Accommodative Convergence Research Articles

Comparison of Four Methods for Measuring Heterophoria and Accommodative Convergence over Accommodation Ratio.

The study aimed to assess the agreement between OptoTab SERIES, alternating Cover Test, Modified Thorington test, and Von Graefe method in measuring heterophoria and accommodative convergence over accommodation (AC/A) ratio. In an initial step, heterophoria was assessed at both distance and near in a cohort of 76 healthy young volunteers using the previously described tests. Subsequently, to determine the AC/A ratio, near-vision measurements were repeated with +1.00 D and -1.00 D lenses. All tests were performed in a randomized order across participants under consistent conditions. Significant differences were found between the Modified Thorington test and all other tests at distance (Wilcoxon test, all p ≤ 0.001) and between Von Graefe and all other tests at near (Wilcoxon test, all p ≤ 0.005). Regarding the AC/A ratio, significant differences were observed between all methods in +1.00 D AC/A ratio, except for the Modified Thorington test vs. the alternating Cover Test (Wilcoxon test, p = 0.024). In the -1.00 D AC/A ratio, differences were observed between OptoTab POCKET and all the other tests (Wilcoxon test, all p ≤ 0.001). The results indicate that all methods are interchangeable except the Modified Thorington test at distance and Von Graefe at near. For the AC/A ratio, only the Modified Thorington test is interchangeable with the alternating Cover Test using +1.00 D lenses and all are interchangeable using -1.00 D lenses except OptoTab POCKET.

Frequency of Non-strabismic Binocular Vision Anomalies among Optometrists in a Tertiary Eye Care Center in Southern India.

Lifestyle in the modern era has drastically changed across the globe, and the healthcare profession was no exception. The increased time spent in the virtual space for various purposes, including online classes and webinars, is hypothesized to increase the risk of vision-related disorders such as asthenopia, dry eyes, and visual fatigue. The purpose of this study was to evaluate fusional vergence and ocular accommodation among optometry professionals in a tertiary eye care center during the immediate post-coronavirus disease 2019 (post-COVID-19) lockdown period. Optometrists posted in the general out-patient department, specialty clinics, and the ocular diagnostics department were included in the study. A total of 65 optometrists were included in the study. All optometrists underwent a comprehensive binocular vision assessment. Convergence Insufficiency Symptom Survey questionnaires were administered to all optometrists at the beginning of the assessment. Out of 65 optometrists, 48 (73.8%) were women. The mean (standard deviation) age of the participants was 24 (3) years. Eleven (16.9%) optometrists had normal binocular vision parameters, and the rest 54 (83.1%) had non-strabismic binocular vision anomalies. Reduced accommodative facility and convergence insufficiency were seen among 43 (66.2%) optometrists, whereas 30 (46.2%) had reduced accommodative facility alone. Twelve (18.5%) participants were symptomatic as per the convergence insufficiency symptom survey. This study highlights the fact that a large proportion of optometrists have undetected non-strabismic binocular vision anomalies in a tertiary eye care center. It is important for eye care professionals to undergo regular binocular vision assessments in association with ophthalmic examinations and relevant management. This will ensure that these dysfunctions do not impede work productivity and overall quality of life.

Accommodation Strategy of PT Inko Forwarding in Building a Cross-Cultural Virtual Team with Taiwanese Companies

Advancements in communication technology have opened up opportunities for companies to engage in virtual business collaborations. Establishing cross-cultural virtual teams and devising effective strategies for their operation can significantly benefit companies. The research aims to explore the challenges and hurdles faced when working in cross-cultural virtual teams, strategies for forming and managing such teams, as well as communication accommodation strategies within them. Communication Accommodation Theory serves as the theoretical framework, utilizing a descriptive qualitative approach through case study methodology. In-depth interviews were conducted for data collection. Findings reveal the implementation of convergence accommodation strategies by each virtual team studied, particularly exemplified by Inko Forwarding. The company aims to nurture business relationships with agents to achieve specific objectives by establishing networks. To succeed in these endeavors, understanding cultural nuances and employing Communication Accommodation Theory strategies to enhance communication quality within virtual teams are crucial.

