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Life (Basel, Switzerland) Feb 2024The diagnostic value of the computer accommodation method remains insufficiently studied. Accommodative and refractive error is a common problem, accounting for 23% of...
The diagnostic value of the computer accommodation method remains insufficiently studied. Accommodative and refractive error is a common problem, accounting for 23% of the world's population. The aim of the study was to investigate the objective parameters of accommodative insufficiency in young people with and without myopia. A cross-sectional study was carried out using a random sample of 116 of university students at the age of 21-23 years. Normal ranges for accommodation parameters in non-myopic participants were defined by 10th and 90th percentile values. The normal ranges were from -0.17 to -0.38 conventional units (c.u.) for accommodative response coefficient (ARC), from 0.08 to 0.41 c.u. for deviation of ARC (σARC), from 0.0 to 0.43 c.u. for accommodogram growth coefficient (AGC), from 54.26 to 58.55 microfluctuations per minute (mcf/min) for coefficient of microfluctuations (CMF), and from 2.58 to 5.26 c.u. for deviation of CMF (σCMF). Signs of computer visual syndrome were observed in 40.9% of non-myopic participants, eye strain in 11.9%, accommodation cramp in 4.5%, and absence or little accommodative response in 3.6%. Therefore, computer accommodation assessment allowed the detection of young people with an increased risk of myopia among those without this ophthalmic pathology.
PubMed: 38541650
DOI: 10.3390/life14030324 -
Journal of Cataract and Refractive... Jun 2024
Topics: Humans; Lens Implantation, Intraocular; Incidence; Accommodation, Ocular; Lenses, Intraocular; Visual Acuity; Risk Factors; Phacoemulsification
PubMed: 38535978
DOI: 10.1097/j.jcrs.0000000000001450 -
Frontiers in Physiology 2024Optic nerve sheath diameter (ONSD) increases significantly at high altitudes, and is associated with the presence and severity of acute mountain sickness (AMS)....
Optic nerve sheath diameter (ONSD) increases significantly at high altitudes, and is associated with the presence and severity of acute mountain sickness (AMS). Exposure to hypobaria, hypoxia, and coldness when hiking also impacts intraocular pressure (IOP). To date, little is known about ocular physiological responses in trekkers with myopia at high altitudes. This study aimed to determine changes in the ONSD and IOP between participants with and without high myopia (HM) during hiking and to test whether these changes could predict symptoms of AMS. Nine participants with HM and 18 without HM participated in a 3-day trek of Xue Mountain. The ONSD, IOP, and questionnaires were examined before and during the trek of Xue Mountain. The ONSD values increased significantly in both HM ( = 0.005) and non-HM trekkers ( = 0.018) at an altitude of 1,700 m. In the HM group, IOP levels were greater than those in the non-HM group ( = 0.034) on the first day of trekking (altitude: 3,150 m). No statistically significant difference was observed between the two groups for the values of ONSD. Fractional changes in ONSD at an altitude of 1,700 m were related to the development of AMS ( = 0.448, = 0.019) and the presence of headache symptoms ( = 0.542, = 0.004). The area under the ROC curve for the diagnostic performance of ONSD fractional changes at an altitude of 1,700 m was 0.859 for predicting the development of AMS and 0.803 for predicting the presence of headache symptoms. Analysis of changes in ONSD at moderate altitude could predict AMS symptoms before an ascent to high altitude. Myopia may impact physiological accommodation at high altitudes, and HM trekkers potentially demonstrate suboptimal regulation of aqueous humor in such environments.
PubMed: 38523807
DOI: 10.3389/fphys.2024.1350051 -
Journal of Vision Mar 2024Accommodation is the process of adjusting the eye's optical power so as to focus at different distances. Uncorrected refractive error and/or functional presbyopia mean...
