Translation and validation of a Swedish version of the Visual Vertigo Analogue Scale

PURPOSE

The present study aimed to construct and validate a Swedish translation (VVAS-S) of the Visual Vertigo Analogue Scale (VVAS).

MATERIALS AND METHODS

The original English VVAS was translated into Swedish by the two authors and back-translated by an independent professional translator. Pilot-tests were performed on two healthy participants and five patients suffering from Visually Induced Dizziness (VID). The translation was deemed understandable by all subjects. Twenty-one patients with VID were recruited to complete the VVAS-S, once in-lab and once at home after 2-3 weeks. Cronbach's alpha, inter-item consistency and internal consistency were calculated.

RESULTS

Test-retest values were reliably strong across all items. Cronbach's alpha was 0.843, which is considered to represent very-high reliability. The corrected-item total-correlation was above 0.3 for all items, meaning they were appropriately associated with one-another. Fourteen out of 36 inter-item correlation interactions were within the 0.2-0.4 range.

CONCLUSIONS

The VVAS-S was found to be comparable to the original VVAS in terms of internal reliability. The translation was perceived as easy to implement by all participants and can be considered ready for clinical use in a Swedish-speaking setting. Item-specific correlations may be valuable for developing future vertigo questionnaires.Key messagesThe Swedish version of the Visual Vertigo Analogue Scale is a questionnaire suitable for evaluating visually induced dizziness in a Swedish population. This study found that the Swedish questionnaire was comparable to the original in terms of internal consistency. The Swedish Visual vertigo Analogue Scale can be found as an appendix to this article.

The prognostic implication of visual acuity at the time of uveal melanoma diagnosis

BACKGROUND

Visual outcomes after primary tumour treatment of uveal melanoma (UM) have been investigated repeatedly. This study evaluates the correlation between best-corrected visual acuity (BCVA) before treatment with clinicopathological factors and patient survival.

SUBJECTS/METHODS

Pre-treatment BCVA was examined in relation to tumour dimensions and location, and survival in a retrospective cohort of 1809 patients who underwent plaque brachytherapy. BCVA was also correlated to tumour histological factors in a second cohort of 137 enucleated eyes.

RESULTS

The mean BCVA of the tumour eye prior to plaque brachytherapy was LogMAR 0.42 (SD 0.46). Patients with low BCVA (LogMAR ≥ 1.00) did not differ in age (p = 0.19) and had similar frequency of ciliary body involvement (p = 0.99) but had tumours with greater apical thickness (p < 0.0001), greater diameter (p < 0.0001) and shorter distance to the optic disc and fovea (p < 0.0001). There were no significant relations between low BCVA and any of 13 examined tumour histological factors at a Bonferroni-corrected significance level (p > 0.004). Patients with low BCVA had greater incidence of UM-related mortality in competing risk analysis (p = 0.0019) and shorter overall survival (p < 0.0001). Low BCVA was also associated with increased hazard ratio (HR) for UM-related mortality in univariate analysis (HR 1.5, 95% confidence interval 1.2 to 1.9), but not in multivariate analysis with tumour size and location as covariates.

CONCLUSIONS

UM patients with low BCVA before primary tumour treatment have a worse prognosis, likely related to increased tumour dimensions. Future studies should examine the prognostic significance of BCVA in relation to macula-involving retinal detachment and genetic factors.

Clinical characteristics of visual motion hypersensitivity: a systematic review

This qualitative systematic review presents an overview of the state of the research relating to visual motion hypersensitivity (VMH) and offers a reference tool for future studies in the field. The study set out to identify and collate articles investigating risk groups with aberrant responses to visual motion as compared to healthy control groups, presenting evidence for risk factors associated with visual motion hypersensitivity. Data were synthesized into the state of the research and analyzed in the context of the clinical characteristics of each risk factor. Literature searches were performed on Medline Ovid, EMBASE, Web of Science, and Cinahl, identifying a total of 586 studies of which 54 were finally included. Original articles published between the dates of commencement for each database and 19th January 2021 were included. JBI critical appraisal tools were implemented for each corresponding article type. In total, the following number of studies was identified for each respective risk factor: age (n = 6), migraines (n = 8), concussions (n = 8), vestibular disorders (n = 13), psychiatric conditions (n = 5), and Parkinson's disease (n = 5). Several studies described VMH as the primary concern (n = 6), though these primarily included patients with vestibulopathies. There were considerable differences in the nomenclature employed to describe VMH, depending largely on the investigating group. An overview of investigated risk factors and their evaluation methods was presented in a Sankey diagram. Posturography was the most implemented methodology but due to diverse measurements meta-analyses were not possible. One may however note that while the easily implemented Vestibular Ocular Motor Screening (VOMS) was designed for concussed patients, it may prove useful for other risk groups.