Understanding accommodative control in the clinic: Modeling latency and amplitude for uncorrected refractive error, presbyopia and cycloplegia.

Accommodation is the process of adjusting the eye's optical power so as to focus at different distances. Uncorrected refractive error and/or functional presbyopia mean that sharp focus may not be achievable for some distances, so observers experience sustained defocus. Here, we identify a problem with current models of accommodative control: They predict excessive internal responses to stimuli outside accommodative range, leading to unrealistic adaptation effects. Specifically, after prolonged exposure to stimuli outside range, current models predict long latencies in the accommodative response to stimuli within range, as well as unrealistic dynamics and amplitudes of accommodative vergence innervation driven by the accommodative neural controller. These behaviors are not observed empirically. To solve this issue, we propose that the input to blur-driven accommodation is not retinal defocus, but correctable defocus. Predictive models of accommodative control already estimate demand from sensed defocus, using a realistic "virtual plant" to estimate accommodation. Correctable defocus can be obtained by restricting this demand to values physically attainable by the eye. If we further postulate that correctable defocus is computed using an idealized virtual plant that retains a young accommodative range, we can explain why accommodative-convergence responses are observed for stimuli that are too near-but not too far-to focus on. We model cycloplegia as a change in gain, and postulate a form of neural myopia to explain the additional relaxation of accommodation often seen with cycloplegia. This model produces plausible predictions for the accommodative response and accommodative convergence signal in a wide range of clinically relevant situations.

Preoperative visual function characteristics having an effect on the success of exotropia surgery

Background: There are individual reports on the effect of some preoperative characteristics of visual functions (like convergence, angle of deviation, presence of fusion and type of binocular vision) on the success of exotropia surgery. To date, however, it has not been established what are the major diagnosis-related prognostic factors for the success of surgery for exotropia. Purpose: To identify the preoperative characteristics of visual functions which have an effect on the success of surgery for exotropia. Material and Methods: Of the 59 exotropes (age range, 10 to 21 years) included in this study, 33 had basic constant exotropia (group 1) and 26, intermittent exotropia (group 2). Patients underwent an ophthalmological and ortoptic examination of the motor and sensory systems of the eye. Patients with surgery success (postoperative orthotropes) were compared to those who had a residual exotropia of more than 10 prism diopters (PD) postoperatively in terms of the preoperative accommodative convergence–accommodation (AC/A) ratio, near point of convergence (NPC), distance stereopsis and near stereoacuity threshold. Results: Our analysis of the preoperative NPC, AC/A ratio and stereopsis for the group with postoperative orthotropic alignment and the group with postoperative exotropic alignment found preoperative close to normal values of AC/A ratio (4.0 ± 1.65 PD/D), NPC (8.03 ± 3.02 cm), the presence of distance stereopsis and near stereopsis (passing the 200 second of arc image on the Lang II stereo card) and the absence of medial rectus hypofunction of hyperfunction in 83.05% of patients of the former group. Conclusion: Preoperative close to normal values of AC/A ratio (4.0 ± 1.65 PD/D), NPC (8.03 ± 3.02 cm), the presence of distance stereopsis and near stereopsis (passing the 200 second of arc image on the Lang II stereo card) and the absence of medial rectus hypofunction of hyperfunction can be the factors favoring the success of exotropia surgery.