Accommodation is the process of adjusting the eye's optical power so as to focus at different distances. Uncorrected refractive error and/or functional presbyopia mean that sharp focus may not be achievable for some distances, so observers experience sustained defocus. Here, we identify a problem with current models of accommodative control: They predict excessive internal responses to stimuli outside accommodative range, leading to unrealistic adaptation effects. Specifically, after prolonged exposure to stimuli outside range, current models predict long latencies in the accommodative response to stimuli within range, as well as unrealistic dynamics and amplitudes of accommodative vergence innervation driven by the accommodative neural controller. These behaviors are not observed empirically. To solve this issue, we propose that the input to blur-driven accommodation is not retinal defocus, but correctable defocus. Predictive models of accommodative control already estimate demand from sensed defocus, using a realistic "virtual plant" to estimate accommodation. Correctable defocus can be obtained by restricting this demand to values physically attainable by the eye. If we further postulate that correctable defocus is computed using an idealized virtual plant that retains a young accommodative range, we can explain why accommodative-convergence responses are observed for stimuli that are too near-but not too far-to focus on. We model cycloplegia as a change in gain, and postulate a form of neural myopia to explain the additional relaxation of accommodation often seen with cycloplegia. This model produces plausible predictions for the accommodative response and accommodative convergence signal in a wide range of clinically relevant situations.
Topics: Humans; Presbyopia; Refractive Errors; Accommodation, Ocular; Myopia; Retina
PubMed: 38488409
DOI: 10.1167/jov.24.3.4 -
Journal of Optometry Mar 2024Many sports-related concussion (SRC) outcomes can be prevented by removing affected athletes and allowing return after full recovery. Diagnosing concussions on the...
PURPOSE
Many sports-related concussion (SRC) outcomes can be prevented by removing affected athletes and allowing return after full recovery. Diagnosing concussions on the side-line is challenging, as tools often rely on visual performance assessment. Since acute exercise can affect vision, it is vital to determine if exercise can mask potential brain injury if visual performance assessments are used. The aim of this study was to determine the effect of a single bout of maximal aerobic exercise on acute visual performance.
METHODS
Eighty previously sedentary females were randomly assigned to an experimental group (N = 40) or control group (N = 40) and completed an identical visual task test battery. Two weeks later, participants returned to participate in the test battery, with the experimental group doing so immediately following a maximal treadmill exercise protocol.
RESULTS
Significant (P < 0.05) improvements were found in accommodation facility, saccadic eye movement, speed of recognition, peripheral awareness, and hand-eye coordination (P < 0.001 for all), but not in visual memory (P = 0.556). All visual tasks, barring visual memory, loaded onto a single factor and approximated the root mean square error of approximation (RMSEA) threshold value (RMSEA = 0.112 [90 %CI: 0.047-0.182]), and a significant large main effect was found on all factors as a universal visual task performance (P < 0.001; d = 1.01).
CONCLUSION
This study shows that exercise can affect performance across multiple, but not all, visual tasks and should be utilised with caution in comprehensive side-line SRC assessments. Visual memory may be more stable to the effects of acute exercise and be considered for inclusion in side-line SRC assessments.
PubMed: 38479117
DOI: 10.1016/j.optom.2024.100515 -
Scientific Reports Mar 2024How the human eye focuses for near; i.e. accommodates, is still being evaluated after more than 165 years. The mechanism of accommodation is essential for understanding...
How the human eye focuses for near; i.e. accommodates, is still being evaluated after more than 165 years. The mechanism of accommodation is essential for understanding the etiology and potential treatments for myopia, glaucoma and presbyopia. Presbyopia affects 100% of the population in the fifth decade of life. The lens is encased in a semi-elastic capsule with attached ligaments called zonules that mediate ciliary muscle forces to alter lens shape. The zonules are attached at the lens capsule equator. The fundamental issue is whether during accommodation all the zonules relax causing the central and peripheral lens surfaces to steepen, or the equatorial zonules are under increased tension while the anterior and posterior zonules relax causing the lens surface to peripherally flatten and centrally steepen while maintaining lens stability. Here we show with a balloon capsule zonular force model that increased equatorial zonular tension with relaxation of the anterior and posterior zonules replicates the topographical changes observed during in vivo rhesus and human accommodation of the lens capsule without lens stroma. The zonular forces required to simulate lens capsule configuration during in vivo accommodation are inconsistent with the general belief that all the zonules relax during accommodation.
