Vergence Amplitudes Research Articles

Evaluation of Accommodation Amplitude and Convergence Insufficiency in Patients with Multiple Sclerosis

ABSTRACT Purpose To evaluate the near reflex components, including accommodation, convergence, and binocular fusional vergences in patients with multiple sclerosis (MS). Material-Method MS patients under 35 years of age without visual evoked potential (VEP) abnormalities (MS Group) and age-matched healthy individuals of (Control Group) were included in the study. Fusional vergence amplitudes, the amplitude of accommodation (AA), stereopsis measurements, near-object fixation and near point of convergence (NPC) measurements, Convergence Insufficiency Symptoms Survey (CISS) results, and the presence of nystagmus were recorded retrospectively from the files of the cases. Statistical comparison was made between the groups. Results The mean age was 28.04 ± 3.7 years in the MS group (20 females, 4 males) and 27.16 ± 3.1 years in the control group (20 females, 5 males) (p = .763). There was no statistically significant difference between groups in stereopsis (p = .395), mean convergence (p = .666), and divergence amplitudes (p = .773) at a distance, and mean convergence and (p = .836) divergence amplitudes (p = .877) at near, and NPC measurements (p = .908). The mean AA was 5.31 ± 0.7 D in the MS group and 6.1 ± 0.8 D in the control group (p < .001). CISS results were lower in the control group (p < .001). In addition, gaze-evoked nystagmus was statistically significantly higher in the MS group (p < .001). Conclusion Compared to the healthy control group, MS patients under 35 who did not have optic neuritis had lower accommodation amplitude and more signs in favor of convergence insufficiency symptoms. In addition, gaze evoked nystagmus was observed at a higher rate in the MS group. These findings may guide us in understanding the asthenopia findings of MS patients without optic neuritis.

No agreement between expected phoropter Risley prism and prism bar fusional vergences in a prospective cross-sectional study of African school children.

Purpose: To determine the agreement between phoropter Risley prism and prism bar fusional vergence amplitudes in a normative group of school-aged children, aged 8 to 17 years. Method: This prospective cross-sectional study utilized multistage sampling to recruit participants with normal binocular vision. Horizontal fusional vergence amplitudes were measured at distance and near using the phoropter with Risley prisms and the prism bar. Result: The study included 422 normal participants (48.1% male, 51.9% female) with a mean age of 12.39 ± 1.94 years. There were significant differences in the base-in break, base-in recovery, base-out blur, base-out break, and base-out recovery at distance and near between phoropter Risley prism and prism bar fusional vergences (p < 0.05); amplitudes for phoropter Risley prism were higher than that for prism bar. Their mean differences were clinically meaningful except for base-in recovery at distance; however, there was no level of agreement on Bland Altman analysis. Conclusion: Fusional vergence amplitudes measured with the phoropter Risley prism and prism bar should not be considered interchangeable in African schoolchildren.

Fusional Vergence amplitude measurement among students of ISRA School of optometry, Isra University, Karachi campus

Purpose: To determine mean fusional vergence amplitudes FVA and the effect age and gender on FVA. Methodology: A cross sectional descriptive study was conducted among Isra School of optometry, Isra University, Karachi campus students from August 2023 to December 2023. A total of 120 students consisting of 43 males (35.8%) and 77 females (64.1%) were recruited using a convenient sampling technique. Inclusion criteria included subjects with 6/6 vision, no any ocular disease, strabismus and subjects with exophoria or esophoria. The age ranged from 18-27 years. Patients underwent ophthalmic procedure i.e. visual acuity for both distance and near and ophthalmoscopy was performed to check the clarity of the patient’s media. After assessing the ocular media, cover test was used to check the type of phoria. By using horizontal prism bars, Positive Fusion Vergence (PFV) and Negative Fusion Vergence (NFV) were recorded as break, and recovery points at near and distance. All the information was recorded in self-made Performa. Data was analyzed using SPSS. Result: Students were categorized into three age groups: Group 1 (18-21 years), Group 2 (22-24 years), and Group 3 (25-27 years). The data showed negative fusional divergence break-up and recovery points at distance and near, with mean values of 10.06±4.8 Δ and 7.3±4.7 Δ, respectively. Positive fusional convergence break-up and recovery points at distance and near had mean values of 10.95±6.11 Δ and 8.1±5.57 Δ, respectively. The result for negative divergence break and recovery point at distance were significant with p-value of 0.021 and 0.026, respectively Conclusion: This study concluded that the mean fusional vergence amplitudes FVA at near and distance are reduced while distance and near FV revealed no effects of age and gender. However, negative fusional break point and positive fusional recovery point were significantly affected by age.

