In addition, these individuals could not have been diagnosed with more than mild brain injury [e.g., no loss of consciousness (LOC) or LOC <30 min, no subdural hematoma, no need for admission to the intensive care unit, and a Glasgow Coma Score of 14 or above]. Gen Hosp Psychiatry. Ophthalmic Res. Over 395 Vivid Vision Providers prescribe virtual reality alongside patching and vision therapy to treat your lazy eye. Convergence Insufficiency (CI) is a common binocular (two-eyed) vision disorder in which the eyes do not work at near easily. According to an article in the Khaleej Times, convergence insufficiency may prevent people from seeing three-dimensional movies, because 3D glasses require healthy convergence and strong vision 3 . Balaban CD, Hoffer ME, Szczupak M, Snapp H, Crawford J, Murphy S, et al. For example, the subjects with acute mTBI had lower magnitude vergence eye movements in either task than the control or the Havana affected subjects. Swanson R, Hampton S, Green-Mckenzie J, Diaz-Arrastia R, Sean MG, Verma R, et al. These dynamic movement findings are likely to be predominantly a supranuclear oculomotor control phenomenon that is related to generating the parallel drive to the extraocular muscles and the pupil controller (14). Hence, it tests a low-frequency response. *Correspondence: Carey D. Balaban,, Front. The end result is often fatigue, headache, and likely avoidance of near work. (1982) 32:757–62. Non-linear least squares regression (“lsqnonlin.m” function in MATLAB) was used to estimate the parameters for the vergence disparity response as a weighted sum of high-pass (Kvhse-tvss+1) and low-pass (Kvle-tvs0.25s+1) processes, with delay tv and gains Kvh (phasic process) and Kvl (tonic process), respectively. CB performed the data analysis and wrote the first draft of the manuscript. Convergence insufficiency can even limit entertainment or leisure activities. Common symptoms include: Reading is a great example of a task that requires normal convergence. J Neurophysiol. Neurol. Hence, given the high coherence between the pupils, the main analyses were conducted on their averaged area. Convergence is the ability to turn the two eyes inward toward each other to look at a close object. (8), the pupil controller dynamics were fitted from the vergence data by a transfer function for pupil motion, Kpe-tps0.28s+1, with delay tp and gain Kp, which estimates the near response sensitivity directly. The singular emergence of this cluster of individuals, the limited acute clinical information, the wide publicity about perceptions and symptoms, and the lack of etiologic information raise the practical issue of how one recognizes a similar presentation objectively in other individuals reporting the same perceptions. Figure A1. No use, distribution or reproduction is permitted which does not comply with these terms. Near point of convergence after a sport-related concussion: measurement reliability and relationship to neurocognitive imapairment and symptoms. When seen at the University of Miami, these patients underwent diagnostic examinations that were guided by their symptoms and standard of care. These findings indicate that the amplitudes of the convergence movements were reduced significantly in the subjects with acute mTBI relative to the control subjects. Krenz WC, Stark L. Systems model for pupil size effect. Maxwell J, Tong J, Schor CM. Primary CI is thought to be caused by an imbalance of vergence eye movements that is either an inborn deficiency or an acquired etiology. (2015) 5:439–73. For that stimulus, the response was reduced significantly in the acute mTBI group relative to the control group (HSD test, p < 0.05, with the Havana exposed subjects not differing from either group). The linear discriminant analysis (Wilks-lambda criterion) demonstrated that the results of the two binocular disparity vergence and the pupillary light response tests are sufficient to classify individual subjects with high accuracy as control, acute mTBI, or Havana affected (Table 3). Discriminant function for control, acute traumatic brain injury (mTBI), and Havana affected patients from binocular disparity tests. Let's use a VR example. Hoffer ME, Levin BE, Snapp H, Buskirk J, Balaban CD. Because the binocular disparity stimuli were predictable and relatively brief, one cannot exclude the possibility of a contribution of an impaired executive function to performance on these tasks, given the elevated prevalence of abnormal antisaccade task error rates in both subjects with acute mTBI (21) and the Havana affected cohort (2) Randomized disparity testing may be helpful in resolving the latter issue in the future. In our example, the chicken is visible only in the left eye and the egg is shown only to the right eye (watch the video of the actual task here). To diverge, the opposite of the near triad must occur. These affected individuals often reported hearing a loud, high-frequency, localized sound, and were under the impression that it could follow them in a room. Video-based eye tracking is performed under continuous 940-nm infrared illumination at a sampling rate of 100 Hz. Significant group differences in model parameter values for the disparity step responses. Diagnosis of convergence insufficiency (e.g., in mTBI) is typically documented by (1) a minimum near point of convergence >6 cm from the face, (2) greater exodeviation for near objects than far objects, and (3) a positive fusional vergence during a prism test. doi: 