Vergence and Strabismus in Neurodegenerative Disorders

A Review of Ocular Movement Abnormalities in Hereditary Cerebellar Ataxias

Cerebellar ataxias are a wide heterogeneous group of disorders that may present with fine motor deficits as well as gait and balance disturbances that have a significant influence on everyday activities. To review the ocular movements in cerebellar ataxias in order to improve the clinical knowledge of cerebellar ataxias and related subtypes. English papers published from January 1990 to May 2022 were selected by searching PubMed services. The main search keywords were ocular motor, oculomotor, eye movement, eye motility, and ocular motility, along with each ataxia subtype. The eligible papers were analyzed for clinical presentation, involved mutations, the underlying pathology, and ocular movement alterations. Forty-three subtypes of spinocerebellar ataxias and a number of autosomal dominant and autosomal recessive ataxias were discussed in terms of pathology, clinical manifestations, involved mutations, and with a focus on the ocular abnormalities. A flowchart has been made using ocular movement manifestations to differentiate different ataxia subtypes. And underlying pathology of each subtype is reviewed in form of illustrated models to reach a better understanding of each disorder.

Eye movements in Parkinson's disease: from neurophysiological mechanisms to diagnostic tools

Movement disorders such as Parkinson's disease (PD) impact oculomotor function - the ability to move the eyes accurately and purposefully to serve a multitude of sensory, cognitive, and secondary motor tasks. Decades of neurophysiological research in monkeys and behavioral studies in humans have characterized the neural basis of healthy oculomotor control. This review links eye movement abnormalities in persons living with PD to the underlying neurophysiological mechanisms and pathways. Building on this foundation, we highlight recent progress in using eye movements to gauge symptom severity, assess treatment effects, and serve as potential precision biomarkers. We conclude that whereas eye movements provide insights into PD mechanisms, based on current evidence they appear to lack sufficient sensitivity and specificity to serve as a standalone diagnostic tool. Their full potential may be realized when combined with other disease indicators in big datasets.

Objective assessment of eye alignment and disparity-driven vergence in Parkinson's disease

Background

Self-reported diplopia is described in up to one-third of Parkinson's disease (PD) patients.

Objective

The purpose of our study was to expand our understanding of the mechanistic underpinnings of diplopia in PD. We hypothesize that the time-based control of eye alignment and increased eye deviation under binocular viewing will be related to the fusion-initiating and fusion-maintaining component deficits of disparity-driven vergence in PD.

Methods

We used high-resolution video-oculography to measure eye alignment under binocular and monocular viewing and disparity-driven vergence in 33 PD and 10 age-matched healthy participants. We computed eye deviation and time-based control of eye alignment, occurrence of conjugate saccadic eye movements, latency and gain of vergence (fusion initiation), and variance of eye position at the end of dynamic vergence (fusion maintenance).

Results

We categorized PD subjects into three groups, considering their time-based control of eye alignment as compared to healthy controls in binocular viewing. Group 1 = 45% had good control and spent >80% of the time when the eyes were well-aligned, Group 2 = 26% had intermediate control and spent <80% but greater >5% of the time when the eyes were well-aligned, and Group 3 = 29% had very poor control with increased eye deviation majority of the times (<5% of the time when the eyes were well-aligned). All three groups exhibited greater eye deviation under monocular viewing than controls. PD subjects exhibited fusion-initiating and fusion-maintaining vergence deficits (prolonged latencies, reduced vergence gain, increased variance of fusion-maintaining component) with a greater probability of saccadic movements than controls. Group 2 and Group 3 subjects were more likely to exhibit failure to initiate vergence (>20%) than Group 1 (13%) and controls (0%) trials. No significant difference was found in the Unified Parkinson's Disease Rating Scale (UPDRS-a tool to measure the severity of PD) values between the three PD groups (Group 1 = 33.69 ± 14.22, Group 2 = 38.43 ± 22.61, and Group 3 = 23.44 ± 1, p > 0.05).

Conclusion

The majority of PD subjects within our cohort had binocular dysfunction with increased eye deviation under monocular viewing and disparity-driven vergence deficits. PD subjects with intermediate or poor control of eye deviation under binocular viewing had greater fusion-initiating and fusion-maintaining vergence deficits. The study highlights the importance of assessing binocular dysfunction in PD subjects independent of the severity of motor symptoms.

