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Adolfo M. Bronstein - One of the best experts on this subject based on the ideXlab platform.
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using transcranial magnetic stimulation tms to probe effects of visual motion adaptation on primary visual cortex v1 excitability in bilateral vestibular failure bvf patients
Journal of Neurology Neurosurgery and Psychiatry, 2015Co-Authors: Hena Ahmad, Re Roberts, Qadeer Arshad, Mitesh Patel, Adolfo M. BronsteinAbstract:Background and aim Patients with BVF report Oscillopsia due to a defective vestibulo-ocular reflex causing retinal slip. No previous studies have probed visual cortical excitability using TMS and visual motion processing in these patients. We investigated the effects of visual motion adaptation on V1 cortical excitability in BVF patients and correlated this with psychophysical parameters. Methods 12 BVF patients (7 males) aged 29–65 (mean=54.5) and 12 controls (6 males) aged 42–73 (mean=55) were recruited. Biphasic TMS pulses were applied at V1 and phosphene threshold (PT) was estimated. 3 measurement phases were (1) Stationary (2) Motion with optokinetic stimulation (OKS) Adaptation: OKS rightwards for 5 minutes 3) Post adaptation during viewing motion. All subjects completed questionnaires prior to the experiment. Results were analysed offline by calculating the probability of phosphene perception. Results Baseline phosphene thresholds were significantly higher in BVF patients (p=0.024) reflecting reduced visual cortical excitability. Lower Oscillopsia scores correlated with reduced baseline V1 excitability (p=0.009). Conclusions This novel finding acts as a neurophysiological correlate for clinical observations of adaptive visual motion perception and is also correlated with psychophysical parameters. These results provide evidence for adaptive mechanisms leading to cortical plasticity following BVF.
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nystagmus and Oscillopsia
European Journal of Neurology, 2012Co-Authors: Andreas Straube, Adolfo M. Bronstein, Dominik StraumannAbstract:The ocular motor system consists of several subsystems, including the vestibular ocular nystagmus saccade system, the pursuit system, the fixation and gaze-holding system and the vergence system. All these subsystems aid the stabilization of the images on the retina during eye and head movements and any kind of disturbance of one of the systems can cause instability of the eyes (e.g. nystagmus) or an inadequate eye movement causing a mismatch between head and eye movement (e.g. bilateral vestibular failure). In both situations, the subjects experience a movement of the world (Oscillopsia) which is quite disturbing. New insights into the patho-physiology of some of the ocular motor disorders have helped to establish new treatment options, in particular in downbeat nystagmus, upbeat nystagmus, periodic alternating nystagmus, acquired pendular nystagmus and paroxysmal vestibular episodes/attacks. The discussed patho-physiology of these disorders and the current literature on treatment options are discussed and practical treatment recommendations are given in the paper.
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symptomatic recovery in miller fisher syndrome parallels vestibular perceptual and not vestibular ocular reflex function
Frontiers in Neurology, 2011Co-Authors: Barry M Seemungal, Panos Masaoutis, David A Green, Gordon T Plant, Adolfo M. BronsteinAbstract:Unpleasant visual symptoms including Oscillopsia and dizziness may occur when there is unexpected motion of the visual world across the subject’s retina (‘retinal-slip’) as in an acute spontaneous nystagmus or on head movement with an acute ophthalmoplegia. In contrast, subjects with chronic ocular dysmotility, e.g. congenital nystagmus or CPEO (chronic progressive external ophthalmoplegia), are typically symptom free. The adaptive processes that render chronic patients asymptomatic are obscure but may include a suppression of Oscillopsia perception as well as an increased tolerance to perceived Oscillopsia. Such chronic asymptomatic patients display an attenuation of vestibular-mediated angular velocity perception, implying a possible contributory role in the adaptive process. In order to assess causality between symptoms, signs (i.e. eye-movements) and vestibular perceptual function, we prospectively assessed symptom ratings and ocular-motor and perceptual vestibular function, in a patient with acute but transient ophthalmoplegia due to Miller Fisher Syndrome (as a model of visuo-vestibular adaptation). The data show that perceptual measures of vestibular function display a significant attenuation as compared to ocularmotor measures during the acute, symptomatic period. Perhaps significantly, both symptomatic recovery and normalisation of vestibular perceptual function were delayed and then occurred in a parallel fashion. This is the first report showing that symptomatic recovery of visuo-vestibular symptoms is better paralleled by vestibular-perceptual testing than VOR (vestibular ocular reflex) measures. The findings may have implications for the understanding of patients with chronic vestibular symptoms where VOR testing is often unhelpful.
