Optometry and Vision Sciences - Research Publications

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    Investigating the cause and maintenance of Anorexia Nervosa - The I-CAN study: Protocol and open call for study sites and collaboration
    Phillipou, A ; Croce, S ; Abel, LA ; Castle, DJ ; Dean, B ; Eikelis, N ; Elwyn, R ; Gurvich, C ; Jenkins, Z ; Meyer, D ; Miles, S ; Neill, E ; Ralph-Nearman, C ; Rocks, T ; Rossell, SL ; Ruusunen, A ; Simpson, TN ; Urbini, G ; West, M ; Malcolm, A (ELSEVIER IRELAND LTD, 2023-10)
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    A guide to optometrists for appraising and using artificial intelligence in clinical practice
    Murphy, T ; Armitage, JA ; van Wijngaarden, P ; Abel, LA ; Douglass, AG (TAYLOR & FRANCIS LTD, 2023-08-18)
    Artificial intelligence systems are becoming increasingly available as diagnostic aids for optometric practice. These perform well but are often 'black-box' systems offering little or no insight into how a decision was reached. While there is potential for artificial intelligence to improve patient outcomes, clinicians without training in computer science may find it difficult to ascertain whether these technologies are suitable for their practice, or how they should be used. This review provides an overview of how artificial intelligence systems work in optometry, their strengths, weaknesses, and regulatory considerations. A checklist is provided for appraising a system, covering regulatory approvals, ascertaining what the system can and cannot do, how it can be used in practice, whether it is suitable for the clinical population, and whether the outputs can be explained. Artificial intelligence has the potential to improve accuracy and efficiency in many areas of optometry if used correctly, and should be embraced by clinicians as an assistive tool.
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    A biomarker and endophenotype for anorexia nervosa?
    Phillipou, A ; Rossell, SL ; Gurvich, C ; Castle, DJ ; Meyer, D ; Abel, LA (SAGE PUBLICATIONS LTD, 2022-08-01)
    OBJECTIVE: Recent research has suggested that a type of atypical eye movement, called square wave jerks, together with anxiety, may distinguish individuals with anorexia nervosa from those without anorexia nervosa and may represent a biomarker and endophenotype for the illness. The aim of this study was to identify the presence of this proposed marker in individuals currently with anorexia nervosa relative to healthy controls, and to identify the state independence and heritability of this putative marker by exploring whether it also exists in individuals who are weight-restored from anorexia nervosa and first-degree relatives (i.e. sisters of people with anorexia nervosa). METHODS: Data from 80 female participants (20/group: current anorexia nervosa, weight-restored from anorexia nervosa, sisters of people with anorexia nervosa and healthy controls) were analysed. Square wave jerk rate was acquired during a fixation task, and anxiety was measured with the State Trait Anxiety Inventory. RESULTS: Current anorexia nervosa, weight-restored from anorexia nervosa and sisters of people with anorexia nervosa groups made significantly more square wave jerks than healthy controls, but did not differ from one another. Square wave jerk rate and anxiety were found to discriminate groups with exceptionally high accuracy (current anorexia nervosa vs healthy control = 92.5%; weight-restored from anorexia nervosa vs healthy control = 77.5%; sisters of people with anorexia nervosa vs healthy control = 77.5%; p < .001). CONCLUSION: The combination of square wave jerk rate and anxiety was found to be a promising two-element marker for anorexia nervosa, and has the potential to be used as a biomarker or endophenotype to identify people at risk of anorexia nervosa and inform future treatments.
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    Video game training in traumatic brain injury patients: an exploratory case report study using eye tracking
    Azizi, E ; Fielding, J ; Abel, LA (INT GROUP EYE MOVEMENT RESEARCH, 2022)
    Remediation of attentional impairments is an essential component of cognitive rehabilitation after traumatic brain injury (TBI). Evidence from healthy participants has demonstrated attentional improvement following playing an action video game. This exploratory study investigated its application in TBI participants in a multiple baselines single case experimental design (SCED). Saccadic eye movements, recognized as the visible indicators of visual attention, were assessed to evaluate the effectiveness of the game training. Three severe TBI participants were trained in an action game for 10 hours. Saccadic eye movements during a self-paced saccade and an abstract visual search task were investigated during baseline, mid training and post-training. Using Percentage of Non-overlapping Data (PND), analysis showed consistent increase in the rate of the self-paced saccades in participants 1 (PND=80%) and 2 (PND=70%). In abstract search, fixation duration showed a minimally effective decrease for participant 2 (PND= 60%) and a moderately effective reduction in participant 3 (PND= 80%). Search time showed a highly effective reduction in participant 2 (PND = 100%) and moderately effective decrease in participant 3 (PND=70%). Overall, video game training might modify allocation of attention in eye movements. More evidence is required to validate the usefulness of this novel method of the cognitive training.