Surgical outcome of graded Harada-Ito procedure in the treatment of torsional diplopia ‒ a retrospective case study with long-term results

To review and evaluate the surgical outcomes of the Fells-modified Harada-Ito procedure using a dosage scale approach with long-term follow up in patients with torsional diplopia. The records of patients who underwent the modified Harada-Ito procedure by the same surgeon during 2012-2019 were retrospectively reviewed regarding pre- and post-operative data and individual dose-scale used for the surgery. The modified Harada-Ito procedure involved advancing the anterior half of the superior oblique tendon toward the inferior edge of the lateral rectus muscle by a distance determined using a five-graded scale. A total of 27 patients (mean age 57.6 years, range, 22-81 years; 10 female) were included. Evaluating surgical outcome showed a significant difference in pre- to post-operative cyclodeviation (p = <0.001). Pre-operative mean extorsion was -10.4° and mean torsional correction achieved was 7.7°. The dose-effect relationship showed a wide spread effect, yet yielded a high success rate. All but two patients were symptom free from their torsional diplopia at the last post-operative evaluation, on average 24 months after surgery. Post-operative results and the dose-effect of the modified Harada-Ito corresponded with the aimed-for correction of torsional diplopia.. Fusion evaluation and individually based pre-operative assessments proved essential in determining individual doses for successful surgical outcomes.

Visuo-motor integration, vision perception and attention in mTBI patients. Preliminary findings

Patients with mild traumatic brain injuries (mTBI) often report difficulties in motor coordination and visuo-spatial attention. However, the consequences of mTBI on fine motor and visuo-motor coordination are still not well understood. We aimed to evaluate whether mTBI had a concomitant effect on fine motor ability and visuo-motor integration and whether this is related to visual perception and visuo-spatial attention impairments, including patients at different symptoms stage. Eleven mTBI patients (mean age 22.8 years) and ten healthy controls participated in the study. Visuo-motor integration of fine motor abilities and form recognition were measured with the Beery-Buktenica Developmental Test of Visual-Motor Integration test, motion perception was evaluated with motion coherence test, critical flicker fusion was measured with Pocket CFF tester. Visuo-spatial was assessed with the Ruff 2 & 7 Selection Attention Test. mTBI patients showed reduced visuo-motor integration, form recognition, and motor deficits as well as visuo-spatial attention impairment, while motion perception and critical flicker fusion were not impaired. These preliminary findings suggest that the temporary brain insults deriving from mTBI compromise fine motor skills, visuomotor integration, form recognition, and visuo-spatial attention. The impairment in visuo-motor coordination was associated with speed in visuo-attention and correlated with symptoms severity while motor ability was correlated with time since concussion. Given the strong correlation between visuomotor coordination and symptom severity, further investigation with a larger sample seems warranted. Since there appeared to be differences in motor skills with respect to symptom stage, further research is needed to investigate symptom profiles associated with visuomotor coordination and fine motor deficits in mTBI patients.

The effect of vertical gaze position on ocular tear film stability

BACKGROUND

An enlarged exposed ocular surface area is known to degrade tear film stability. Little is known of how tear film stability alters with vertical gaze and the change of palpebral fissure height.

METHODS

Tear film break-up time (TBUT; fluorescent dye) and palpebral fissure height were measured in three vertical gaze positions (primary position and 20 degrees up and 20 degrees down) on 23 healthy volunteers. The effect of gaze direction on TBUT was analysed by ANOVA.

RESULTS

Gaze had a significant influence on tear film stability [F(2,44)=27.6, p<0.001]. In up-gaze with an enlarged palpebral fissure height (11.1 +/- 1.4 mm), TBUT was degraded (17.3 +/- 12.7 seconds). In down-gaze and decreased palpebral fissure height (6.7 +/- 1.2 mm) TBUT was extended (43.5 +/- 35.4 seconds).

CONCLUSION

Ocular tear film stability alters with vertical gaze. Our hypothesis is that the change of the palpebral fissure height and the exposed ocular surface area alters the thickness of the lipid layer and with it tear film evaporation.

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.

Developmental trajectories of global motion and global form perception from 4 years to adulthood

Literature on the development of global motion and global form perception demonstrated their asynchronous developmental trajectories. However, former studies have failed to clearly establish the critical period of maturation for these specific abilities. This study aimed to analyze the developmental trajectories of global motion and global form discrimination abilities by controlling for basic visual functions and general cognitive ability and to present the global motion and global form normative scores. A sample of 456 children and adolescents (4-17 years of age) and 76 adults recruited from the Italian and Swedish general population participated in the study. Motion and form perception were evaluated by the motion coherence test and form coherence test, respectively. Raven's matrices were used to assess general cognitive ability, the Lea Hyvärinen chart test was used for full- and low-contrast visual acuity, and the TNO test was used for stereopsis. General cognitive ability and basic visual functions were strongly related to motion and form perception development. Global motion perception had an accelerated maturation compared with global form perception. For motion perception, an analysis of the oblique effect's development showed that it is present at 4 years of age. The standardized scores of global motion and form coherence tests can be used for clinical purposes.

