Binocular Accommodative Facility Research Articles

Association of smartphones use, ocular symptoms and binocular dysfunctions in adolescents: a hospital-based cross-sectional study

ABSTRACT Purpose Given the current scenario of increased smartphone use in youth, this study aims to evaluate the proportion of ocular symptoms and binocular dysfunction and their association with smartphone use in adolescents through a hospital-based cross-sectional study. Methods The participants were asked to fill out questionnaires related to smartphone use and symptoms of eyestrain experienced (Balik et al. and Kucer). They were asked about the following seven symptoms: blurring of vision, redness, visual disturbance, secretion, inflammation, lacrimation, and dryness. Each symptom out of the 7, was scored on a scale of 0–1 and was used to calculate an Ocular Symptom Score (OSS) by summing the scores of each symptom.Depending upon the duration of smartphone usage, the participants were classified into four groups: <2 hours/day, 2–4 hours/day, 4–6 hours/day, and >6 hours/day. Binocular functions were assessed using near point of convergence (NPC), near point of accommodation (NPA), Accommodative convergence/Accommodation (AC/A) ratio, dissociated heterophoria, and binocular accommodative facility (BAF). Results A total of 123 smartphone user adolescents, aged 10–19 years were included in this study. The mean age of the study population was 16.58 + 2.8 years, out of which 52.03% were males. Prevalence of ocular symptoms was higher in groups with greater duration of smartphone use (2 to 4, 4 to 6, and >6 hours/day as compared to <2 hours/day: 90.48%, 94.74%, 100% vs. 75% respectively). The mean of NPC was 8.51, it was highest in subjects using smartphones for >6 hours. (p-value = .001). The mean AC/A ratio was 2.83 + 1.03: 1. A low AC/A ratio was associated with a longer duration of smartphone usage (p-value = .0001). The mean of BAF was 7.4 + 3.18 cycles/min, only 30 (24.4%) participants had BAF beyond the normal range (<5 cycles/min). The mean of BAF was lowest in the group with >6 hours/day of smartphone use (p-value < .0001). No significant change was found in NPA and dissociated heterophoria with the duration of smartphone usage. Conclusion Higher duration of smartphone use (>2 hours/day) is associated with various ocular symptoms and binocular dysfunction. However, additional research is necessary to authenticate the results of the study.

The relationship between accommodative and binocular function with myopia progression in myopic children undergoing orthokeratology

PurposeTo determine the relationship between changes in accommodative and binocular function with myopia progression in myopic children over a two-year follow-up period, and to determine when changes in visual functions stabilized after switching from spectacles to orthokeratology (Ortho-K). MethodsThis prospective, self-controlled study followed thirty-six participants (aged 8–14 years) for two years after they switched from spectacles to Ortho-K. Accommodative and binocular function were assessed prior to and 1, 3, 6, 12, 18 and 24 months after commencing Ortho-K. Measurements included accommodative amplitude, accommodative response, accommodative facility, accommodative convergence/accommodation (AC/A), ocular alignment, positive relative accommodation (PRA), negative relative accommodation (NRA), horizontal vergence range, reading ability and stereoacuity. Myopia progression was quantified by the change in axial length. ResultsOcular alignment, monocular and binocular accommodative facility, and PRA stabilized after 1 month. The distance blur point in the convergence range, the distance break and recovery point in the divergence range, accommodative amplitude, calculated AC/A, stereoacuity and reading ability stabilized within 6 months. After two years of Ortho-K, NRA significantly increased (p = 0.044), while it showed no significant difference after one-year of lens wear (p = 0.49). The distance break point in the convergence range showed no significant difference (p = 0.20), but significantly decreased after one-year (p = 0.005). There were no significant correlations between the change in axial length with changes in accommodative or binocular function (p > 0.05). ConclusionAccommodative and binocular function changed significantly after switching from spectacles to Ortho-K and most of the parameters stabilized within the first 6 months. There was no association between the change in accommodative or binocular function and myopia progression.

Pilot Study Assessing the Safety and Acceptance of a Novel Virtual Reality System to Improve Visual Function

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.

