Received: 29 July 2019; Accepted: 29 April 2020; Published: 16 June 2020. The only remedy is to strengthen your eyes muscles by regular eye exercises. The behavior of normal subjects and the methods of analysis are described in detail in a recent publication (1). Science. The full results of the analyses are described in the text. The editor and reviewers' affiliations are the latest provided on their Loop research profiles and may not reflect their situation at the time of review. doi: 10.1002/cphy.c140014, 15. Misdiagnosis of spasm of the near reflex. The Havana affected subjects showed a shorter estimated pupil response delay than the control group for mm2/° data (HSD test, p < 0.05; marginal for comparison with the mTBI group) and the mTBI group for data normalized to the pupil light response (HSD test, p < 0.05; marginal for comparison with the control group). Separate analyses expressed the magnitude of the pupil response during disparity-driven vergence as either (1) pupil area per degree vergence (mm2/°) or (2) pupil area as a normalized percentage of light reflex range per degree vergence. doi: 10.1126/science.170.3962.1043, 24. (1983) 48:101–8. Five cycles of alternating convergence and divergence were presented over a 40-s duration (Figure 3, right traces). (1957) 20:17–26. A different picture emerged from the analyses of the dynamic pupil responses during the disparity step task. doi: 10.1177/0363546514543775, 6. (1993) 15:102–14. Handbook of Clinical Neurology. Table 4. Alvarez TL, Kim ET, Vicci VR, Dhar SK, Biswal BB, Barrett AM. CB, BL, and MH wrote sections of the manuscript. 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. Thirdly, the findings are not inconsistent with either peripheral effects on the inner ear and eye or accompanying effects on the central nervous system (20). VIDEO S2: Left eye weak convergence and without eye misalignment. Over 395 Vivid Vision Providers prescribe virtual reality alongside patching and vision therapy to treat your lazy eye. Vision Res. To diagnose convergence insufficiency, your eye doctor might: 1. But, if the eyes are unable to maintain a converged position, reading becomes quite difficult! The goodness of fit was uncorrelated with age. (B) Plot of the relationship between the two discriminant dimensions, collapsed across subject ages. A systems model for pupil size effect. Note that the group separation does not vary with age. Neuro-ophthalmology and psychiatry. For the former observation, the pupil velocity was calculated from the pupil area data (in mm2) with a “fitted slope” method, which fits a straight line between points from i–n to i + n (n = half-width of a user-specified window. Video-based eye tracking is performed under continuous 940-nm infrared illumination at a sampling rate of 100 Hz. The top-left image is the projected location of the chicken/egg images, while the image in the screen to the left shows what the patient's brain interprets the image as. First, the average pupil area was significantly smaller in the Havana affected group than that of the control subjects, with an intermediate baseline pupil area in the acute mTBI subjects. To perform this test, a clinician will use a small penlight or other fixation target and then slowly move the light towards the patient. We hypothesize that the acute neurosensory presentation of these individuals will show features that are distinct from those of the standard acute mTBI. All authors read and approved the submitted version. Convergence insufficiency can even limit entertainment or leisure activities. However, despite these limitations and the absence of a detailed neuro-ophthalmologic consultation and exam, it remains uncertain whether the changes in pupil responses during the binocular disparity vergence tasks reflect direct ocular effects, effects on visual pathways, or adaptive responses to perturbations yet to be identified. Convergence insufficiency is a common problem with the eyes, and is the main culprit behind eyestrain, blurred vision, and headaches. Miller NR. Common symptoms include: Reading is a great example of a task that requires normal convergence. In ophthalmology, convergence is the simultaneous inward movement of both eyes toward each other, usually in an effort to maintain single binocular vision when viewing an object. Dimension 2 showed lower scores for either the Havana affected or the acute mTBI group (Figures 5B,D). In short, absolutely. (A) Three-dimensional plot of the distribution of individual discriminant function scores for subjects as a function of age at time of testing. The binocular disparity pursuit task tests the disparity vergence performance over a slow, smooth pursuit cycle of 10 s. The traces in Figure 3 (left traces) show smooth, sinusoidal vergence eye movement tracking responses in the control and the Havana affected groups, with coordinated pupillary responses that display a clear sinusoidal component. doi: 10.1007/BF00344393, 9. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). As noted previously (2), their findings are not inconsistent with either a partially compensated vestibulopathy or a mild brain trauma (or both). doi: 10.1016/B978-0-444-52903-9.00024-8, 20. Schematic of approach for model estimation of binocular disparity-driven vergence eye movement and pupil responses (1). Suzuki R, Yoshino H, Kobayashi S. Different time courses of bovine iris sphincter and dilator muscles after stimulation. Figure 1. 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). If you are struggling, please do not hesitate to … This is the first report that examines the function of these individuals on a test that examined binocular disparity-driven eye and pupil movements during the acute time period after exposure. To diverge, the opposite of the near triad must occur. Treatment often focuses on working the ability of the eyes to converge and focus at different distances. Neurol. As we have discussed in our initial publication (2), this study is limited by being a retrospective analysis of the data obtained on this group of individuals in which only medically necessary information could be collected. (This examination actually tests convergence and accommodation, and is not terribly accurate but gives me a sense of where to ... and external Video providers. By contrast, the disparity step-driven eye movements in the Havana affected subjects did not differ significantly from those of the control subjects. As in the case of the disparity step task, the goodness of fit (R2) for vergence eye movements (to the stimulus profile) showed no difference between the control and the Havana affected subjects. Moreover, as in the case of the binocular disparity step task, the goodness of fit of the vergence eye movements of the acute mTBI subjects to the stimulus profile was reduced relative to those of both the control and Havana affected subjects (HSD tests, p < 0.01). The luminance signals were then processed in parallel by a high-pass mechanism with transfer function Klh s 0.085s+1 and a low-pass mechanism with transfer function Kll 0.15s+1 (where “s” is a variable for the Laplace representation of the transfer function). Neruoimaging findings in US government personnel with possible exposure to directional phenomena in Havana, Cuba. The eye movement and the pupil responses were attenuated and less sharply demarcated in the acute mTBI group. Hence, given the high coherence between the pupils, the main analyses were conducted on their averaged area. In addition, the study is limited by a small sample size. The reduced pupil coupling to the vergence eye movements in the latter group was apparent from the R2 values for the model fits, which indicated that the eye movement component explained an average of 47% of pupil variability in the control subjects and 55% of the variability in Havana affected subjects, but only 32% of the variance (HSD test, p > 0.01 re: either group) in the acute mTBI subjects. These conditions that affect convergence or divergence may cause symptoms such as seeing double at near or far while viewing an object. Vivid Vision and Vivid Vision Home October 2020 Update! This problem is most commonly found in children. The penlight is then moved farther away and the patient is asked when the recovery point (resolution of double vision) occurs. In addition, these individuals had no significant medical issues, no history of ear disease or ear surgery, no history of developmental learning issues, and no history of concussion for at least 1 year, with no lingering sequelae before the current injury. These findings assess the final behavior of fusion on static targets. Convergence Insufficiency (CI) is a common binocular (two-eyed) vision disorder in which the eyes do not work at near easily. 11:469. doi: 10.3389/fneur.2020.00469. The goal of this study was to provide a more detailed look at the eye motion seen in this patient group and compare these findings to other groups of individuals undergoing the same tests. For the analyses of the peak constriction velocity data (a measure of dynamic performance), the only significant effect was noted at one flash intensity (47.8 cd/mm2). Barnyard Bounce is a game designed to treat convergence insufficiency. These findings suggest that there is an impairment of the fidelity of disparity-driven vergence pursuit eye movement control in the acute mTBI subjects, but not in the Havana affected subjects. In addition to the analysis of raw pupil area data, the pupillary light response range was used to normalize the pupil area for analysis of coordinated eye and pupil movements during the vergence tasks. © All Rights Reserved, Vivid Vision, Inc. EYEBAB vision therapy software now available through Vivid Vision. The first and second order dynamics of accommodative convergence and disparity vergence. The pupil data were analyzed both as peak