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Piñero DP, Leal-Vega L, Molina-Martín A, Hernández-Rodríguez CJ, Cuadrado-Asensio R, Martín-Gutiérrez A, Arenillas Lara JF, Coco Martín MB. Pilot Study Assessing the Safety and Acceptance of a Novel Virtual Reality System to Improve Visual Function. Semin Ophthalmol 2024:1-6. [PMID: 38426308 DOI: 10.1080/08820538.2024.2324074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 02/22/2024] [Indexed: 03/02/2024]
Abstract
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 (p = .016), but these changes were not clinically relevant. No significant changes were observed in VRSQ oculo-motricity and disorientation scores after exposure (p = .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.
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Affiliation(s)
- David P Piñero
- Group of Applied Clinical Neurosciences, Department of Medicine, Dermatology and Toxicology, University of Valladolid, Valladolid, Spain
- Clinical Optometry Unit, Department of Ophthalmology, Hospital Vithas Medimar International, Alicante, Spain
| | - Luis Leal-Vega
- Group of Applied Clinical Neurosciences, Department of Medicine, Dermatology and Toxicology, University of Valladolid, Valladolid, Spain
| | - Ainhoa Molina-Martín
- Group of Optics and Visual Perception, Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
| | - Carlos J Hernández-Rodríguez
- Group of Optics and Visual Perception, Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
- Clinical Optometry Unit. Department of Ophthalmology, Centro Médico Virgen de la Caridad Hospital, Cartagena, España
| | | | - Adrián Martín-Gutiérrez
- Group of Applied Clinical Neurosciences, Department of Medicine, Dermatology and Toxicology, University of Valladolid, Valladolid, Spain
| | - Juan Francisco Arenillas Lara
- Group of Applied Clinical Neurosciences, Department of Medicine, Dermatology and Toxicology, University of Valladolid, Valladolid, Spain
- Stroke Unit & Stroke Program, Department of Neurology, Hospital Clínico Universitario de Valladolid, Valladolid, Spain
| | - María Begoña Coco Martín
- Group of Applied Clinical Neurosciences, Department of Medicine, Dermatology and Toxicology, University of Valladolid, Valladolid, Spain
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Mena-Guevara KJ, de Fez D, Molina-Martín A, Piñero DP. Binocular vision measurements with a new online digital platform: comparison with conventional clinical measures. Clin Exp Optom 2023:1-7. [PMID: 37944504 DOI: 10.1080/08164622.2023.2277880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 10/27/2023] [Indexed: 11/12/2023] Open
Abstract
CLINICAL RELEVANCE New digital systems are being developed for evaluating different aspects of the visual function, such as binocularity, and it is important to know their real performance in clinical practice in order to use them appropriately. BACKGROUND The aim was to compare binocular vision measures obtained with an online digital platform with conventional measures using prisms and printed tests. METHODS Prospective study enrolling 49 healthy patients (mean age: 35.5 ± 13.6 years). A complete visual examination was performed including measurement of near phoria (cover test), negative fusional vergence (NFV) and positive fusional vergence (PFV) ranges (prism bar), and stereopsis (24 patients Randot Stereo Test and 25 patients TNO Random Dot Test 19th edition). These same parameters were also measured with the Bynocs system (Kanohi Eye Pvt Ltd). Bland - Altman plots were used to analyse the agreement between methods. RESULTS Digital measurement of near phoria was significantly lower than that obtained with the cover test, with a median difference (MD) of 4.71 (-0.07-20.07) prism dioptres (pd) (p < 0.001). No significant differences were found between Bynocs and prism bar methods in NFV break (MD 2.00, range -21-26 pd, p = 0.584) and recovery points (MD 0.00, range -16-24 pd, p = .571). Near PFV were significantly lower with Bynocs (break: MD -9.00, range -38-12 pd; recovery: MD -14.00, range -43-20 pd; p < 0.001). Bynocs stereoacuity threshold was significantly lower than that obtained with TNO (p = 0.004), but significantly higher compared to Randot (p < 0.001). Large and clinically relevant confidence intervals for the comparison between digital and conventional measures were detected in Passing-Bablok analysis. CONCLUSIONS Digital measures of near phoria, NFV, PFV, and stereopsis with the Bynocs platform cannot be used interchangeably with conventional measures. The normal ranges of normality for this new tool are defined.
