How to assess visual function in acquired brain injury-Asking is not enough.

BACKGROUND: Acquired brain injury affects many brain areas and causes a range of dysfunctions including vision-related issues. These issues can have negative impacts on rehabilitation progress and activities of daily life but may easily be overlooked. There is no common recommendation about how to assess visual impairments after ABI. The purpose of this study was to estimate the frequency of objectively measures oculomotor dysfunctions, and also how these findings are related to two inventories intended to support detection of visual impairment. METHODS: The study was cross-sectional and included 73 outpatients. In addition to the standard evaluation program, the patients went through a comprehensive optometric examination. The inventories used were the Vision Interview (VI) and the Convergence Insufficiency Symptom Survey (CISS). RESULTS: All three types of examinations showed a high proportion vision-related symptoms. Fusion vergence was the most common objectively measured finding, 83%. There were seven statistically significant associations between five VI items and five visual deficits. The strength of associations was moderate (Phi 0.261-0.487, p < .05). The sensitivity and specificity of the CISS were moderate. CONCLUSION: We found high percentages of the patients with visual symptoms and dysfunctions. Due to the complexity of visual symptoms and functional deficits in ABI, we find it necessary to combine both symptom assessment and vision examination in order to capture visual function issues.

Vision-related symptoms after acquired brain injury and the association with mental fatigue, anxiety and depression.

BACKGROUND: Brain injury causes multiple symptoms. Among these, visual disturbances are common; 50-70% of patients experience some change in vision after injury/illness. Other very common and disabling symptoms are fatigue, anxiety and depression. This study examines whether levels of fatigue, anxiety and depression are increased if the patients also experience vision disorders. MATERIALS AND METHODS: A total of 123 patients enrolled in day care rehabilitation unit for medium-to-severe brain injury completed questionnaires about self-experienced fatigue, anxiety, depression and self-experienced level and type of visual disturbances. Symptoms of fatigue, anxiety and depression were compared with the occurrence of visual disturbances. Analyses were performed using binary logistic regression. RESULTS: An association was found between visual symptoms and fatigue, but not between visual symptoms and anxiety/depression. However, some visual symptoms, such as glare, blurred vision and reading difficulties, showed great differences between patients with or without anxiety/depression. CONCLUSION: Vision rehabilitation may be a tool for mitigating fatigue after acquired brain injury.

Visual dysfunction is underestimated in patients with acquired brain injury.

OBJECTIVES: More than 50% of human cerebral activity is related to vision. Visual impairments are therefore common after acquired brain injury, although they are often overlooked. In order to evaluate the prevalence of visual deficits in our Out-patient Brain Injury Program, a structured screening questionnaire, the Visual Interview, was administered. METHODS: A total of 170 patients with acquired brain injury, mean age 47 years, who were enrolled in the programme during 2010-12, underwent the Visual Interview. The interview consists of 18 questions concerning visual impairment and was performed on admission. The different types of visual impairment were compared with regard to sex and diagnosis. RESULTS: Fifty-four percent of the patients reported visual changes, mainly reading difficulties, photosensitivity, blurred vision and disorders of the visual field. Sixteen patients who did not experience visual changes also reported visual symptoms in 4-9 questions. Only slight differences were noted in the occurrence of visual symptoms when correlated with sex or diagnosis. CONCLUSION: Visual impairments are common after acquired brain injury, but some patients do not define their problems as vision-related. A structured questionnaire, covering the most common visual symptoms, is helpful for the rehabilitation team to facilitate assessment of visual changes.

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.

Progressive brain calcifications and signs in a family with the L9R mutation in the PDGFB gene.

