Binocular Vision Disorders Research Articles

When noise becomes signal: a study of blink rate using an eye tracker

PurposeAlthough blink rate is considered important for digital eye strain and dry eye conditions, its assessment has been mostly manual. This study aimed at quantifying blink rate automatically using the Eyelink 1000 Plus eye tracker and comparing it with manual counting. Additionally, blink rate was correlated with reading eye movements and reading speed. MethodsThirty participants (mean age 26.8±3.5 years; 19 females) were enrolled. An on-screen reading task for 3 minutes duration, was repeated 3 times with a 2-minute break between the repetitions. During this task, eye movements and blinks were measured through the Eyelink 1000 Plus eye tracker. The blink was also counted manually by the examiner in real time from a video feed. ResultsThe blink rate obtained by the eye tracker (median [Q1, Q3]:11.7 [6.8,15.5] blinks/min) and manual counting (11.6 [7.1, 15.4] blinks/min) were comparable (p>0.5). No significant correlations were observed between the blink rate and any of the reading eye movement parameters except saccadic amplitude (Spearman's rho, rs =0.506). No statistically significant correlation was found between the blink rate and reading speed. ConclusionThe Eyelink 1000 Plus eye tracker gives a comparable blink rate compared to that obtained through manual counting. A positive correlation between the blink rate and saccade amplitude could indicate a coupled interaction between the two mechanisms to minimize visual loss during reading. The option of using this tracker to investigate blinks in dry eye and binocular vision disorders can be further explored.

Convergence insufficiency prevalence in attention deficit and hyperactivity disorder children depends on the diagnosis criteria.

Attention deficit and hyperactivity disorder (ADHD) is a neurodevelopmental condition commonly seen in children and adolescents, characterised by an increase in distractibility or inattention. Several studies have noted a higher rate of visual problems in this group, especially convergence insufficiency (CI), but when using different diagnostic criteria. The aim of this study was to evaluate visual function in ADHD children and non-ADHD controls to compare the different signs for diagnosis of CI. In this prospective case-control study, a group of children aged 7-17 years, diagnosed with ADHD before the start of pharmacological treatment and matched for age and gender with non-ADHD controls were examined. Visual acuity (VA), objective and subjective refraction, accommodative amplitude and facility, heterophoria, positive and negative fusional vergences (PFV and NFV) and stereopsis were assessed. Sixty participants (30 ADHD and 30 non-ADHD controls) were evaluated. There was no significant difference between the two groups for VA, refraction and accommodative abilities. There were significant differences in PFV and NFV: PFV break/recovery values for the ADHD and control groups were 18.9/16.2∆ and 26.9/22.1∆, respectively. Respective values for NFV were 15.7/13∆ and 19.3/15.9∆. Using the three signs of receded near point of convergence (NPC), decreased PFV and exophoria 4∆ greater at near than distance, the prevalence of CI was equivalent for the ADHD and controls (p = 0.34) If only two signs were considered for the CI diagnosis, (i.e., receded NPC and decreased PFV), then prevalence was significantly greater for the ADHD group (p < 0.01). These results show a higher prevalence of binocular vision problems in the ADHD group. This suggests a relationship between vergence problems and ADHD, but the direction of this link remains unclear. Further studies with specific samples may be needed to understand fully the association between binocular vision disorders and ADHD.

New Perspective of Multi-dimensional Approach for the Management of Attention-deficit Hyperactivity Disorder: A Review

