmental parameters significantly improved the variance in ∆M explained by aM and aP180 (P < 0.03). The relationship between intrinsic factor and ∆M was stronger when the extrinsic risk was low (P ≤ 0.01), whereas the relationship was abolished when extrinsic risk was high. For mAcc, it also significantly improved the variance in ∆M explained by nearwork environmental parameters.
CONCLUSIONS
The interaction between extrinsic (environment) and intrinsic (RPRE and accommodation) factors is speculated to contribute to juvenile myopia progression. Our findings may also explain the inconsistencies of such intrinsic factors in the literature.
Topics: Accommodation, Ocular; Child; Eye; Female; Humans; Intrinsic Factor; Male; Myopia; Refraction, Ocular; Visual Acuity
PubMed: 34797905
DOI: 10.1167/iovs.62.14.21 -
Clinical & Experimental Optometry Jan 2020Our current understanding of emmetropisation and myopia development has evolved from decades of work in various animal models, including chicks, non-human primates, tree... (Review)
Review
Our current understanding of emmetropisation and myopia development has evolved from decades of work in various animal models, including chicks, non-human primates, tree shrews, guinea pigs, and mice. Extensive research on optical, biochemical, and environmental mechanisms contributing to refractive error development in animal models has provided insights into eye growth in humans. Importantly, animal models have taught us that eye growth is locally controlled within the eye, and can be influenced by the visual environment. This review will focus on information gained from animal studies regarding the role of optical mechanisms in guiding eye growth, and how these investigations have inspired studies in humans. We will first discuss how researchers came to understand that emmetropisation is guided by visual feedback, and how this can be manipulated by form-deprivation and lens-induced defocus to induce refractive errors in animal models. We will then discuss various aspects of accommodation that have been implicated in refractive error development, including accommodative microfluctuations and accommodative lag. Next, the impact of higher order aberrations and peripheral defocus will be discussed. Lastly, recent evidence suggesting that the spectral and temporal properties of light influence eye growth, and how this might be leveraged to treat myopia in children, will be presented. Taken together, these findings from animal models have significantly advanced our knowledge about the optical mechanisms contributing to eye growth in humans, and will continue to contribute to the development of novel and effective treatment options for slowing myopia progression in children.
Topics: Accommodation, Ocular; Animals; Emmetropia; Eye; Humans; Models, Animal; Myopia; Optics and Photonics; Refraction, Ocular
PubMed: 31742789
DOI: 10.1111/cxo.12991 -
Optometry and Vision Science : Official... Dec 2023Our results show significant diurnal variations in accommodative function and the magnitude of the phoria. Therefore, when comparing visual measures in clinical or...
SIGNIFICANCE
Our results show significant diurnal variations in accommodative function and the magnitude of the phoria. Therefore, when comparing visual measures in clinical or laboratory settings, performing the visual examination at the same time of day (±1 hour) is encouraged.
PURPOSE
The aim of this study was to evaluate the accommodation, binocular vergence, and pupil behavior on three different times during the day.
METHODS
Twenty collegiate students (22.8 ± 2.1 years) participated in this study. Participants visited the laboratory on three different days at 2-hourly intervals (morning, 9:00 to 11:00 am ; afternoon, 2:00 to 4:00 pm ; evening, 7:00 to 9:00 pm ). The binocular vergence and accommodative function were measured using clinical optometric procedures, and the accommodative response and pupil function were evaluated in binocular conditions using the WAM-5500 autorefractometer.
RESULTS
The accommodative amplitude for the right and left eyes showed statistically significant differences for the time interval ( P = .001 and P = .02, respectively), revealing higher accommodative amplitude in the morning and afternoon in comparison with the evening. Participants were more esophoric when assessed in the morning in comparison with the evening at far and near ( P = .02 and P = .01, respectively) and when assessed in the afternoon in comparison with the evening at far distance ( P = .02). The magnitude of accommodative response was higher in the morning, and it decreased throughout the day at 500 ( P < .001), 40 ( P = .05), and 20 cm ( P < .001). No statistically significant differences were obtained for any other variable.
CONCLUSIONS
This study shows small diurnal variations in some accommodative and binocular vergence parameters, but no effects were observed for the pupil response. These outcomes are of special relevance for eye care specialists when performing repeated accommodative or binocular vergence measures. However, the diurnal variations were modest and may not influence a routine orthoptic examination.