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EFNS task force--therapy of nystagmus and Oscillopsia.
European journal of neurology, 2004Co-Authors: Andreas Straube, Adolfo M. Bronstein, Richard Leigh, W. Heide, P. Riordan-eva, C. C. Tijssen, I. Dehaene, Dominik StraumannAbstract:An overview of possible treatment options for oculomotor disorders that prevent clear vision is given. Downbeat nystagmus, upbeat nystagmus, seesaw nystagmus, periodic alternating nystagmus, acquired pendular nystagmus, and saccadic oscillations such as opsoclonus/ocular flutter are discussed. In addition, superior oblique myokymia and vestibular paroxysmia are reviewed. All treatment recommendations available in the literature are classified as class C only. In general, only some of the patients benefit from the treatment.
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adaptation to Oscillopsia a psychophysical and questionnaire investigation
Brain, 2000Co-Authors: Elizabeth A Grunfeld, Adolfo M. Bronstein, Antony B Morland, M A GrestyAbstract:In this study we explore the reasons why patients with bilateral vestibular failure report disparate degrees of Oscillopsia. Twelve bilateral labyrinthine-defective (LD) subjects and twelve normal healthy controls were tested using a self- versus visual-motion psychophysical experiment. The LD subjects also completed a questionnaire designed to quantify the severity of handicap caused by Oscillopsia. Additional standardized questionnaires were completed to identify the role of personality, personal beliefs and affective factors in adaptation to Oscillopsia. During the psychophysical experiment subjects sat on a motorized Barany chair whilst viewing a large-field projected video image displayed on a screen in front of them. The chair and video image oscillated sinusoidally at 1 Hz in counter-phase at variable amplitudes which were controlled by the subject but constrained, so that the net relative motion of the chair and video image always resulted in a sinusoid with a peak velocity of 50°/s. The subject's task was to find the ratio of chair versus video image motion that subjectively produced the `most comfortable visual image'. Eye movements were recorded during the experiment in order that the net retinal image slip at the point of maximum visual comfort could be measured. The main findings in the LD subjects were that, as a group, they selected lower chair motion amplitude settings to obtain visual comfort than did the normal control subjects. Responses to the questionnaires highlighted considerable variation in reported handicap due to Oscillopsia. Greater Oscillopsia handicap scores were significantly correlated with a greater external locus of control (i.e. the perception of having little control over one's health). Retinal slip speed was negatively correlated with Oscillopsia handicap score so that patients who suffered the greatest retinal slip were those least handicapped by Oscillopsia. The results suggest that adaptation to Oscillopsia is partly related to the patient's personal attitude to the recovery process and partly associated with the development of tolerance to the movement of images on the retina during self-motion. The latter is likely to be related to previously described changes in visual motion sensitivity in these patients.
Larry A Abel - One of the best experts on this subject based on the ideXlab platform.