Measuring health-related quality of life in individuals with cyclodeviation using the Adult Strabismus 20 (AS-20) questionnaire

PURPOSE

To assess health-related quality of life (HRQoL) in patients diagnosed with cyclodeviation and to evaluate subjective change following surgical treatment using the Adult Strabismus-20 (AS-20) questionnaire.

METHODS

A prospective cohort study was performed from 2014 to 2019 on 29 adult patients with cyclodeviation and cyclodiplopia who were due to undergo corrective strabismus surgery by the same surgeon. The group was divided into two subgroups, according to the type of surgery required for fusion. All scores were analyzed for the whole sample and subgroups. Preoperative scores were compared with those of control patients.

RESULTS

Pre- and postoperative QoL scores were successfully collected from 26 patients (mean age, 56 years; 8 female) using the AS-20 questionnaire. Scores were significantly higher for control subjects than for patients in the cyclodeviation group (P = 0.0001). Postoperative scores for all 20 questionnaire questions were significantly improved for all patients (P = 0.002). There was a significant improvement in the functional subscale score (P = 0.001), but not in the psychosocial subscale score (P = 0.23). Results were enhanced by Rasch analysis.

CONCLUSIONS

Cyclodeviation patients demonstrated significantly lower scores than controls. The functional scores were significantly lower than the psychosocial scores, in contrast to other forms of strabismus. Strabismus surgery had a significant effect on quality-of-life scores in this group of adults.

Visual and Vestibular Integration Express Summative Eye Movement Responses and Reveal Higher Visual Acceleration Sensitivity than Previously Described

Purpose

Acceleration plays a great impact on the vestibular system, but is attributed little influence over vision. This study aims to explore how visual and vestibular acceleration affect roll-plane oculomotor responses, including their addiative effect.

Methods

Seated in a mechanical sled, 13 healthy volunteers (7 men, 6 women; mean age 25 years) were exposed to a series of visual (VIS) optokinetic, vestibular (VES) whole-body, and combined (VIS + VES) rotations. This was carried out at two acceleration intensities. Subjects wore a video-based eye tracker, enabling analysis of torsional and skewing eye movement responses, which were used to evaluate the individual response to each trial. The tracker also contained accelerometers allowing head tracking.

Results

Both ocular torsion and vertical skewing were sensitive to acceleration intensities for VES and VIS + VES. For VIS only, skewing exhibited such a response. An increased acceleration yielded a decreased torsion-skewing ratio for VIS, explained by the change in skewing, but remained unchanged for VES and VIS + VES. Torsion exhibited particularly reliable summative effect, yielding a relative contribution of 32% VIS and 75% VES during low acceleration, and 19% and 85%, respectively, during high acceleration.

Conclusions

The change in the skewing response to different intensities indicates that the visual system is more sensitive to visual accelerations than previously described. Eye movements showed reliable summative effects, indicating a robust visual-vestibular integration that indicates their integrative priorities for each acceleration, with the visual system being more involved during low accelerations. Such objective quantifications could hold clinical utility when assessing sensory mismatch in vertiginous patients.

The effects of meclizine on motion sickness revisited

AIMS

Antihistamines make up the first line of treatments against motion-sickness. Still, their efficacy and specific mechanism have come into question. The aim of this study was to investigate the effect of meclizine on motion-sensitivity.

METHODS

This study was carried out as a triple-blinded randomized trial involving 12 healthy subjects who were exposed to (i) vestibular (VES), (ii) visual (VIS) and (iii) visual-vestibular (VIS+VES) stimulations in the roll plane. Subjects were divided into 2 groups by stratified randomization, receiving either meclizine or a placebo. Stimulations were carried out before, and after, drug administration, presented at 2 intensity levels of 14 and 28°/s² . Eye movements were tracked, and torsional slow-phase velocities, amplitudes and nystagmus beats were retrieved. Subjects initially graded for their motion-sickness susceptibility.

RESULTS

Susceptibility had no effect on intervention outcome. Despite large variations, repeated ANOVAS showed that meclizine led to a relative increase in torsional velocity compared to placebo during vestibular stimulation for both intensities: 2.36 (7.65) from -0.01 (4.17) during low intensities, and 2.61 (6.67) from -3.49 (4.76) during high. The visual-vestibular stimuli yielded a decrease during low acceleration, -0.40 (3.87) from 3.75 (5.62), but increased during high, 3.88 (6.51) from -3.88 (8.55).

CONCLUSIONS

Meclizine had an inhibitory effect on eye movement reflexes for low accelerations during VIS+VES trials. This indicates that meclizine may not primarily work through sensory-specific mechanisms, but rather on a more central level. Practically, meclizine shows promise in targeting motion-sickness evoked by everyday activities, but its use may be counterproductive in high-acceleration environments.