Melanin: a unifying theory of disease as exemplified by Parkinson's, Alzheimer's, and Lewy body dementia

Melanin, a ubiquitous dark pigment, plays important roles in the immune system, including scavenging reactive oxygen species formed in response to ultraviolet radiation absorption, absorbing metals, thermal regulation, drug uptake, innate immune system functions, redox, and energy transduction. Many tissue types, including brain, heart, arteries, ovaries, and others, contain melanin. Almost all cells contain precursors to melanin. A growing number of diseases in which there is a loss of melanin and/or neuromelanin are increasingly thought to have infectious etiologies, for example, Alzheimer's disease (AD), Parkinson's disease (PD), Lewy Body Dementia (LBD), and vitiligo. AD, PD, LBD, and vitiligo have been linked with herpesvirus, which enters melanosomes and causes apoptosis, and with gut dysbiosis and inflammation. Herpesvirus is also linked with gut dysbiosis and inflammation. We theorize that under normal healthy states, melanin retains some of the energy it absorbs from electromagnetic radiation, which is then used to fuel cells, and energy from ATP is used to compliment that energy supply. We further theorize that loss of melanin reduces the energy supply of cells, which in the case of AD, PD, and LBD results in an inability to sustain immune system defenses and remove the plaques associated with the disease, which appear to be part of the immune system's attempt to eradicate the pathogens seen in these neurodegenerative diseases. In addition, in an attempt to explain why removing these plaques does not result in improvements in cognition and mood and why cognitions and moods in these individuals have ebbs and flows, we postulate that it is not the plaques that cause the cognitive symptoms but, rather, inflammation in the brain resulting from the immune system's response to pathogens. Our theory that energy retained in melanin fuels cells in an inverse relationship with ATP is supported by studies showing alterations in ATP production in relationship to melanin levels in melanomas, vitiligo, and healthy cells. Therefore, alteration of melanin levels may be at the core of many diseases. We propose regulating melanin levels may offer new avenues for treatment development.

Evaluation of clinical characteristics and risk factors of strabismus cases

OBJECTIVE

Strabismus, defined as the misalignment of the eyes, is a common disorder that is usually diagnosed in childhood. Strabismus is an important health problem with both functional and psychosocial effects on children. In this study, we aimed to determine the clinical features and risk factors of patients diagnosed with strabismus and followed up in our clinic.

METHODS

The data of pediatric patients who were followed up in our strabismus clinic between February 2016 and September 2022 were retrospectively reviewed. The patients' detailed ophthalmological and strabismus examination findings and anamnesis findings concerning the etiology of strabismus were recorded.

RESULTS

A total of 391 patients were enrolled in the study. The mean age of the patients was 8.66±4.7 years. Of the patients, 207 (52.9%) had esotropia, 172 (43.99%) had exotropia, and 12 (3.07%) had vertical deviation, with the mean ages of these groups being calculated as (7.27±4.1), (10.45±4.8), and (7.16±4.7) years, respectively. Amblyopia was present in 54 (26.09%) of the 207 esotropia cases, 27 (15.70%) of the 172 exotropia cases. Esotropia is more likely than exotropia to be related to amblyopia, according to our research. Of all the patients, 97 (24.81%) had a family history of strabismus, 38 (9.7%) had a history of preterm birth, 39 (10.0%) had a history of neonatal care unit stay, 38 (9.7%) had epilepsy, 4 (1%) had a history of trauma, and 14 (3.6%) had an additional eye disease.

CONCLUSION

Detection of risk factors such as family history, preterm birth, length of stay in the neonatal care unit and epilepsy that may be associated with strabismus can help identify high-risk children for early diagnosis and treatment.

Oculomotor, vestibular, reaction time, and cognitive tests as objective measures of neural deficits in patients post COVID-19 infection

Objective

An alarming proportion (>30%) of patients affected by SARS-CoV-2 (COVID-19) continue to experience neurological symptoms, including headache, dizziness, smell and/or taste abnormalities, and impaired consciousness (brain fog), after recovery from the acute infection. These symptoms are self-reported and vary from patient to patient, making it difficult to accurately diagnose and initiate a proper treatment course. Objective measures to identify and quantify neural deficits underlying the symptom profiles are lacking. This study tested the hypothesis that oculomotor, vestibular, reaction time, and cognitive (OVRT-C) testing using eye-tracking can objectively identify and measure functional neural deficits post COVID-19 infection.