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Oscillopsia and the influence of stress and motivation in fusion maldevelopment nystagmus syndrome
Investigative Ophthalmology & Visual Science, 2013Co-Authors: Kwang Meng Cham, Andrew J Anderson, Larry A AbelAbstract:Purpose We examined factors influencing perceptual stability in observers with fusion maldevelopment nystagmus syndrome (FMNS). In addition, we also investigated the effect of visual demand, task-related physiologic stress, and motivation on the nystagmus waveform. Methods Perception of Oscillopsia during daily activities was assessed via a questionnaire. Perception of Oscillopsia in the laboratory was assessed using central and peripheral (10°) light emitting diodes (LEDs) in front of a background display of random, fixed-contrast shapes. Task-induced stress was achieved via a time restricted acuity task with or without concurrent mental arithmetic challenge, and motivation varied using a reward-penalty paradigm. The experiments have been previously described elsewhere. Results Six out of nine subjects reported experiencing Oscillopsia in certain daily activities. in the laboratory, the percentages of trials with perceptions of motion of the led and background were as follows: neither, 60% to 70%; background only, 20% to 30%; both, 5% to 15%, and LED only, 5% to 15%. Over all trials, six of nine experienced Oscillopsia for both the low- and high-contrast image respectively (i.e., three subjects never experienced Oscillopsia). The background was frequently seen moving for both images regardless of contrast and/or condition. Trials with and without Oscillopsia did not differ when comparing foveation. In the second experiment, task-related physiologic stress and motivation were reflected in an increase in heart rate; nystagmus waveform intensity increased and foveation decreased. The magnitude of changes in heart rate was uncorrelated with changes in waveform parameters for all experiments, however. Conclusions Preliminary results suggest that the FMNS group does perceive spatially inhomogeneous Oscillopsia, similar to infantile nystagmus syndrome (INS), in certain visual environments. In investigating the effect of stress and motivation on FMNS, a new, if tentative, finding suggests that task-induced stress and/or motivation may have a negative impact on the nystagmus. Taken together, our findings provide an insight into the particular environments and tasks that are likely to present particular challenges to persons with FMNS.
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factors influencing the experience of Oscillopsia in infantile nystagmus syndrome
Investigative Ophthalmology & Visual Science, 2008Co-Authors: Kwang Meng Cham, Andrew J Anderson, Larry A AbelAbstract:Purpose Perceptual instability in infantile nystagmus syndrome (INS) has been reported occasionally. This study was conducted to examine the factors that influence perceptual stability in 18 individuals with INS. Methods The subjects were instructed to look continuously at a fixation LED centered in an image (38 degrees x 32 degrees ) at two luminance levels (3.25 and 0.46 cd/m(2), with 21% and 96% contrast, respectively) throughout all trials. A trial consisted of the fixation LED on, followed by a peripheral LED on, and then both LEDs off. Subjects then reported what they perceived. Five trials were conducted per contrast image. Eye movements were recorded with a limbal tracker. After testing, each subject completed a questionnaire to determine whether they ever had or were presently experiencing Oscillopsia. Results Sixteen of 18 subjects reported experiencing Oscillopsia on the questionnaire. In the laboratory, the percentages of trials with perceptions of motion of the LED and background were as follows: neither, 45% to 60%; background only, 15% to 30%; both, approximately 15%; and LED only, approximately 10%. Over all trials, 14/18 and 13/17 subjects experienced Oscillopsia for the low- and high-contrast images, respectively (i.e., four subjects never experienced Oscillopsia). The background was frequently seen moving when both images were displayed, regardless of contrast and/or condition. Trials with and without Oscillopsia did not differ between the foveation periods. Conclusions Subjects with INS may experience spatially inhomogeneous Oscillopsia under certain viewing conditions. The physical attributes of the stimulus, repeated trials, different conduction times, and the role of divided attention may influence a subject's perception differently.
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Oscillopsia in inverse latent infantile nystagmus syndrome
Optometry and Vision Science, 2007Co-Authors: Larry A Abel, Linda MalesicAbstract:PURPOSE A possibly unique individual with infantile nystagmus syndrome presented with incessant Oscillopsia but good stereopsis when viewing binocularly; her nystagmus was greatly reduced with left eye occlusion. We have attempted to explain this and to identify an intervention that preserves binocular vision while maximizing perceptual stability. CASE REPORT AND METHODS Eye movements were recorded and analyzed for duration of foveation (% time when the target was on or near the fovea and the eye was moving at < or = 4 degrees /sec) under different viewing conditions. Changes in foveation were compared with the patient's reports of her perceptual stability. RESULTS In her right gaze null with her right eye fixating, foveation was 52.9%. This fell to 32.3% for the same eye in primary position and to 0.8% when viewing binocularly in primary position. When viewing binocularly Oscillopsia was incessant; when viewing with her right eye vision was stable except in left gaze. Prism correction of her phoria greatly reduced her Oscillopsia when viewing binocularly while preserving stereopsis; foveation went up to 33.7%. CONCLUSION The patient's ability to maintain good foveation only when viewing with her right eye forces her to choose between stereopsis and stable vision. This may result from the rare combination of (1) requiring good foveation for Oscillopsia suppression and (2) nystagmus deteriorating under the stress of maintaining binocularity. There may be many other infantile nystagmus syndrome patients who do not develop Oscillopsia but may suffer sufficient asthenopia from a phoria to exacerbate their nystagmus.