Clinical measurements of normative subjective cyclotorsion and cyclofusion in a healthy adult population

PURPOSE

To investigate normative subjective cyclotorsion values and cyclofusion ranges in a healthy adult population.

METHODS

A cross-sectional investigation was performed in 120 healthy, non-strabismic adults, 60 men and 60 women in the age range of 18-69 years. All subjects were assessed for cyclotorsion using the synoptophore and the single Maddox rod (SMR) methods. Cyclofusion was investigated with the synoptophore in 60 of the subjects.

RESULTS

All age groups showed low values of subjective torsion, mainly excyclotorsion with mean values of -1 degree for both methods. Reference ranges of cyclotorsion were between -0.7 and -1.5 degrees for the SMR method and between -0.7 and -1.4 degrees using the synoptophore method. There were no significant differences between gender (p = 0.48), but the effect of age was significant for both methods (p = 0.026) demonstrating a slight increase in excyclotorsion with age. Cyclofusion showed a total mean amplitude of 16 degrees, the fusion range was +7 degrees of incyclotorsion to -9 degrees of excyclotorsion.

CONCLUSIONS

Subjective reference ranges for cyclotorsion and cyclofusion reveal that low values of torsion are to be expected upon clinical investigation in non-strabismic adult individuals. Values outside of the reference range may be indicators of possible binocular abnormalities or physiological variations. The cyclotorsional measurements and prevalence in this adult population group can be regarded as normative data in clinical settings.

Intensified visual clutter induces increased sympathetic signalling, poorer postural control, and faster torsional eye movements during visual rotation

Many dizzy patients express a hypersensitivity to visual motion and clutter. This study aims to investigate how exposure to rotating visual clutter affects ocular torsion, vertical skewing, body-sway, the autonomic pupillary response, and the subjective feeling of discomfort to the stimulation. Sixteen healthy subjects were exposed to 20 seconds rotational visual stimulation (72 deg/s; 50 deg visual field). Visual stimuli were comprised of black lines on a white background, presented at low and high intensity levels of visual clutter, holding 19 lines and 38 lines respectively. Ocular torsion and vertical skewing were recorded using the Chronos Eye Tracker, which also measured pupil size as a reflection of the autonomic response. Postural control was evaluated by measuring body-sway area on the Wii Balance Board. Values were compared to data retrieved 20 seconds before and after the optokinetic stimulation, as subjects viewed the stationary visual scene. The high intensity stimulus resulted in significantly higher torsional velocities. Subjects who were exposed to low intensity first exhibited higher velocities for both intensities. Both pupil size and body sway increased for the higher intensity to both the moving and stationary visual scene, and were positively correlated to torsional velocity. In conclusion, exposure to visual clutter was reflected in the eye movement response, changes in postural control, and the autonomic response. This response may hold clinical utility when assessing patients suffering from visual motion hypersensitivity, while also providing some context as to why some healthy people feel discomfort in visually cluttered surroundings.

An observational study of trait and state fatigue, and their relation to cognitive fatigability and saccade performance

Aim:

Different fatigue measurements and their relation to saccadic functions were investigated in 15 patients with a mild traumatic brain injury (mTBI) and 15 orthopedic controls.

Materials & methods:

State fatigue was measured with the Fatigue Severity Scale and trait fatigue with the question on fatigue in the Rivermead Post Concussion Questionnaire and fatigability as decreased performance over time on a neuropsychological measure.

Results:

Patients with an mTBI scored significantly higher in state fatigue and showed more fatigability compared with the orthopedic controls. Among patients with mTBI, state fatigue correlated with prosaccade latency and cognitive fatigability, while trait fatigue correlated with anxiety and antisaccade latency and variability.

Conclusion:

This pilot study indicates that saccade measurements might, in the future, be useful in the understanding of fatigue and in the search for prognostic factors after mTBI.

Accommodation and near visual function in children with albinism

PURPOSE

Albinism degrades visual function due to developmental disorders of the eye and visual pathways, larger refractive errors, absent binocularity and poor fixation control. Reading spectacles is commonly prescribed in our clinic and well tolerated. The purpose was to evaluate whether the accommodative response is typical or affected in comparison to a reference group.

METHODS

Twenty-two children with albinism (median: 13.5 years) and 12 controls (median: 13 years) underwent a full optometric examination and an objective accommodation measurement (WAM-5500 @ 6 Hz; Grand Seiko) in response to minus-lens-blur (-1, -2 and -3 D) and to a prolonged near viewing task (20 cm) for 5 min.

RESULTS

Children with albinism displayed less accommodation to minus lens-blur and during sustained near viewing (p < 0.001) compared to the reference group. Higher visual acuity correlates with a better accommodative response (r ≥ 0.5; p ≤ 0.04). The subjective and objective measures of accommodation did not correlate. The habitual reading distance was always closer than the point towards which the subjects with albinism seemed to accommodate according to the measurements at 20 cm.