Methods

Subjects diagnosed with COVID-19 (n = 77) were tested post-infection with a battery of 20 OVRT-C tests delivered on a portable eye-tracking device (Neurolign Dx100). Data from 14 tests were compared to previously collected normative data from subjects with similar demographics. Post-COVID subjects were also administered the Neurobehavioral Symptom Inventory (NSI) for symptom evaluation.

Results

A significant percentage of post COVID-19 patients (up to 86%) scored outside the norms in 12 out of 14 tests, with smooth pursuit and optokinetic responses being most severely affected. A multivariate model constructed using stepwise logistic regression identified 6 metrics as significant indicators of post-COVID patients. The area under the receiver operating characteristic curve (AUC) was 0.89, the estimated specificity was 98% (with cutoff value of 0.5) and the sensitivity was 88%. There were moderate but significant correlations between NSI domain key variables and OVRT-C tests.

Conclusions

This study demonstrates the feasibility of OVRT-C testing to provide objective measures of neural deficits in people recovering from COVID-19 infection. Such testing may serve as an efficient tool for identifying hidden neurological deficits post COVID-19, screening patients at risk of developing long COVID, and may help guide rehabilitation and treatment strategies.

Quality of Life Changes Following the Onset of Cerebellar Ataxia: Symptoms and Concerns Self-reported by Ataxia Patients and Informants

Semi-structured interviews of patient accounts and caregiver, or informant, perspectives are a beneficial resource for patients suffering from diseases with complex symptomatology, such as cerebellar ataxia. The aim of this study was to identify, quantify, and compare the ways in which cerebellar ataxia patients' and informants' quality of life had changed as a result of living with ataxia. Using a semi-structured interview, responses were collected from patients and informants regarding motor, cognitive, and psychosocial variables. Responses were also collected from patients and informants to open-ended questions that were subsequently categorized into 15 quality of life themes that best represented changes experienced by the patients and informants. Ataxia patients and informants agreed as to the severity of posture/gait, daily activities/fine motor tasks, speech/feeding/swallowing, and oculomotor/vision impairment. It was also demonstrated that severity ratings for specific motor-related functions strongly correlated with corresponding functions within the International Cooperative Ataxia Rating Scale (ICARS), and that this interview identified frequency associations between motor impairments and specific psychosocial difficulties, which could be useful for prognostic purposes. Overall, the information obtained from this study characterized the symptoms and challenges to ataxia patients and their caregivers, which could serve as a useful educational resource for those affected by ataxia, clinicians, and researchers.

An unusual presentation of convergence insufficiency in a patient with Parkinson's disease stimulated by deep brain stimulation

Purpose

To report convergence insufficiency in a patient with Parkinson's’ disease stimulated by turning on the deep brain stimulator.

Observations

72-year-old male with Parkinson's disease and hypertension presenting for the evaluation of blurry vision at near and mid distance that started after activation of an implanted Deep brain stimulator.

Baseline ophthalmologic evaluation prior to deep brain stimulator implantation surgery and with the deep brain stimulator turned off demonstrated a full motility, centered eyes for distance and near and a best corrected visual acuity of 20/20, normal pupil exam, confrontational visual fields and dilated fundus exam. Following this examination, the Deep brain stimulator was turned on and re-evaluation few minutes later demonstrated the same findings except for a 6-prism diopter exotropia at near consistent with convergence insufficiency.

Following our evaluation a set of +3 diopters base-in prisms were added to near glasses with total relief of symptoms. The patient did not require surgical adjustment of the deep brain stimulator leads.

Conclusions and importance

Given the therapeutic effects of deep brain stimulation on convergence insufficiency reported in several studies, in addition to the influence of deep brain stimulation as Parkinson's Disease treatment in areas possibly associated with vergence control, convergence insufficiency secondary to deep brain stimulation does not seem very unlikely, although not often reported. Further studies are needed to optimize deep brain stimulation surgery to maximize benefits and limit adverse events, as well as being aware of convergence insufficiency as a possible cause for visual disturbance.

Association of mental disorders and strabismus among South Korean children and adolescents: a nationwide population-based study

PURPOSE

The aim of this study is to determine the association between mental disorders and strabismus in South Korean children and adolescents.

METHODS

Using data from the Korean National Health Claims Database from 2011 to 2017, the prevalence rates of mental illnesses and odds ratio were calculated. Children and adolescents (1-19 years) with strabismus and their randomly selected nonstrabismic age- and sex-matched controls (1:1) were enrolled. The odds ratios were adjusted for preterm birth, cerebral palsy, and mental retardation. Subgroup analysis was performed according to sex and the type of strabismus.