Effectiveness of Clinic-Based Vision Therapy for Non-Strabismic Binocular Vision Anomalies (NSBVA) Among Adults

Background: To assess the effectiveness of clinic-based vision therapy in adults with non-strabismic binocular vision anomalies. Methods: This retrospective study was conducted between January 2018 and December 2021 at a tertiary eye care center in Southern India. Elec-tronic medical records of adults aged 30 years and above diagnosed with non-strabismic binocular vision anomalies, and who underwent a mini-mum of five sessions of clinic-based vision therapy (VT), were reviewed. Clinical parameters of vergence and accommodation were analyzed pre and post-therapy. Results: A total of 44 participants meeting the inclusion criteria were included in the study, with a mean (SD) age of 36 (±6) years. The partic-ipants were categorized into two groups based on the completion of either five sessions (Group A) or ten sessions (Group B) of vision therapy (VT). The overall median (IQR) for near phoria was -4 (-8 to 0) PD, the near point of convergence break point was 8 (4 to 12) cm, fusional conver-gence amplitude for near was 25 (14 to 30) PD, and binocular accommo-dative facility and amplitude were 3 (0 to 6) cpm and 9 (7 to 10) D, respectively. Conclusion: Clinic-based vision therapy is efficacious in managing non-strabismic binocular vision anomalies in adult.

Do monocular myopia children need to wear glasses? Effects of monocular myopia on visual function and binocular balance.

This study aims to compare the binocular visual functions and balance among monocular myopic adolescents and adults and binocular low myopic adolescents and explore whether monocular myopia requires glasses. A total of 106 patients participated in this study. All patients were divided into three groups: the monocular myopia children group (Group 1 = 41 patients), the monocular myopia adult group (Group 2 = 26 patients) and the binocular low myopia children group (Group 3 = 39 patients). The refractive parameters, accommodation, stereopsis, and binocular balance were compared. The binocular refractive difference in Group 1, Group 2, and Group 3 was -1.37 ± 0.93, -1.94 ± 0.91, and -0.32 ± 0.27 D, respectively. Moreover, uncorrected visual acuity (UCVA), spherical equivalent (SE) and monocular accommodative amplitude (AA) between myopic and emmetropic eyes in Group 1 and Group 2 were significantly different (all P < 0.05). There was a significant difference in the accommodative facility (AF) between myopic and emmetropic eyes in Group 2 (t = 2.131, P = 0.043). Furthermore, significant differences were found in monocular AA (t = 6.879, P < 0.001), binocular AA (t = 5.043, P < 0.001) and binocular AF (t = -3.074, P = 0.003) between Group 1 and Group 2. The normal ratio of stereopsis according to the random dots test in Group 1 was higher than in Group 2 (χ2 = 14.596, P < 0.001). The normal ratio of dynamic stereopsis in Group 1 was lower than in Group 3 (χ2 = 13.281, P < 0.001). The normal signal-to-noise ratio of the binocular balance point in Group 1 was lower than Group 3 (χ2 = 4.755, P = 0.029). First, monocular myopia could lead to accommodative dysfunction and unbalanced input of binocular visual signals, resulting in myopia progression. Second, monocular myopia may also be accompanied by stereopsis dysfunction, and long-term uncorrected monocular myopia may worsen stereopsis acuity in adulthood. In addition, patients with monocular myopia could exhibit stereopsis dysfunction at an early stage. Therefore, children with monocular myopia must wear glasses to restore binocular balance and visual functions, thereby delaying myopia progression.

Establishing Normative Values for Amplitude of Accommodation and Accommodative Facility among University Students in Malawi