CONCLUSION

Children with albinism benefits from reading spectacles due to a combination of close habitual reading distance and a poor accommodation. Objective recording of accommodation is not critical for a correct judgement of near visual function. Children already wearing reading spectacles were those with least accommodative response.

Vestibular Eye Movements Are Heavily Impacted by Visual Motion and Are Sensitive to Changes in Visual Intensities

Purpose

Eye movement evaluation constitutes the basis of diagnosis in dizzy patients. Through evaluating ocular torsion and vertical skewing during balance provoking stimulation, the aim of this study was to investigate the impact of vision on a typical vestibular eye movement response.

Methods

Twelve healthy subjects (six young, six old) were exposed to (1) vestibular (VES), (2) visual (VIS), and (3) visual-vestibular (VIS+VES) stimulation. These were carried out as whole-body roll (VES), optokinetic rolling of visual scenes (VIS), and a combination of both (VIS+VES). Visual scenes were presented at two intensity levels. Eye movement velocities were used to evaluate the relative impact of visual and vestibular stimulation.

Results

Torsional velocities were lowest for VIS regardless of age. Velocities for the old group did not differ between VES and VIS+VES, whereas those for the young group were higher for VIS+VES. Regardless of age, amplified visual intensity resulted in an increased torsion-skewing ratio, seen as more degrees of torsion per degrees of skewing. The contributions of VIS and VES in proportion to VIS+VES were calculated as 0.18 (0.08) and 0.74 (0.14), respectively.

Conclusions

Our findings demonstrate that vertical skewing is physiologically seen in combination with ocular torsion as a response to visual stimulation, with young subjects exhibiting a more dynamic response. The torsion-skewing ratio was sensitive to small changes in visual intensities, which may prove useful when evaluating visual motion sensitivity. The visual contribution to the vestibular eye movement response highlights the clinical importance of visual examinations when evaluating dizzy patients.

Longitudinal changes in oculomotor function in young adults with mild traumatic brain injury in Sweden: an exploratory prospective observational study

OBJECTIVES

To assess (1) whether visual disturbances can be demonstrated with objective measures more often in patients with mild traumatic brain injury (mTBI) than in orthopaedic controls and non-injured controls, (2) whether such objectively demonstrated disturbances change over time and (3) whether self-reported visual symptoms after mTBI correlate with objectively measurable changes in visuomotor performance.

DESIGN

A prospective, controlled, observational study, with assessments planned 7-10 and 75-100 days after injury.

SETTING

Emergency department of a general hospital in Sweden.

PARTICIPANTS

15 patients with mTBI, 15 patients with minor orthopaedic injury, 15 non-injured controls, aged 18-40 years.

OUTCOME MEASURES

Visual examination, including assessment of visual acuity, accommodation, eye alignment, saccades and stereoacuity. Symptom assessment using Convergence Insufficiency Symptoms Survey (CISS) and Rivermead PostConcussion Symptoms Questionnaire.

RESULTS

Assessments were performed 4-13 and 81-322 days after injury (extended time frames for logistical reasons). No statistically significant difference was found between the mTBI and control groups regarding saccade performance and stereoacuity at any time point. The accommodative amplitude was significantly lower in the mTBI group compared with non-injured controls at baseline. 6 out of 13 patients with mTBI had accommodative insufficiency at follow-up. Near point of convergence in the mTBI group was receded at baseline and improved statistically significantly at follow-up. At baseline, patients with mTBI had significantly higher CISS score than orthopaedic and non-injured controls. For patients with mTBI, the CISS score correlated with fusional vergence.

CONCLUSION

There were some transient measurable visual changes regarding convergence in patients with mTBI during the subacute period after the injury. Our findings of persistence of accommodative insufficiency in a considerable proportion of patients with mTBI suggest that this visual function should not be overlooked in clinical assessment.

Screening for Dyslexia Using Eye Tracking during Reading

Dyslexia is a neurodevelopmental reading disability estimated to affect 5-10% of the population. While there is yet no full understanding of the cause of dyslexia, or agreement on its precise definition, it is certain that many individuals suffer persistent problems in learning to read for no apparent reason. Although it is generally agreed that early intervention is the best form of support for children with dyslexia, there is still a lack of efficient and objective means to help identify those at risk during the early years of school. Here we show that it is possible to identify 9-10 year old individuals at risk of persistent reading difficulties by using eye tracking during reading to probe the processes that underlie reading ability. In contrast to current screening methods, which rely on oral or written tests, eye tracking does not depend on the subject to produce some overt verbal response and thus provides a natural means to objectively assess the reading process as it unfolds in real-time. Our study is based on a sample of 97 high-risk subjects with early identified word decoding difficulties and a control group of 88 low-risk subjects. These subjects were selected from a larger population of 2165 school children attending second grade. Using predictive modeling and statistical resampling techniques, we develop classification models from eye tracking records less than one minute in duration and show that the models are able to differentiate high-risk subjects from low-risk subjects with high accuracy. Although dyslexia is fundamentally a language-based learning disability, our results suggest that eye movements in reading can be highly predictive of individual reading ability and that eye tracking can be an efficient means to identify children at risk of long-term reading difficulties.