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Affiliation(s)
- Kevin J Mena-Guevara
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
| | - Dolores de Fez
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
| | - Ainhoa Molina-Martín
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
| | - David P Piñero
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
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Hashemi H, Khabazkhoob M, Asharlous A, Hashemi A. Are binocular alignment and convergence amplitude different between phakic and pseudophakic older patients? Strabismus 2022; 30:190-195. [PMID: 36239198 DOI: 10.1080/09273972.2022.2134432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
PURPOSE To compare the binocular alignment status and convergence amplitude between phakic and pseudophakic older adults. METHODS The present report is a part of the Tehran Geriatric Eye Study (TGES), a population-based study performed on the elderly population above 60 years of age in Tehran, Iran. All study participants were transferred to the examination site and underwent complete ocular examinations including the measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, unilateral and alternating cover tests, and slit-lamp biomicroscopy. RESULTS Of 3791 invitees, 3310 participated in the TGES (response rate: 87.3%). After applying the exclusion criteria, the data of 1969 individuals were analyzed for this report. The mean of far exophoria, far esophoria, near exophoria, and near esophoria was 5.09 ± 3.66, 8.20 ± 9.60, 6.94 ± 3.69, 7.00 ± 5.83 prism diopter in phakic and 5.15 ± 2.43, 6.50 ± 5.80, 7.77 ± 4.00, 4.75 ± 1.50 prism diopter in pseudophakic individuals, respectively. The mean of far exotropia, far esotropia, near exotropia, and near esotropia was 14.92 ± 9.49, 22.00 ± 13.86, 15.09 ± 7.20, 21.33 ± 14.47 prism diopter in phakic and 19.67 ± 22.5, 8.00 ± 0, 17.36 ± 7.55, 17.36 ± 7.55, 0 prism diopter in pseudophakic individuals, respectively. Near exophoria (P = .003) was significantly higher in pseudophakic than in phakic participants after controlling the effects of age, sex, body mass index, diabetes, and hypertension. The mean near point of convergence was 7.94 ± 3.27 cm in phakic and 7.99 ± 3.3 cm in pseudophakic participants. CONCLUSION Near exophoria was significantly higher in pseudophakic compared to phakic individuals while other deviations and near point of convergence were not significantly different between phakic and pseudophakic groups.
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Affiliation(s)
- Hassan Hashemi
- Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran
| | - Mehdi Khabazkhoob
- Department of Basic Sciences, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran
| | - Amir Asharlous
- Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran
| | - Alireza Hashemi
- Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran
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Omar R, Kuan YM, Zuhairi NA, Manan FA, Knight VF. Visual efficiency among teenaged athletes and non-athletes. Int J Ophthalmol 2017; 10:1460-1464. [PMID: 28944208 DOI: 10.18240/ijo.2017.09.20] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 03/31/2017] [Indexed: 11/23/2022] Open
Abstract
AIM To compare visual efficiency, specifically accom-modation, vergence, and oculomotor functions among athletes and non-athletes. METHODS A cross-sectional study on sports vision screening was used to evaluate the visual skills of 214 elementary students (107 athletes, 107 non-athletes), aged between 13 and 16y. The visual screening assessed visual parameters such as ocular motor alignment, accommodation, and vergence functions. RESULTS Mean visual parameters were compared between age-group matched athletes (mean age 14.82±0.98y) and non-athletes (mean age 15.00±1.04y). The refractive errors of all participants were corrected to maximal attainable best corrected visual acuity of logMAR 0.0. Accommodation function assessment evaluated amplitude of accommodation and accommodation facility. Vergence functions measured the near point of convergence, vergence facility, and distance fusional vergence at break and recovery point. Ocular motor alignment was not statistically significant between both groups. Athletes had a statistically significant amplitude of accommodation for both the right eye (t=2.30, P=0.02) and the left eye (t=1.99, P=0.05). Conversely, non-athletes had better accommodation facility (t=-2.54, P=0.01) and near point of convergence (t=4.39, P<0.001) when compared to athletes. Vergence facility was found to be better among athletes (t=2.47, P=0.01). Nevertheless, non-athletes were significantly better for both distance negative and positive fusional vergence. CONCLUSION Although the findings are still inconclusive as to whether athletes had superior visual skills as compared to non-athletes, it remains important to identify and elucidate the key visual skills needed by athletes in order for them to achieve higher performance in their sports.