Primary familial brain calcifications (PFBC) are a heterogeneous group of rare autosomal dominant disorders. Mutations in the PDGFB gene are the second most common cause of PFBC. A model for PDGFB-associated PFBC, hypomorphic PDGFB (ret/ret) mouse, displays impaired blood-brain barrier (BBB), progressive brain calcifications and increased flux of the oxysterol 24S-hydroxycholesterol from the brain into the circulation.(1,2) Only 8 families and 2 sporadic cases with PDGFB mutations have been identified so far, one of them a Swedish-Finnish family previously described as F13.(1,3-6) Very little is known about the natural history of PDGFB-associated PFBC. Here, we provide a comprehensive long-term follow-up of the F13 family.

Ocular Motor Score (OMS): a clinical tool to evaluating ocular motor functions in children. Intrarater and inter-rater agreement.

PURPOSE: Ocular motor score (OMS) is a new clinical test protocol for evaluating ocular motor functions in children and young adults. OMS is a set of 15 important and relevant non-invasive ocular motor function parameters derived from clinical practice. The aim of the study was to evaluate OMS according to intrarater and inter-rater agreement. METHODS: Forty children aged 4-10 years, 23 girls median age 6.5 (range 4.3-9.3) and 17 boys median age 5.8 (range 4.1-9.8) were included. The ocular motor functions were assessed and scored according to the OMS protocol. The examinations were videotaped. To obtain the intrarater agreement, the first author examined and scored the children twice, first in the clinic and 2 weeks later by watching the videotape. To obtain the inter-rater agreement, three other raters independently scored the ocular motor function of the children by watching the videotapes. RESULTS: The overall observed intrarater agreement was 88%, and the observed inter-rater agreement between the three raters was 80%. For none of the subtests was there an observed intrarater agreement lower than 65%. Three of the subtests had an observed inter-rater agreement of 65% or below. CONCLUSION: Overall there was high observed intra- and inter-rater agreement for the OMS test protocol. Subtests such as saccades and smooth pursuit were more difficult for raters to score similarly according the clinical OMS test protocol.

The effect of contrast on monocular versus binocular reading performance.

The binocular advantage in reading performance is typically small. On the other hand research shows binocular reading to be remarkably robust to degraded stimulus properties. We hypothesized that this robustness may stem from an increasing binocular contribution. The main objective was to compare monocular and binocular performance at different stimulus contrasts and assess the level of binocular superiority. A secondary objective was to assess any asymmetry in performance related to ocular dominance. In a balanced repeated measures experiment 18 subjects read texts at three levels of contrast monocularly and binocularly while their eye movements were recorded. The binocular advantage increased with reduced contrast producing a 7% slower monocular reading at 40% contrast, 9% slower at 20% contrast, and 21% slower at 10% contrast. A statistically significant interaction effect was found in fixation duration displaying a more adverse effect in the monocular condition at lowest contrast. No significant effects of ocular dominance were observed. The outcome suggests that binocularity contributes increasingly to reading performance as stimulus contrast decreases. The strongest difference between monocular and binocular performance was due to fixation duration. The findings may pose a clinical point that it may be necessary to consider tests at different contrast levels when estimating reading performance.

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 influence of horizontal convergence on slow oscillatory eye movements during visual fixation.

PURPOSE: Slow oscillatory eye movements (SOMs) occur simultaneously with tremor, drifts, and microsaccades during visual fixation. In a previous study, the amplitude of SOM was found to be affected by the visual characteristics of the stimuli. This indicates a perceptual influence on the control of the movement. However, the frequency of SOM did not change. The aim of our study was to investigate how SOM is affected by extraocular muscle tension. METHODS: In a repeated-measurement experiment, 14 subjects were instructed to maintain fixation for 3 minutes on a bright dot presented at four distances (15, 30, 60, and 120 cm). The level of extraocular muscle tension is assumed to increase with decreased fixation distance due to convergence angle. Eye movements were recorded binocularly using a video eye tracker, and the amplitude and frequency of SOM for each eye were obtained by independently filtering the horizontal and vertical eye position signals with a discrete Fourier transformation. RESULTS: The results showed no significant differences for the amplitude. However, the horizontal frequency was found to be significantly lower at the closest distance. No significant differences were found for the vertical frequency. CONCLUSIONS: Based on these findings we conclude that extraocular muscle tension does have an effect on the frequency, but not the amplitude, of the oscillations. The apparent double dissociation between perceptual effects on amplitude versus muscle tension effects on frequency is discussed in relation to the origin and control of SOM.