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effects of stimulus size and luminance on Oscillopsia in congenital nystagmus
Vision Research, 2003Co-Authors: Linda A Tkalcevic, Larry A AbelAbstract:Although the absence of Oscillopsia is a common feature of congenital nystagmus (CN), it is occasionally noted by patients under poor viewing conditions and has been provoked in laboratory settings with stabilised images. In the present study, the effects of reductions in background stimulus size and luminance on perceptual stability in CN were examined. Sixteen CN subjects were first interviewed using a structured questionnaire about whether they ever experienced Oscillopsia and, if so, under what circumstances and with what perceptions. They next fixated an LED centred in projected images of three sizes (21x14 degrees, 10x6 degrees and 7x4 degrees) and four luminance levels (115.5, 24.5, 2.7 and 0.1 cd/m2, with contrasts from 96 down to 20%). Eye movements were recorded with a limbal tracker. They were asked after viewing each image "whether anything happened to the image while they watched it." Occasional Oscillopsia was reported by 12/16 of the CN subjects on the questionnaire. In the laboratory, 13/16 subjects experienced Oscillopsia in some manner for at least one of the stimuli. 8/13 CN subjects experienced it for the dimmest and smallest slides. 11/13 perceived certain parts (either the LED or background) of the visual stimuli as moving, with the perception of LED movement most pronounced at low background luminance. Foveation did not differ when trials with and without reported Oscillopsia were compared (independent samples t-test, p>0.05). Oscillopsia may occur in CN with normal viewing of bright fixation targets against dim backgrounds. Under these conditions, the Oscillopsia may be spatially inhomogeneous. Luminance differences between the fixation point and surround may have caused transmission time differences as the image moved across the retina, therefore leading to the perception of motion in one portion of the scene and not the other.
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intermittent Oscillopsia in a case of congenital nystagmus dependence upon waveform
Investigative Ophthalmology & Visual Science, 1991Co-Authors: Larry A Abel, Isla M Williams, Leah LeviAbstract:Spontaneous reports of Oscillopsia are rare in cases of congenital nystagmus (CN). We examined the relationship between nystagmus waveform characteristics and Oscillopsia in one such case. To reduce the patient's nystagmus, she was fitted with contact lenses. We examined the effects of tactile feedback by applying local anesthetic while she wore the lenses. When she was without lenses, we provided tactile feedback by applying gentle finger pressure to one eyelid. She was also asked to look at a peripheral afterimage. Nystagmus was analyzed for frequency, amplitude, foveation duration, and drift velocity, if foveation was not perfectly stable. Perceived target stability was recorded. The patient noted Oscillopsia during the initial baseline recording and with lid pressure. The image was stable with contact lenses with and without anesthesia and during the second session baseline; at these times, drift velocity was less than 4 degrees/sec and foveation duration was greater than 100 msec. No Oscillopsia of the afterimage in dark was noted; she perceived it moving with her gaze as she attempted to look at it. It appears that in some CN patients, the suppression of Oscillopsia operates only within fixed limits of foveation stability and duration. When, because of internal or external factors, their nystagmus exceeds these, Oscillopsia results.
Ronald J Tusa - One of the best experts on this subject based on the ideXlab platform.