Stepwise increase of hypermetropic correction using contact lenses in intermittent partially accommodative esotropia

BACKGROUND

The aim was to present a series of patients with intermittent partially accommodative esotropia (pAcc-ET) in evaluating the effect of over-plus correcting the hypermetropia relative to the non-cycloplegic refraction using contact lenses.

METHODS

Twenty-three patients (23.8 ± 8.9 years) with intermittent pAcc-ET were fitted with soft daily single-vision contact lenses and the hypermetropia was over-plus corrected relative to the original subjective non-cycloplegic refraction, reducing distance visual acuity to 0.8 (decimal acuity). Hypermetropia correction was increased at follow-ups (every second week) until visual acuity stabilised or symptoms ceased. The contact lenses were worn for the entire study period.

RESULTS

After eight weeks of treatment (two to four follow-ups) the intermittent esotropia stabilised into esophoria and the magnitude of the deviation at distance was reduced in 70 per cent (16/23) of patients and at near in 91 per cent (21/23) of patients. As a result calculated accommodative-convergence and the level of accommodation (stimulus AC/A ratio) was reduced in 83 per cent (19/23) of patients but still classified as high (less than 5:1).

CONCLUSIONS

Compared to correction based on original non-cycloplegic subjective refraction, increasing correction of hypermetropia with contact lenses in partially accommodative esotropia reduced the magnitude of the eso-deviation at distance and near. In addition to reducing accommodative demand and stimulus AC/A with increasing hyperopic correction, contact lenses may provide additional benefit given the increased hyperopic correction and the decreased stimulus for accommodation required at the corneal plane.

Eye dominance in binocular viewing conditions

Different degrees of eye dominance may need to be considered when comparing monocular and binocular performance or estimating binocular summation effects. The purpose of this study was to explore eye dominance under binocular viewing conditions and observe gradual differences in preference. Two binocular eye-dominance tests were evaluated and compared to the hole-in-the-card sighting test. The first experiment was based on a binocular sighting test. The second originated from the variable-angle mirror test, utilizing physiological diplopia to determine which eye dominates the binocular percept. The participants were 32 healthy subject with normal sight. For both experiments there were plausible effects of different degrees of eye dominance affecting how the subjects positioned or perceived the scene. The outcomes were supported by a statistically significant correlation with an interocular difference in sensitivity to degraded visibility. A statistically significant correlation was found between the hole-in-the-card test and the variable-angle mirror test (r = 0.527, p &lt; 0.01). The experiments confirm the plausible occurrence of forms of eye dominance under binocular viewing conditions. The correlation with the hole-in-the-card test was weak to moderate, due to factors that appear to be related to testing and viewing conditions. Interocular differences in sensitivity to blur appear to be a useful factor in further grading of eye dominance.

Slow fluctuations in eye position and resting-state functional magnetic resonance imaging brain activity during visual fixation

The neuronal circuitry that supports voluntary changes in eye position in tasks that require attention-driven oculo-motor control is well known. However, less is known about the neuronal basis for eye control during visual fixation. This, together with the fact that visual fixation is one of the most commonly used baseline conditions in resting-state functional magnetic resonance imaging (fMRI) studies, prompted us to conduct a study in which we employed resting-state fMRI and concurrent recordings of eye gaze to investigate the relationship between spontaneous changes in eye position during passive visual fixation and intrinsic brain activity. As a control experiment, we recorded fMRI brain activity related to cued voluntary vertical and horizontal changes in eye position in a block-related task-evoked fMRI experiment. Our results for the voluntarily performed changes in eye position elicited brain activity in the bilateral occipitotemporal cortex, supplementary motor cortex and frontal eye fields. In contrast, we show that slow fluctuations in eye position during passive visual fixation are linked to intrinsic brain activity, foremost in midline cortical brain regions located in the posteromedial parietal cortex and the medial prefrontal cortex, brain regions that act as core cortical hubs in the brain's default mode network. Our results suggest that subconscious and sustained changes in behavior are tied to intrinsic brain activity on a moment-by-moment basis.

Monocular and binocular reading performance in subjects with normal binocular vision

BACKGROUND

It is well known that problems with binocular vision can cause issues for reading; less known is to what extent binocular vision improves reading performance. The purpose of this study was to explore the role of binocularity by directly comparing monocular and binocular reading in subjects with typical reading skills and normal binocular vision. A secondary purpose was to assess any asymmetry in monocular performance and its association with the sighting dominant eye.