One of the most common mental diseases in childhood, attention-deficit/hyperactivity disorder (ADHD) often lasts into adulthood for many individuals. The neurodevelopmental condition known as ADHD impacts three areas of the brain: hyperactivity, impulsivity, and attention. The visual field is where attention is most affected by ADHD. Non-strabismic binocular vision disorder (NSBVD), which impairs eye coordination and makes it challenging to focus, has been linked to ADHD. Through a critical cognitive process called visual attention, humans are able to take in and organize information from their visual environment. This greatly affects how one observes, processes, and understands visual information in day-to-day living. Vision therapy is a non-invasive therapeutic approach that aims to improve visual talents and address visual attention deficits. This study aims to provide an overview of the research on the many approaches to treating ADHD, the relationship between NSBVD and ADHD, and whether vision therapy is a viable treatment option for ADHD. After a comprehensive search of many online resources, relevant studies were found. The review's findings provide insight into the range of ADHD patients' treatment choices. In order to improve treatment outcomes, non-pharmacological treatments can be employed either alone or in conjunction with medicine. Medicine by itself is insufficient and has several severe side effects when used continuously. The efficacy of vision therapy in improving visual attention and making recommendations for potential directions for further research in this field. Multiple studies are needed to identify the most effective treatment modalities for achieving positive outcomes for ADHD patients.

Accommodation and vergence functions among children with dyslexia: A review of literature

Based on a qualitative study of a broad and varied body of literature, this review of literature reveals the potential roles of accommodation and vergence in children with dyslexia. With a thorough literature study, this review of literature aims to provide an all-encompassing perspective on the binocular vision parameters in children with dyslexia and its significance in clinical practice in this review, addressing the lack of a comprehensive study in this area. By summarizing the latest research, this article is a valuable resource for researchers, clinicians, educators, and individuals interested in comprehending the relationship between dyslexia and binocular vision and exploring potential connections and implications. Both original and review papers were examined by searching research databases from 1991 to 2022, including PubMed, Google Scholar, and Ovid. The ROBINS-I risk of bias assessment approach for non-randomized trials was used to evaluate the quality of the included papers. This review includes a total of eighteen articles. Because only the dyslexic population was studied in this study, all of the studies were non-randomized. Changes in Ocular parameters, the function of Accommodation, and Vergence in the dyslexic population were observed and included in this study. This review of literature provides educators and clinicians with crucial insights and awareness to enhance their understanding of the parameters associated with non-strabismic binocular vision disorders in children with dyslexia, as well as strategies for detection. Evidence-based guidelines can be created for controlling and assessing binocular vision parameters in children with dyslexia and their importance in clinical practice.

A comprehensive review of binocular vision in myopia control

Myopia is a growing problem worldwide and is particularly common among young people. Myopia is a disease that affects the retina responsible for detail in the middle eye and can lead to permanent vision loss. Myopia, a prevalent refractive error causing distant objects to appear blurred, is increasingly affecting global populations, particularly children. By 2050, it's projected that half the world's population will be myopic, largely due to genetic predispositions and environmental factors like excessive near work and limited outdoor activities. A promising approach to managing myopia is binocular vision training, which involves using both eyes to create a single, clear image, potentially slowing myopia progression. Understanding the benefits of this method is critical as we move forward, especially considering the surge in myopia cases during the COVID-19 pandemic due to increased digital device use. Research underscores the importance of addressing lifestyle and promoting outdoor activities and mitigating the impact of near work can help manage myopia progression and associated binocular vision disorders. Binocular vision training shows promise for myopia control by enhancing eye coordination, potentially slowing progression. Key factors include accommodation, AC/A ratios, and phoria, which are essential for effective diagnostics and therapy. Recent research emphasizes a holistic assessment of these elements for precise management of myopia and related binocular vision disorders in children. Understanding the mechanisms and innovative approaches of binocular vision in controlling myopia, highlighting the significance of continuous research and patient education in improving eye health.

Relation between binocular vision alteration and prehension movements in children: a scoping review.

To investigate, map, and synthesize evidence regarding the correlation between changes in binocular vision and fine motor skills among children. We conducted a scoping review of existing evidence, following the guidelines and checklist outlined in "Preferred Reporting Items for Systematic Reviews and Meta-Analyses - Scoping Reviews" (PRISMAScR). Sixteen papers were systematically included in our scoping review. A predominant focus was placed on assessing the impact of strabismus on motor skills. Most of the studies used motor test batteries for comprehensive analysis, while the remaining employed methodologies, such as questionnaires or laboratory-based tests. Vision stands as a pivotal perceptual modality essential for the optimal development of children. Alterations in visual acuity can significantly affect fine motor skills. Pediatric ophthalmology and orthoptics frequently encounter binocular vision disorders, such as amblyopia and strabismus. Our finding showed that impaired binocular vision affects fine motor skills.