constriction velocity for each flash intensity and from the parameter estimation for a model described in the Appendix. Convergence Insufficiency and the Standard 20/20 Eye Test. (9). Instruct the patient to focus on the object and then slowly move the object closer to the patient at a steady rate, stopping 1 to 2 inches away from the patient's nose. Laryngoscope Investig Otolaryngol. The studies involving human participants were reviewed and approved by The Institutional Review Boards (IRBs) at the University of Miami and Madigan Army Medical Center approved the prospective studies of control subjects and subjects with mTBI. Discriminant function for control, acute traumatic brain injury (mTBI), and Havana affected patients from binocular disparity tests. Concussion. For those analyses, the maximum (Amax) and the minimum (Amin) pupil areas were determined separately for the left and the right eyes for responses on the range of low-intensity (0.42 cd/m2) to high-intensity (65.4 cd/m2) stimuli. Online Health & Safety Training. Convergence insufficiency is a common eye neuromuscular coordination issue found in the general population. 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). 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. Because there are significant negative linear relationships between these measures and age in the control subjects, the analyses were repeated with age as a covariate (Table 1). Our online safety training videos are based on industry best practices and international standards established by OSHA, the EPA, and other leading safety organizations. (1971) 170:1043–50. However, it is noteworthy that the pattern of oculomotor and otologic findings in this cluster of individuals has no precedent in the “psychogenic” literature. The product of the slope and the sampling frequency yields the velocity. This can be achieved using following theorem: Let {} = ∞ be a sequence of positive numbers. Figure 4 shows the examples of model performance for a representative Havana affected subject. Prolonged visual strain leads to weakness of eye muscles or convergence weakness and discomfort in eyes. The brain is constantly rapidly sampling the visual environment, quickly altering between convergence and divergence, then just as quickly holding eye posture so that the image of interest is stabilized on the retina. Non-linear least squares regression (“lsqnonlin.m” function in MATLAB) was used to estimate the power function and the gain parameters from experimental data. (2019). I HEART VT Q&A: Dr. Glen Steele on infant and toddler vision, sore or watery eyes after a near or far task, words moving about on a page while reading, frequenting losing your place while reading. The models were fitted initially for each eye. Video-based eye tracking is performed under continuous 940-nm infrared illumination at a sampling rate of 100 Hz. doi: 10.1371/journal.pone.0162168, 22. While the good news is that CI responds well to proper treatment— unfortunately, since many children are not assessed for CI, they are not getting the help they need early in life, if ever at all. Krenz WC, Stark L. Systems model for pupil size effect. Neural events and the psychophyxical law. Gen Hosp Psychiatry. While most of the tests deal with the convergence of infinite series, they can also be used to show the convergence or divergence of infinite products. Convergence of products. (2016) 11:e162168. This set of three processes - technically termed convergence, accommodation, and miosis - is known as the near triad. Oculomotor, vestibular, and reaction time tests in mild traumatic brain injury. Our short 5-minute videos explain complicated Convergence tests concepts in a manner that's easy for you to understand. (D) Separation of acute mTBI, control, and Havana affected subject by discriminant dimension 2 across ages. Although the patient may perceive the images as overlapping, the actual location of the images is rather far apart. 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. The binocular disparity step response test revealed several differences between the control, acute mTBI, and Havana affected subject groups. 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). Further, three arguments suggest that it is premature to invoke a functional etiology. The analyses of the disparity pursuit task data (Table 3) revealed reduced vergence eye movement modulation (low pass) in the acute mTBI group (Kruskal–Wallis test, p < 0.01) relative to that of the control group, with the Havana affected group showing a reduction so that it differed from neither the control subjects nor the acute mTBI subjects. The 20-20 passing grade simply means that a person can see clearly with at least one eye at the distance of 20 feet only. However, when pupil area was normalized as a percentile of the pupil response range, the Havana affected subjects had significantly higher sensitivity per degree of eye