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Affiliation(s)
- Rokiah Omar
- Optometry & Vision Science Program, School of Healthcare Sciences, Faculty of Health Sciences, University Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur 50300, Malaysia
| | - Yau Meng Kuan
- Optometry & Vision Science Program, School of Healthcare Sciences, Faculty of Health Sciences, University Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur 50300, Malaysia
| | - Nurul Atikah Zuhairi
- Optometry & Vision Science Program, School of Healthcare Sciences, Faculty of Health Sciences, University Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur 50300, Malaysia
| | - Faudziah Abd Manan
- Department of Optometry & Vision Science, Kulliyyah of Allied Health Sciences, International Islamic University Malaysia, Bandar Indera Mahkota, Kuantan 25200, Pahang, Malaysia
| | - Victor Feizal Knight
- Faculty of Medicine and Defence Health, National Defence University of Malaysia, Sungai Besi Camp, Kuala Lumpur 57000, Malaysia
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Yu X, Zhang B, Bao J, Zhang J, Wu G, Xu J, Zheng J, Drobe B, Chen H. Design, methodology, and baseline data of the Personalized Addition Lenses Clinical Trial (PACT). Medicine (Baltimore) 2017; 96:e6069. [PMID: 28296722 PMCID: PMC5369877 DOI: 10.1097/md.0000000000006069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND The aim of this study was to describe the design, methods, and baseline characteristics of children enrolled in the Personalized Addition lenses Clinical Trial (PACT). PACT aims to test the myopia control efficacy of progressive addition lenses (PALs) with personalized addition values compared with standard (+2.00 D) addition PALs and single vision lenses (SVLs). METHODS PACT is a randomized, controlled, double-masked clinical trial. Two hundred eleven myopic Chinese children (7-12 years) were enrolled and randomized into 1 of the 3 following groups: personalized addition PALs; +2.00 addition PALs; and SVLs. Personalized addition values were determined based on the highest addition that satisfied Sheard criterion. Axial length and other biometric data were also recorded. RESULTS At baseline, no differences were found between the right and left eyes for any of the main parameters. The enrolled children were 9.7 ± 1.1 years' old with cycloplegic autorefraction (right eye [OD]: -2.36 ± 0.64 D), near phoria (1.0 ± 5.0 prism diopter esophoria), lag of accommodation (1.40 ± 0.50 D) and axial length (OD: 24.58 ± 0.74 mm). The personalized addition values ranged from +0.75 to +3.00 (average ± SD: 2.19 ± 0.73 D). CONCLUSION PACT is a clinical trial evaluating whether myopia progression in children can be slowed by wearing personalized addition PALs compared with fixed addition PALs and SVLs as measured by cycloplegic autorefraction and axial length. Baseline data were comparable with those of previous myopia control studies in children. Subjects will be followed up every 6 months for 2 years.