METHODS

In a balanced repeated measures experiment, 18 subjects read paragraphs of text under monocular and binocular conditions. All subjects went through an optometric examination before inclusion. Reading speed and eye movements were recorded with an eye tracker.

RESULTS

The mean difference in reading speed (2.1 per cent) between monocular (dominant and non-dominant eye averaged) and binocular reading speed was not significant. A significant difference in reading speed was found between binocular and the non-dominant eye, as determined by the far sighting test (p = 0.03). Monocular reading showed significantly increased (8.9 per cent) fixation duration (p < 0.01) and longer regressive saccades by 0.43 character spaces (p < 0.01). Reading with the non-dominant eye, as determined by the near sighting test, showed increased progressive saccade length by 0.2 characters compared to the dominant eye (p = 0.03). No other significant differences between dominant and non-dominant eyes were found. The agreement between the faster reading eye and ocular dominance was 44 to 56 per cent depending on whether dominance was determined at near or far.

CONCLUSION

The outcomes suggest that in subjects with normal binocular vision, there is no marked enhancement in reading performance by binocular vision when reading paragraphs of text. Furthermore, the monocular reading performance appears to be close to equal and any small differences in performance appear not to be strongly associated with ocular dominance.

The accommodative process in children with cerebral palsy: different strategies to obtain clear vision at short distance

AIM

Accommodation is the ability of the eye to change focus in order to maintain a sharp image of objects at various distances. The accommodative process is largely unknown in children and requires new assessment techniques. The aim of the study was to investigate this process in children with and without cerebral palsy (CP).

METHOD

In a descriptive case-control study, children with CP (n=15; nine females, six males; median age 14y) and 21 typically developing children (11 females, 10 males; median age 12y) underwent standard ophthalmological examination and examination by the PowerRefractor. Six of the children had spastic bilateral CP, five had spastic unilateral CP, and four had dyskinetic CP. The children's Gross Motor Function Classification System (GMFCS) levels were as follows: level I, seven children; level II, two children; level III, three children; and level IV, three children. The PowerRefractor measures accommodation in response to minus lens stimuli. Continuous measurements of refraction/accommodation, eye position, and pupil size are obtained. The Kruskal-Wallis analysis of variance (ANOVA) and Mann-Whitney U test were used for between-group analysis (α=0.05), and Friedman ANOVA was used for within-group analysis.

RESULTS

The stimuli-response gain (input/output) was approximately 80% in typical children inducing a focusing error (0.2-0.5D) increasing with minus lens power. Children with CP accommodated significantly less (gain: ~30%; p<0.001), inducing a larger focusing error (1.1-1.7D) increasing with minus lens power. The accommodative response was slower and more variable in children with CP. The pupil response did not mirror the accommodative response.

INTERPRETATION

Children with CP exhibit problems in generating an appropriate accommodative response. This can affect everyday living and reading skills.

Ocular vestibular-evoked myogenic potentials (oVEMP) to skull taps in normal and dehiscent ears: mechanisms and markers of superior canal dehiscence

The site of stimulus delivery modulates the waveforms of cervical- and ocular vestibular-evoked myogenic potentials (cVEMP and oVEMP) to skull taps in healthy controls. We examine the influence of stimulus location on the oVEMP waveforms of 18 patients (24 ears) with superior canal dehiscence (SCD) and compare these with the results of 16 healthy control subjects (32 ears). oVEMPs were recorded in response to taps delivered with a triggered tendon-hammer and a hand-held minishaker at three midline locations; the hairline (Fz), vertex (Cz) and occiput (Oz). In controls, Fz stimulation evoked a consistent oVEMP waveform with a negative peak (n1) at 9.5 ± 0.5 ms. In SCD, stimulation at Fz produced large oVEMP waveforms with delayed n1 peaks (tendon-hammer = 13.2 ± 1.0 ms and minitap = 11.5 ± 1.1 ms). Vertex taps produced diverse low-amplitude waveforms in controls with n1 peaks at 15.5 ± 1.2 and 13.2 ± 1.3 ms for tendon-hammer taps and minitaps, respectively; in SCD, they produced large amplitude oVEMP waveforms with n1 peaks at 12.9 ± 0.8 ms (tendon-hammer) and 12.1 ± 0.5 ms (minitap). Occiput stimulation evoked oVEMPs with similar n1 latencies in both groups (tendon-hammer = 11.3 ± 1.3 and 10.7 ± 0.8; minitap = 10.3 ± 0.9 and 11.1 ± 0.4 for control and SCD ears, respectively). Compared to reflex amplitudes, n1 peak latencies to Fz taps provided clearer separation between SCD and control ears. The distinctly different effects of Fz and vertex taps on the oVEMP waveforms may represent an additional non-osseous mechanism of stimulus transmission in SCD. For skull taps at Fz, a prolonged n1 latency is an indicator of SCD.

