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Tony Pansell

Publications and source records attributed to Tony Pansell.

10 recordsLinked to original sources
PubMed2007

The influence of accommodative insufficiency on reading.

BACKGROUND: It is not known how accommodative insufficiency influences reading performance. METHODS: Reading eye movements were recorded before and after treatment for accommodative insufficiency in 12 school children (eight to 16 years). During the eight-week treatment period all subjects wore a +1.00 D addition when reading. RESULTS: Large variations in reading patterns were found. Despite successful accommodative treatment (p < 0.001), no correlation was found to suggest improved reading velocity. DISCUSSION: Three case reports will be presented and the implications discussed.

Accommodation, Ocular↗
PubMed2006

Visual spatial clues enhance ocular torsion response during visual tilt.

Ocular torsion in response to a static tilt of a visual stimulus has been, and still remains in doubt. Furthermore, the possible underlying mechanism is not well understood. The authors' hypothesize that if the torsional response is related to the vestibular otolith system, then a visual stimulus with spatial clues important for maintaining body posture will induce a larger torsional response as compared to a stimulus lacking spatial information. Eye movements were recorded objectively in 15 healthy individuals using a 3D video oculography system. Three visual stimuli were used. In two tests, an identical photographic image of a city scene with spatial clues relevant for body posture were used, with the only difference being a square periphery in one stimulus (test 1) and a circular periphery in the other (test 2). The third stimulus (test 3) consisted of yellow rectangles on a black background with no natural spatial information. The scenes were tilted in 15 degrees steps from 0 degrees to 45 degrees in CCW and CW direction, and each position were held static for 15 s. All visual scene tilts induced a compensatory torsional response, which increased with stimuli angle. The stimuli with spatial clues induced more torsion compared to the stimulus without spatial clues. No difference was found when analysing the peripheral contour effect or direction of stimulus tilt. The present results support the hypothesis of an origin in the otolith system for the torsional response found to a static tilted visual scene.

Adolescent↗
PubMed2006

Posterior canal dehiscence syndrome caused by an apex cholesteatoma.

OBJECTIVE: To compare audio-vestibular findings caused by a dehiscence of the posterior semicircular canal with those found in the superior canal dehiscence syndrome. STUDY DESIGN: Case report. SETTING: University hospital, tertiary referral center. PATIENT: The 44-year-old woman suffered from a gradual hearing loss with pulse-synchronous tinnitus as well as sound and pressure-induced vertigo. INTERVENTION: Audio-vestibular testing and high-resolution computed tomography. MAIN OUTCOME MEASURE: The superior canal dehiscence syndrome is caused by failure of normal postnatal bone development in the middle cranial fossa leading to absence of bone at the most superior part of the superior semicircular canal. The typical features for this syndrome are sound- and pressure-induced vertigo with torsional eye movements, pulse synchronous tinnitus and apparent conductive hearing loss in spite of normal middle-ear function. We present a patient with very similar symptoms and findings who, instead, had a posterior semicircular canal dehiscence caused by an apex cholesteatoma. CONCLUSION: Patients with semicircular canal dehiscence have common auditory-vestibular features regardless of which of the two vertical semicircular canals is affected. The only obvious difference between the two is the vertical component of the sound and pressure-induced eye movements (which beats in opposite directions).

Adult↗
PubMed2005

Drift in ocular torsion during sustained head tilt.