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Affiliation(s)
- Xinping Yu
- The Eye Hospital of Wenzhou Medical University
- WMU-Essilor international Research Centre
| | - Binjun Zhang
- The Eye Hospital of Wenzhou Medical University
- WMU-Essilor international Research Centre
| | - Jinhua Bao
- The Eye Hospital of Wenzhou Medical University
- WMU-Essilor international Research Centre
| | - Junxiao Zhang
- The Eye Hospital of Wenzhou Medical University
- WMU-Essilor international Research Centre
| | - Ge Wu
- The Eye Hospital of Wenzhou Medical University
- WMU-Essilor international Research Centre
| | - Jinling Xu
- The Eye Hospital of Wenzhou Medical University
- WMU-Essilor international Research Centre
| | - Jingwei Zheng
- The Eye Hospital of Wenzhou Medical University
- WMU-Essilor international Research Centre
| | - Björn Drobe
- WMU-Essilor international Research Centre
- R&D Asia, Essilor International, Wenzhou, Zhejiang, China
| | - Hao Chen
- The Eye Hospital of Wenzhou Medical University
- WMU-Essilor international Research Centre
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Abstract
BACKGROUND Measurement of for near point of convergence (NPC), amplitude of accommodation (AA) and phoria are important components of diagnosing nonstrabismic binocular vision anomalies. There is a huge variation in the normative data established for orthoptic parameters because of the variation in measurement technique. There are only limited studies for normative data based on nonclinical population in Indian population. Therefore, we aim estimate the normative values for NPC, AA, and phoria measurement in Indian population using techniques, which has good repeatability and reliability. MATERIALS AND METHODS Subjects between the age group 10-35 years participated in this prospective cross-sectional study. A self-administered symptom questionnaire was used to exclude patients with asthenopic symptoms. Clinical techniques which have good repeatability and reliability were used. NPC was measured using pen light red, green glass test. AA was measured using minus lens technique. Horizontal and vertical phoria at distance and near was measured using modified Thorington method. RESULTS One hundred and fifty subjects participated in the study. We found that NPC receded with age, which could because of the increase in horizontal phoria at near with age. The mean normative value for objective NPC, break and recovery of subjective NPC, monocular and binocular AA, horizontal and vertical phoria at distance and near for the three age groups are reported in the study. CONCLUSION The data presented in this study can be used as a cut-off by eye care practitioners while diagnosing convergence, accommodation related anomalies in Indian population.
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Affiliation(s)
- Neethu G. Abraham
- Department of Optometry, School of Allied Health Sciences, Manipal University, Manipal, Karnataka, India
| | - Krithica Srinivasan
- Department of Optometry, School of Allied Health Sciences, Manipal University, Manipal, Karnataka, India
| | - Jyothi Thomas
- Department of Optometry, School of Allied Health Sciences, Manipal University, Manipal, Karnataka, India
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Gnanaseelan R, Gonzalez DA, Niechwiej-Szwedo E. Binocular advantage for prehension movements performed in visually enriched environments requiring visual search. Front Hum Neurosci 2014; 8:959. [PMID: 25506323 PMCID: PMC4246685 DOI: 10.3389/fnhum.2014.00959] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 11/11/2014] [Indexed: 11/13/2022] Open
Abstract
The purpose of this study was to examine the role of binocular vision during a prehension task performed in a visually enriched environment where the target object was surrounded by distractors/obstacles. Fifteen adults reached and grasped for a cylindrical peg while eye movements and upper limb kinematics were recorded. The complexity of the visual environment was manipulated by varying the number of distractors and by varying the saliency of the target. Gaze behavior (i.e., the latency of the primary gaze shift and frequency of gaze shifts prior to reach initiation) was comparable between viewing conditions. In contrast, a binocular advantage was evident in performance accuracy. Specifically, participants picked up the wrong object twice as often during monocular viewing when the complexity of the environment increased. Reach performance was more efficient during binocular viewing, which was demonstrated by shorter reach reaction time and overall movement time. Reaching movements during the approach phase had higher peak velocity during binocular viewing. During monocular viewing reach trajectories exhibited a direction bias during the acceleration phase, which was leftward during left eye viewing and rightward during right eye viewing. This bias can be explained by the presence of esophoria in the covered eye. The grasping interval was also extended by ~20% during monocular viewing; however, the duration of the return phase after the target was picked up was comparable across viewing conditions. In conclusion, binocular vision provides important input for planning and execution of prehension movements in visually enriched environments. Binocular advantage was evident, regardless of set size or target saliency, indicating that adults plan their movements more cautiously during monocular viewing, even in relatively simple environments with a highly salient target. Nevertheless, in visually-normal adults monocular input provides sufficient information to engage in online control to correct the initial errors in movement planning.