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computerized dynamic visual acuity test in the assessment of vestibular deficits
American Journal of Otology, 2010Co-Authors: Susan J Herdman, Ronald J Tusa, P J Blatt, A Suzuki, P J Venuto, D RobertsAbstract:Publisher Summary This chapter describes the measurement characteristics that each of these tests must meet to be effective tools for the clinician and will discuss the utility of both of these tests in the management of people with vestibular hypofunction. Many patients with vestibular hypofunction complain of visual blurring (Oscillopsia) during head movements. Oscillopsia is a potentially serious problem because it can contribute to the avoidance of activities, such as driving, and ultimately can lead to limited social interactions with increased isolation. The chapter discusses that Oscillopsia occurs when vestibulo-ocular reflex gain is inadequate and suggests that compensation for the vestibular loss has not occurred. The measurement of visual acuity during head movement, therefore, should provide clinicians with a method of assessing the functional impact of the loss of vestibular function as well as a means of assessing the effectiveness of interventions to foster compensation. The chapter reviews that two tools have been developed to quantify visual acuity during head movement— that is, the clinical dynamic visual acuity (DVA) test and the computerized DVA test.
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recovery of dynamic visual acuity in bilateral vestibular hypofunction
Archives of Otolaryngology-head & Neck Surgery, 2003Co-Authors: Susan J Herdman, Courtney D Hall, Michael C Schubert, Vallabh E Das, Ronald J TusaAbstract:Results: As a group, patients who performed vestibular exercises showed a significant improvement in DVA (P=.001), whereas those performing placebo exercises did not (P=.07). Only type of exercise (ie, vestibular vs placebo) was significantly correlated with change in DVA. Other factors examined, including age, time from onset, initial DVA, and complaints of Oscillopsia and disequilibrium, were not significantly correlated with change in DVA. Change in Oscillopsia did not correlate with change in DVA. Conclusions: Use of vestibular exercises is the main factor involved in recovery of DVA in patients with BVH. We theorize that exercises may foster the use of centrally programmed eye movements that could substitute for the vestibulo-ocular reflex. Trial Registration: clinicaltrials.gov Identifier: NCT00411216
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Oscillopsia and pseudonystagmus in kidney transplant patients
American Journal of Ophthalmology, 1999Co-Authors: Michael T Yen, Susan J Herdman, Ronald J TusaAbstract:Abstract PURPOSE: Modern immunosuppressants have improved the success of kidney transplantation for renal failure patients. They also may induce neurotoxic effects including tremor. We report two cases of pseudonystagmus and Oscillopsia in transplant patients caused by immunosuppressant-induced head tremor and gentamicin-induced vestibulotoxicity. METHODS: Case reports. Head tremor, static visual acuity, and dynamic visual acuity were measured. Vestibular function was evaluated with ice water calorics. RESULTS: Both patients had significant head tremor and pseudonystagmus. Head stabilization improved static visual acuity. Dynamic visual acuity revealed a 4-line and 10-line loss of visual acuity, respectively. CONCLUSIONS: These findings of pseudonystagmus and Oscillopsia are likely to become more prevalent as more renal failure patients receive transplants. Improvement may be seen with reduction of immunosuppressant, reduction of stimulant intake, use of medications to reduce head tremor, and vestibular rehabilitation.
Andreas Straube - One of the best experts on this subject based on the ideXlab platform.
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nystagmus and Oscillopsia
European Journal of Neurology, 2012Co-Authors: Andreas Straube, Adolfo M. Bronstein, Dominik StraumannAbstract:The ocular motor system consists of several subsystems, including the vestibular ocular nystagmus saccade system, the pursuit system, the fixation and gaze-holding system and the vergence system. All these subsystems aid the stabilization of the images on the retina during eye and head movements and any kind of disturbance of one of the systems can cause instability of the eyes (e.g. nystagmus) or an inadequate eye movement causing a mismatch between head and eye movement (e.g. bilateral vestibular failure). In both situations, the subjects experience a movement of the world (Oscillopsia) which is quite disturbing. New insights into the patho-physiology of some of the ocular motor disorders have helped to establish new treatment options, in particular in downbeat nystagmus, upbeat nystagmus, periodic alternating nystagmus, acquired pendular nystagmus and paroxysmal vestibular episodes/attacks. The discussed patho-physiology of these disorders and the current literature on treatment options are discussed and practical treatment recommendations are given in the paper.