Evaluation of convergence, accommodation and fusional vergence in pre-presbyopes with asthenopia

Background: Pre-presbyopes may suffer from ocular symptoms such as asthenopia of near work.Aim: This study aimed to evaluate near points of convergence, amplitudes of accommodation, and fusional vergence among pre-presbyopes with asthenopia symptoms.Setting: The study was conducted at El-Walidain Eye Hospital, Khartoum, Sudan in 2022.Methods: The study was a hospital-based prospective, including 107 pre-presbyopes aged 35–40 years who complained of asthenopia symptoms. Clinical examinations included an assessment of amplitude of accommodation, near point of convergence and fusional vergence.Results: The findings showed receded in near points of convergence and a decrease in the accommodation was highly significantly associated with increased age among emerging presbyopes with asthenopia symptoms (p = 0.0001). Conversely, positive and negative fusional vergence amplitudes were not significantly correlated with age with p = 0.109 and p = 0.355, respectively. Positive and negative fusional amplitudes were not significantly different between males and females (p ˃ 0.05). Esophoria was more common in pre-presbyopia 62 (57.4%) and exophoria 45 (43.6) with p = 0.503.Conclusion: The pre-presbyopes presented with low accommodation amplitude and receded near point of convergence, but without significant changes in positive and negative fusional vergence amplitudes.Contribution: This study added by demonstrating how early presbyopia altered accommodation amplitude and near point of convergence significantly while having no significant impact on amplitudes of positive and negative fusional vergence.

Heterophoria, fusional vergence, and near point of convergence in Sudanese hospital-based population

Background: Fusional vergence amplitude is the amount of convergence and divergence that can be induced before fusion is lost and fusional vergence amplitude controls heterophoria.Aim: This study aimed to investigate the relationship between near heterophoria, near fusional vergence (NFV), and near point of convergence (NPC).Setting: Al-Neelain Eye Hospital Khartoum, Sudan.Methods: A hospital-based prospective study from February to October 2019, included 230 patients with age range of 15–30 years and mean age and standard deviation of 19.46 ± 3.33 years. The alternate cover test with prism was used to measure near heterophoria and a prism bar was used to measure quantity of fusional vergence. All measurements were taken at near heterophoria (0.33 m). Then the associations between near heterophoria, NFV and NPC were assessed.Results: The most common heterophoria at near among the participants was exophoria: 200 (87.0%). Reported complaints of asthenopia were commonly found among these exophoric patients: 106 (86.9%) (P = 0.735). Positive fusional vergence (PFV) to the break point varied according to the forms of heterophoria (P = 0.003). Esophoria had a higher PFV to break point than exophoria (30.83 ± 8.79Δ compared to 25.59 ± 10.07Δ). Negative fusional vergence at the break and recovery points were higher among those with exophoria and lower in esophoria (P ˃ 0.05). The NPC differed by the type of heterophoria (P = 0.01), with exophoria and slightly receded NPC (8.38 cm ± 3.33 cm) than for participants with esophoria (6.77 cm ± 1.52 cm).Conclusions: Exophoria was the most common type of near heterophoria, with asthenopia being the most reported complaint. Esophoria was found to be strongly associated with high PFV. Exophoria, on the contrary, is related to significant high NFV at the blur, beak, and recovery point. The NPC differed significantly by the type of near heterophoria, with exophoria having more receded NPC compared to those with esophoria.Contribution: This study provides information on the commonest type of near heterophorias among a sample of Sudanese adolescents and young adults, namely exophoria. Near point of convergence and NFV at break and recovery points were significantly different according to forms of near heterophoria.

Functional changes in fusional vergence-related brain areas and correlation with clinical features in intermittent exotropia using functional magnetic resonance imaging.