Aim: The study aimed to examine the distribution of Accommodative Facility (AF) and Amplitude of Accommodation (AA) and compare the findings with established guidelines.&#x0D; Place and Duration of Study: Mzuzu University, Malawi. Between May and July 2022.&#x0D; Methods: This cross-sectional study was conducted among students at Mzuzu university in Malawi. We recruited 77 students using a stratified random sampling technique. The participants' age ranged from 16 to 35 years of age. We measured AA using the push-up method while AF was measured using +/- 1.50 Diopters (D) flippers. Both techniques utilized black reading material on white background held at 40 centimeters (cm). Next, we measured the accommodation facility by counting the number of Cycles per Minute (c/m). We utilized the Pearson correlation test and the One-way ANOVA where appropriate. The value of p&lt; 0.05 was considered statistically significant. &#x0D; Results: The participants comprised 44 (57.1%) males and 33 (42.9%) females. Monocular AA was 10.04D (SD=2.71) and Binocular AA was 10.51 (3.641). The difference was statistically significant (p=0.04). While Monocular AF and Binocular AF were 9 c/m (SD= SD=1.84) and 8.96 (SD=1.539) respectively but the difference was non-significant (p=0.868). AF and AA were not significantly different between males and females. All the parameters decreased with age. The measured AA was significantly higher than using Hofstetter’s formula.&#x0D; Conclusion: The study provides a cut-off value for practitioners diagnosing Accommodation anomalies. However, indices in the study differ from the well-established guidelines hence practitioners should endeavor to perform the clinical assessment instead of relying on equations.

Effects of Continuous Online Multiplayer Gaming on Ocular Health

Purpose: To study the ocular effects of continuous online multiplayer gaming and reading using smartphones. Methodology: In the study, inclusion criteria were 25 active gamers and 25 readers between the ages of 18 to 25 years of either sex, and the Indian population with ametropia &lt; ± 4.00D sph and -1.25 cyl. Exclusion criteria were subjects with a history of non-strabismic binocular vision anomalies, ocular surgery, strabismus, ocular trauma &amp; pathologies, and systemic illness. The GAMERS were allowed to play PUBG for 2hrs, and READERS were allowed to read for 2hrs on their smartphones. The pre- and post-activity values were collected and analyzed using SPSS software. Results: There were significant changes in NPC with accommodative target and RG filter, monocular and binocular accommodative amplitudes, monocular and binocular accommodative facility, and vergence facility (Wilcoxon signed-rank test, p&lt;0.05) among the GAMERS and READERS. No significant change in accommodative response, vergence amplitudes, tear film volume, and stability. The differences observed between the pre- and post-activity values of the binocular vision and tear film parameters were the same when compared between GAMERS and READERS (Mann Whitney U test, p&gt;0.05). Conclusion: The ocular effects of GAMING are similar to continuous READING on mobile phones. However, the addictive nature of the activity "GAMING" could aggravate the ocular symptoms of exhaustive use.

Accommodation Response Variations in University Students under High Demand for Near-Vision Activity.

The objective of this study was to investigate accommodation changes and visual discomfort in a university student population after a period of high demand for near-vision activity. A total of 50 university students aged between 20 and 22 years were recruited. The tests performed involved positive relative accommodation (PRA), negative relative accommodation (NRA), accommodation amplitude (AA), and monocular and binocular accommodative facility (MAF and BAF). Visual discomfort was measured on a scale involving a visual discomfort questionnaire (VDQ). All accommodative variables underwent changes during the exam period; specifically, regarding NRA and PRA, 30.4% and 15.1% of the studied population, respectively, appeared to be below average. Moreover, 42.3% of the population exhibited values below average in the second measure of AA. On the other hand, a small percentage of the population was below average in MAF and BAF measurements: 3% in the monocular right eye test, 6% in the left eye test, and 9.1% in the binocular facility test. Finally, the VDQ score did not reveal a statistically significant difference between the two measurements. Prolonged near-distance work, such as a university exams period, changed all accommodation systems (amplitude of accommodation, relative accommodation, and accommodation facility). These changes influence an accommodation excess that results in blurred vision, headache, and problems with focusing.

Eye Habits Affect the Prevalence of Asthenopia in Patients with Myopia.