Refractive Profile of Surgical Patients with Intermittent Exotropia: A Large-Sample Cross-Sectional Study in Southern China

Purpose To describe the refractive profile of surgical patients with intermittent exotropia (IXT) residing in southern China. Methods Medical records of patients who received strabismus surgery between June 2014 and August 2020 were retrospectively reviewed. Clinical data, including age, sex, refractive errors, preoperative angle of deviation, types of exotropia, accommodative convergence to accommodation ratio (AC/A ratio) and stereopsis, were investigated. Results A total of 2250 patients were included, and 93.6% of patients were younger than 30 years of age. The mean angle of exodeviation was 37.0 ± 14.7 prism degree (PD) and 37.5 ± 15.8 PD at distance and near, respectively. Mean spherical equivalent refraction (SER) values were -0.7 ± 2.4 D and −0.8 ± 2.5 D in the dominant eye and nondominant eye, respectively. Significant differences in SER were observed between the dominant eye and nondominant eye among children at 6 years old or younger. The percentage of myopia increased from 11.0% in children (≤6 years old) to 77.9% in teenagers (13-18 years of age). Significant positive associations between the magnitude of exodeviation and the magnitude of myopia were observed (p < 0.0001). Patients with convergence insufficiency type IXT (p < 0.0001) or AC/A < 2 (p < 0.05) showed a greater magnitude of myopia. The mild hyperopia group included a larger proportion of subjects showing a certain degree of stereopsis (p < 0.05). Conclusions Myopia was present in more than half of our patients (51.2%), which is much higher than the percentage in the general population of southern China. Patients with convergence insufficiency, an AC/A ratio < 2, or a larger angle of deviation tended to have a greater magnitude of myopia.

Predicting Subjective Discomfort Associated with Lens Distortion in VR Headsets During Vestibulo-Ocular Response to VR Scenes.

With advances in Virtual Reality (VR) technology, user expectation for a near-perfect experience is also increasing. The push for a wider field-of-view can increase the challenges of correcting lens distortion. Past studies on imperfect VR experiences have focused on motion sickness provoked by vection-inducing VR stimuli and discomfort due to mismatches in accommodation and binocular convergence. Disorientation and discomfort due to unintended optical flow induced by lens distortion, referred to as dynamic distortion (DD), has, to date, received little attention. This study examines and models the effects of DD during head rotations with various fixed gazes stabilized by vestibulo-ocular reflex (VOR). Increases in DD levels comparable to lens parameters from poorly designed commercial VR lenses significantly increase discomfort scores of viewers in relation to disorientation, dizziness, and eye strain. Cross-validated results indicate that the model is able to predict significant differences in subjective scores resulting from different commercial VR lenses and these predictions correlated with empirical data. The present work provides new insights to understand symptoms of discomfort in VR during user interactions with static world-locked / space-stabilized scenes and contributes to the design of discomfort-free VR headset lenses.

Normative Value of Accommodative Convergence to Accommodation in Indian Population Measured by Heterophoria Method

Abstract Introduction: Near response is a complex synkinesis required for a good binocular vision. accommodative convergence per diopter of accommodation (AC/A ratio) is a value of significance in this synkinetic movement. In addition, the value is used to classify and treat ocular movement abnormalities. The two commonly used methods for determining the AC/A ratio are Gradient Method and Heterophoria method. The normative data for Indian population by gradient method was described in two studies. However, the normative data for heterophoria method is lacking in Indian population. Objective: The purpose of this cross-sectional study is to generate the normative value for AC/A ratio for the Indian population by heterophoria method. One hundred healthy ophthalmologically normal adults with no presbyopia or refractive error were chosen consecutively among the attendants of patients visiting the center. Materials and Methods: After thorough ophthalmic evaluation, the participants were subjected to AC/A ratio calculation by heterophoria method using 6/9 fixation target and PMMA Prism bar. Results: One hundred healthy adults with no refractive error or ocular abnormality were selected with a mean age of 25.70 years (standard deviation [SD] = 4.92) and equal gender distribution. The mean Inter Pupillary Distance (IPD) was found to be 62.88 mm with a SD of 3.91 mm. The average phoria at distance was 1.82 prism diopters (SD = 2.03pd) of exophoria and for near at 33 cm was 4.20pd (SD = 1.92pd). The mean AC/A ratio by heterophoria method was found to be 5.49PD/D with an SD of 0.54PD/D. The highest being 6.90PD/D and the lowest being 4.27PD/D with no statistically significant difference between genders. Conclusion and Relevance: According to the previous studies, the normative data arrived is lesser than the value reached in the current study for similar population groups when considering both methodologies of testing. This variation between the gradient method and heterophoria method accounted for by the involvement of proximal convergence during the heterophoria method.