To explore the functional changes of the frontal eye field (FEF) and relevant brain regions and its role in the pathogenesis of intermittent exotropia (IXT) children via functional magnetic resonance imaging (fMRI). Twenty-four IXT children (mean age, 11.83 ± 1.93 years) and 28 normal control (NC) subjects (mean age, 11.11 ± 1.50 years) were recruited. During fMRI scans, the IXT children and NCs were provided with static visual stimuli (to evoke sensory fusion) and dynamic visual stimuli (to evoke motor fusion and vergence eye movements) with binocular disparity. Brain activation in the relevant brain regions and clinical characteristics were evaluated. Group differences of brain activation and brain-behavior correlations were investigated. For dynamic and static visual disparity relative to no visual disparity, reduced brain activation in the right FEF and right inferior occipital gyrus (IOG), and increased brain activation in the left middle temporal gyrus complex (MT+) were found in the IXT children compared with NCs. Significant positive correlations between the fusional vergence amplitude and the brain activation values were found in the right FEF, right IPL, and left cerebellum in the NC group. Positive correlations between brain activation values and Newcastle Control Scores (NCS) were found in the left MT+ in the IXT group. For dynamic visual disparity relative to static visual disparity, reduced brain activation in the right middle occipital gyrus, left cerebellum, and bilateral IPL was found in the IXT children compared with NCs. Significant positive correlations between brain activation values and the fusional vergence amplitude were found in the right FEF and right cerebellum in the NC group. Negative correlations between brain activation values and NCS were found in the right middle occipital gyrus, right cerebellum, left IPL, and right FEF in the IXT group. These results suggest that the reduced brain activation in the right FEF, left IPL, and cerebellum may play an important role in the pathogenesis of IXT by influencing fusional vergence function. While the increased brain activation in the left MT+ may compensate for this dysfunction in IXT children.

Feasibility of measuring fusional vergence amplitudes objectively.

Two tests to measure fusional vergence amplitudes objectively were developed and validated against the two conventional clinical tests. Forty-nine adults participated in the study. Participants' negative (BI, base in) and positive (BO, base out) fusional vergence amplitudes at near were measured objectively in an haploscopic set-up by recording eye movements with an EyeLink 1000 Plus (SR Research). Stimulus disparity changed in steps or smoothly mimicking a prim bar and a Risley prism, respectively. Break and recovery points were determined offline using a custom Matlab algorithm for the analysis of eye movements. Fusional vergence amplitudes were also measured with two clinical tests using a Risley prism and a prism bar. A better agreement between tests was found for the measurement of BI than for BO fusional vergence amplitudes. The means ± SD of the differences between the BI break and recovery points measured with the two objective tests were -1.74 ± 3.35 PD and -1.97 ± 2.60 PD, respectively, which were comparable to those obtained for the subjective tests. For the BO break and recovery points, although the means of the differences between the two objective tests were small, high variability between subjects was found (0.31 ± 6.44 PD and -2.84 ± 7.01 PD, respectively). This study showed the feasibility to measure fusional vergence amplitudes objectively and overcome limitations of the conventional subjective tests. However, these tests cannot be used interchangeably due to their poor agreement.

Comparison of Measured Fusional Vergence Amplitudes using Prism Bar and Synoptophore in Sudanese Patients with Near Exophoria

Background: Assessment of the fusional vergence amplitudes constitutes one of the most important diagnostic tools to obtain information about the ability to maintain binocular vision. Several techniques can be used to assess this function. However, those methods are not interchangeable, and the measurement repeatability has been questioned. Objective: This study aimed to compare fusional vergence range measurements using prism bars and synoptophore in Sudanese patients with near exophoria Methods: The study was a comparative cross-sectional hospital-based, performed in the binocular vision clinic at the Al-Neelain Eye Hospital. Fusional vergence amplitudes (positive and negative) were measured on 122 patients (67 females and 55 males), and the mean age and standard deviation were 16.79 ± 5.22 years old using prism bar and synoptophore methods. Results: The findings showed that the higher positive fusional vergence was obtained using the synoptophore method (24.7 ± 7.2 Δ base-out), whereas the prism bar method provided the lower finding (22.6± 7.6 Δ base-out). Conversely, the prism bar method revealed a higher measurement for negative fusional vergence (13.9± 3.9 Δ base-in) than the synoptophore method (12.7± 3.7 Δ base-in). Using the t-test, significant differences were found between all measurements with the two techniques, P&lt;0.05. Measurements of positive and negative fusional vergence amplitudes by the two methods showed no relationship between age and fusional vergence, P&gt;0.05. Conclusion: Given the significant difference in the results obtained between the two methods for measuring the positive and negative fusional vergence amplitudes, caution should be taken when making decisions regarding fusional vergence assessment in patients with latent and manifest strabismus.