Cross-cultural adaptation and validation of the Arabic convergence insufficiency symptom survey (Arab-CISS) in Saudi Arabia

Background: Convergence insufficiency (CI) is a common binocular vision disorder characterized by difficulty maintaining close visual focus. The Convergence Insufficiency Symptom Survey (CISS) is widely used to assess the presence and severity of CI symptoms, yet its applicability across different linguistic and cultural groups requires validation. This study aimed to translate, validate, and culturally adapt the CISS for Arabic-speaking populations, focusing on a sample from Saudi Arabia. Methods: Following established guidelines for questionnaire adaptation, the CISS was translated into Arabic and back-translated to ensure accuracy. The Arab-CISS underwent rigorous validation processes, including expert review and pre-testing. A sample of 104 participants from Qassim University, aged 18–40 years, was recruited with a Best-Corrected Visual Acuity (BCVA) of 0.1 (20/25) or better in both eyes. Internal consistency was evaluated using Cronbach’s alpha, and test–retest reliability was assessed through the Intraclass Correlation Coefficient (ICC). Results: The Arab-CISS demonstrated excellent internal consistency (Cronbach’s alpha = 0.88) and test–retest reliability (ICC = 0.93, 95% confidence interval (CI): 0.69–0.97). The Bland–Altman analysis supported these findings, showing minimal mean difference between test and retest scores (−0.1 ± 1.51), indicating stable and consistent responses over time without significant bias. Conclusion: The Arab-CISS is a reliable and valid instrument for assessing CI symptoms among Arabic-speaking individuals. Its introduction is a significant step toward improving the diagnosis and management of CI in Arabic-speaking populations.

Orbicularis oculi muscle activity during computer reading under different degrees of artificially-induced aniseikonia.

Aniseikonia is a binocular vision disorder that has been associated with asthenopic symptoms. However, asthenopia has been evaluated with subjective tests that make difficult to determine the level of aniseikonia. This study aims to objectively evaluate the impact of induced aniseikonia at different levels on visual fatigue by measuring the orbicularis oculi muscle activity in the dominant and non-dominant eyes while performing a reading task. Twenty-four collegiate students (24.00 ± 3.86 years) participated in this study. Participants read a passage for 7 minutes under four degrees of aniseikonia (0%, 3%, 5% and 10%) at 50 cm. Orbicularis oculi muscle activity of the dominant and non-dominant eye was recorded by surface electromyography. In addition, visual discomfort was assessed after each task by completing a questionnaire. Orbicularis oculi muscle activity increased under induced aniseikonia (i.e., greater values for the 10% condition in comparison to 0%, and 3% conditions (p=0.034 and p=0.023, respectively)). No statistically significant differences were observed in orbicularis oculi muscle activity for the time on task and between the dominant and non-dominant eyes. Additionally, higher levels of subjective visual discomfort were observed for lower degrees of induced aniseikonia. Induced aniseikonia increases visual fatigue at high aniseikonia degrees as measured by the orbicularis oculi muscle activity, and at low degrees as measured with subjective questionnaires. These findings may be of relevance to better understand the visual symptomatology of aniseikonia.