Subduction initiation at an oceanic transform fault experiencing compression: Role of the fault structure and of the brittle-ductile transition depth

It has recently been shown that among the subduction zones initiated in the Cenozoic era, the subducting oceanic lithosphere could have any age, and was as often older than the overriding plate as younger than it. To try to explain this observation, we consider the simple setup of an oceanic transform fault and perform 2D thermomechanical experiments by applying the same convergence velocity on the two adjacent plates. We combine a non-Newtonian viscous rheology and a pseudo-brittle behavior. We focus on the influence of the fault structure at convergence onset, by testing the effects of the fault gouge depth, zwz, and of the width of the thermal transition between the lithospheres, which allows for mimicking the settings of a transform fault as well as of an old fracture zone. We investigate large ranges of plate age and of plate age offset. In most of our experiments, the mode of convergence accommodation is basically a function of the gouge depth, zwz, that we compare to the mean of the 2 plate thicknesses. We observe three main behaviors: (1) failure of subduction initiation if zwz is shallow, i.e., ≲15% of the mean depth of the 2 plate bottoms if the age offset scaled by the younger age is very low (≲1) or ≲30% otherwise, (2) old plate subduction, that is best favored for ratios zwz/zTT∼0.25 and for low offsets in relative plate ages, and (3) young plate subduction if zwz is quite deep (≳40%), whatever the age offset. The thermal transition width only has a second-order effect, that facilitates subduction initiation when the transition is wide. Compressive forces are overshooting reasonable thresholds (≳1013 N/m) if at least one of the two plates is older than ∼30 Myr. The success of a young plate subduction and, to a lesser extent, of an old plate subduction, can be predicted by comparing zwz at convergence onset to the depth of the brittle-ductile transition inside the future upper plate. The subduction success and polarity depend on the possibility to form a low shear stress plane. We predict that only the young plate subduction can initiate at an active transform fault, while the old plate subduction is restricted to the setup of an old fracture zone separating two lithospheres with a small age offset scaled by the younger age. The significant predominance in our modeling of the thin plate underthrusting results from the strong influence of the plate strength contrast when lithospheres are stiff. Our experimental results are consistent with the recent records of subduction initiation at the Mussau and Hjort Trenches, as well as at the Gagua ridge (W Pacific).

80‐1: Invited Paper: Tunable liquid crystal lens for dynamic Prescription (Rx) correction and Accommodation‐Convergence (AC) conflict correction in AR/VR/3D HMDs

While the near‐to‐eye HMDs are advancing in display resolution, there are active challenges related to accommodation‐convergence (AC) conflict correction as well as prescription correction (Rx). Many approaches are reported previously to solve AC conflict using variable focal lenses, however, very few of them included dynamic Rx correction. While AC correction requires only adjustment of focal plane, Rx correction requires simultaneous correction of focal length and astigmatism. In this report, we have shown concept, design, fabrication, and demonstration of liquid crystal based tunable lens that is capable of dynamic correction of both the issue without needing any mechanical moving parts. The device is lightweight, thin, flat, low voltage driven and has potential to replace the eyeglasses worn by the users with the HMDs.