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Affiliation(s)
- Roshani Gnanaseelan
- Visuomotor Neuroscience Lab, Department of Kinesiology, University of Waterloo Waterloo, ON, Canada
| | - Dave A Gonzalez
- Visuomotor Neuroscience Lab, Department of Kinesiology, University of Waterloo Waterloo, ON, Canada
| | - Ewa Niechwiej-Szwedo
- Visuomotor Neuroscience Lab, Department of Kinesiology, University of Waterloo Waterloo, ON, Canada
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Dysli M, Vogel N, Abegg M. Reading performance is not affected by a prism induced increase of horizontal and vertical vergence demand. Front Hum Neurosci 2014; 8:431. [PMID: 24987346 PMCID: PMC4060573 DOI: 10.3389/fnhum.2014.00431] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 05/28/2014] [Indexed: 11/13/2022] Open
Abstract
PURPOSE Dyslexia is the most common developmental reading disorder that affects language skills. Latent strabismus (heterophoria) has been suspected to be causally involved. Even though phoria correction in dyslexic children is commonly applied, the evidence in support of a benefit is poor. In order to provide experimental evidence on this issue, we simulated phoria in healthy readers by modifying the vergence tone required to maintain binocular alignment. METHODS Vergence tone was altered with prisms that were placed in front of one eye in 16 healthy subjects to induce exophoria, esophoria, or vertical phoria. Subjects were to read one paragraph for each condition, from which reading speed was determined. Text comprehension was tested with a forced multiple choice test. Eye movements were recorded during reading and subsequently analyzed for saccadic amplitudes, saccades per 10 letters, percentage of regressive (backward) saccades, average fixation duration, first fixation duration on a word, and gaze duration. RESULTS Acute change of horizontal and vertical vergence tone does neither significantly affect reading performance nor reading associated eye movements. CONCLUSION Prisms in healthy subjects fail to induce a significant change of reading performance. This finding is not compatible with a role of phoria in dyslexia. Our results contrast the proposal for correcting small angle heterophorias in dyslexic children.
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Affiliation(s)
- Muriel Dysli
- Department of Ophthalmology, Inselspital, University of Bern Bern, Switzerland ; Graduate School for Cellular and Biomedical Sciences, University of Bern Bern, Switzerland
| | - Nicolas Vogel
- Department of Ophthalmology, Inselspital, University of Bern Bern, Switzerland
| | - Mathias Abegg
- Department of Ophthalmology, Inselspital, University of Bern Bern, Switzerland
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Bosten JM, Hogg RE, Bargary G, Goodbourn PT, Lawrance-Owen AJ, Mollon JD. Suggestive association with ocular phoria at chromosome 6p22. Invest Ophthalmol Vis Sci 2014; 55:345-52. [PMID: 24327614 DOI: 10.1167/iovs.13-12879] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We conducted a genome-wide association study to identify genetic factors that contribute to the etiology of heterophoria. METHODS We measured near and far vertical and horizontal phorias in 988 healthy adults aged 16 to 40 using the Keystone telebinocular with plates 5218 and 5219. We regressed degree of phoria against genotype at 642758 genetic loci. To control for false positives, we applied the conservative genome-wide permutation test to our data. RESULTS A locus at 6p22.2 was found to be associated with the degree of near horizontal phoria (P = 2.3 × 10(-8)). The P value resulting from a genome-wide permutation test was 0.014. CONCLUSIONS The strongest association signal arose from an intronic region of the gene ALDH5A1, which encodes the mitochondrial enzyme succinic semialdehyde dehydrogenase (SSADH), an enzyme involved in γ-aminobutyric acid metabolism. Succinic semialdehyde dehydrogenase deficiency, resulting from mutations of ALDH5A1, causes a variety of neural and behavioral abnormalities, including strabismus. Variation in ALDH5A1 is likely to contribute to degree of horizontal phoria.