Topics: Humans; Pupil; Convergence, Ocular; Vision, Binocular; Accommodation, Ocular; Strabismus
PubMed: 38019970
DOI: 10.1097/OPX.0000000000002091 -
Journal of Vision Aug 2021Vergence and accommodation can be mismatched under virtual reality viewing conditions, and this mismatch has been thought to be one of the main causes of visual...
Vergence and accommodation can be mismatched under virtual reality viewing conditions, and this mismatch has been thought to be one of the main causes of visual discomfort. The goal of this study was to investigate how optical conditions of the eyes affect accommodative responses to different convergence. Specifically, we hypothesized that extending the depth of focus (DoF) could weaken the control of the screen on accommodation, so that accommodation could be induced by convergence. To test this hypothesis, we extended the DoF using Zernike spherical aberrations (fourth and sixth orders) induced by a binocular adaptive optics (AO) vision simulator. Nine normal subjects between the ages of 21 and 34 (26 ± 5) years were recruited. Three optical conditions were generated: AO condition (aberration-free), monovision condition, and extended depth of focus (EDoF) condition. Binocular accommodative responses, along with binocular visual acuity and stereoacuity, were measured under all three optical conditions with varied binocular vergence levels. At 3 diopters of binocular convergence, the EDoF condition was the most efficient in inducing excessive accommodative response compared with the monovision condition and the AO condition. Visual acuity was impaired with EDoF as compared with the other two conditions. The average stereoscopic thresholds (at 0 vergence) under the EDoF condition were degraded compared with the AO condition but were superior to those of the monovision condition. Therefore, despite some compromise to visual performance, extending the DoF could allow for a more natural vergence-accommodation relationship, providing the potential for alleviating the vergence-accommodation conflict and associated visual fatigue symptoms in virtual reality.
Topics: Accommodation, Ocular; Adult; Convergence, Ocular; Humans; Vision, Binocular; Vision, Monocular; Visual Acuity; Young Adult
PubMed: 34415998
DOI: 10.1167/jov.21.8.21 -
Optometry and Vision Science : Official... Aug 2019This study reports prevalence data combined independently for accommodative dysfunction, convergence insufficiency, visual field loss, and visual acuity loss in patients... (Meta-Analysis)
Meta-Analysis
SIGNIFICANCE
This study reports prevalence data combined independently for accommodative dysfunction, convergence insufficiency, visual field loss, and visual acuity loss in patients with traumatic brain injury in the absence of eye injury.
OBJECTIVE
The objective of this study was to conduct a systematic review and meta-analysis to determine the prevalence rates of accommodative dysfunction, convergence insufficiency, visual field loss, and visual acuity loss in TBI patients without concomitant eye injury.
DATA SOURCES
The data sources used in this study were PubMed, EMBASE, EBSCO, and Cochrane Library.
STUDY APPRAISAL AND SYNTHESIS METHODS
Publications reporting the prevalence of diagnosed accommodative dysfunction, convergence insufficiency, visual field loss, or visual acuity loss to the level of legal blindness in TBI patients of any age were included. Univariate metaregression analyses and subgroup analyses were performed to account for statistical heterogeneity.
RESULTS
Twenty-two eligible publications were identified across the four visual conditions. Random-effects models yielded combined prevalence estimates: accommodative dysfunction (42.8; 95% confidence interval [CI], 31.3 to 54.7), convergence insufficiency (36.3%; 95% CI, 28.2 to 44.9%), visual field loss (18.2%; 95% CI, 10.6 to 27.1%), and visual acuity loss (0.0%; 95% CI, 0.0 to 1.1%). Metaregression and subgroup analyses revealed that visual field loss was significantly more prevalent in moderate to severe (39.8%; 95% CI, 29.8 to 50.3%) compared with mild TBI (6.6%; 95% CI, 0 to 19.5%).
CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS
This study demonstrates that accommodative dysfunction, convergence insufficiency, and visual field loss are common sequelae of TBI. Prospective longitudinal research with rigorous and uniform methodology is needed to better understand short- and long-term effects of TBI on the vision system.
Topics: Accommodation, Ocular; Brain Injuries, Traumatic; Humans; Ocular Motility Disorders; Vision Disorders; Visual Acuity; Visual Fields
PubMed: 31343512
DOI: 10.1097/OPX.0000000000001407