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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 -
Journal of Refractive Surgery... Mar 2024To evaluate the dynamic changes in anterior segment parameters during accommodation following Implantable Collamer Lens (ICL) implantation with swept-source optical...
PURPOSE
To evaluate the dynamic changes in anterior segment parameters during accommodation following Implantable Collamer Lens (ICL) implantation with swept-source optical coherence tomography (SS-OCT).
METHODS
Under the accommodation of 0.00 diopters (D), 3.00 D, and maximum amplitude, SS-OCT was used to examine the anterior segment parameters, including ICL vault, ICL depth (the distance between the corneal endothelium and the posterior surface of ICL), crystalline lens thickness, anterior chamber depth, and various parameters of the anterior chamber angle, comprising angle opening distance, angle recess area, trabecular iris space area, and trabecular iris angle.
RESULTS
During accommodation, the ICL vault showed a significant decrease from baseline (536 ± 278 μm) to 3.00 D (522 ± 281 μm), followed by an increase from 3.00 D to maximum amplitude (548 ± 306 μm) (analysis of variance [ANOVA], < .001). Four eyes (2.61%) exhibited a decrease in ICL vault to less than 100 μm (47 ± 32 μm) at maximum accommodation. The ICL depth decreased significantly as accommodation increased (ANOVA, < .001). Crystalline lens thickness increased, whereas anterior chamber depth decreased during accommodation (ANOVA, < .001). The anterior chamber angle widened during 3.00 D of accommodation but narrowed at maximum accommodation, leading to significant changes in the angle opening distance, angle recess area, trabecular iris space area, and trabecular iris angle during accommodation (ANOVA, < .001 for all).
CONCLUSIONS
The anterior segment, including ICL vault and anterior chamber angle, undergo significant dynamic changes during accommodation. These accommodative changes may require careful monitoring for the surgery design of ICL implantation. [. .
Topics: Humans; Lens Implantation, Intraocular; Phakic Intraocular Lenses; Myopia; Accommodation, Ocular; Anterior Chamber; Pseudophakia; Tomography, Optical Coherence; Biometry; Lens, Crystalline
PubMed: 38466765
DOI: 10.3928/1081597X-20240212-01 -
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 -
Applied Optics Feb 2024Most near-eye displays with one fixed focal plane suffer from the vergence-accommodation conflict and cause visual discomfort to users. In contrast, light field displays...
Most near-eye displays with one fixed focal plane suffer from the vergence-accommodation conflict and cause visual discomfort to users. In contrast, light field displays can provide natural and comfortable 3D visual sensation to users without the conflict. This paper presents a near-eye light field display consisting of a geometric lightguide and a light field generator, along with a collimator to ensure the light rays propagating in the lightguide are collimated. Unlike most lightguides, which reduce thickness by employing total internal reflection that can easily generate stray light, our lightguide directly propagates light rays without total internal reflection. The partially reflective mirrors of the lightguide expand the exit pupil to achieve an eyebox of 13 ( )×6.5 ( ) with an eye relief of 18 mm. The collimator and the light field generator, both having effective focal lengths different in the horizontal and vertical directions, are designed to provide a 40-deg diagonal field of view. The working range of the light field generator, which is 30 cm to infinity, is verified qualitatively and quantitatively by experiments. We optimize the illuminance uniformity and analyze the illuminance variation across the eyebox. Further, we minimize the ghost artifact (referring to the split-up of light fields replicated by the partially reflective mirrors) by orienting the partially reflective mirrors at slightly different angles to enhance the image quality for short-range applications such as medical surgery.
PubMed: 38437357
DOI: 10.1364/AO.503572 -
IEEE Transactions on Visualization and... May 2024We provide the first perceptual quantification of user's sensitivity to radial optic flow artifacts and demonstrate a promising approach for masking this optic flow...