10.1371/journal.pone.0162168, 22. Five cycles of alternating convergence and divergence were presented over a 40-s duration (Figure 3, right traces). Concurrent visual dysfunctions in convergence insufficiency with traumatic brain injury. Firstly, the new eye movement findings are sufficiently distinctive to reliably classify these individuals, control subjects, and subjects with acute mTBI with high accuracy (>91% by discriminant analysis). A person can pass the 20/20 eye chart test and still have convergence insufficiency. In the above example, the patient must match their convergence ability to the location of the chicken and egg in the VR headset. The patient is to report when the light breaks into two lights (double vision). Stevens SS. Think of this as the distance from your eyes to the point where both eyes are just unable to maintain focus and start to experience double vision. This can be achieved using following theorem: Let {} = ∞ be a sequence of positive numbers. This analysis was supported by the Office of Naval Research (Grant No. A systems model for pupil size effect. Secondly, the affected individuals reported perceptions that coincided with symptom onset. Relying on subjective near point convergence (NPC) measures and not objective observation of the eye fixation. These movements are modeled as a parallel response to the signal generating the vergence eye movements [e.g., Balaban et al. In late 2016, diplomats in Havana, Cuba, began presenting with a unique symptom complex after perceiving a strange noise and/or feeling a pressure field in their domicile. Table 3. Am J Sports Med. However, two significant differences emerged in parameters between groups (Table 1). Online Health & Safety Training. Convergence insufficiency can’t be diagnosed with a typical eye-chart exam. Figure 4 shows the examples of model performance for a representative Havana affected subject. (1983) 48:101–8. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Mcdougal DH, Gamlin PDR. The general architecture of this simple model is diagrammed in Figure 1. doi: 10.1126/science.170.3962.1043, 24. II Feedback model Biol Cybern. The R2 values indicate that the eye movement component explained at least 50% of pupil variability in the control and the Havana affected groups, but only 32% of the variance (HSD test, p > 0.01 re: either group) in the acute mTBI subjects. Patterns of pupillary activity during binocular disparity resolution. For the step task, the magnitude was less than half the control value, which would be consistent with an apparent increase in the distance of the near point of convergence (relative to the subject's head). But, if the eyes are unable to maintain a converged position, reading becomes quite difficult! This problem is most commonly found in children. The model fit, based upon the eye movement vergence response, is shown for each trace in red. Convergence insufficiency (CI) is one of the most common disorders of binocular vision; CI affects approximately 5% of children in the United States and may have a serious impact on an individual's performance in school, choice of jobs, and quality of life. doi: 10.1037/h0031324, 23. The criteria used for the diagnosis included a standard military definition of having a head injury, suffering an alteration or loss of consciousness, and having new neurosensory symptoms with onset at the time of injury and persisting until during our team's evaluation (all individuals ended up to have symptoms for at least 1 week). The analysis of the responses (Table 2) showed that the acute mTBI group had significantly lower gains for the low-pass components of the eye movements than either the control or the Havana affected subjects (Kruskal–Wallis tests, p < 0.01) as well as a significantly poorer goodness of fit (HSD tests, p < 0.01). Patients that suffer from CI are unable to keep the eyes converged for an extended period of time. (2016) 11:e162168. When 21 exposed individuals were examined in a more chronic time frame (average of 201 days post-perception of exposure), 20 subjects reported persistent symptoms and signs that resembled the aspects of mild traumatic brain injury (3). Some patients struggle with convergence or divergence. Dimension 1 produced scores centered around zero for the control subjects, negative scores for the acute mTBI group, and positive scores for the Havana affected individuals (Figure 5B) across the entire age range of the subjects (Figure 5C). These findings were reviewed, respectively, on an approved protocol (2) and formed the basis of the data set used in this study. (1985) 51:391–7. The eye movements in the disparity step and the pursuit tasks were modeled as the weighted sum of first-order high- and low-pass representations of the vergence target position with a processing delay (1). The analysis of de-identified clinical video-oculographic data was approved by institutional review board of the University of Miami and the University of Pittsburgh, respectively. Privitera CM, Stark LW. Vision therapy uses a series of activities to build up progressively the ability to converge, diverge, and the rapidly alternate between convergence and divergence. Go back to the thumb again and use the same procedure for the right image of the object. JAMA. Normal consensual pupil responses were confirmed during the neurological examination. Our short 5-minute videos explain complicated Convergence tests concepts in a manner that's easy for you to understand. doi: 10.1002/lio2.231, 3. Compr