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pharmacology of vertigo nystagmus Oscillopsia
Current Opinion in Neurology, 2005Co-Authors: Andreas StraubeAbstract:Purpose of reviewTo describe recent developments in the pharmacological treatment of vertigo and nystagmus while focusing on vestibular neuritis, Meniere's disease, downbeat nystagmus, periodic alternating nystagmus, acquired pendular nystagmus, and superior oblique myokymia.Recent findingsIn the la
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EFNS task force--therapy of nystagmus and Oscillopsia.
European journal of neurology, 2004Co-Authors: Andreas Straube, Adolfo M. Bronstein, Richard Leigh, W. Heide, P. Riordan-eva, C. C. Tijssen, I. Dehaene, Dominik StraumannAbstract:An overview of possible treatment options for oculomotor disorders that prevent clear vision is given. Downbeat nystagmus, upbeat nystagmus, seesaw nystagmus, periodic alternating nystagmus, acquired pendular nystagmus, and saccadic oscillations such as opsoclonus/ocular flutter are discussed. In addition, superior oblique myokymia and vestibular paroxysmia are reviewed. All treatment recommendations available in the literature are classified as class C only. In general, only some of the patients benefit from the treatment.
L F Dellosso - One of the best experts on this subject based on the ideXlab platform.
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development and surgical removal of an epiretinal membrane in infantile nystagmus syndrome a new type of Oscillopsia
Japanese Journal of Ophthalmology, 2018Co-Authors: L F Dellosso, Suber S HuangAbstract:To report and discuss a focal Oscillopsia in a small area of the visual field produced by, and after the removal of, an epiretinal membrane (ERM) in an individual with infantile nystagmus syndrome (INS) since birth with no associated afferent visual deficits. A retrospective case report. A chart review, including clinical and electrophysiological data. A 74 y/o man with INS and an epiretinal membrane was studied. Detailed studies of the retina post-removal of an epiretinal membrane, with consequent changes in best-corrected visual acuity (BCVA), and subjective Oscillopsia compared to INS waveforms. OCT measurements and eye-movement data from digital video and scleral search-coil systems were used. The monocular ERM produced an unexpected focal area of torsional/vertical Oscillopsia (noted 1 year prior to the ERM surgery) in the portion of the visual field that corresponded with distortions from the ERM. The remainder of the visual field, corresponding with normal healthy retina was unaffected and stable in all planes. Post-removal, BCVA improved with redevelopment of the foveal pit and focal Oscillopsia became less noticeable but remained due to the retinal distortion. In patients with INS, complete Oscillopsia suppression across the visual field requires undistorted vision. If a retinal area of visual distortion develops or results from retinal surgery, a symptomatic island of Oscillopsia in one or more planes may result.
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the mechanism of Oscillopsia and its suppression
Annals of the New York Academy of Sciences, 2011Co-Authors: L F DellossoAbstract:We studied the mechanisms of Oscillopsia suppression in subjects with infantile nystagmus syndrome, fusion maldevelopment nystagmus syndrome, and acquired nystagmus (AN). Hypothetical possibilities for perceptual stability were the following: (1) epochs of clear and stable vision during foveation periods of nystagmus waveforms; (2) cancellation by efference copy of motor output; (3) a combination of the effects of both foveation-period stability and efference-copy cancellation; or (4) elevated motion-detection threshold and vision suppression. Observations, studies, and models of Oscillopsia suppression allowed comparison of these possibilities. Data from individual subjects supported some of the putative hypotheses. However, only one hypothesis remained viable that could explain how all subjects maintained perceptual stability despite their different nystagmus types, waveforms, and variability. Robust suppression of Oscillopsia was only possible using efference-copy feedback of the motor output containing these specific nystagmus signals to cancel that motion from the retinal error signals. In cases of AN, where Oscillopsia could not be suppressed, the deficit was postulated to interfere with or lie outside of this efference-copy feedback loop.