RESULTS

A total of 327,076 subjects (male, 158,597; female, 168,479) identified as strabismus patients were enrolled. After adjusting for preterm birth, cerebral palsy, and mental retardation, the corrected odds ratio of overall mental illness was 1.10 (95% CI, 1.08-1.12) for the strabismus group compared to the controls: 1.7 (95% CI, 1.62-1.78) for developmental disorder, 1.36 (95% CI, 1.27-1.45) for pervasive developmental disorder (autism), 1.14 (95% CI, 1.10-1.17) for attention-deficit hyperactivity disorder (ADHD), 1.15 (95% CI, 1.05-1.27) for obsessive-compulsive disorder (OCD), 1.08 (95% CI, 1.05-1.11) for pediatric behavioral and emotional disorders, 0.93 (95% CI, 0.88-0.99) for post-traumatic stress disorder (PTSD), and 0.85 (95% CI, 0.82-0.89) for tic disorder.

CONCLUSION

South Korean children and adolescents with strabismus had a higher relative risk for various types of mental disorders such as a developmental disorder, autism, ADHD, and OCD than the controls, whereas they had a relatively lower risk of tic disorder.

Computational models to delineate 3D gaze-shift strategies in Parkinson's disease

Objective: Parkinson's disease (PD) frequently affects vergence eye movements interfering with the perception of depth and dimensionality critical for mitigating falls. We examined neural strategies that compensate for abnormal vergence and their mechanistic underpinning in PD.Approach:Thea priorihypothesis was that impaired vergence is compensated by incorporating rapid eye movements (saccades) to accomplish gaze shifts at different depths. Our experiments examined the hypothesis by simulating biologically plausible computational models of saccade-vergence interactions in PD and validating predictions in the actual patient data.Main results:We found four strategies to accomplish 3D gaze shift; pure vergence eye movements, pure saccadic eye movements, combinations of vergence followed by a saccade, and combination of saccade followed by vergence. The gaze shifting strategy of the two eyes was incongruent in PD. The latency of vergence was prolonged, and it was more so when the saccades preceded the vergence or when the saccades only made 3D gaze shift. Computational models predicted at least two possible mechanisms triggering saccades along with vergence. One is based on the lack of foveal accuracy when the vergence gain is suboptimal. The second mechanism reflects the noise in the gating mechanism, the omnipause neurons, for vergence and saccades. None of the two model predictions alone were completely supported by the patient data. However, a combined model incorporating both abnormal vergence velocity gain and impaired gating accurately simulated the results from PD patients.Significance:The combined strategy is biologically plausible for two reasons: (a) The basal ganglia that is prominently affected in PD projects to the vergence velocity neurons in the midbrain via the cerebellum. The projection directly affects the vergence velocity gain. (b) The basal ganglia, via superior colliculus, influences the pattern of omnipause neuronal activity. Abnormal basal ganglia activity may introduce noise in the omnipause neurons.

Prevalence and Risk Factors for Double Vision in Parkinson Disease

Background

Some patients with Parkinson Disease (PD) report double vision, but its prevalence and determinants are unknown.

Objectives

To determine the prevalence and risk factors for diplopia in PD.

Methods

Using data from 26,790 PD patients and 9257 controls in the Fox Insight Study, we compared the prevalence of diplopia using the Non-Movement Symptom Questionnaire. Associations with age, race, gender, disease duration, and scores on MDS-UPDRS part II, and Penn Parkinson's Daily Activity Questionnaire were assessed with generalized estimating equations.

Results

The point prevalence of diplopia was higher in PD (18.1%) than controls (6.3%, P < 0.001) at baseline, and 28.2% of all PD patients reported diplopia at least once during the study (period prevalence). PD patients with diplopia were more likely to be older, non-white, have greater disease duration, and report greater motor, non-motor, and daily activity limitations.

Conclusions

Diplopia is common and associates with motor and non-motor severity in PD.

Binocular Vision in Patients with Multiple Sclerosis

PURPOSE

Oculomotor disorders have been reported in multiple sclerosis (MS) in up to 80% of cases. There have been studies evaluating binocular vision in several neurological diseases, but not in MS. Considering that a high percentage of eye-movement anomalies have been reported, the aim of this study was to analyze binocular vision in these subjects.