PURPOSE: A head tilt towards the shoulder (roll) induces an ocular counter-roll (OCR), i.e. torsion in the opposite direction to the head. How this counter-rolled position is maintained during a static head tilt is in debate. In a previous study, we reported an OCR-increasing drift subsequent to the head tilt. This finding is in contrast to other reports where no such response was found. The primary aim of this study was to repeat the experiment during a prolonged head-tilt test and to describe the OCR characteristics. A secondary aim was to investigate the influence of spatial visual cues on OCR. METHODS: Five male subjects performed a head tilt (30 degrees ) towards the right shoulder while the eye position was recorded during a 10-minute interval. In test 1, the subjects viewed a target with no cues for spatial orientation. The same head-tilt paradigm was repeated in test 2 with a visual target with spatial cues. Two samples of data were extracted from the start and the end of the recordings for statistical analysis. RESULTS: Subsequent to the head tilt, a slow OCR-increasing drift in the opposite direction to the head roll was found in all subjects. On average, this drift lasted for 30 sec (+/- 5) in test 1 and for 55 sec (+/- 18) in test 2. The drift was then found to change its direction, i.e. the eyes were rotated in the same direction as the head roll. When measured after 10 minutes, the OCR was significantly decreased. CONCLUSIONS: The OCR during static head tilt is not constant. During the first minute there is a gradually increasing OCR. Thereafter, the amplitude of the OCR decreases gradually. These changes are influenced to some extent by spatial visual cues. Possible mechanisms are adaptive responses in otolithic afferents as well as central nervous memory functions related to the semicircular canal system.

Adult↗
PubMed2005

Drift in ocular counterrolling during static head tilt.

A decreasing drift of the counter-rolled eye position (OCR) during head tilt was recently described. The underlying mechanism is not known. OCR in eleven healthy subjects was recorded (Search coil, Skalar) during a head tilt paradigm in two test conditions. The head was tilted with a velocity below (test 1) and above (test 2) detection threshold for the semicircular canals (SC) and held static for eight minutes. A significant drift of OCR was revealed in test 2 (P = .0006, ANOVA) and close to significant in test 1 (P = .07). No statistical difference was found between the two test conditions. The results suggest that the OCR drift was not caused by the SC complex merely.

Adaptation, Physiological↗
PubMed2004

Subarcuate venous malformation causing audio-vestibular symptoms similar to those in superior canal dehiscence syndrome.

OBJECTIVE: To present a patient with symptoms similar to those of superior canal dehiscence syndrome due to another cause. STUDY DESIGN: Case report. SETTING: University hospital, tertiary referral center. PATIENT: The 65-year-old woman had suffered for 4 years from hearing loss, tinnitus, and pressure-induced vertigo. INTERVENTION: Audio-vestibular testing, high-resolution computed tomography, and magnetic resonance angiography. MAIN OUTCOME MEASURE: The superior canal dehiscence syndrome is caused by failure of normal postnatal bone development in the middle cranial fossa leading to absence of bone at the most superior part of the superior semicircular canal. The typical features for this syndrome are sound and pressure-induced vertigo with torsional eye movements, pulse synchronous tinnitus and apparent conductive hearing loss in spite of normal middle ear function. We present a patient with very similar symptoms and findings, who instead had a superior canal dehiscence close to the common crus. Neuroradiologic findings suggested that the dehiscence was related to a venous malformation. CONCLUSIONS: Symptoms and findings suggesting superior canal dehiscence syndrome can have a different cause.

Aged↗
PubMed2003

Conjugacy of torsional eye movements in response to a head tilt paradigm.

PURPOSE: Vertically skewed eye movements are induced by head tilt toward the shoulder (roll). Because vertical and torsional eye movements are tightly coupled both mechanically and neuronally, the purpose of the present study was to investigate the conjugacy of torsional eye movements during the Bielschowsky head tilt test (BHTT). Furthermore, the purpose was to investigate the influence of different visual and viewing condition on torsional conjugacy. The issue has clinical relevance in interpreting the outcome of the BHTT. METHODS: Eye movement recordings were performed using the infrared three-dimensional video-oculography (3D-VOG) technique. Objective cycloposition of 20 healthy individuals was measured in presumed primary position and in head tilt positions of 15 degrees, 30 degrees, and 45 degrees to the right and left, respectively. The same paradigm was performed under three different viewing conditions: binocularly without spatial orientation and both binocularly and monocularly with spatial orientation. The stimulus used with spatial orientation was a photographic picture of a historic building, whereas the stimulus with no spatial cues consisted of concentric circles. RESULTS: Consistent excyclovergence occurred in all subjects in head tilt. The relative amount increased with head tilt, regardless of the visual stimulus. Maximum excyclovergence was 0.7 degrees in 45 degrees head tilt during monocular fixation. Binocular viewing enhanced the torsion conjugacy by means of vergence stability (SD), whereas spatial visual cues improved the torsional conjugacy only slightly. CONCLUSIONS: Consistent excyclovergence was induced in head tilt. A vestibular origin seems to provide a plausible explanation of the induced torsional disconjugacy, whereas visual feed-back seems plausible in explaining the better conjugacy in binocular viewing.