Призматическая коррекция остаточного или рецидивирующего косоглазия

Introduction. Recurrent strabismus is a common issue after operations because of heterotrophy. Many scientific works have examined clinical parameters that may predispose to relapse of esotropia after surgery, including poor sensory status, high ratio of accommodative convergence to accommodation, uncorrected farsightedness or combination of these factors. Purpose. To evaluate the effectiveness of prismatic correction of recurrent esotropia in patients after the first stage of surgical treatment. Material and methods. The study group included 24 patients. They were divided into two groups in depends on the postoperative functional treatment. 1st group consisted of 12 patients with partially accommodative esotropia aged 5 to 8 years (6,48 ± 1,12 years) with average hypermetropic refraction +3,10 ± 0,54 diopters. This group of patients was assigned prismatic correction after a relapse of esotropia. 2st group consisted of 12 patients with partially accommodative esotropia aged 5 to 8 years (6,22 ± 1,29 years) with average hypermetropic refraction +3,13 ± 0,61 diopters. This group of patients was assigned orthoptic treatment after a relapse of esotropia. Results. Prismatic correction contributed to recovery binocular vision at 75 % of patients with recurrent esotropia ≤ 20 PD, in the comparison group (orthoptic treatment) – at 50 %. Moreover, the number of patients with stereopsis in the group «EFP» after the treatment was higher than in the group «Synoptophore» (p &lt; 0,05). Conclusion. Prismatic correction ensures optimal motor status while maintaining sufficient sensory balance in most patients with recurrent esotropia after performing recession rectus medialis in combination with median duplication m. rectus lateralis. Keywords: Recurrent strabismus, binocular vision, elastic Frensel prism

Binocular vision parameters and body mass index

Background: Abnormal body mass Index (BMI) can adversely affect binocular vision. We aimed to assess the presence of possible differences in binocular vision parameters among the four BMI categories.&#x0D; Methods: In this comparative cross-sectional study, we enrolled young adults and categorized them into underweight, normal weight, overweight, and obese groups based on their BMI. A complete orthoptic evaluation was performed to assess the mean values of binocular vision skills.&#x0D; Results: We recruited 120 participants with a mean (standard deviation) age of 21.30 (1.80) years with best-corrected distance and near visual acuities of 6/6 and N6, respectively. The frequency of exophoria &gt; 4 PD was high in the obese group. The frequency of binocular vision dysfunction was higher in the obese and underweight groups, with vergence dysfunction being the most common. The mean values for near negative fusional vergence (NFV), distance positive fusional vergence (PFV), negative relative accommodation, positive relative accommodation, monocular accommodation facility (AF), and monocular estimation method were comparable among the groups (all P &gt; 0.05). The obese group had significantly receded near point of convergence, and reduced accommodative convergence to accommodation ratio and binocular AF than the normal, overweight, and underweight groups (all P &lt; 0.05). The distance and near vergence facilities were significantly lower in the obese group than in the overweight and normal groups, and the distance vergence facility was significantly lower than in the underweight group (all P &lt; 0.05). The mean values of distance NFV and near PFV in the obese group were significantly lower compared to the normal and overweight groups, and the mean values of distance NFV were significantly lower compared to the underweight group (all P &lt; 0.05). The mean values of near PFV were significantly lower in the underweight group than in the overweight group (both P &lt; 0.05). Both the underweight and obese groups had a significantly lower amplitude of accommodation compared to the normal group (both P &lt; 0.05).&#x0D; Conclusions: The frequency of binocular vision dysfunction was higher in the obese and underweight groups. Most convergence and some accommodation parameters were adversely affected in individuals with obesity. Being underweight adversely affects certain binocular vision skills. Further studies are required to determine the relevance of BMI as a predictor of binocular vision abnormalities.

Routine binocular examination of young Taiwanese adults as a predictor of visual behavior performance