A Systematic Review and Meta-analysis of Convergence Insufficiency Prevalence and Management Options

Background: Convergence insufficiency (CI) is one of the most common binocular vision disorders. The condition negatively affects the quality of life through its impact on near activities, while there is a large gap in the information on its global prevalence and consensus on treatment. Objectives: The purpose of this systematic review and meta-analysis was to assess the prevalence and treatment options available for convergence insufficiency. Methods: The study was performed in 2023 using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA-2020) guidelines. The authors have searched Google Scholar, Research Gate, Scopus, PubMed, Index Medicus, Web of Science, and the JAMA network. This review included peer-reviewed studies published between January 2000 to January 2023 that assessed the prevalence and treatment modalities of convergence insufficiency. Results: The authors screened 13250 studies, 20 for prevalence and 15 for treatment from 12 countries that met the inclusion criteria for the study. The overall pooled prevalence of convergence insufficiency was 7.98%, and the heterogeneity between the studies was highly significant P &lt; 0.0001. Majorities of the studies 12(80%) reported that office-based vision therapy is the most effective treatment of CI, form those studies 5(42.0%) highlighted that office-based vergence/accommodative therapy with home reinforcement is the best modality of treatment. Whereas, home-based pencil push-up therapy, vision therapy with modified refractive correction, and vision therapy with prismatic correction were reported as effective treatment options for CI. The reviewed studies showed that vision therapy is highly effective to recover from symptomatic CI in both adults and children. Conclusion: The prevalence of convergence insufficiency was high, there was highly significant heterogeneity between the reviewed studies. Office-based vergence/accommodative therapy with home reinforcement is the best modality of treatment, followed by home-based pencil push-up therapy, vision therapy with modified refractive correction, and vision therapy with prismatic correction. There is consensus among reviewed studies that vision therapy is highly effective to recover from symptomatic CI in both adults and children.

Clinical features of Sudanese patients presenting with binocular vision anomalies: A hospital-based study.

Binocular vision anomalies are major causes of asthenopia symptoms, particularly among the younger population. This study aimed to report the clinical characteristics of Sudanese patients with binocular disorders who attended the orthoptic clinic at Al-Neelain Eye Hospital. In this retrospective hospital-based study, we analyzed data from 304 patients with binocular vision anomalies who visited the orthoptic clinic between October 2020 and June 2021. We collected information on demographics, symptoms, and eye tests such as visual acuity (VA), refractive error (RE), angle of deviation, and the assessment of fusional vergence. Our findings indicated that exophoria was the most common binocular vision anomaly, affecting 79.8% of males and 71.6% of females (p=0.731). Children between 6 and 17 years old showed the highest prevalence of exophoria (75.9%) (p=0.0001). Among patients with exophoria, 100% reported itching associated with tearing during fixation, while 89.5% experienced difficulty in fixation. Refractive error varied by the type of binocular vision disorders (p=0.0001), with higher hyperopia observed in cases of unilateral esotropia and alternate esotropia (+3.571±1.238 D and +3.023±1.553 D, respectively). Positive fusional vergence (PFV) differed by types of binocular vision disorders (p=0.0001) with high PFV in esophoria (18.063±6.848∆) compared to low PFV in exophoria (12.80±5.313∆). The most common types of exophoria were convergence weakness exophoria (45.39%), followed by convergence insufficiency (20.39%). The study concluded that exophoria was the most common binocular vision anomaly among Sudanese patients, with convergence weakness and convergence insufficiency being the predominant anomalies. Headache was commonly prevalent among patients with binocular vision problems. Higher hyperopia was found in esodeviation, while low PFV was associated with exodeviation.

Extended perceptive field revealed in humans with binocular fusion disorders

Binocular vision disorders or dysfunctions have considerable impact on daily visual activities such as reading. Heterophoria (phoria) is a latent eye misalignment (with a prevalence of up to 35%) that appears in conditions that disrupt binocular vision and it may affect the quality of binocular fusion. Our recent study, which used lateral masking (LM), suggests that subjects with binocular fusion disorders (horizontal phoria) exhibit an asymmetry and an abnormal pattern of both binocular and monocular lateral interactions, but only for the horizontal meridian (HM). The perceptive field (PF) is the fundamental processing unit of human vision and both masking and crowding depend on its size. An increased PF size is found in amblyopic populations or in young children. We hypothesized that the PF’s size would be asymmetric only for the phoric group (larger along the HM). We estimated the PF’s size using two different methods (LM with equal-phase and opposite-phase flankers). Phoric subjects exhibited a larger binocular PF size, only for the HM, confirming our hypothesis of an asymmetric PF size. However, the monocular PF size of phoric and control subjects was similar. Phoria affects the PF’s size similarly to meridional amblyopia but without being attributed to abnormal refraction. We suggest that these findings could help explain the inter-observer variability found in the masking literature and the reading difficulties often encountered in subjects with high heterophoria. Since perceptual learning can reduce the PF’s size, further investigation of training may provide a novel therapy to reduce some symptoms related to heterophoria.