Ophthalmologic findings in patients with non-surgically treated blowout fractures

We evaluated the ocular and visual status in a group of patients with a non-surgically treated blowout fracture. Clinical examination with refraction, test of binocular function, and tear film evaluation was performed in 23 patients. These values were statistically correlated with the orbital volume measurements and ocular finding from the patient records at presentation. About 50% of the study group was symptomatic due to low visual acuity from refractive errors and decompensated phorias as a consequence of the blowout fracture. Several patients displayed changes in tear film production. There was no strong correlation between the measured parameters and orbital volume measurements. Patients with a non-surgically treated blowout fracture often display ocular and visual changes after discharge. A routine visual exam is advocated in all patients after the ocular status has stabilized after a blowout fracture.

Relative difference in orbital volume as an indication for surgical reconstruction in isolated orbital floor fractures

In orbital floor fractures, the estimation of the herniated orbital content in the maxillary sinus has traditionally been the dividing line between surgical and nonsurgical management. In this study, we evaluated whether a relative change in volume would function as an indicator for surgical versus nonsurgical treatment of orbital floor fractures. This was a follow-up study in patients with untreated unilateral isolated orbital floor fractures admitted to our department from March 2003 to April 2007. Patients were contacted by regular mail and invited to have a clinical eye examination. The volume of the orbital content was calculated digitally from the patients' computed tomography scans at the time of their injury. Eighteen subjects with no facial skeleton fracture were included for reference of orbital content volumes. Five of 23 patients showed 2 to 4 mm of enophthalmos, and only three of them had intermittent diplopia. No statistical correlation was found between the herniated volume and enophthalmos. No statistical correlation supporting the supposition that 1 mL of herniated orbital content would result in 1 mm of enophthalmos was found. The relative volume change between the fractured and nonfractured orbit in an individual does not appear to be a useful criterion for surgery. The importance of the herniated orbital tissue for the development of enophthalmos is unclear.

Mechanisms compensating for visual field restriction in adolescents with damage to the retro-geniculate visual system

BACKGROUND

To describe visual field (VF) outcome in three adolescents with damage to the optic radiation and to focus on mechanisms that may compensate the practical functional limitations of VF defects.

DESIGN

Descriptive, prospective multi-case study in a hospital setting.

PARTICIPANTS

Three teenagers with cerebral visual dysfunction because of damage to the retro-geniculate visual pathways.

METHODS

Best-corrected visual acuity and eye alignment were assessed. Visual field function was tested with Goldmann perimetry, and with Rarebit, Humphrey Visual Field Analyzer and Esterman computerized techniques. Fixation was registered with video oculography during Rarebit examination. Magnetic resonance imaging of the brain illustrated brain damage and its relation to the posterior visual system.

RESULTS

One of the three subjects had bilateral asymmetric white matter damage of immaturity, early-onset exotropia, and a relative homonymous VF defect, but normal binocular VF. The second subject also had bilateral asymmetric white matter damage of immaturity and showed an inferior right quadrantanopia, confirmed by the binocular field. Registration of fixation revealed automatic scanning during perimetry. The third subject had an almost total left homonymous hemianopia after resection of a brain tumour in the right temporal lobe. The hemianopia could be compensated for by fast voluntary scanning.

CONCLUSION

Congenital and later-acquired homonymous VF defects may, at least in young subjects, be compensated for by scanning. Exotropia may compensate VF defects and, therefore, the VF should be tested before strabismus surgery.

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.

Evaluation of accommodative Insufficiency with the Visual Analogue Scale (VAS)

PURPOSE

The purpose of this study was to evaluate whether asthenopic symptoms in schoolchildren diagnosed with accommodative insufficiency (AI) and graded with the Visual Analogue Scale (VAS) could be correlated with the degree of accommodative deficiency in these children, and to investigate if VAS grading of the asthenopic symptoms could be used as an instrument to indicate the level of improvement of AI.

METHODS

Forty-nine children (mean age 10.2 years +/- 2.7) diagnosed with AI graded their degree of asthenopia on the VAS before and after a 12-week treatment period wearing individually dispensed reading glasses.

RESULTS

The improvement in accommodation after treatment was statistically significant (p < 0.001) and 83.7% of the children obtained normal accommodative amplitude in relation to age. The reduction in asthenopic symptoms as graded with the VAS was also statistically significant (p < 0.001) after treatment and 89.9% of the children obtained a normal VAS score. However, no correlation between the degree of accommodative deficiency and the VAS grading could be found, neither before nor after treatment.

DISCUSSION

Based on these results we conclude that the visual analogue scale (VAS) cannot be used as an instrument to indicate the degree of accommodative deficiency nor can it be used to indicate the level of improvement during the course of treatment. However, the VAS can be used as an instrument to verify and document whether or not asthenopic symptoms are present, and therefore also to indicate when symptoms have been relieved.

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.

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.

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).

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.

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.

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.