BackgroundMorgan and Scheiman’s Optometric Extension Program (OEP) expected binocular vision findings have longstanding use in optometry. With technological advances, the demands and standards of binocular function have changed. This study aimed to investigate which binocular visual functions can effectively predict visual behavior performance.MethodsParticipants aged 15–24 years were recruited from two colleges and two universities. After completing the CSMU-Visual Behavioral Performance questionnaire (CSMU-VBP, with four components: near work, visual perception, visual comfort, and whole-body balance), participants were divided into symptomatic and asymptomatic groups based on questionnaire findings (cutoff: < 12 vs. ≥ 12 symptoms). Then a 24-step binocular visual examination was undertaken. Data were analyzed with one-sample, Student’s, and paired t-tests. Additionally, receiver operating characteristic analysis was used to determine the predictors of binocular visual function required for near work, visual perception, visual comfort, and body balance dimensions.ResultsAmong 308 participants, 43 (14%) and 265 (86%) were symptomatic and asymptomatic, respectively. Among the 46 participants with abnormal binocular vision, 36 (78%) reported that they had no obvious symptoms. The commonest dysfunctions were accommodative excess and convergence excess. Most of the binocular visual findings significantly diverged from traditional normal values: amplitude of accommodation, as well as base-in prism to break and recovery points at distance were higher than traditional normal values, whereas others were lower than traditional normal values. Total CSMU-VBP scores indicated that the asymptomatic and symptomatic groups had significant differences in DBO recovery (t = 2.334, p = 0.020) and BAF (t = 1.984, p = 0.048). Receiver operating characteristic curve analysis yielded the following binocular visual functional cutoff points: near work (DBO blur < 7, DBO recovery < 5.5), visual perception (MAF < 10.5, BAF < 10.25), visual comfort (DLP < − 2.25, DBI break > 11.5, NBI blur > 15, NBI break > 17.5, NBI recovery > 13, NPC < 5.75), and body balance (NFD_H > − 0.5, gradient AC/A [minus] > 2.25, NPC < 4.75).ConclusionsThe mean values of binocular visual function among young Taiwanese adults were statistically different from traditional normative values. Further research is required to confirm whether these findings reflect impaired binocular vision or stringent criteria. Assessments of binocular visual function, especially binocular accommodation sensitivity, are crucial in routine optometric examination.

Vergence and accommodation responses in the control of intermittent exotropia.

Individuals with different types of intermittent exotropia (IXT) may use neurally coupled accommodation and vergence responses differently from those without exotropia to achieve eye alignment. This study examined the relationship between simultaneously recorded accommodation and vergence responses in children and young adults with a range of types of IXT while aligned and deviated. Responses of 29 participants with IXT (4-31 years) and 24 age-matched controls were recorded using simultaneous eye-tracking and eccentric photorefraction while they watched a movie in binocular or monocular viewing at varying viewing distances. Gradient response AC/A ratios and fusional vergence ranges were also assessed. Eight participants had divergence or pseudo-divergence excess type IXT, 5 had convergence insufficiency and 16 had basic IXT. Control and IXT participants accommodated similarly both in monocular and binocular-aligned conditions to visual targets at 80 and 33 cm. When deviated in binocular viewing, most participants with IXT exhibited changes in accommodation <0.5D relative to alignment. Gradient response AC/A ratios were similar for control [0.56 MA/D (IQR: 0.51 MA/D)] and IXT participants [0.42 MA/D (0.54 MA/D); p = 0.60]. IXT participants showed larger vergence to accommodation ratios with changes from distance to near fixation [1.19 MA/D (1.45 MA/D)] than control participants [0.78 MA/D (0.60 MA/D); p= 0.02], especially among IXT participants with divergence or pseudo-divergence excess. Participants with IXT exhibited typical fusional divergence ranges beyond their dissociated position [8.86 Δ (7.10 Δ)] and typical fusional convergence ranges from alignment [18 Δ (15.75 Δ)]. This study suggests that control of IXT is typically neither driven by accommodative convergence alone nor associated with over-accommodation secondary to fusional convergence efforts. These simultaneous measurements confirmed that proximal vergence contributed significantly to IXT control, particularly for divergence or pseudo-divergence excess type IXT. For IXT participants in this study, achieving eye alignment did not conflict with having clear vision.

The impact of visual environment on the evolution of myopia

Our study represents the impact of the visual environment on the evolution of myopia. We established a statistical study of different types of myopia in Morocco. We classed with degrees of myopia. The long-term work of near vision increases a vision-postural stress leads to an increase in accommodative visual stress and convergence, and the correction with traditional lenses leads to hyperopic defocusing peripheral, which stimulates the elongation of the optical axis [1, 4]. We found that the number of myopia is changing during the four years of study and that the correction by traditional lenses does not allow us to slow down the evolution of myopia., this type of management and the visual environment leads us to an increase in the degrees and number of myopia during the four years. The increase in the power of myopia can lead to a pathological state that is preoccupant. We find that the visual environment has an impact on the increase of different types of myopia, especially average myopia in young people. So we have to try new alternatives for myopia compensation as special lenses for myopia braking and orthokeratology lens contact as well as behavioral and environmental measures to decrease visuals.