Purpose This study aims to explore the risk factors of asthenopia in the myopic population. Methods In this cross-sectional study, myopia patients were inquired about their eye habits and were requested to complete an asthenopia questionnaire and ocular examinations. Age, gender, occupation, anisometropia, eye care education, weekly outdoor activity time, duration of continuous near work, daily screen time, dry eye, near phoria, and binocular accommodative facility were calculated using the Student's test-test, Mann Whitney U test, and Pearson's chi-square test. Spherical equivalents and astigmatism were calculated using a generalized estimating equation. Binary logistic regression was performed on factors with a p-value <0.05. Results Of the 65 myopic patients, 57% showed asthenopia, 52% experienced blurry vision, 37% felt their eyes hurt or sore, and 28% felt tired when performing close work. Asthenopia patients were older than patients without asthenopia (Z = −2.887, p=0.004). Daily screen time, continuous near-work time, eye care education, and dry eye were positively correlated with asthenopia (χ2 = 8.64, p=0.003; χ2 = 13.873, p < 0.001, χ2 = 9.643, p=0.002; χ2 = 7.035, p=0.008). After eliminating collinearity, eye care education and continuous near-work time were identified as independent risk factors of asthenopia, with odds ratios of 0.115 and 4.227, respectively. Conclusion This study shows that receiving eye care education from schools and hospitals and limiting near-work duration to less than 45 minutes per session could reduce the occurrence of asthenopia in myopic patients. This approach may be a more economical and convenient way for myopic people to relieve asthenopia.

Changes to Visual Parameters Following Virtual Reality Gameplay.

Introduction:Virtual reality (VR) gameplay is popular with a range of games and educational resources available. However, it puts high demands on the visual system. Current evidence shows conflicting impacts on visual parameters. Therefore, this study explores the changes to vision following VR gameplay.Methods:The study was conducted at the School of Health Sciences, University of Liverpool. All participants had binocular vision with good visual acuity and no manifest strabismus. Participants were assessed before and after playing 15 minutes of the VR game Beat Saber, which incorporated convergence and divergence movements. Clinical assessments including near point of convergence (NPC) and near point of accommodation (NPA) using the RAF rule; accommodative convergence to accommodation (AC/A) ratio; motor fusion using the prism fusion range (at 33cm), accommodation facility using +2.00/–2.00DS flipper lenses, and stereoacuity using the Frisby stereo test were assessed before and after playing.Results:Seventy-eight participants (19–25 years old) were included in the study, with 16 males and 41 females respectively. The breakpoint of convergence reduced by 0.5 cm (p = 0.001). The binocular accommodative facility improved by 2 cycles per minute (cpm); p = 0.004. The mean, near horizontal prism fusion range (PFR) base break and recovery points both worsened by of 5.0 dioptres (p = 0.003), whereas the mean near horizontal PFR base in recovery point improved by of 4.0 dioptres (p = 0.003).Discussion:The study validated previous findings as VR gameplay over-exercised and fatigued convergence muscles, but to a small degree. The VR experience improved the participants’ ability to change focus quickly and improve accommodation, as well as the divergence function of the eye. However, as the participants were retested directly after the VR gameplay, the findings were limited to short term effects on vision.

Comparison of Short-Term Effects of Treatment of Accommodative Infacility with Low Plus Addition in Single Vision Rx or Vision Therapy: A Pilot Study.

PurposeTo compare the short-term treatment effect of low plus reading addition (ADD) and home-based vision therapy (VT) in a small group of symptomatic children with accommodative infacility (AIF) being the most significant dysfunction.MethodsNineteen children, 8 to 12 years of age, with a first-time diagnosis of AIF were consecutively and alternately allocated to treatment with ADD (+0.50 D addition in single vision Rx) or VT (accommodation exercises using Hart Charts) for a period of 6 weeks. Accommodation facility (AF) was measured monocularly (MAF-R, MAF-L) and binocularly (BAF) with +2 D/-2 D flipper and registered in cycles per minute (cpm). Symptoms were graded using the convergence insufficiency symptom survey (CISS). Measurements were compared before and after treatment and between groups using nonparametric statistics (p < 0.05).ResultsTen children were allocated to ADD (median age 9.0 F:5) and 9 to VT (median age 11.0 F:7). Baseline median measurements of MAF-R, MAF-L, BAF and CISS were 3.0, 3.0, 2.2 cpm, and 27.5 points, respectively, for ADD, and 2.0, 2.0, 2.0 cpm, and 27.0 points, respectively, for VT. There were no significant differences between groups at baseline. After 6 weeks of treatment, the median change of MAF-R, MAF-L, BAF and CISS was +5.0, +4.5, +4.7 cpm, and –7.5 points, respectively, for ADD and +8.0, +8.0, +10.0 cpm, and –20.0 points, respectively for VT. All changes within groups were significant. Comparison of groups showed a significantly greater effect of treatment with VT compared to ADD for BAF (p = 0.008) and CISS (p = 0.017).ConclusionIn children with newly diagnosed AIF, treatment with accommodation exercises for 6 weeks gives greater short-term relief of symptoms and improvement of binocular accommodative facility compared to treatment with spectacle single vision correction with a weak plus addition.