We provide the first perceptual quantification of user's sensitivity to radial optic flow artifacts and demonstrate a promising approach for masking this optic flow artifact via blink suppression. Near-eye HMOs allow users to feel immersed in virtual environments by providing visual cues, like motion parallax and stereoscopy, that mimic how we view the physical world. However, these systems exhibit a variety of perceptual artifacts that can limit their usability and the user's sense of presence in VR. One well-known artifact is the vergence-accommodation conflict (VAC). Varifocal displays can mitigate VAC, but bring with them other artifacts such as a change in virtual image size (radial optic flow) when the focal plane changes. We conducted a set of psychophysical studies to measure users' ability to perceive this radial flow artifact before, during, and after self-initiated blinks. Our results showed that visual sensitivity was reduced by a factor of 10 at the start and for ~70 ms after a blink was detected. Pre- and post-blink sensitivity was, on average, ~O.15% image size change during normal viewing and increased to ~1.5- 2.0% during blinks. Our results imply that a rapid (under 70 ms) radial optic flow distortion can go unnoticed during a blink. Furthermore, our results provide empirical data that can be used to inform engineering requirements for both hardware design and software-based graphical correction algorithms for future varifocal near-eye displays. Our project website is available at https://gamma.umd.edu/ROF/.
Topics: Optic Flow; Computer Graphics; Accommodation, Ocular; Algorithms; Software
PubMed: 38437086
DOI: 10.1109/TVCG.2024.3372075 -
European Journal of Ophthalmology Mar 2024Physiological adaptation of the eye to the visual perception of near objects consists of the "near triad": convergence, accommodation, and pupil miosis. Normally, these... (Review)
Review
Physiological adaptation of the eye to the visual perception of near objects consists of the "near triad": convergence, accommodation, and pupil miosis. Normally, these tend to revert when one stops fixating on a near object. Spasm of the near reflex (SNR) is a pathological phenomenon, which manifests itself by the persistence of the above-mentioned adjustments, which prevents the eye from returning to its relaxed state. In this narrative review, we aim to summarize the etiology, diagnostics, treatment, and prevention of SNR. The literature review was performed by searching online databases. The clinical presentation of SNR is diverse; it presents as isolated accommodative spasm more frequently than impairment of all three components of the near triad. Patients usually present with fluctuations in visual acuity, blurred vision, diplopia, and asthenopia. The etiology is not fully understood. Potential causes include neuroanatomic, organic, and psychogenic disorders. The diagnosis is clinical, based on the constellation of symptoms and assessment of the near triad. The diagnostic golden standard is a cycloplegic examination of refraction, preferably using cyclopentolate hydrochloride (1%, 0.5%, or 0.1% solution). The first-line treatment requires the administration of a cycloplegic drug in combination with plus lenses, flipper lenses, optical fogging, or miotics. For secondary cases, causal treatment should be implemented. Prevention of SNR should be based on eliminating modifiable risk factors. We propose including screening for SNR symptoms in every ophthalmic examination, especially among patients with psychogenic or neural disorders, after brain trauma, or young adults spending much time in front of computer screens.
PubMed: 38433348
DOI: 10.1177/11206721241237309 -
Experimental Eye Research Apr 2024Currently, researchers have mainly focused on the role of the tissues of the posterior segment of the eyes in the development of myopia. However, the ciliary body, an...
Currently, researchers have mainly focused on the role of the tissues of the posterior segment of the eyes in the development of myopia. However, the ciliary body, an anterior ocular tissue that contracts to initiate the process of accommodation, may also play an important role in the progression of myopia due to the increased demand for near work. In the present study, we established a lens-induced myopia (LIM) animal model in guinea pigs and investigated the molecular changes in the ciliary body associated with the development of myopia based on RNA sequencing. As a result, 871 differentially expressed (DE) mRNAs and 19 DE lncRNAs were identified in the ciliary body between the LIM group and the normal control group. In addition, the lncRNA-mRNA co-expression analysis was performed to explore the target genes of lncRNAs, which were mainly enriched in the Rap1 signaling pathway, cytokine-cytokine receptor interaction, and complement and coagulation cascades pathways based on the functional enrichment analysis. Among the target genes of lncRNAs, three hub genes, including Ctnnb1, Pik3r1, and Itgb1, were found to be involved in the Rap1 signaling pathway. Interestingly, two crucial genes, Grk1 and Pde6a, which are mainly expressed in retinal photoreceptors, were enriched in visual perception in the ciliary body in functional analysis and were verified to be expressed in the ciliary body. These findings indicate the molecular pathogenetic role of the ciliary body in myopia and provide new insights into the underlying mechanism of myopia development. Further studies are needed to explore the specific contributions of these identified lncRNAs and mRNAs to the development of myopia.