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.

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.

Contributed Session I: The effect of spherical defocus on vergence and diplopia in adults and children

Anisometropic children (with unequal refractive error in the two eyes) are at risk for strabismus or amblyopia. We simulated unilateral and bilateral spherical defocus to clarify the link between anisometropia, vergence eye movements and the perception of single vision. Adults (N=20, 15-51 yrs) and typically developing children (N=9, 5-8 yrs) viewed a dichoptic cartoon character presented in the fixation plane. Step changes in disparity of between 0 and 8 deg were introduced for 320 ms, followed by a blank screen. Vergence responses were recorded with an Eyelink 1000 and subjects reported whether they perceived a single (fused) or double (diplopic) character. Spherical defocus from 0.5 to 4D was applied to one or both eyes' stimuli using convolution of the point spread function for the subject's pupil size. Open loop vergence amplitude was used to estimate the reflex response (without feedback). For no defocus, open loop vergence peaked at +/-2 deg disparity with amplitudes of 0.29 deg convergence and -0.44 deg divergence for adults, and 0.56 deg and -0.46 deg for children. Bilateral defocus had no effect on this reflex response; however, 4D unilateral defocus significantly reduced vergence amplitudes in both age groups with no corresponding change in diplopia thresholds. Our results confirm that anisometropic blur is particularly disruptive to reflex vergence responses, which could limit the accurate realignment of the eyes and lead to atypical binocular development.

Contrast Sensitivity of Vertical Vergence Eye Alignment

Purpose: The purpose of the study was to measure the response of vertical vergence eye movement to bandpass filtered noise of various spatial frequencies and contrasts. The results of our previous experiment in which we measured the contrast sensitivities using vertical vergence response to sine-wave gratings suggested that vertical vergence responses were robust for middle spatial frequencies (0.5 to 4 cycles per degree). However, the responses to higher and lower spatial frequencies were weaker. The weak responses at higher spatial frequencies could have been due to matching ambiguity of the gratings in the two eyes. So, to eliminate this ambiguity we used bandpass filtered noise as the stimulus to measure the contrast sensitivity of vertical vergence eye alignment. Methods: Subjects were 2 adults with normal vision. A Dual Purkinje image eye tracker was used for eye tracking. Vertical vergence was measured in response to full-screen bandpass filtered noise patterns of all orientations with one-octave bandwidth. A block of trials comprised combinations of 8 contrasts [0%, 1%, 2%,4%,8%,16%,32%,64%] and 8 spatial frequencies [0.125, 0.25, 0.50, 1, 2, 4, 8 ,16 cpd] presented in shuffled order. Various Oculometric functions (AUC, Percent Correct, Weibull fit, Vergence amplitudes) were created to determine the oculometric CSFs. The psychophysical CSF was obtained with a 2AFC staircase method for the same spatial frequencies using bandpass filtered noise patterns as stimuli. Results: Vertical vergence responses were robust for middle spatial frequencies. The responses for higher spatial frequencies were weaker or absent, similar to the results with sine-wave gratings. Conclusion: The results of this study suggest that matching ambiguity was not the primary limiting factor in the response of vertical vergence at higher spatial frequencies, despite being easily detected psychophysically. Further research is needed to understand why vertical vergence does not show a response at higher spatial frequencies.

Longitudinal Rehabilitation of Binocular Function in Adolescent Intermittent Exotropia After Successful Corrective Surgery.