Binocular vision parameters in chronic heavy alcoholics: Short-term outcomes of alcohol detoxification

Background: Alcohol consumption is rising in developing countries such as India, and alcohol addiction has systemic and ocular impacts. This study aimed to investigate the binocular functions of chronic heavy alcoholics before and after alcohol detoxification.&#x0D; Methods: A prospective before–after study was designed and conducted at Treda De-Addiction Centre, Bengaluru, India. Males in the age range of 30–40 years who had been alcohol addicts for more than six years and met the inclusion criteria were recruited. We performed a routine optometric examination followed by detailed binocular vision assessment, including accommodative, vergence, and oculomotor tests on the first day of rehabilitation and one month after initiation of rehabilitation.&#x0D; Results: Twenty-five males with of the age (mean ± standard deviation [SD]) 36.24 ± 4.33 years were evaluated. The pre- and post-detoxification mean ± SD of the monocular (right eye: 5.98 ± 3.50, 6.60 ± 3.49; left eye: 6.18 ± 3.69, 7.10 ± 3.78) and binocular accommodative facility (7.10 ± 3.93, 7.40 ± 4.51) did not change significantly (all P &gt; 0.05). Eighteen (72%) of the participants had non-strabismic binocular vision anomalies (NSBVA), among whom the accommodative infacility and convergence insufficiency were higher in frequency and remained constant after alcohol detoxification. Furthermore, the binocular vision parameters showed no statistically significant difference between the pre- and post-detoxification values (all P &gt; 0.05).&#x0D; Conclusions: The binocular vision parameters did not change significantly after one month of alcohol detoxification in the chronic heavy drinkers. Most long-term alcoholics had NSBVA with no change after rehabilitation, indicating that short-term alcohol detoxification may not aid in the recovery of binocular parameters. However, further validation is required. Assessing the impact of vision therapy in addition to a longer period of abstinence can confirm or refute the persistence of observed effects of chronic alcohol consumption on binocular functions and NSBVA in this population.

Developing dynamic defocus curve for evaluating dynamic vision accommodative function

BackgroundTo assess dynamic visual acuity (DVA) under different defocus statuses and explore the assessment of dynamic vision accommodation.MethodsTwenty 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.ResultsThe 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 AUCdynamic (p<0.001). Significant associations were observed between AUCdynamic 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).ConclusionsOur 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.

Clinical Effectiveness of Facility and Accuracy of Accommodation in Diagnosis of Non Strabismic Binocular Vision Anomalies in Young Adults: A Prospective Cross-sectional Observational Study