A case of fusional vergence disorder associated with myopia

Aim: This case study demonstrates the management options for fusional vergence dysfunction (FVD) and uncorrected myopia. Background: Binocular vision disorder with abnormalities in fusional vergence dynamics is referred to as “fusional vergence dysfunction (FVD).” A patient with FVD has asthenopic symptoms, no refractive error, healthy eyes, normal accommodative functions, a normal accommodative convergence/accommodation ratio, and normal distant and near phoria status. Case presentation: A 19-year-old female diagnosed to have FVD along with simple myopia presented to the clinic with a complaint of asthenopic symptoms. Complete vergence-related and accommodation-related vision therapies were advised and provided. After 2 months from the initial presentation, the patient successfully recovered from the existing condition. Conclusion: Uncorrected myopia with FVD was determined based on the patient’s complaint and the results of the examination. The condition was treated with vision therapy and a distance optical correction. An office-based and home-based program can successfully cure FVD.

Prevalence of vision conditions in children in a very remote Australian community

ABSTRACT Clinical relevance Understanding the prevalence of vision conditions in a population is critical for determining the most appropriate strategies for detecting and correcting eye conditions in a community. This is particularly important in very remote regions where access to vision testing services is limited. Background Although recent studies have provided detailed analyses of the prevalence of vision conditions in Aboriginal and/or Torres Strait Islander children in urban and regional areas of Australia, there is a paucity of research examining vision conditions in children in remote regions. Importantly, a significant proportion of the population in remote and very remote regions identify as Aboriginal and/or Torres Strait Islander people. Methods Comprehensive eye examinations were provided to 193 primary school children in a very remote Australian region. Ninety eight percent of children identified as Aboriginal and/or Torres Strait Islander. The eye examination included measures of visual acuity, cycloplegic autorefraction, binocular vision and accommodative function, ocular health and colour vision. Previous history of eye examinations and refractive correction were assessed through parental questionnaire. Results Although the average unaided vision in the population was good (mean: 0.02 ± 0.13 logMAR) and the prevalence of reduced unaided visual acuity (>0.3 logMAR in either eye) was low (4%), vision conditions were detected in 32% of children. The most common conditions were clinically significant refractive errors (18% of children) and binocular vision or accommodative disorders (16%). Of the total population of children tested, 10% had previously had an eye examination, and 2% were reported to have previously been prescribed spectacles. Conclusions In this population of children in a very remote Australian region, up to 1 in 3 children had a vision condition, with many of these conditions being uncorrected and undetected. These findings highlight the important need for additional resources to be made available to very remote communities for the detection and correction of vision conditions in childhood.

PENYULUHAN TENTANG PENTINGNYA PENERAPAN INTERVENSI TRIK 20-20-20 DALAM PENCEGAHAN COMPUTER VISION SYNDROME PADA MAHASISWA FAKULTAS KESEHATAN MASYARAKAT