Topics: Animals; Guinea Pigs; Ciliary Body; RNA, Long Noncoding; RNA, Messenger; Myopia; Vision, Ocular
PubMed: 38430983
DOI: 10.1016/j.exer.2024.109849 -
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 -
Seminars in Ophthalmology Jul 2024To assess the feasibility of the clinical use of a novel Virtual Reality (VR) training software designed to be used for active vision therapy in amblyopic patients by...
PURPOSE
To assess the feasibility of the clinical use of a novel Virtual Reality (VR) training software designed to be used for active vision therapy in amblyopic patients by determining its preliminary safety and acceptance on the visual function of healthy adults.
METHODS
Pilot study enrolling 10 individuals (3 men, 7 women, mean age: 31.8 ± 6.5 years) with a best-corrected visual acuity (BCVA) of ≥ .90 (decimal) in both eyes were evaluated before and after 20 minutes of exposure to the NEIVATECH VR system using the HTC Vive Pro Eye head mounted display. Visual function assessment included near (40 cm) and distance (6 m) cover test (CT), stereopsis, binocular accommodative facility (BAF), near point of convergence (NPC), near point of accommodation (NPA), accommodative-convergence over accommodation (AC/A) ratio and positive and negative fusional vergences. Safety was assessed using the VR Sickness Questionnaire (VRSQ) and acceptance using the Technology Acceptance Model ;(TAM). Changes in all these variables after VR exposure were analyzed.
RESULTS
Short-term exposure to the NEIVATECH VR system only induced statistically significant changes in distance phoria ( = .016), but these changes were not clinically relevant. No significant changes were observed in VRSQ oculo-motricity and disorientation scores after exposure ( = .197 and .317, respectively). TAM scores showed a good acceptance of the system in terms of perceived enjoyment and perceived ease of use, although some concerns were raised in relation to the intention-to-use domain.
CONCLUSION
Exposure to the NEIVATECH VR system does not seem to adversely affect the visual function in healthy adults and its safety and acceptance profile seems to be adequate for supporting its potential use in other populations, such as amblyopic patients.
Topics: Humans; Male; Pilot Projects; Female; Adult; Visual Acuity; Virtual Reality; Accommodation, Ocular; Vision, Binocular; Amblyopia; Young Adult; Feasibility Studies; Depth Perception; Surveys and Questionnaires
PubMed: 38426308
DOI: 10.1080/08820538.2024.2324074 -
The American Journal of Occupational... Mar 2024Occupational therapy practitioners' knowledge of and advocacy for clients with visual symptoms postconcussion can have a considerable impact on recovery.
IMPORTANCE
Occupational therapy practitioners' knowledge of and advocacy for clients with visual symptoms postconcussion can have a considerable impact on recovery.
OBJECTIVE
To compare the frequency of vision symptoms and occupational performance deficits in a sample of participants with and without concussion.
DESIGN
Cross-sectional study.
SETTING
Sports medicine clinic.
PARTICIPANTS
Adolescents and adults with concussion (n = 20) and musculoskeletal injuries (n = 19).
OUTCOMES AND MEASURES
Measures included monocular amplitude of accommodation, near point of convergence, Binocular Vision Assessment (BVA) computerized screening for phoria, BVA computerized screening for fusional vergence, the Developmental Eye Movement Test, the Canadian Occupational Performance Measure, and the Convergence Insufficiency Symptom Survey-Concussion Version (CISS-CON).
RESULTS
We found significant differences between participants with and without concussion using the CISS-CON (p = .001), positive fusional vergence (p = .02), and near point of convergence (p = .02). Participants with concussion scoring above cutoffs on multiple measures reported poorer performance (p = .005) and satisfaction (p = .004) with valued occupations.
CONCLUSIONS AND RELEVANCE
Concussion has a detrimental effect on vision and occupation, and occupational therapy practitioners are well-positioned to assess and address issues arising from this relationship. Plain-Language Summary: Vision symptoms commonly experienced after a concussion are associated with reduced occupational performance and satisfaction and can have a considerable impact on recovery. Occupational therapy assessment for clients with concussion should include screening for vision difficulties.
Topics: Adult; Adolescent; Humans; Cross-Sectional Studies; Canada; Brain Concussion; Ocular Motility Disorders; Eye Movements
PubMed: 38422432
DOI: 10.5014/ajot.2024.050353