Comparing the AC/A Ratio with spectacles and soft contact lenses in Myopes

Purpose: To compare accommodative convergence over accommodation (AC/A) ratio when Myopic patient changes from Spectacles to Contact lenses. Methods: A prospective, cross-sectional study group of 50 subjects and Myopic error from -0.75DS to -6.00DS. The AC/A ratio was measured by two methods; the heterophoria method and the gradient method. Gradient method was measured by plus and minus Lenses technique. Heterophoria in near and distance was measured to calculate heterophoria method. Wilcoxon Signed Ranks Test was used to compare between two methods p value < 0.05. Results: The mean AC/A ratio in Gradient method when using Soft Contact Lenses in comparison to Spectacles was: with+3(2.21,2.24), and with-3(1.51,150) respectively. Although the AC/A ratio was less in amount with +3D lens in near and more in distance with -3D lens as compared to Spectacles, there were no significant differences found between the two (P:0.285 and P:0.317 respectively). The means of AC/A ratio as calculated by Heterophoria method was increased with soft contact lenses (5.97) as compared to spectacles (5.96) with no significant difference p: 0.317 Conclusion: No significant difference has been found for myope when changing from spectacles to contact lenses.

Preliminary study for Neurovisual Assessment Model using Eye Tracking (NAMET) related to cognitive functions for TBI patients

Introduction: Traumatic brain injury can cause visual dysfunction (if not treated with visual therapy) and it can hinder a patient's rehabilitative progress. Screening for a Visual processing assessment to identify visual symptoms in TBI patients at the HCFMUSP Neurology Clinic. Previous literature presents common visual symptoms that were identified in these patients, such as: visual field loss, double vision, posture and balance difficulties, blurred vision, attention and concentration problems difficulties in near visual tasks, headaches, reading difficulties, reading problems. motor coordination problems, difficulties locating objects accurately. accommodative dysfunction convergence insufficiency This study presents a Neuro Visual assessment model for visual and cognitive rehabilitation following TBI and it can include Visual Acuity (VA) Visual Field, eye movements (Eye Tracking), Accommodation and Convergence. Results: In the preliminary study, similarity was found between existing literature and visual dysfunctions from patients following TBI. Conclusion: The assessment protocol following TBI can identify changes in saccadic eye movements, segments and their impacts on cognitive functions, sensory, motor and emotional systems. The treatment to improve visual dysfunctions can improve Reading problems; oculomotor, balance and binocular disorders using prisms, lenses and filters for both attention and concentration difficulties. Literature shows cases of improvement post-TBI visual symptoms using nonfunctional lenses, prisms, filters, binasal occlusions. Previous literature can found cases of improvement of depressive symptoms, aggressive behavior, self-confidence, self-esteem, posture and balance.

Functional magnetic resonance imaging activation for different vergence eye movement subtypes.

Maddox suggested that there were four convergence subtypes, each driven by a different stimulus. The purpose of this study was to assess the neural correlates for accommodative convergence, proximal convergence (convergence stimulus provided), disparity convergence and voluntary convergence (no specific convergence stimulus provided) using functional magnetic resonance imaging (fMRI). Ten subjects (mean age=24.4 years) with normal binocular vision participated. The blood oxygenation level-dependent (BOLD) signals of the brain from fMRI scans were measured when subjects made vergence eye movements while: (1) alternately viewing letters monocularly where one eye viewed through a -2.00 D lens, (2) alternately viewing Difference of Gaussian targets monocularly at distance and near, (3) viewing random dot stereograms with increasing disparity and (4) voluntarily converging the eyes with binocular viewing. The accommodative convergence paradigm resulted in activation on the right side in the right fusiform cortex and the right middle occipital cortex. The proximal convergence stimulus mainly activated areas in the right occipital lobe. The disparity stimulus activated areas in the left occipital cortex and the left frontal cortex. Finally, the voluntary convergence paradigm resulted in activation primarily in the occipital lobe and mostly bilaterally. The accommodative, proximal, disparity and voluntary convergence paradigms resulted in activation in unique areas in the brain with functional MRI. Activation was found in more areas in the proximal and voluntary conditions compared with the accommodative and disparity conditions.