PurposeTo study the longitudinal rehabilitation of binocular visual function in adolescent intermittent exotropia (IXT) after successful surgery and compare the results with those of a normal population. The role of binocular function in ocular alignment stability was also evaluated postoperatively.MethodsIn this prospective study, 30 adolescents with IXT successfully corrected after 1 month were followed for 12 months, and 30 children with normal vision were enrolled as controls. Stereopsis, the fusional vergence amplitude, sensory fusion, and accommodative flexibility were measured to assess binocular function at baseline and 6 and 12 months postoperatively. The controls were tested once when they were enrolled in the study.ResultsThe deviation was −32.00 ± 8.60 prism diopters (PD) at distance fixation and −36.0 ± 9.10 PD at near fixation preoperatively with an average correction of 28.53 ± 3.79 PD and 30.67 ± 1.34 PD at 1 month postoperatively. Distance stereoacuity and near stereoacuity improved from 1 to 12 months postoperatively (p = 0.025 and p = 0.041, respectively). Compared with the controls, the fusional convergence reserve at distance (p = 0.025) and near (p = 0.033) fixations and fusion reserve ratio at distance (p = 0.000) and near (p = 0.000) fixations remained subnormal, whereas sensory fusion (p = 0.237), distance stereopsis (p = 0.120), and the fusional divergence amplitude at a distance (p = 0.168) were normal. However, no significant correlations were found between binocular functions at 1 month postoperatively and the postoperative drift.ConclusionBinocular function significantly improved from before to after successful corrective surgery and continued to improve from 1 to 12 months postoperatively in adolescents with IXT. No significant correlations were found between binocular functions at 1 month postoperatively and ocular alignment stability.

Comparison of Binocular Vision Parameters Pre- and Post-EPILASIK Laser Vision Correction Surgery for Myopia in a Pilot Study - Can Vision Therapy Augment Refractive Results?

Purpose:To analyze the changes in the binocular vision parameters after bilateral Epilasik laser vision correction surgery (LVCS).Setting:Medical Research Foundation, Tamil Nadu, India.Study design:Prospective cohort study.Methods:Subjects with a best corrected visual acuity of ≤ 0.0 Log MAR scale and refractive error: < 6.00DS of myopia, < 0.75D of astigmatism, and < 1D of anisometropia were included in the study. All subjects underwent a comprehensive eye examination, LVCS workup which included corneal topography, tomography, aberrometry, and dry eye assessment prior to binocular vision assessment. Complete Binocular vision assessment which included stereopsis, fusion for distance and near, near point of convergence, phoria measurement, vergence amplitudes and facility, accommodative amplitudes, response, and facility was performed with the best corrected vision prior to LVCS, one month and six months after the surgery.Results:Twenty-five subjects of age 23.8 ± 2.9 years were included. Age ranged from 20 to 32 years. Ten were female and 15 were male. The median spherical power was –2.00DS with an inter quartile range (IQR) of –1.50DS to –3.00DS for both eyes. The median cylindrical power was plano with IQR –0.50DC to –1.00DC for both eyes. There was a statistically significant decrease in monocular and binocular accommodative amplitudes (accounting for age-related changes) as well as positive fusional vergence recovery for near between baseline and one month after surgery (p < 0.05).Conclusion:Though subjects were asymptomatic post LVCS, still there is an indication that myopic LVCS could precipitate or aggravate an existing non-strabismic binocular vision anomaly. Comprehensive binocular vision assessment and appropriate management is recommended before and after LVCS.

Efficacy of Vision Therapy Software (CureSee) in Amblyopia

A developmental disorder of spatial vision, Amblyopia is defined clinically as a decrease in visual acuity (VA) in one, or more often in both eyes, in the absence of a clear disorder or ocular disease Amblyopia is the most common cause of monocular vision loss in children [1]. Affected individuals exhibit stereo acuity impairment and abnormal binocular summation [2]. Binocular therapies designed to improve amblyopia by binocular stimulation are highly differentiated into perceptual learning and differential training. Objective • To determine the efficacy of Vision Therapy software (CureSee) in Amblyopia. • To compare Stereopsis findings before and after VT • To compare Visual Acuity before and after VT • To compare Vergence amplitude before and after VT. Methodology: 68 Amblyopic Subjects who are visiting Ahooja Eye &amp; Dental Institute, Gurugram for eye examination and Amblyopia management were taken. Patients diagnosed with Amblyopia were included as well as Patients with Ocular surgery done within 2 months and Patients with any Ocular pathology were excluded. Verbal Consent was taken and selected patients were enrolled into CureSee Vision Therapy Software management for Amblyopia. Data is collected prior and post the use of CureSee Vision Therapy Software by patients and the collected data were decoded and tabulated using the Ms. Excel 2010 computer program and IBM Statistical Package for Social Sciences (SPSS) statistics version 23.0 was used for the analysis of data. Result and Conclusion: Visual Acuity improved significantly by 0.14 LogMar to the Median Values of Right Eye and by 0.60 LogMar to the Median Values of Left Eye. Stereopsis improved from 800 ± 520 sec of arc to 60 ± 60 sec of arc with P≤0.001. PFV and NFV also improved significantly after the use of Vision Therapy Software. Results conclude that Vision Therapy software is effective in improving Stereopsis, Visual Acuity and Vergence values in Amblyopic patients.