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Affiliation(s)
- Jenny M Bosten
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom
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Momeni-Moghaddam H, Goss DA, Sobhani M. Accommodative response under monocular and binocular conditions as a function of phoria in symptomatic and asymptomatic subjects. Clin Exp Optom 2013; 97:36-42. [PMID: 23808381 DOI: 10.1111/cxo.12074] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 12/20/2012] [Accepted: 01/07/2013] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND The neurological linkage of vergence and accommodation is a factor which can affect accuracy of accommodation, is in turn associated with symptoms of near-related visual discomfort. The purpose of this study was to compare the accommodative response under monocular and binocular conditions in symptomatic and asymptomatic participants with different near phorias. METHODS Seventy students at Zahedan University of Medical Sciences, Iran (mean age: 21.2 ± 1.7 years; age range: 18 to 25 years) participated. The participants were divided into symptomatic and asymptomatic groups according to the convergence insufficiency symptom survey questionnaire score. The type and magnitude of the near dissociated phoria were determined using the prism neutralised cover test. The accommodative lag was measured by the 'monocular estimate method' (MEM) retinoscopy, at first under binocular and then monocular conditions. Testing distance was 40 cm. RESULTS The accommodative lag in exophoric participants was lower under binocular conditions compared to monocular and in esophoric participants greater under binocular than under monocular conditions. The binocular accommodative response (AR) was greatest in participants with high exophoria at near vision and least in participants with esophoria at near vision (p < 0.001; one-way analysis of variance). The difference between binocular lag and monocular lag was significantly greater in symptomatic participants than in asymptomatic participants in both exophoria (p < 0.001) and esophoria (p = 0.009) (independent samples t-test). CONCLUSION The near binocular accommodative response was related to near heterophoria. Higher levels of vergence accommodation, resulting in differences in lag under monocular and binocular conditions, may be a factor in near point asthenopia.
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Affiliation(s)
- Hamed Momeni-Moghaddam
- Health Promotion Research Center, Zahedan University of Medical Sciences, Zahedan, Iran.