Assessment of distance-near control disparity in basic and divergence excess paediatric intermittent exotropia

ABSTRACT Clinical Relevance In intermittent exotropia (IXT), deviation is better controlled at near fixation. Understanding of the mechanism responsible for this common observation may improve clinical management of IXT. Background The physiological basis for the distance-near difference in control of deviation in IXT is vastly undetermined. A new parameter, ‘control score disparity (CSD)’, defined as the difference between distance and near control scores, is introduced. Association of CSD with positive fusional amplitude (PFA), accommodative convergence to accommodation (AC/A) ratio and distance angle of deviation was investigated to further understand the mechanisms. Method Patients aged between four and fifteen years with basic and divergence excess IXT were included. Subjects with previous strabismus surgery, amblyopia and inability to perform clinical tests were excluded. A standardized office-based scoring system was used to assess IXT controls. Subjects were sub-divided into group 1 (CSD <2) and group 2 (CSD ≥2). Pearson’s univariate and regression analysis were used to determine relationships between CSD and other independent variables. Results Mean age of the total 141 subjects (57.6% female) was 6.8 ± 2.5 years. Basic IXT was more common (60%) and 60% had CSD ≥2. The mean±SD distance angle of deviation, AC/A ratio, PFA and CSD were 22.1 ± 6.6 prism dioptres, 5.0 ± 1.0, 28.6 ± 6.3 prism dioptre and 2.0 ± 0.5, respectively. CSD was significantly correlated to PFA (r = 0.64, p < 0.001) and AC/A ratio (r = 0.27, p < 0.001) in overall samples and Group 2 subjects (r = 0.41, p = 0.001). Conclusions PFA is a major factor associated with the distance/near difference of IXT control. Individuals with a higher PFA demonstrated greater CSD. While AC/A ratio was associated in better control at near in divergence excess IXT, magnitude of angle appears irrelevant.

Clinical features and treatment of near-work-related acquired esotropia.

To investigate the characteristics of near-work-related esotropia and the clinical efficacy of botulinum toxin type A (BTXA) injection therapy on it. A total of 107 patients aged 15-57y with near-work-related esotropia were taken as the BTXA-treated group, and 30 other peers without near-work-related esotropia were included in the control group. All participants were refractive corrected to analyse the clinical characteristics of near-work-related esotropia. All subjects were examined including Worth4 spot examination, stereoscopic vision, strabismus angle, accommodative convergence to accommodation ratio (AC/A), far and near positive and negative convergence, positive and negative fusion range, positive and negative relative accommodation. Clinical efficacy was evaluated at a period of 10mo follow-up. The distant and near stereopsis were found in 84.9% and 77.5% of patients in the BTXA-treated group, respectively. In the control group, all patients had distant and near stereopsis. The incidence of taking off one's glasses to see close objects was significantly higher in the BTXA-treated group than in the control group (P<0.05). The BTXA-treated group showed a smaller range of in-fusion (9.84±5.72)° than the control group (22.04±8.71)° (P<0.05). The near esotropia angle of the BTXA-treated group (17.08±11.98)Δ was significantly smaller than the distant esotropia angle (19.07±11.68)Δ (P<0.05). Ten months after injection, the diplopia and esotropia of most patients underwent improvements after treatment (P<0.05). This study reveals that the accommodation function and the habit of near work without wearing spectacles are associated with near-work-related esotropia, while the length of time for near work and the onset time are independent of near-work-related esotropia. Additionally, BTXA injection therapy plays a vital role in relieving diplopia and restoring eye position.