It is worried that the increasing use of gadgets during the Covid-19 pandemic will pose a health threat, especially for students studying online. One of the things that often occurs due to excessive use of tools called computer vision syndrome (CVS), is one of the eye problems that causes serious eye disorders. This CVS refers to prolonged close work that a person experiences during or in connection with computer use. The most common visual symptoms reported by computer users are double vision and blurred vision at near, far and medium distances. Common causes of blurred computer use include refractive errors, accommodation disorders (impaired focusing system of the eye), presbyopia (decreased ability to focus at longer distances with age), and binocular vision disorders (impaired binocular alignment). Musculoskeletal symptoms commonly experienced by computer users include neck, back, shoulder, wrist, and finger pain. Computer posture errors are an important factor associated with musculoskeletal symptoms. The American Optometric Association recommends performing the 20-20-20 trick every 20 minutes, focusing the eyes at a distance of 20 feet (6 meters) for the remaining 20 seconds, this trick is especially helpful for the following. Solve the problem. Symptoms of CVS experienced by computer users.This activity was held at the Auditorium of the DELI HUSADA Institute of Health in September 2021. The entire academic community at the Faculty of Public Health who attended the meeting was very enthusiastic. The counseling activity has been able to increase the knowledge of participants at the DELI HUSADA Faculty of Public Health regarding the importance of implementing the 20-20-20 Trick Intervention for the prevention of Computer Vision Syndrome.

The effect of convergence insufficiency treatment on reading performance in school age children – A meta-analysis

Introduction/purpose: Convergence insufficiency (CI) is a binocular vision disorder characterised by difficulty maintaining convergence and fixation at near. Depending on the severity of the CI, patients can present with a variety of symptoms during near vision tasks. Some studies indicate an increased incidence of CI in children with reading difficulties. Although a lot of research has been done on the effects of CI-treatments on eye-related symptoms, not much is known about its effect on performance related symptoms such as reading difficulties. The purpose of this meta-analysis is to determine if CI-treatments have a positive effect on reading performance. Methods: A search string was created to gather all relevant clinical trials on the National Centre for Biotechnology Information (NCBI) and Cochrane libraries. Only clinical trials were included that provided pre- and post treatment data on the effect of CI-treatment on reading performance in school aged children (5-18y). A total of three relevant clinical trials were found that provided pre-and post-treatment data. Results: A total of 352 subjects in CI-treatment groups across three clinical trials and 104 subjects in a placebo group provided pre-and post CI-treatment data on the improvements of reading performance in school aged children. The cumulative within-group treatment effect size (0.21(SD 0.03) [95%CI: 0.15, 0.27]) and the cumulative within-group placebo effect size (0.22(SD 0.05) [95%CI: 0.13, 0.32]) for the improvement of reading performance after CI-treatment in school aged children with CI was calculated. Conclusion: CI-treatment has little to no true effect size on reading performance. Though CI-treatments will cause an increase in reading performance, this is likely caused by improvements in attention, motivation, or other psychological factors (placebo effect).

EVALUATION OF STEREOVISION FINDINGS USING THE TITMUS TEST IN CHILDREN AND ADOLESCENTS WITH REFRACTIVE ERRORS

The purpose of the study: to evaluate the indicators of stereovision using the Titmus test for an accurate assessment of stereovision and its correction in children and adolescents. Materials and methods. The study was carried out in 143 patients (286 eyes), including 73 girls (51.0%) and 70 boys (49.9 %). The participants were divided into two groups: the first group involved 6 children with myopia and 11 children with hypermetropia; the second group included 126 people with astigmatism. The second group with astigmatism (252 eyes) included 24 children with myopic astigmatism (19.04 %), 92 children with hypermetropic astigmatism (73.01 %) and 10 people (7.93 %) with mixed astigmatism. All patients of the two groups underwent advanced testing of visual functions that involved a series of the following procedures: visiometry with distance correction, autorefractometry (assessment of spherical refraction and astigmatism using an autorefractometer) before and after cycloplegia, assessment of binocular vision by four-point color test, Worthtest test, (assessment of the nature of vision), heterophoria measurements (cover test), ophthalmoscopy with a dilated pupil (diagnosis of the retina and optic nerve). Results. All 143 patients (286 eyes) were examined by using the Titmus test. The findings obtained showed that gross changes were observed in 14 (5.6 %) patients with astigmatism in the first group and pronounced changes were found in 81 (45.0 %) patients with hypermetropic astigmatism in the second subgroup. In this study, the Titmus test was carried out at medium distances that should be taken into account when assessing stereovision by graded tests. Conclusion. The use of the Titmus test can significantly improve the accuracy of measuring stereovision indicators; it makes screening procedures more comfortable and increases the effectiveness of timely diagnosis of binocular vision disorders. Screening examination of stereovision is promising, as it will significantly improve the quality of screening diagnostics of stereoscopic perception.&#x0D; Overall conclusions show that the Titmus test is reliable and valid, and can be used to improve the accuracy of measuring stereovision, make screening procedures more comfortable and enhance the effectiveness of timely diagnosis of binocular vision disorders. Screening examination of stereospecies is promising as it will significantly improve the quality of eye health monitoring.&#x0D; Prospects for further research imply the development of methods for correcting the most common functional disorders.