Topics: Animals; Humans; Presbyopia; Lens Capsule, Crystalline; Accommodation, Ocular; Lens, Crystalline; Macaca mulatta
PubMed: 38467700
DOI: 10.1038/s41598-024-56563-8 -
Contact Lens & Anterior Eye : the... Jun 2024To assess accommodation and spherical aberration changes during one year of orthokeratology lens wear and one month after lens cessation. (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
To assess accommodation and spherical aberration changes during one year of orthokeratology lens wear and one month after lens cessation.
METHODS
A prospective, randomized, longitudinal study was conducted on forty-seven young healthy subjects at the Optometry Clinic of the Complutense University of Madrid (Spain). Non-cycloplegic refraction, high and low uncorrected visual acuity, high and low best corrected visual acuity, accommodative lag, horizontal near phoria, corneal topography, and high-order aberrations were performed at baseline, 1-day, 1-week, 1-, 6- and 12-months of lens wear and after one month of wash out period. p < 0.05 was considered as statistically significant.
RESULTS
Spherical equivalent refraction (SE) was -3.23 ± 1.57D at baseline and -0.36 ± 0.64D after 12-months of lens wear, while accommodative lag changed from 0.53 ± 0.39D to 0.15 ± 0.29D after one year of lens wear. No significant differences were found when comparing SE at baseline and after one month of lens cessation (p > 0.05). A high correlation was found between the accommodative lag at baseline and after 12 M of lens wear. 22 out of 25 subjects with exophoria at baseline showed a significant reduction in the deviation at 12-months (p < 0.05). Total spherical aberration increased during all visits due to the lens wear (p < 0.05) although internal spherical aberration showed a significant decrease for 1-week, 1-month and 12-month visits (p < 0,05).
CONCLUSION
Orthokeratology lenses may change the accommodative response of the patient as a reduction on accommodative lag on exophoric patients and an overall increase on the internal spherical aberrations was found during treatment but return to nearly baseline values when cessation.
Topics: Humans; Orthokeratologic Procedures; Male; Female; Accommodation, Ocular; Prospective Studies; Refraction, Ocular; Visual Acuity; Young Adult; Corneal Wavefront Aberration; Corneal Topography; Adult; Myopia; Follow-Up Studies; Adolescent; Contact Lenses
PubMed: 38467534
DOI: 10.1016/j.clae.2024.102133 -
Optics Express Feb 2024In many areas ranging from medical imaging to visual entertainment, 3D information acquisition and display is a key task. In this regard, in multifocus computational...
In many areas ranging from medical imaging to visual entertainment, 3D information acquisition and display is a key task. In this regard, in multifocus computational imaging, stacks of images of a certain 3D scene are acquired under different focus configurations and are later combined by means of post-capture algorithms based on image formation model in order to synthesize images with novel viewpoints of the scene. Stereoscopic augmented reality devices, through which is possible to simultaneously visualize the three dimensional real world along with overlaid digital stereoscopic image pair, could benefit from the binocular content allowed by multifocus computational imaging. Spatial perception of the displayed stereo pairs can be controlled by synthesizing the desired point of view of each image of the stereo-pair along with their parallax setting. The proposed method has the potential to alleviate the accommodation-convergence conflict and make augmented reality stereoscopic devices less vulnerable to visual fatigue.
PubMed: 38439309
DOI: 10.1364/OE.510688 -
Alternative Therapies in Health and... Mar 2024Some treatments for myopia, such as corneal surgery and scleral shortening, aren't suitable for adolescents under the age of 18. The orthokeratology lens (OKL) and the...