METHODS

A total of 59 participants with MS - 21 with monocular optic neuritis, eleven with binocular optic neuritis, and 27 without optic neuritis - and 26 age-matched controls were enrolled. Binocular vision was analyzed using near point of convergence (NPC), positive and negative fusional vergence for far and near distance, measurement of heterophoria at both distances with cover and modified Thorington tests, and random-dot stereoscopy.

RESULTS

The percentage of subjects with abnormal NPC values was highest in the MS group, followed by the MSONm (MS with optic neuritis in one eye), MSONb (MS with optic neuritis in both eyes), and control groups. MS patients showed an esophoric trend at near distance. Positive fusional vergence showed no significant differences between control and MS groups, but higher variability in recovery was found in MS groups. Negative fusional vergence at near distance showed significant differences between the control group and the two MS groups, with optic neuritis for both break-point and recovery values. A high percentage of patients with MS had alterations on stereopsis.

CONCLUSION

Alterations in binocular vision were present in MS, with divergence at near distance and stereopsis the most affected parameters. Likewise, MS patients with optic neuritis showed worse binocular vision.

Effects of subthalamic deep brain stimulation on fixational eye movements in Parkinson's disease

Miniature yoked eye movements, fixational saccades, are critical to counteract visual fading. Fixational saccades are followed by a return saccades forming squarewaves. Present in healthy states, squarewaves, if too many or too big, affect visual stability. Parkinson's disease (PD), where visual deficits are not uncommon, is associated with the squarewaves that are excessive in number or size. Our working hypothesis is that the basal ganglia are at the epicenter of the abnormal fixational saccades and squarewaves in PD; the effects are manifested through their connections to the superior colliculus (affecting saccade frequency and amplitude) and the cerebellum (affecting velocity and amplitude). We predict that the subthalamic deep brain stimulation (DBS) variably affects the amplitude, frequency, and velocity of fixational saccade and that the effect depends on the electrode's proximity or the volume of activated tissue in the subthalamic nucleus' connections with the superior colliculus or the cerebellum. We found that DBS modulated saccade amplitude, frequency, and velocity in 11 PD patients. Although all three parameters were affected, the extent of the effects varied amongst subjects. The modulation was dependent upon the location and size of the electrically activated volume of the subthalamic region.

Diplopia associated with loop routing in deep brain stimulation: illustrative case

BACKGROUND

Deep brain stimulation (DBS) is a powerful surgical option for drug-resistant movement disorders; however, electromagnetic interference (EMI) from external sources poses a potential risk for implanted electronics.

OBSERVATIONS

A 61-year-old woman with Parkinson’s disease originally had two implantable pulse generators (IPGs) for bilateral subthalamic DBS, which were then replaced with one dual-channel IPG routed in a loop. After the replacement surgery, with the same DBS programming as before the IPG replacement (bipolar setting for right, unipolar setting for left), the patient began to complain of transient paroxysmal diplopia. After multiple attempts to adjust the stimulation parameters, the diplopia was resolved by changing the left unipolar setting to a bipolar setting. At the authors’ institution, before the present case, four other patients had undergone IPG replacement with loop routing. None of these previous patients complained of diplopia; however, two of the four presented with diplopia in an experimental unipolar setting.

LESSONS

Clinicians should be aware that loop-routed circuits may generate distortion of the stimulus field in DBS, even in the absence of external EMI sources.

Binocular Vision, Visual Function, and Pupil Dynamics in People Living With Dementia and Their Relation to the Rate of Cognitive Decline and Structural Changes Within the Brain: Protocol for an Observational Study

BACKGROUND

Visual impairment is a common comorbidity in people living with dementia. Addressing sources of visual difficulties can have a significant impact on the quality of life for people living with dementia and their caregivers. Depth perception problems are purportedly common in dementia and also contribute to falls, visuomotor task difficulties, and poorer psychosocial well-being. However, depth perception and binocular vision are rarely assessed in dementia research. Sleep fragmentation is also common for people living with dementia, and binocular cooperation for depth perception can be affected by fatigue. Pupillary responses under cognitive load also have the potential to be a risk marker for cognitive decline in people living with dementia and can be combined with the above measures for a comprehensive evaluation of clinical visual changes in people living with dementia and their relation to changes in cognitive status, sleep quality, and cortical structure or function.