Introduction: Orthoptic evaluation is highly recommended in children and young adults to diagnose binocular dysfunctions. Binocular vision dysfunctions may hamper academic performance in children. Accommodative facility and accommodative accuracy are two orthoptic tests to evaluate accommodative flexibility and accommodative status of eye. Aim: To investigate the effectiveness of facility and accuracy of accommodation in diagnosis Non Strabismic Binocular Vision Anomalies (NSBVA) in young adults. Materials and Methods: This prospective, cross-sectional observational study was conducted at Optsight Eye Care in association with Amity Medical School, Gurugram, Haryana, India, from August 2020 to August 2021. A total of 175 subjects (both symptomatic and asymptomatic) with normal anterior and posterior segment findings, and aged between 18-25 years were evaluated for accommodative facility test with the help of accommodative lens flipper ±2D and for accommodative status test with the help of monocular estimation method (dynamic retinoscopy). Both the tests were done over their best corrected visual acuity after refractive error correction and the Pearson correlation test was applied to find out the correlation. Further, complete orthoptic examination was performed for all the subjects to correlate the abnormal findings from the two tests and conventional orthoptic tests. Independent sample t-test was applied to compare the accommodative facility between refractive groups. Results: Out of 175 subjects, 84 (48%) of the subjects were found to have NSBVA which included 26 (14.86%) Convergence insufficiency, 30 (17.14%) with accommodative insufficiency, 25 (14.29%) with convergence insufficiency secondary to accommodative insufficiency, and 3 (1.71%) with accommodative infacility. A positive correlation between binocular accommodative facility and status of accommodation was found with a p-value &lt;0.001 (r=0.51). Conclusion: Status of accommodation and facility test can help to differentiate the accommodative and vergence problems making examination less time consuming. Both of these procedures should be a part of general routine eye examination protocol in the young adult group so that detection of these anomalies become less time consuming and patient gets benefitted from early intervention

Diagnostic accuracy of indigenously developed computer-based binocular vision assessment.

CONTEXT:The increased prevalence of nonstrabismic binocular vision anomalies (NSBVA) has given rise to the need for cost-effective screening and diagnostic tools.AIMS:The aim of the study is to assess the efficacy of an indigenously developed computer-based binocular vision assessment software (Train Your Eyes®) in screening NSBVA.SUBJECTS AND METHODS:Subjects who visited the binocular vision clinic of a tertiary eye care center with asthenopic symptoms between January 2019 and January 2020 were included in the study. Patients with other ocular comorbidities and stereopsis poorer than 500 arc seconds were excluded. All subjects underwent a comprehensive eye examination followed by binocular vision assessment using both the manual and computer-based methods.STATISTICAL ANALYSIS USED:Receiver operating characteristic (ROC) curves were utilized to choose the cut-off points that maximize the sensitivity and specificity.RESULTS:The mean (standard deviation) age of 88 subjects was 22 (4.5) years with 34 males. Based on the conventional manual assessment, 71 (81%) were diagnosed to have NSBVA and 17 (19%) had normal binocular vision. Based on the ROC analysis, the following cut-off points are proposed: 14 prism diopter (PD) for near positive fusional vergence amplitudes, 4.5 PD for near negative fusional vergence amplitudes, 4.5 cycles per minute (cpm) for binocular accommodative facility, and 3.5 cpm for monocular accommodative facility. All the binocular vision parameters demonstrated statistical significance in the ROC analysis (P < 0.05).CONCLUSIONS:The software-based screening tool was found to be highly sensitive in identifying NSBVA and thus could be used as a potential screening tool in the clinic and community.

Normative Data for Parameters of Accommodation in African Schoolchildren.

The reported interracial differences in normative data for parameters of accommodation call for investigating population-specific normative values. The study investigated and presents expected data for accommodative parameters among Ghanaian children. This study aimed to determine expected values for parameters of accommodation among schoolchildren in the Central Region of Ghana. This prospective cross-sectional study used a multistage cluster sampling approach. Normal participants were asymptomatic (Convergence Insufficiency Symptom Survey score ˂16), with unaided visual acuity or best-corrected visual acuity of 0.0 or better logMAR for each eye and having no ocular disease or no manifest strabismus. Normal participants underwent push-up and minus-lens-to-blur amplitude of accommodation tests, accuracy of accommodative response (using the monocular estimation method), and monocular and binocular accommodative facility testing. A total of 1261 normal participants within ages 11 to 17 years (mean, 14.75 ± 1.53 years) met the inclusion criteria. The mean normative data for the population include push-up amplitude of accommodation (14.04 ± 2.95 D), minus-lens-to-blur amplitude of accommodation (12.33 ± 2.55 D), and accuracy of accommodative response using the monocular estimation method (0.62 ± 0.22 D), monocular accommodative facility (9.80 ± 3.20 cycles per minute), and binocular accommodative facility (9.40 ± 3.30 cycles per minute). Age-predicted linear regression equations for the amplitude of accommodation are push-up amplitude of accommodation (16.74 - 0.18 × age in years) and minus-lens-to-blur amplitude of accommodation (15.7 - 0.23 × age in years). The study provides normative data for accommodative parameters that clinicians may use with Ghanaian populations of similar ages.