movement than either the control or the acute mTBI subjects. As shown in our previous publication (1), the residuals from this approach showed no activity in the range of the vergence eye movements, which indicates the descriptive adequacy of this simple model for the present analyses. These tests are ready for operational use to help distinguish the “worried well” and the symptomatic disorders with other potential causes. These findings were reviewed, respectively, on an approved protocol (2) and formed the basis of the data set used in this study. FDA Owner Operator Number 10057298. Kolmogorov–Smirnov tests (Lilliefors correction) were used to test the assumption of a Gaussian distribution for each dependent variable and group. Convergence Tests. Convergence insufficiency limits a person’s ability to work with visual information at close distances. doi: 10.1016/j.visres.2010.05.029, 10. 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. Newman NJ. Secondly, the affected individuals reported perceptions that coincided with symptom onset. The appearance and the diagnosis of changes in pupillary size and reactivity are among the five psychogenic patterns that are discussed in neuro-ophthalmologic literature (15–19). 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). (2006) 94:215–24. doi: 10.1016/0163-8343(93)90106-X, 19. Most commune errors. This pattern difference may be a useful screen for individuals who report a similar exposure pattern. CB, MS, BL, and MH contributed to the conception and design of the study and contributed to manuscript revision. These movements are modeled as a parallel response to the signal generating the vergence eye movements [e.g., Balaban et al. doi: 10.1016/0014-4886(83)90404-1, 12. “Functional neuro-ophthalmology,” in Kennard C, Leigh RJ, editors. 1. Stated bluntly, one entertains a psychogenic or functional diagnosis after excluding known organic explanations. Neurol., 16 June 2020 Never feel confused in Convergence tests class again! 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]. The findings might allow investigators to begin to develop a set of objective findings that are typical for the acute neurosensory dysfunction among some members of the Havana diplomatic community. Understanding the effects of mild traumatic brain injury on the pupillary light reflex. (2018) 319:1125–33. Doing the test only once. Verma R, Swanson RL, Parker D, Ismaeli AAO, Shinohara RT, Alappatt JA, et al. No use, distribution or reproduction is permitted which does not comply with these terms. Furthermore, their distinctive presentation may help guide in treatment decisions to address the mechanisms that contribute to their unusual symptom complexes. We suggest that pupillary light reflex and binocular disparity vergence tests can be utilized to produce sensitive and selective measures that, paired with otolith tests (subjective visual vertical and vestibular-evoked myogenic potentials), identify symptomatic Havana-type exposures objectively on the basis of clinical features. Table 1. Two different subjects (black and green traces) are shown for each group. For testing the pupillary light reflex quantitatively, the subjects viewed binocularly a 5° (visual angle) disc centered on the visible area of each screen half while 13 homogeneous illumination flashes (0.42 to 65.4 cd/m2, 0.300 s on, 2.00–4.00 s off) were presented binocularly in an ascending order of intensity (Figure 2). If the patient's convergence ability is good enough to meet the convergence amount needed in the headset, the chicken and egg match perfectly! For the vergence pursuit (tracking) task, the trial began with the illumination of the two monocular targets at the initial focal point phoria (equivalent to ~1 m in virtual depth). Patterns of pupillary activity during binocular disparity resolution. doi: 10.1002/lio2.231, 3. Vision therapy uses a series of activities to build up progressively the ability to converge, diverge, and the rapidly alternate between convergence and divergence. Your optometrist may perform a simple eye test. The pupil controller Laplace form was adopted from Sun et al. The canonical discriminant function for this three-way classification (Table 4) identified two classifier dimensions that produced a remarkable 91.8% correct rate overall, with a one-out cross-validation correct classification rate of 81.6%. Finally, for data expressed as % pupil range, the Havana affected subjects had more robust pupil constriction responses than either the control or the acute mTBI group (Kruskal–Wallis tests, p < 0.01). The patients/participants provided their written informed consent to participate in this study. This is a test that the optometrist does in order to test the ability of your eyes to come together effectively as you focus close to. The general architecture of this simple model is diagrammed in Figure 1.
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