Ophthalmologic findings in Russian children with fetal alcohol syndrome.

PURPOSE: To study functional and anatomic characteristics of eyes of Russian children with fetal alcohol syndrome (FAS).
 METHODS: One hundred children aged 10-16 years from Russian orphanages (St. Petersburg) were examined: 50 with verified diagnosis of FAS and 50 healthy children. All children were tested for distance visual acuity (VA) with subjective optimal correction (Sivtsev chart), skiascopy, visual inspection for FAS external ocular features, biomicroscopy, eye alignment using cover test, and indirect ophthalmoscopy.
 RESULTS: All analyzed parameters were worse in children with FAS compared with controls. Children with FAS showed a higher incidence of amblyopia, hyperopia, astigmatism, and anisometropia. In children with FAS, the incidence of blepharophimosis was 34% (8% in controls), epicanthus 14% (2% in controls), telecanthus 32% (compared to 4% in controls), eyelid ptosis 9% (none in controls), and strabismus 26% (10% in controls). Ophthalmoscopy revealed a tilted optic disc in 5 children with FAS (7%) compared with none in controls.
 CONCLUSION: Russian children with FAS have a higher incidence of vision problems and eye pathology that needs to be taken into account and requires ophthalmologist monitoring.

Ocular motor score a novel clinical approach to evaluating ocular motor function in children.

PURPOSE: Ocular motility disturbances are common in a number of neuropaediatric and neurometabolic disorders. Assessment of ocular motor function can be a source of information for diagnosis and follow-up of these patients. AIM: To evaluate a new clinical ocular motor function test: ocular motor score (OMS) and provide reference values in children and young adults without known ocular or neurological disorders. MATERIAL AND METHODS: A total of 233 children and young adults, 103 males and 130 females between the ages of 6 months and 19 years, were assessed according to a specific OMS protocol. They were divided into four different age groups: 0.5-3, 4-6, 7-10 and 11-19 years. The OMS protocol consists of 15 different subtests evaluating ocular motor function, and a total score of minimum 0 up to max 15 can be obtained: the minimum score, 0, is considered normal while 1 represents an abnormal function. RESULTS: The median OMS in the whole reference group was 0.3 (range 0-4.8). The median OMS in the different age groups, starting with the youngest, was: 0.9 (range 0.3-4.8), 0.3 (range 0-3.4), 0.3 (range 0-2.3) and 0 (range 0-3.5), respectively. The youngest subjects, aged 0.5-3, showed a significantly higher total OMS compared with the other age groups (p < 0.001). CONCLUSION: This study provides reference values for the OMS test in a population aged 0.5-19 years. The test may be valuable as a screening tool for identification and follow-up of ocular motor dysfunction in children and young adults.

Motion perception in children with foetal alcohol syndrome.

AIM: To evaluate the visual magnocellular pathway by a coherent motion perception test in children with foetal alcohol syndrome (FAS). METHODS: Eighty-nine children (49 with verified FAS and 40 without FAS) aged from 10 to 16 years were included into the study. Both the study and the control group were children living in orphanages. A coherent motion perception test was used. The test consisted of 150 white moving dots on a black background presented in different signal-to-noise ratio conditions. The task was direction detection of the coherently moving dots whose percentage decreased at each step. RESULTS: A significant difference between the two groups was found (p = 0.018). Children with FAS had lower coherent motion perception ability in all the signal-to-noise ratio conditions. A significant difference between difficulty levels (p < 0.001) was found for all subjects in both groups - decreasing the stimulus signal-to-noise level decreased the motion perception score. In both groups, the motion perception score differed for vertical and horizontal stimuli (p = 0.003) with better performance with vertical stimuli. CONCLUSION: Impaired motion perception in FAS children could be indicative of a dorsal stream developmental dysfunction resulting from alcohol brain damage.