The Effect of Age on Binocular Vision Normative Values.

To establish a relationship between age and horizontal heterophoria, horizontal fusional vergence amplitudes, and vergence facility testing. The sample consisted of 112 patients with a mean age of 39.8 ± 14.97 years (range: 18 to 65 years) and was composed of 61 women (54.5%) and 51 men (45.5%). The non-presbyopic group included patients 18 to 39 years old (n = 49) and the presbyopic group included patients 41 to 65 years old (n = 63). Binocular vision was studied by heterophoria horizontal magnitude (prism diopters [PD]), horizontal fusional vergences amplitudes (PD), and vergence facility testing (cycles per minute [cpm]) and quantified with a combination of 3 PD base-in and 12 PD base-out prisms. Significant differences were obtained in near heterophoria with compensation (exophoria increased by 3.74 PD, t = 2.12, P < .05), distance positive fusional vergence (PFV) recovery (decreased by 2.86 PD, t = 3.03, P < .01), near PFV blur (decreased by 3.13 PD, t = 1.98, P = .05), near PFV break (decreased by 4.45 PD, t = 2.75, P < .01), near PFV recovery (decreased by 4.69 PD, t = 3.30, P < .01), and vergence facility testing (decreased by 2.63 PD, t = 2.77, P < .01). The results indicated an increase of exophoria, a decrease in near positive horizontal fusional vergences, and vergence facility was dependent on age; thus, the authors suggest that changes in the normal values should be considered for each age range. [J Pediatr Ophthalmol Strabismus. 2020;57(6):363-371.].

BYNOCS®1 – A Cloud-Based Indigenous Tele-Health Vision Therapy Software for the Assessment and Management of Binocular Vision Disorders

Background: Binocular vision assessment is an integral part of an eye and vision care practice. With the need for a user friendly, simplified, and comprehensive tool especially in this digital era, we propose a new indigenous cloudbased software, Bynocs.® This manuscript describes the technical details, the functioning of this indigenous software, and a case series demonstrating the application and efficacy of Bynocs® as a tele-health vision therapy tool. All the three cases were handled remotely through the Bynocs tele-health vision therapy platform. Case Reports: Case 1: This is a case of symptomatic convergence insufficiency who had prior compliance issues with a conventional vision therapy approach. With 10 sessions of Bynocs vision therapy focused on improving convergence amplitudes, the patient showed significant improvements in both subjective and objective parameters. Case 2: This case is of a 12 year old child with residual anisometropic amblyopia who had excellent compliance with patching therapy for 3 years but visual acuity had plateaued over the last 6 months. After 20 sessions of Dichoptic amblyopia therapy, best-corrected visual acuity (BCVA) improved by 3 log MAR lines, with improvements in stereoacuity to 100 sec of arc. Case 3: This case of a 10 year old child with residual exophoria after strabismus surgery was referred for managing the residual deviation and associated visual complaints. The child had 20/20 visual acuity in both eyes and 10 prism diopters of residual exophoria at distance and near. After 30 sessions of vision therapy, improvements in fusional vergence amplitudes was achieved along with the deviation restoring to orthophoria at both distance and near, with further improvements in stereoacuity from 400 sec of arc to 120 sec of arc. Conclusions: As tele-health is finding favor across the globe, Bynocs® can be a valuable tele-health vision therapy tool for in the management of binocular vision anomalies and amblyopia with the functionality for remote diagnosis and therapy.