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Alanazi SA, Alanazi MA, Osuagwu UL. Influence of age on measured anatomical and physiological interpupillary distance (far and near), and near hetero phoria, in Arab males. Clin Ophthalmol 2013; 7:711-24. [PMID: 23620654 PMCID: PMC3633581 DOI: 10.2147/opth.s43626] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
PURPOSE To compare the effects of age and near phoria on interpupillary distance measured at far (FIPD) and near (NIPD) using the Viktorin's and pupillometer (PD-5) methods. METHODS Interpupillary distance (IPD) by Viktorin's method and the corneal reflex pupillometer (PD-5) method, as well as near heterophoria by the Saladin near point card, were each obtained on 133 randomly selected normal subjects aged 20-67 years. Comparison within and between techniques, influence of age on IPD, and near heterophoria were assessed. RESULTS The mean FIPD varied significantly from the NIPD (P < 0.001 for both methods). Overall, FIPD ranged from 56-73 mm, and NIPD ranged from 50-70 mm. For FIPDs of 55 mm, 63 mm, and 71 mm, the corresponding NIPDs were less by 3.9 mm, 4.4 mm, and 5.0 mm, respectively, which were measured by Viktorin's method, and 4.0 mm, 4.6 mm, and 5.2 mm, respectively, measured by the PD-5 method. Between methods, the limits of agreement were: -3.9 mm and 3.2 mm (P > 0.05) for FIPD, and -3.1 mm and 2.9 mm (P > 0.05) for NIPD. Both IPDs varied significantly across age groups (P < 0.0001). Post hoc analysis revealed a significant variation (P < 0.01 in both techniques) only in the comparison between age groups 16-25 years and 41-67 years. The mean difference was -2.2 mm (-4.0 mm to -0.3 mm) and -2.8 mm (-4.7 mm to -1.0 mm) for Viktorin's method for FIPD and NIPD, respectively. For PD-5, the corresponding values were -1.3 mm (-3.2 mm to 0.4 mm) and -1.7 mm (-4.1 to -0.5 mm). Also, the near phoria differed significantly (P < 0.0001) across age groups and correlated positively with age (r(2) = 0.27, P < 0.0001) and NIPD (r(2) > 0.04; P < 0.03, both techniques). CONCLUSION The difference between FIPD and NIPD (about 4.4 mm in Arab males) was observed independent of the technique used. The Viktorin's and the PD-5 methods of IPD assessment resulted in similar values, and therefore, could be interchangeably used. However, caution is advised in cases of high power refractive corrections as the difference could vary from -4 mm to +3 mm (FIPD) and -3 mm to +3 mm (NIPD). Both IPDs have demonstrated an increase until the patients are in their early 40s, and a slight decrease has been observed thereafter. Age and NIPD were significantly associated with heterophoria in our subjects.
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Affiliation(s)
- Saud A Alanazi
- Corneal Research Chair, Department of Optometry and Vision Science, College of Applied Medical Sciences, King Saud University, Kingdom of Saudi Arabia
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Nguyen D, Vedamurthy I, Schor C. Cross-coupling between accommodation and convergence is optimized for a broad range of directions and distances of gaze. Vision Res 2008; 48:893-903. [PMID: 18281073 PMCID: PMC2323401 DOI: 10.1016/j.visres.2008.01.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Revised: 01/04/2008] [Accepted: 01/08/2008] [Indexed: 11/19/2022]
Abstract
Accommodation and convergence systems are cross-coupled so that stimulation of one system produces responses by both systems. Ideally, the cross-coupled responses of accommodation and convergence match their respective stimuli. When expressed in diopters and meter angles, respectively, stimuli for accommodation and convergence are equal in the mid-sagittal plane when viewed with symmetrical convergence, where historically, the gains of the cross coupling (AC/A and CA/C ratios) have been quantified. However, targets at non-zero azimuth angles, when viewed with asymmetric convergence, present unequal stimuli for accommodation and convergence. Are the cross-links between the two systems calibrated to compensate for stimulus mismatches that increase with gaze-azimuth? We measured the response AC/A and stimulus CA/C ratios at zero azimuth, 17.5 and 30 deg of rightward gaze eccentricities with a Badal Optometer and Wheatstone-mirror haploscope. AC/A ratios were measured under open-loop convergence conditions along the iso-accommodation circle (locus of points that stimulate approximately equal amounts of accommodation to the two eyes at all azimuth angles). CA/C ratios were measured under open-loop accommodation conditions along the iso-vergence circle (locus of points that stimulate constant convergence at all azimuth angles). Our results show that the gain of accommodative-convergence (AC/A ratio) decreased and the bias of convergence-accommodation increased at the 30 deg gaze eccentricity. These changes are in directions that compensate for stimulus mismatches caused by spatial-viewing geometry during asymmetric convergence.
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Affiliation(s)
- Dorothy Nguyen
- University of California, School of Optometry, 512 Minor Hall, Berkeley, CA 94720-2020, USA
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