Visual function, ocular motility and ocular characteristics in patients with mitochondrial complex I deficiency.

PURPOSE: The aims of the present study were to investigate visual function, ocular motility and ocular characteristics in children and young adults with complex I deficiency. MATERIAL AND METHODS: In a prospective study with longitudinal follow-up, the visual and ocular outcome in 13 patients with deficiency in complex I [nicotine-amide adenine dinucleotide (NADH) dehydrogenase] in the mitochondrial respiratory chain is presented. The patients were diagnosed during 1995-2007 and assessed during 1997-2009 at a median age of 12.8 years (range 3.1-23.4). RESULTS: Twelve of 13 patients had visual impairment and/or ocular pathology. Four of 10 patients who co-operated in visual assessment had a best corrected decimal visual acuity of ≤ 0.5 in one or both eyes. Cataract surgery was performed in one patient and another patient showed retinal pigmentations and ptosis. Eleven patients demonstrated ocular motility problems, mainly saccade deficiencies. Five patients had optic atrophy (OA), which was bilateral in four patients. In four siblings, the OA showed a similarity to Leber's Hereditary Optic Neuropathy. These patients also had the 11778 G → A mutation in mitochondrial DNA. Only one patient had normal visual acuity and ocular outcome including refraction and visual fields. Follow-up time was median 3.0 years (range 0-11). CONCLUSION: Visual impairment, ocular motility problems and OA are common in children and young adults with complex I deficiency and should prompt the paediatric ophthalmologist to consider mitochondrial disorders.

Changes of saccadic eye movements in thyroid-associated ophthalmopathy.

PURPOSE: To establish whether or not the dynamics of saccadic eye movements are significantly changed in patients with different stages of thyroid-associated ophthalmopathy (TAO) and, subsequently, if analysis of saccades could serve as an additional diagnostic tool for early detection of inflammatory activity in TAO. METHODS: Thirty-seven patients with TAO and 10 age- and gender-matched control subjects were investigated. The patients were divided into four groups according to the stage of the disease: (i) early mild disease (n = 10), (ii) early severe disease (n = 11), (iii) long-standing restrictive disease (n = 10) and (iv) proven auto-immune hyperthyroidism without any signs of TAO (n = 6). Horizontal and vertical saccades with amplitudes of 10°, 20°, 30° and 40° were recorded binocularly using the induction scleral search coil technique. The two main sequence constants V(max) and C were calculated for each eye. Repeated measurement analysis of variance was carried out to test for differences between different gaze directions, eyes and groups. RESULTS: In horizontal saccades, significant differences were found between groups but not between abduction and adduction. In vertical saccades, differences between groups and the interaction between groups and up- and down-gaze saccades were significant. Compared with the control group, analysis of the main sequence curves revealed larger differences in patients of group 3 and 4 than in those of group 1 and 2. Whereas in the control group down-gaze saccades were faster than up-gaze saccades, the opposite behaviour was found in all patient groups. The largest differences were detected among those patients who had no signs of TAO (group 4). CONCLUSIONS: In this study, significant saccade differences were detected in all patients with TAO. In contrast to our earlier studies where evaluation of multiple individual saccade parameters did not reveal significant differences, analysis of the main sequence constants and mathematical reconstruction of the main sequence curves turned out to be a sensitive technique for reliable detection of subtle ocular motility changes. Significant differences were detected even in patients with auto-immune thyroiditis where no clinical signs of TAO were apparent.

Evaluation of an international benchmarking initiative in nine eye hospitals.