OBJECTIVE

This study aims to characterize the nature of clinical visual changes and altered task-evoked pupillary responses that may occur in people living with dementia and evaluate whether these responses relate to changes in cognitive status (standardized Mini Mental State Examination [MMSE] score), Pittsburgh sleep quality index, and cortical structure or function.

METHODS

This proposed exploratory observational study will enroll ≤210 people with recently diagnosed dementia (within the last 24 months). The following parameters will be assessed on 3 occasions, 4 months apart (plus or minus 2 weeks): visual function (visual acuity and contrast sensitivity), binocular function (motor fusion and stereopsis), task-evoked pupillary responses (minimum and maximum pupil size, time to maximum dilation, and dilation velocity), cognitive status (MMSE score), and sleep quality (Pittsburgh Sleep Quality Index). A subset of patients (n=30) with Alzheimer disease will undergo structural and functional magnetic resonance imaging at first and third visits, completing a 10-day consensus sleep diary to monitor sleep quality, verified by sleep actimetry.

RESULTS

This research was funded in February 2018 and received National Health Service Research Ethics Committee approval in September 2018. The data collection period was from October 1, 2018, to November 30, 2019. A total of 24 participants were recruited for the study. The data analysis is complete, with results expected to be published before the end of 2020.

CONCLUSIONS

Findings will demonstrate how often people with dementia experience binocular vision problems. If frequent, diagnosing and treating them could improve quality of life by reducing the risk of falls and fine visuomotor task impairment and by relieving psychosocial anxiety. This research will also demonstrate whether changes in depth perception, pupillary responses, and quality of vision relate to changes in memory or sleep quality and brain structure or function. If related, these quick and noninvasive eye tests help monitor dementia. This would help justify whether binocular vision and pupillary response testing should be included in dementia-friendly eye-testing guidelines.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR1-10.2196/16089.

Contributions to the study of spinocerebellar ataxia type 38 (SCA38)

OBJECTIVE

To report clinical and ancillary findings in a kindred with spinocerebellar ataxia 38 (SCA38).

PATIENTS AND METHODS

Five family members spanning two generations developed gait ataxia and intermittent diplopia. On examination, a cerebellar syndrome accompanied by downbeat nystagmus and a saccadic head impulse test (HIT) were found.

RESULTS

Whole-exome sequencing demonstrated a heterozygous variant in ELOVL5, c.779A > G (p.Tyr260Cys), in four tested patients. Intermittent concomitant esotropia and hypertropia caused transient diplopia in one individual each. Saccadic HIT responses were found in four subjects. Sensorineural hypoacusis was present in every case. Electrophysiological studies demonstrated a sensory neuronopathy in patients from the first generation, with prolonged disease duration. Baseline serum docosahexaenoic acid (DHA) percent was diminished in four individuals. Oral 26-week dietary DHA supplementation, 650 mg/day, raised serum DHA percent and induced a statistically significant reduction in Scale for the Assessment and Rating of Ataxia (SARA) total scores, and in stance and heel-shin slide item scores.

CONCLUSION

The mentioned ELOVL5 variant segregated with disease in this kindred. Downbeat nystagmus, intermittent heterotropia causing transient diplopia, vestibular impairment demonstrated by abnormal HIT, and sensory neuronopathy were part of the clinical picture in this series. DHA supplementation raised serum DHA percent in cases with diminished levels, and induced a clinical amelioration and a statistically significant reduction in SARA scores in the study group. Further studies are needed to investigate the role of these findings in SCA38, and to determine the response to prolonged DHA supplementation.

Soft, wireless periocular wearable electronics for real-time detection of eye vergence in a virtual reality toward mobile eye therapies

Recent advancements in electronic packaging and image processing techniques have opened the possibility for optics-based portable eye tracking approaches, but technical and safety hurdles limit safe implementation toward wearable applications. Here, we introduce a fully wearable, wireless soft electronic system that offers a portable, highly sensitive tracking of eye movements (vergence) via the combination of skin-conformal sensors and a virtual reality system. Advancement of material processing and printing technologies based on aerosol jet printing enables reliable manufacturing of skin-like sensors, while the flexible hybrid circuit based on elastomer and chip integration allows comfortable integration with a user's head. Analytical and computational study of a data classification algorithm provides a highly accurate tool for real-time detection and classification of ocular motions. In vivo demonstration with 14 human subjects captures the potential of the wearable electronics as a portable therapy system, whose minimized form factor facilitates seamless interplay with traditional wearable hardware.