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    Optimising visual attention in children with autism spectrum disorder: a comparison of fixation distributions viewing singing and speech
    Abel, LA ; Thompson, GA (Association for Research in Vision and Ophthalmology, 2017-06-01)
    Purpose : Many children with autism spectrum disorder (ASD) are at risk of social isolation and limited social development due to difficulties with gaze and visual attention to people. Studies have shown that children with ASD may prefer music to other stimuli. We hypothesised that a short video of a singer would elicit more attention to the performer, particularly to her face, than a video of her reading a story and that the child’s familiarity with the song and story would enhance attention. Methods : 16 children aged 7-10 (14 M, 2 F) with ASD took part. Stimuli were 4 videos 1 minute long. Content was a favourite song or story of the child, along with a song and story which were the same for all children. The performer, her clothing, lighting and sound level were the same across tasks. Props were a pair of drums for the songs and a storybook of similar size for the stories. Eye movements were recorded with an Eyelink 1000; areas of interest (AOIs) were defined for the face, prop and body. 3-way repeated measures ANOVAs were used to examine the proportion of total dwell time, the proportion of total fixations and pupil area for each AOI in each trial. Results : For dwell time proportion, a significant interaction was found for familiarity*AOI (F=7.45, p=.004), with gaze time to the face being increased for familiar trials (Table 1). Similarly, medium*AOI was significant (F=6.01, p=.013), with increased gaze time to the face and body and decreased time to the prop for the songs (Table 2). The same patterns were seen for proportion of fixation counts to the AOIs (familiarity*AOI F=4.97, p =.016; medium*AOI F=10.33, p=.001). For the pupil, only familiarity and AOI were significant; pupils were larger for familiar stimuli (F=16.70, p=.001) and for the face and prop (F=6.8, p=.015), with the body eliciting less dilation. Conclusions : As hypothesised, the videos of singing attracted children's gaze to the performer more than did those of her reading a story. Familiarity with the material being performed also attracted more attention to her face. Familiarity and gaze to the face also increased arousal, as indexed by pupil dilation. Observation by children with ASD of a singer, particularly one performing their favourite songs, may be a useful intervention for improving their social engagement skills.
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    Perception of Coherent Motion in Infantile Nystagmus Syndrome
    Dai, B ; Cham, KM ; Abel, LA (ASSOC RESEARCH VISION OPHTHALMOLOGY INC, 2022-01)
    PURPOSE: Research on infantile nystagmus syndrome (INS) and motion perception is limited. We investigated how individuals with INS perform coherent motion tasks. Particularly, we assessed how the null position affects their performance. METHODS: Subjects with INS and controls identified the direction of coherent motion stimuli (22 subjects with INS and 13 controls) in a two-alternative forced-choice design. For subjects with INS, testing was done at the null position and 15 degrees away from it. If there was no null, testing was done at primary gaze position and 15 degrees away from primary. For controls, testing was done at primary gaze position and 20 degrees away from primary. Horizontal and vertical motion coherence thresholds were determined. RESULTS: Subjects with INS showed significantly higher horizontal and vertical motion coherence thresholds compared with controls at both gaze positions (P < 0.001). Within the INS group, for 12 subjects with INS who had an identified null position, no differences in coherence thresholds were found between their null and 15 degrees away from it (P > 0.05). CONCLUSIONS: Coherent motion perception was impaired in subjects with INS. The null position did not significantly influence motion coherence thresholds for either horizontal or vertical motion.
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    A cross-sectional, prospective ocular motor study in 72 patients with Niemann-Pick disease type C
    Bremova-Ertl, T ; Abel, L ; Walterfang, M ; Salsano, E ; Ardissone, A ; Malinova, V ; Kolnikova, M ; Bayarri, JG ; Tavasoli, AR ; Ashrafi, MR ; Amraoui, Y ; Mengel, E ; Kolb, SA ; Brecht, A ; Bardins, S ; Strupp, M (WILEY, 2021-09)
    OBJECTIVE: To characterize ocular motor function in patients with Niemann-Pick disease type C (NPC). METHODS: In a multicontinental, cross-sectional study we characterized ocular-motor function in 72 patients from 12 countries by video-oculography. Interlinking with disease severity, we also searched for ocular motor biomarkers. Our study protocol comprised reflexive and self-paced saccades, smooth pursuit, and gaze-holding in horizontal and vertical planes. Data were compared with those of 158 healthy controls (HC). RESULTS: Some 98.2% of patients generated vertical saccades below the 95% CI of the controls' peak velocity. Only 46.9% of patients had smooth pursuit gain lower than that of 95% CI of HC. The involvement in both downward and upward directions was similar (51°/s (68.9, [32.7-69.3]) downward versus 78.8°/s (65.9, [60.8-96.8]) upward). Horizontal saccadic peak velocity and latency, vertical saccadic duration and amplitude, and horizontal position smooth pursuit correlated best to disease severity. Compensating strategies such as blinks to elicit saccades, and head and upper body movements to overcome the gaze palsy, were observed. Vertical reflexive saccades were more impaired and slower than self-paced ones. Gaze-holding was normal. Ocular-motor performance depended on the age of onset and disease duration. CONCLUSIONS: This is the largest cohort of NPC patients investigated for ocular-motor function. Vertical supranuclear saccade palsy is the hallmark of NPC. Vertical upward and downward saccades are equally impaired. Horizontal saccadic peak velocity and latency, vertical saccadic duration and amplitude, and horizontal position smooth pursuit can be used as surrogate parameters for clinical trials. Compensating strategies can contribute to establishing a diagnosis.