Dynamics of the accommodative response and facility with dual-focus soft contact lenses for myopia control

ObjectiveTo assess the impact of using dual-focus soft contact lenses for myopia control on the dynamics of the accommodative response and facility. Methods24 young adult myopes were fitted with dual-focus soft contact lenses for myopia control (MiSight®) and single-vision soft contact lenses (Proclear®). The WAM-5500 open-field autorefractor was used to measure the dynamics of the accommodative response (magnitude and variability) in binocular conditions, with accommodative data being gathered from the dominant eye, at three viewing distances (500 cm, 40 cm, and 20 cm) during 90 s. Also, the binocular accommodative facility was assessed with the WAM-5500 autorefractor. All participants performed the same experimental protocol with the dual-focus (MiSight) and single-vision (Proclear) soft contact lenses, with both experimental sessions being carried in two different days and following a counterbalanced order. ResultsThis study showed greater lags of accommodation with the MiSight than the Proclear lenses at near distances (40 cm: 1.27 ± 0.77 vs. 0.68 ± 0.37 D, corrected p-value = 0.002, Cohen-d = 0.90; and 20 cm: 1.47 ± 0.84 vs. 1.01 ± 0.52 D, corrected p-value = 0.007, Cohen-d = 0.75), whereas a higher variability of accommodation was observed with the dual-focus than the single-vision lenses at 500 cm (0.53 ± 0.11 vs. 0.23 ± 0.10 D), 40 cm (0.82 ± 0.31 vs. 0.68 ± 0.37 D), and 20 cm (1.50 ± 0.56 vs. 1.15 ± 0.39 D) (corrected p-value < 0.001 in all cases, and Cohen-ds = 0.67–2.33). Also, a worse quantitative (27.75 ± 8.79 vs. 34.29 ± 10.08 cycles per minute, p = 0.029, Cohen-d = 0.48) and qualitative (23.68 ± 7.12 vs. 28.43 ± 7.97 score, p = 0.039, Cohen-d = 0.45) performance was observed with the MiSight when compared to the Proclear lenses. ConclusionsThe use of dual-focus soft contact lenses for myopia control alters the dynamics of accommodative response and facility in the short-term. Although this optical design has demonstrated its effectiveness for myopia control, eye care specialists should be aware of the acute effects of these lenses on accommodation performance.

Examining the Validity of a New Method for the Objective Assessment of Binocular Accommodative Facility (2Q-AF Test): A Comparison with ± 2.00 DS Lens Flippers

ABSTRACT Purpose Recent technological advances have permitted to objectively record the accommodative response while shifting between two different levels of accommodation. This study is aimed at examining the concurrent validity of a new objective method for the qualitative and quantitative assessment of binocular accommodative facility, which is named 2Q-AF test, in comparison to the ±2.00 DS lens flippers. Methods Fifty-six individuals took part in this study (36 healthy young adults [24.4 ± 3.2 years] and 20 children [12.2 ± 0.4 years]). Participants randomly performed the 2Q-AF and the ±2.00 DS lens flipper tests. For the 2Q-AF test, a binocular open-field autorefractor was used to record the magnitude of accommodative response during a 60-sec period, while participants repeatedly changed fixation from a 5 m to a 40 cm chart when clarity of vision was achieved at each level. Due to the advantages of the proposed method, we have determined the number of cycles and the 2Q-AF score, with the latter also considering the accuracy of changes in accommodation. A standard procedure was followed for the ±2.00 DS flipper test. Results Our data exhibited a moderate association between the number of cycles with the ±2.00 DS lens flippers and the number of cycles in the 2Q-AF test in the group of young adults (p = .005, r = 0.46 [0.15–0.68]) and children (p = .007, r = 0.58 [0.19–0.81]), whereas a stronger relationship was observed when considering the number of cycles with the ±2.00 DS lens flippers and the 2Q-AF score (young adults: p < .001, r = 0.83 [0.69–0.91]; and children: p < .001, r = 0.78 [0.52–0.91]). Conclusions The current findings show that the 2Q-AF test is a valid method for accommodative facility assessment, as suggested by its good levels of reliability and validity. This method allows to examine the accommodative facility in qualitative terms and solve most of the limitations associated with the ±2.00 DS lens flipper test.