BACKGROUND: Benchmarking has become very popular among managers to improve quality in the private and public sector, but little is known about its applicability in international hospital settings. PURPOSE: The purpose of this study was to evaluate the applicability of an international benchmarking initiative in eye hospitals. METHODOLOGY: To assess the applicability, an evaluation frame was constructed on the basis of a systematic literature review. The frame was applied longitudinally to a case study of nine eye hospitals that used a set of performance indicators for benchmarking. Document analysis, nine questionnaires, and 26 semistructured interviews with stakeholders in each hospital were used for qualitative analysis. FINDINGS: The evaluation frame consisted of four areas with key conditions for benchmarking: purposes of benchmarking, performance indicators, participating organizations, and performance management systems. This study showed that the international benchmarking between eye hospitals scarcely met these conditions. The used indicators were not incorporated in a performance management system in any of the hospitals. Despite the apparent homogeneity of the participants and the absence of competition, differences in ownership, governance structure, reimbursement, and market orientation made comparisons difficult. Benchmarking, however, stimulated learning and exchange of knowledge. It encouraged interaction and thereby learning on the tactical and operational levels, which is also an incentive to attract and motivate staff. PRACTICE IMPLICATIONS: Although international hospital benchmarking seems to be a rational process of sharing performance data, this case study showed that it is highly dependent on social processes and a learning environment. It can be useful for diagnostics, helping local hospitals to catalyze performance improvements.

Drift of visually induced optostatic torsion.

PURPOSE: Compensatory ocular torsion has been found in response to static tilted visual stimuli. The purpose was to investigate if visually induced ocular torsion is maintained during continuous stimulation and to reinvestigate the effect of stimuli tilt angle. METHODS: Eye movements were recorded in 19 healthy individuals using a 3-D video oculography system. One visual stimulus was used in the tests, a photographic image of a city scene with spatial clues relevant for body posture. The scenes were tilted counterclockwise around a central pivot point from 0 to 15 degrees (test A), from 0 to 30 degrees (test B), and from 0 to 45 degrees (test C). Each tilted stimulus position was held static for 4 min, 40 sec. RESULTS: A compensatory torsional response was found in all subjects and test conditions. No significant difference was found between the different stimuli tilt angles. The torsional response was not maintained but drifted back towards the reference position. CONCLUSIONS: Visually induced ocular torsion in response to a static tilted scene is not maintained, but drifts back towards the initial reference position. Higher cognitive functions such as imagination and attention certainly have an influence on the outcome.

Visuospatial skills, ocular alignment, and magnetic resonance imaging findings in very low birth weight adolescents.

PURPOSE: To describe ocular alignment and stereoacuity in adolescents with very low birth weight (VLBW) in comparison with a matched control group and to investigate associations with white matter damage of immaturity (WMDI) and visuospatial skills in the VLBW group. METHODS: Fifty-nine 15-year-old VLBW subjects and 55 age- and sex-matched controls with normal birth weight underwent examination, including measurement of ocular alignment using cover test and Maddox rod and cycloplegic refraction. Stereoacuity was assessed with the TNO test, best-corrected visual acuity with a Konstantin Moutakis letter chart, and visuospatial skills with the performance tests, defined as performance intelligence quotient (IQ), in the Wechsler Intelligence Scale for Children (WISC-III). All VLBW subjects underwent magnetic resonance imaging of the brain. RESULTS: Ocular misalignment was significantly more common in the VLBW group than in the control group (22% compared with 4%; p = 0.004). Exophoria, subnormal stereoacuity, and subnormal performance IQ were significantly more common in the VLBW group than in the control group (p = 0.006, p = 0.011, and p = 0.015, respectively). Ocular misalignment was associated with WMDI (p = 0.035) and subnormal performance IQ (p = 0.020). Of the VLBW subjects with ocular misalignment, 69% had WMDI and/or subnormal performance IQ. CONCLUSIONS: The VLBW adolescents had more visuospatial problems, lower stereoacuity, and more ocular misalignment than the control subjects. Ocular misalignment was associated with visuospatial deficiencies and/or WMDI in the VLBW group and was a better predictor for visuospatial deficits than WMDI.