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combining recessions nystagmus and strabismus with tenotomy improved visual function and decreased Oscillopsia and diplopia in acquired downbeat nystagmus and in horizontal infantile nystagmus syndrome
Journal of Aapos, 2007Co-Authors: L F Dellosso, Robert L Tomsak, Zhong I Wang, Jonathan B JacobsAbstract:Purpose To investigate the effects of combined tenotomy and recession procedures on both acquired downbeat nystagmus and horizontal infantile nystagmus. Methods Patient 1 had downbeat nystagmus with a chin-down (upgaze) position, Oscillopsia, strabismus, and diplopia. Asymmetric superior rectus recessions and inferior rectus tenotomies reduced right hypertropia and rotated both eyes downward. Patient 2 had horizontal infantile nystagmus, a 20° left-eye exotropia, and alternating ( ab ducting-eye) fixation. Lateral rectus recessions and medial rectus tenotomies were performed. Horizontal and vertical eye movements were recorded pre- and postsurgically using high-speed digital video. The eXpanded Nystagmus Acuity Function (NAFX) and nystagmus amplitudes and frequencies were measured. Results Patient 1: The NAFX peak moved from 10° up to primary position where NAFX values improved 17% and visual acuity increased 25%. Vertical NAFX increased across the −10° to +5° vertical range. Primary-position right hypertropia decreased ∼50%; foveation time per cycle increased 102%; vertical amplitude, Oscillopsia, and diplopia were reduced, and frequency was unchanged. Patient 2: Two lateral, narrow high-NAFX regions (due to alternating fixation) became one broad region with a 43% increase in primary position (acuity increased ∼92.3%). Diplopia amplitude decreased; convergence and gaze holding were improved. Primary-position right exotropia was reduced; foveation time per cycle increased 257%; horizontal-component amplitude decreased 45.7%, and frequency remained unchanged. Conclusions Combining tenotomy with nystagmus or strabismus recession procedures increased NAFX and visual acuities and reduced diplopia and Oscillopsia in downbeat nystagmus and infantile nystagmus.
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Oscillopsia suppression and foveation period variation in congenital latent and acquired nystagmus
Neuro-Ophthalmology, 1997Co-Authors: L F Dellosso, Lea Averbuchheller, R J LeighAbstract:We studied the relative importance of clear and stable epochs of vision and extraretinal signals of eye movements in suppressing illusory motion of the world (Oscillopsia) in eight subjects with two types of infantile nystagmus, congenital nystagmus (CN) and latent/manifest latent nystagmus (LMLN), and two acquired forms of nystagmus (AN), pendular and jerk. Three subjects with CN and no Oscillopsia did not always exhibit well-developed foveation periods, unless their CN was therapeutically damped. Two subjects with CN and AN had transient Oscillopsia that coincided in time and plane with the lack of well-developed foveation. Two subjects with AN and Oscillopsia had well-developed foveation (one after gabapentin). One subject with LMLN and vertical AN experienced Oscillopsia solely in the plane of the AN, despite the presence of good foveation in both planes. Our findings argue against the role of foveation periods in suppression of Oscillopsia. In CN, lack of well-developed foveation does not result in o...
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ocular motor stability of foveation periods required conditions for suppression of Oscillopsia
Neuro-Ophthalmology, 1992Co-Authors: L F Dellosso, R J LeighAbstract:Individuals with congenital nystagmus (CN) usually do not experience Oscillopsia. We hypothesized that the ability to suppress Oscillopsia in CN is the result of perceptual mechanisms that differentiate retinal image motion caused by the oscillation itself from that of real target motion. In previous studies we showed that: (1) by inducing Oscillopsia in CN subjects who did not experience it under normal conditions, retinal image stability was insufficient to suppress Oscillopsia in the presence of nystagmus; (2) the presence of repeatable, well-developed (retinal error position ≤ 0.5° and error velocity ≤ 4°/sec) foveation periods was necessary for visual constancy. The present study is of a subject with diagonal CN whose direction of perceived Oscillopsia varied with the eye used for fixation; the Oscillopsia corresponded to the absence of well-developed foveation periods in either (horizontal or vertical) or both planes. Thus, poorly developed foveation periods in the horizontal, vertical or both plane...