CONTEXT
Some treatments for myopia, such as corneal surgery and scleral shortening, aren't suitable for adolescents under the age of 18. The orthokeratology lens (OKL) and the defocus incorporated multiple segments (DIMS) lens are two possible nonsurgical alternatives, but their comparative advantages and disadvantages remain unclear.
OBJECTIVE
The study intended to compare the effects of the OKL and the DIMS lens on adolescent myopia and to analyze the related factors affecting corneal injury, to provide a reference for clinical practice.
DESIGN
The research team conducted a retrospective case-control study.
SETTING
The study took place at Chongqing Aier Eye Hospital in Chongqing, China.
PARTICIPANTS
Participants were 84 myopic adolescents who had been admitted to the hospital between March 2021 and December 2022.
INTERVENTIONS
The research team divided participants into two groups: (1) 43 participants who received treatment with orthokeratology lens (OKL), the OKL group, and (2) 41 participants who received treatment with defocus incorporated multiple segments (DIMS) because their parents refused to accept OKL lenses, the DIMS group.
OUTCOME MEASURES
At baseline and postintervention, the research team: (1) comparatively analyzed the uncorrected visual acuity (UCVA), axial length (AXL), and diopter; (2) measured the spherical equivalent (SE), central corneal thickness (CCT), anterior chamber depth (ACD), accommodative lag (PRA), and negative relative accommodation (NRA); (3) counted the adverse reactions during treatment; and (4) evaluated the factors related to corneal injury.
RESULTS
No significant differences existed between the groups in AXL, diopter, or NRA postintervention (P > .05), but the OKL group had significantly higher UCVA and significantly lower SE, CCT, and ACD than the DIMS group did (P < .05). In terms of safety, the incidence of adverse reactions was significantly higher for the OKL group than for the DIMS group (P = .016). According to the logistic regression analysis, the OKL treatment, corneal edema, and abnormal intraocular pressure (IOP) were independent risk factors for corneal injury (all P < .001).
CONCLUSIONS
Both DIMS and OKL can effectively control myopia progression in adolescents, with OKLs being significantly better at improving UCVA and DIMS being safer. Therefore, in the future clinical conservative treatment of myopic adolescents, it's still necessary to choose appropriate myopia-relief methods according to the actual situation and the specific needs of the children.
PubMed: 38430182
DOI: No ID Found -
Journal of Vision Feb 2024The longitudinal chromatic aberration (LCA) of the eye creates a chromatic blur on the retina that is an important cue for accommodation. Although this mechanism can...
The longitudinal chromatic aberration (LCA) of the eye creates a chromatic blur on the retina that is an important cue for accommodation. Although this mechanism can work optimally in broadband illuminants such as daylight, it is not clear how the system responds to the narrowband illuminants used by many modern displays. Here, we measured pupil and accommodative responses as well as visual acuity under narrowband light-emitting diode (LED) illuminants of different peak wavelengths. Observers were able to accommodate under narrowband light and compensate for the LCA of the eye, with no difference in the variability of the steady-state accommodation response between narrowband and broadband illuminants. Intriguingly, our subjects compensated more fully for LCA at nearer distances. That is, the difference in accommodation to different wavelengths became larger when the object was placed nearer the observer, causing the slope of the accommodation response curve to become shallower for shorter wavelengths and steeper for longer ones. Within the accommodative range of observers, accommodative errors were small and visual acuity normal. When comparing between illuminants, when accommodation was accurate, visual acuity was worst for blue narrowband light. This cannot be due to the sparser spacing for S-cones, as our stimuli had equal luminance and thus activated LM-cones roughly equally. It is likely because ocular LCA changes more rapidly at shorter wavelength and so the finite spectral bandwidth of LEDs corresponds to a greater dioptric range at shorter wavelengths. This effect disappears for larger accommodative errors, due to the increased depth of focus of the eye.
Topics: Humans; Accommodation, Ocular; Face; Retina; Blue Light; Pupil
PubMed: 38411958
DOI: 10.1167/jov.24.2.11