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    High-definition transcranial direct current stimulation in anorexia nervosa: A pilot study
    Phillipou, A ; Kirkovski, M ; Castle, DJ ; Gurvich, C ; Abel, LA ; Miles, S ; Rossell, SL (WILEY, 2019-11)
    OBJECTIVE: Anorexia nervosa (AN) is a serious psychiatric condition often associated with poor outcomes. Biologically informed treatments for AN, such as brain stimulation, are lacking, in part due to the unclear nature of the neurobiological contributions to the illness. However, recent research has suggested a specific neurobiological target for the treatment of AN, namely stimulation of the inferior parietal lobe (IPL). The aim of this study was to stimulate-noninvasively-the left IPL in individuals with AN using high-definition transcranial direct current stimulation (HD-tDCS). METHOD: Twenty participants will be randomized to receive 10 daily sessions of HD-tDCS or sham HD-tDCS (placebo). Assessments will be carried out at baseline and end point, as well as 4- and 12-week follow-ups. DISCUSSION: This pilot investigation will primarily determine the feasibility and acceptability of this intervention.
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    Differences in regional grey matter volumes in currently ill patients with anorexia nervosa
    Phillipou, A ; Rossell, SL ; Gurvich, C ; Castle, DJ ; Abel, LA ; Nibbs, RG ; Hughes, ME (WILEY, 2018-01)
    Neurobiological findings in anorexia nervosa (AN) are inconsistent, including differences in regional grey matter volumes. Methodological limitations often contribute to the inconsistencies reported. The aim of this study was to improve on these methodologies by utilising voxel-based morphometry (VBM) analysis with the use of diffeomorphic anatomic registration through an exponentiated lie algebra algorithm (DARTEL), in a relatively large group of individuals with AN. Twenty-six individuals with AN and 27 healthy controls underwent a T1-weighted magnetic resonance imaging (MRI) scan. AN participants were found to have reduced grey matter volumes in a number of areas including regions of the basal ganglia (including the ventral striatum), and parietal and temporal cortices. Body mass index (BMI) and global scores on the Eating Disorder Examination Questionnaire (EDE-Q) were also found to correlate with grey matter volumes in a region of the brainstem (including the substantia nigra and ventral tegmental area) in AN, and predicted 56% of the variance in grey matter volumes in this area. The brain regions associated with grey matter reductions in AN are consistent with regions responsible for cognitive deficits associated with the illness including anhedonia, deficits in affect perception and saccadic eye movement abnormalities. Overall, the findings suggest reduced grey matter volumes in AN that are associated with eating disorder symptomatology.
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    Velocity Discrimination in Infantile Nystagmus Syndrome
    Dai, B ; Cham, KM ; Abel, LA (Association for Research in Vision and Ophthalmology, 2021-08)
    Purpose: Research on infantile nystagmus syndrome (INS) and velocity discrimination is limited, and no research has examined velocity discrimination in subjects with INS at their null position and away from it. This study aims to investigate how individuals with INS perform, compared with controls, when carrying out velocity discrimination tasks. Particularly, the study aims to assess how the null position affects their performance. Methods: INS subjects (N = 21, mean age 24 years; age range, 15-34 years) and controls (N = 16, mean age 26 years; age range, 22-39 years) performed horizontal and vertical velocity discrimination tasks at two gaze positions. Eighteen INS subjects were classified as idiopathic INS and three had associated visual disorders (two had oculocutaneous albinism, and one had congenital cataract). For INS subjects, testing was done at the null position and 15° away from it. If there was no null, testing was done at primary gaze position and 15° away from primary. For controls, testing was done at primary gaze position and 20° away from primary. Horizontal and vertical velocity discrimination thresholds were determined and analyzed. Results: INS subjects showed significantly higher horizontal and vertical velocity discrimination thresholds compared with controls at both gaze positions (P < 0.001). Horizontal thresholds for INS subjects were elevated more than vertical thresholds (P < 0.0001) for INS subjects but not for controls. Within the INS group, 12 INS subjects who had an identified null position showed significantly lower horizontal and vertical thresholds at the null than at 15° away from it (P < 0.05). Conclusions: Velocity discrimination was impaired in INS subjects, with better performance at the null. These findings could assist in understanding how INS affects the daily activities of patients in tasks involving moving objects, and aid in developing new clinical visual function assessments for INS.