Adult↗
PubMed2003

Torsional and vertical eye movements during head tilt dynamic characteristics.

PURPOSE: As the first response to a Bielschowsky head tilt test (BHTT), a fast transient torsional eye movement in the same direction as the head tilt has been shown with the three-dimensional (3D)-video oculography (3D-VOG) technique, and this movement is paralleled by a transient vertical vergence shift inducing a physiological skew deviation. The purpose of the present study was to investigate these dynamic eye movements further in response to a BHTT paradigm with the magnetic search coil technique. METHODS: Ten healthy subjects performed a BHTT (15 degrees, 30 degrees, and 45 degrees) toward each shoulder while (search coil) the monocular eye and head positions were recorded. The same head tilt paradigm was repeated in a second test while (3D-VOG) the binocular eye position was recorded. RESULTS: Subsequent to the initiation of the head tilt (latency, approximately 160 ms) a rapid torsional eye movement (mean peak velocity: 40 deg/s; mean amplitude: 4 degrees) was seen in the same direction as the head movement, followed by a somewhat slower return movement. This torsion was synchronous with a vertical vergence eye movement (mean amplitude 3 degrees). The vertical vergence was always with left eye over right eye in the rightward head tilt and in head straightening from the left shoulder. In the left head tilt and in the head straightening from the right shoulder, this movement was always with the right eye over the left eye. CONCLUSIONS: A torsional and vertical vergence back-and-forth eye movement induced by a BHTT was confirmed with the search coil technique. Utricular inertia due to an interaural head translation, combined with a stimulation of the vertical semicircular canals, seems to be a plausible explanation for these eye movements.

Adult↗
PubMed2002

Assessment of ocular counterroll during head tilt using binocular video oculography.

PURPOSE: According to recent literature, the presence and the amount of true compensatory ocular counterroll is still debatable. The purpose of the current study was to assess compensatory counterroll in response to lateral head tilt using a new noninvasive recording technique, and, furthermore, to find out whether the amount of counterroll is influenced by the presence or absence of spatial orientation. METHODS: Eye movement recordings were performed using the infrared three-dimensional video oculography (3D-VOG) technique. Objective cycloposition of five healthy individuals was measured in presumed primary position and in head tilt positions of 15 degrees, 30 degrees, and 45 degrees to the right and left. The same paradigm was performed under three viewing conditions: binocularly without spatial orientation and both binocularly and monocularly with spatial orientation. RESULTS: A consistent ocular counterroll corresponding to the amount of head tilt was observed in all subjects. Maximum torsional amplitude was 10 degrees at a 45-degree head tilt. The relative amount of compensation ranged between 13% and 22% of the actual head tilt, decreasing with increasing head tilt. Compensatory counterroll and torsional conjugacy between both eyes revealed minor differences between the experimental paradigms. Incomplete cycloductional reorientation in primary position after head tilt was detected in all subjects, regardless of the stimulus. CONCLUSIONS: A consistent compensatory ocular counterroll was demonstrated in response to static lateral tilting of the head in healthy individuals. The amplitude of counterroll and the gain of compensatory cycloversion were higher than has been generally reported. Infrared 3D-VOG technique was a reliable and comfortable method for the assessment of ocular cycloduction. It can be considered to be a promising tool for advanced evaluation of disturbances of the oblique eye muscles.

Adult↗