Physiol. Keywords: vergence eye movements, pupil regulation, human, objective diagnosis, video-oculography, Citation: Balaban CD, Szczupak M, Kiderman A, Levin BE and Hoffer ME (2020) Distinctive Convergence Eye Movements in an Acquired Neurosensory Dysfunction. Hence, the features that distinguish the acute mTBI and the Havana Affected subjects from the control sample need to be viewed as objective, empirical “markers.” One feature of interest is that the rapid step and the slower smooth pursuit (0.1 Hz) binocular disparity tasks showed consistent results across the different subject groups. To our knowledge, this report is the first demonstration of the potential diagnostic utility of a quantitative analysis of binocular disparity-driven eye and pupil movements. Words may become blurry, doubled, or appear to move around on the page. They provided data with written informed consent under protocols approved by the IRBs at the University of Miami and the Madigan Army Medical Center and in accordance with the Declaration of Helsinki. When the Gaussian assumption was rejected (p < 0.05), a distribution-free Kruskal–Wallis approach in the SPSS Non-parametric tests → Independent Samples menu was used. The three-way group separation remained at 89.8% correct overall (with no cross-classification errors between the mTBI and the Havana affected groups) when the variables with a significant age relationship were adjusted to a value for a standard age of 33.3939 years based upon estimated linear relationships in the control group. The basic separation is shown for the scores in Figure 5B. [unreliable source?] Get help with your Convergence tests homework. doi: 10.1212/WNL.26.11.1018, 16. Divergence excess is an over-divergence when attempting to look at distant objects. Convergence insufficiency is a common condition that is characterized by a person's inability to maintain proper binocular eye alignment on objects as they approach from distance to near. This pattern difference in eye and pupil behavior may be a useful screen to help objectively distinguish blunt trauma from Havana-type effects in the future and to guide the affected individuals to appropriate care. The Havana affected subjects, on the other hand, had smaller baseline pupil areas than the control subjects for light reflex testing and during binocular disparity tests, associated with larger pupil changes per degree of vergence when data were normalized to the pupil area range. Stark L, Sherman PM. For the disparity step test (Figure 3, right panels), the targets move abruptly. Although these movements are highly consistent in control subjects (1), the neurologic significance of the differences that we observed has yet to be probed. Further, three arguments suggest that it is premature to invoke a functional etiology., The vergence disparity step task began with the illuminated targets at a central fixation position for each eye. N00014-18-1-2157). The targets were then shifted at 4-s intervals between a disparity requiring 1.5° convergence (from the initial fixation target) and a disparity requiring 1.5° divergence (from the initial fixation target) in order to achieve binocular fusion. Examinations and formal testing at the University of Miami in the acute to the subacute time frames found had objective evidence of both an otolithic abnormality and of cognitive dysfunction in a group of 25 individuals (2). Neurology. The patterns of response in these 19 individuals are markedly different than those seen in a group of individuals with the usual acute mild traumatic brain injury (17 subjects) and from 62 control subjects (21–60 years old) with no injury. Test results should be written down for example convergence 8 centimetre (Brock String) In an individual with a good convergence ability both tests should show the similar results. Nevertheless, our data demonstrate that the behavior of the Havana affected subjects in these tasks differed markedly from the convergence eye and the pupil coordination pattern in the acute mTBI subjects. A brief vestibular/ocular motor screening (VOMS) assessment to evaluate concussions: preliminary findings. The correction for age indicated that only the mTBI subjects had smaller average pupil areas than those of the controls. Fifty-two subjects are described in a previous communication (1), supplemented by 12 subjects to span the age range of the mTBI and Havana affected cohorts. The opposite of divergence insufficiency is divergence excess. Note the strong similarity in the dynamic responses across groups, which was confirmed by the lack of differences between the response parameters in quantitative analyses (see text). CB, MS, BL, and MH contributed to the conception and design of the study and contributed to manuscript revision. The responses during the binocular disparity step task are shown on the right. The numerator for the slope calculation is the sum (points multiplied by offset), where offset is the range from –n to n, while the denominator is n (n + 1) (2n + 1)/3. Suzuki R, Yoshino H, Kobayashi S. Different time courses of bovine iris sphincter and dilator muscles after stimulation. Video_2.MOV (15M) ... VI was clinically screened for in both groups by the physician via a simple screening test for weak or asymmetrical eye convergence movements and eye misalignment (see Figure 1 and Supplementary Videos … There were no significant group differences in any parameter of dynamic behavior. 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