5.2: Correlation between CSF and Accommodation/Vergence in University Students

Objective: To investigate the relationship among visual fatigue, accommodation, vergence, and CSF.Methods: 104 students were recruited (25 males, 79 females, Age 23.4±2.5), from Wenzhou Medical University, excluding high myopia, strabismus, anisometropia, eye disease and history of ophthalmological surgery. They were asked to accomplish visual fatigue survey (1) firstly. Binocular accommodative facility (BAF), vergence facility (VF) and qCSF (the area under low spatial frequency of CSF curve, LCSF; the area under middle spatial frequency of CSF curve, MCSF; the area under high spatial frequency of CSF curve, HCSF; the area under the log CSF curve, AULCSF; the cutoff spatial frequency, Cut‐Off SF) were examined in random sequence. Spearman correlation was used in study.Results: Correlations between Cut‐off SF and symptoms ‘Did you notice greater blur from the scene you were viewing?’ (r (104) = −.294, P = .002), ‘Did you see the words move, jump, swim or appear to float on the page more?’ (r (104) = −.333, P = .001), ‘Did you have greater difficulty concentrating in the task?’ (Spearman's r (104) = −.226, P = .021) were found. Correlations between BAF and symptom ‘Did you see multiple images of the sce ne more?’ (r (104) = −.308, P = .001) and ‘Did you have greater difficulty concentrating in the task?’ (r (104) = −.307, P = .002) were found. Correlations between VF a nd symptom ‘Did you have greater trouble visually focusing on the scene?’ and ‘Did you notice greater blur from the scene you were viewing?’ were found, as well. All correlations were shown in Table 1. Moreover, correl ations among BAF, VF and CSF were found in our re search. BAF was positively correlated with HCSF (r (104) =.259, P = .008) and Cut‐off SF (r (104) = .238, P = .015), shown in Figure 1. VF was negatively correlated with LCSF (r (104) = −.271, P = .005), positively conelated with Cut‐off SF (r (104) = .185, P = .060); and no correlation between VF and HCSF was found, shown i n Figure 2. Correlation between BAF and VF (r (104) = .270, P = .006), shown in Figure 3.Conclude: BAF, VF and CSF were related with visual fatigue symptoms. CSF have different correlation with BAF and VF, Cut‐off SF were positively correlated with BAF and CSF. Cut‐off SF would be an objective measurement to evaluate symptoms of visual fatigue and treatment effect of accommodative and vergence therapy.

Investigation of the Relationship Between Subjective Symptoms of Visual Fatigue and Visual Functions.

PurposeTo investigate whether the severity of symptoms of visual fatigue might be associated with clinical visual measures and basic visual functions, such as accommodation, vergence, and contrast sensitivity.MethodsIn this study, 104 students were recruited (25 males, 79 females, Age 23.4 ± 2.5) for this study. Those with high myopia, strabismus, anisometropia, eye disease or history of ophthalmological surgery were excluded. The included subjects completed a questionnaire that assesses the severity of visual fatigue. Then, binocular accommodative facility, vergence facility and contrast sensitivity using a quick contrast sensitivity function approach were measured in a random sequence. Next, the correlations between each symptom of visual fatigue in the questionnaire and accommodative facility, vergence facility and contrast sensitivity were examined.ResultsFactor analysis indicated that visual fatigue, as captured by the scores of a subset of the questionnaire items, could be strongly related to binocular accommodative facility and binocular contrast sensitivity, but not to vergence facility. We also found that binocular accommodative facility and contrast sensitivity at high spatial frequencies are related.ConclusionOur findings suggest that visual fatigue is related to the ability of human observers to encode visual details through their binocular vision.