Monocular Depth Estimation (Literature Review)

Background. The physiological basis of spatial perception is traditionally attributed to the binocular system, which integrates the signals coming to the brain from each eye into a single image of the three-dimensional outside world. The perception of three-dimensionality, however, is also possible due to the evolutionarily older monocular system of spatial perception. Normally, the binocular mechanism plays the leading role in depth perception, and its violations lead to a shift towards the monocular. In this regard, one of the relevant areas of ophthalmology and neurophysiology is the study of the features of monocular depth estimation in normal conditions and cases of ophthalmic pathology.Purpose: to study the literature data on the monocular depth estimation mechanism, methods of its assessment, as well as the peculiarities of its manifestations in normal conditions and cases of ophthalmic pathology.Materials and methods. The literature analysis of publications on PubMed, eLibrary, Cyberleninka and crossref metadata search was carried out.Results. The review considers modern ideas regarding monocular depth cues that can ensure the effective operation of the monocular mechanism of spatial vision. The stereokinetic effect (SE) is considered in detail. The possibilities of using SE assessment methods to evaluate the state of spatial vision mechanisms in cases of ophthalmic and neurological pathology have been studied.Conclusion. There are a number of monocular depth cues that can ensure the effective operation of the monocular mechanism of spatial vision, such as: perspective, light and color effects, accommodation and knowledge of the true sizes of the objects acquired with experience. Stereokinetic effect caused by the successive displacement of projections of circular eccentric images on the retina, which allows to evaluate relationship of monocular and binocular mechanisms of spatial perception, has a particular importance for ophthalmology practice. In patients with binocular vision disorders (amblyopia and strabismus), a decrease in monocular and an increase in binocular SE indicators were observed, whereas only a decrease in monocular indicators is more typical for organic ocular fundus pathology. At the same time, changes in SE indicators can serve as additional criteria for evaluating the efficacy of functional treatment of binocular disorders.

Clinical Management of Monofixation Syndrome due to Microtropia

BACKGROUND: Monofixation syndrome is a binocular vision disorder characterized by peripheral fusion with a central suppression of one eye due to smallangle strabismus (microtropia) or anisometropic amblyopia. Reduced stereopsis and acuity are noted in the non-fixating eye. Although often left untreated due to good cosmetic appearance, central suppression and reduced stereopsis can affect visual performance, comfort, and depth perception. CASE REPORT: EJ, a 17-year-old Caucasian female was previously treated for amblyopia of the left eye (OS) with glasses and patching since age 8 with no improvement to vision. EJ experienced the following symptoms: blurred vision at near when reading, blurred vision at far distances, eye pain and fatigue, difficulty copying from the board, difficulty seeing at night while driving, and poor depth perception. Entering uncorrected visual acuity was 20/20-2 OD and 20/50-2 OS with Snellen Letter Chart. Near uncorrected acuity was 20/20 OD and 20/200 OS with a reduced Snellen chart at 40 cm. Microtropia of 2 to 12 prism diopters of esotropia, eccentric fixation on visuoscopy, and central suppression on various tests were measured. EJ was diagnosed with monofixation syndrome, monocular esotropia of the left eye, strabismic amblyopia of the left eye, suppression of binocular vision (OS), and fusion with defective stereopsis. The patient completed 19 sessions of in-office vision therapy with the practice of home reinforcement activities between therapy sessions. Visual performance was reassessed after 10 and 19 sessions of vision training with improvements noted in acuity, accommodation, oculomotor accuracy and speed, eye alignment, fusional vergence skills, and stereopsis. CONCLUSION: Optometric vision therapy can decrease suppression, improve central fusional ability, visual acuity, accommodative accuracy, and stereopsis in a patient with monofixation syndrome.