Optokinetic stimulation induces vertical vergence, possibly through a non-visual pathway

Vertical vergence is generally associated with one of three mechanisms: vestibular activation during a head tilt, induced by vertical visual disparity, or as a by-product of ocular torsion. However, vertical vergence can also be induced by seemingly unrelated visual conditions, such as optokinetic rotations. This study aims to investigate the effect of vision on this latter form of vertical vergence. Eight subjects (4m/4f) viewed a visual scene in head erect position in two different viewing conditions (monocular and binocular). The scene, containing white lines angled at 45° against a black background, was projected at an eye-screen distance of 2 m, and rotated 28° at an acceleration of 56°/s2. Eye movements were recorded using a Chronos Eye-Tracker, and eye occlusions were carried out by placing an infrared-translucent cover in front of the left eye during monocular viewing. Results revealed vergence amplitudes during binocular viewing to be significantly lower than those seen for monocular conditions (p = 0.003), while torsion remained unaffected. This indicates that vertical vergence to optokinetic stimulation, though visually induced, is visually suppressed during binocular viewing. Considering that vertical vergence is generally viewed as a vestibular signal, the findings may reflect a visually induced activation of a vestibular pathway.

Perceptual effects of unequal saccadic adaptation produced by a dichoptic step.

The binocular coordination of eye movements in a three-dimensional environment involves a combination of saccade and vergence movements. To maintain binocular accuracy and control in the face of sensory and motor changes (that occur with e.g., normal aging, surgery, corrective lenses), the oculomotor system must adapt in response to manifest visual errors. This may be achieved through a combination of binocular and monocular mechanisms, including the recalibration of saccade and vergence amplitudes in response to different visual errors induced in each eye (Maiello, Harrison, & Bex, 2016). This work has used a double-step paradigm to recalibrate eye movements in response to visual errors produced by dichoptic target steps (e.g., leftward in the left eye and rightward in the right eye). Here, we evaluated the immediate perceptual effects of this adaptation. Experiment 1 measured localization errors following adaptation by comparing the apparent locations of pre- and postsaccadic probes. Consistent with previous work showing localization errors following saccadic adaptation, our results demonstrated that adaptation to a dichoptic step produces different localization errors in the two eyes. Furthermore, in Experiment 2, this effect was reduced for a vergence shift in the absence of a saccade, indicating that saccade programming is responsible for a large component of this illusory shift. Experiment 3 measured postsaccadic stereopsis thresholds and indicated that, unlike localization judgments, adaptation did not influence stereoacuity. Together, these results demonstrate novel dichoptic visual errors following oculomotor adaptation and point to monocular and binocular mechanisms involved in the maintenance of binocular coordination.

Stereoacuity, Fusional Vergence Amplitudes, and Refractive Errors Prior to Treatment in Patients with Attention-Deficit Hyperactivity Disorder

Objectives:To evaluate stereoacuity, fusional vergence amplitudes, and refractive errors in patients with attention-deficit hyperactivity disorder (ADHD).Materials and Methods:Twenty-three patients who were newly diagnosed as having ADHD and had not started medication, and 48 children without ADHD were included. Retrospective data analysis of comprehensive eye examination, stereoacuity, and fusional vergence amplitudes of the patients were performed.Results:The mean age at ADHD diagnosis was 10.68±2.34 (7-16) years in the ADHD group (14 male, 9 female) and 12.23±2.16 (7-15) years in the control group (25 male, 23 female) patients (p=0.605). The mean stereoacuity was 142.14±152.65 (15-480) sec/arc in patients with ADHD and 46.3±44.11 (15-240) sec/arc in the control group (p<0.001). For ADHD patients, the mean convergence and divergence amplitudes at distance were 19.87±8.40 (6 to 38) prism diopter (PD) and -9.09±-4.34 (-4 to -25) PD, and 37.30±12.81 (14 to 70) PD and -13.13±-3.45 (-4 to -20) PD at near, respectively. The mean cycloplegic spherical equivalent was 1.06±1.13 (-1 to 4.63) diopter in ADHD patients, with 6 patients having significant refractive errors (hyperopia in 4 patients, astigmatism in 2 patients). There were no significant differences between groups in terms of spherical equivalents (p=0.358) or convergence and divergence amplitudes at distance (p=0.289 and p=0.492, respectively) or near (p=0.452 and p=0.127, respectively).Conclusion:Fusional vergence amplitudes did not present significant difference, while the mean value of stereoacuity was significantly lower in newly diagnosed ADHD patients prior to treatment.