Validity and repeatability of contour-based visotec distance stereoacuity test

ABSTRACTClinical RelevanceThe clinical assessment of distance stereoacuity is important in some ocular conditions. Given the different neurophysiological mechanism for crossed and uncrossed stereoacuities, evaluation of both may provide additional insight into binocular vision disorders.BackgroundClinical devices measuring distance crossed and uncrossed stereopsis are not readily available. Visotec Distance Stereo Test (VDST) is a contour-based device designed to measure both forms of distance stereoacuity. This study assesses the validity and test–retest reliability of the device in comparison to the random dot-based Randot Distance Stereo Test (RDST).MethodVDST and RDST were administered to a total of 107 children, that included 51 ‘normal’ and 56 ‘abnormal’ (37 intermittent exotropia and 19 amblyopia) between the ages of 5 and 15 years. Two examiners retested stereoacuities in a sub-set of 62 randomly selected subjects. Stereoacuity was transformed to log scale. 95% limits of agreement were calculated for test–retest reliability. The Bland–Altman plot was used to demonstrate the agreement between the tests and the examiners.ResultsThe mean ± SD crossed distance stereoacuities using VDST in normal, intermittent exotropia and amblyopic children were 93.1 ± 43.8, 161.9 ± 89.8 and 236.3 ± 122.4 arcseconds, respectively. For uncrossed stereoacuity, these were 104.7 ± 54.0, 187.6 ± 89.6 and 265.5 ± 144.0 arcseconds, respectively. Crossed stereoacuity was significantly better than uncrossed stereoacuity. 95% limits of test–retest agreement for crossed and uncrossed stereoacuities using the VDST were 0.27 and 0.30, respectively. An exact test–retest match using VDST was 84% in normals and 77% in abnormals for crossed and 83% in normal and 74% in abnormal for uncrossed stereoacuities.ConclusionVDST is a reliable, valid and easy-to-administer distance crossed and uncrossed stereoacuity measuring device. Further studies are required to establish the clinical importance of assessing these two forms stereoacuities in relation to various binocular vision disorders.

The impact of the COVID-19 pandemic, online-learning on the state of visual system and psychological state of students

The aim of this study: to identify and analyze changes in the lifestyle and psychological sphere of students who are undergoing online training in quarantine isolation due to the COVID-19 pandemic.&#x0D; Material and methods: 160 students were examined for the myopic refraction using the Duochrome Test, as well as shifts in the quality of vision as a result of online learning. All participants were also interviewed to ascertain living conditions and psychological status during domestic learning related to COVID-19 isolation.&#x0D; Result: it was found that 42.5 % participants have myopia, most of them students of 1 and 4 courses (26.5 % and 30.9 %, respectively). 85.6 % respondents noted deterioration in health after long-term visual work with personal computer and/or smartphone. The leading symptoms associated with work on digital displays were: decreased visual acuity and binocular vision disorders (81.9 %), headache (75.6 %), back muscle pain (71.9 %), eyes redness (55.6 %), dry and itchy eyes (45 % of respondents). It has been established what 75.6 % respondents indicated deterioration in their psychological condition as a result of quarantine restrictions: 68.1 % – stress, 48.8 % – emotional instability (irritability), 51.9 % – sleep disorders (insomnia), 16.3 % – depression. It is determined that daily average working time in the conditions of domestic online learning was 6.4±2.6 hours (compared to 4.1±1.7 hours in the pre-quarantine period).&#x0D; Conclusion: revealed deterioration in the quality of vision, general well-being and the psychological sphere of students who are undergoing online quarantine training due to the COVID-19 pandemic.