2007 Abstracts
British & Irish Orthoptic Journal 2007
Editorial: The future of the British and Irish Orthoptic Journal
Sarah J Shea
Saccades in Strabismus: A Literature Review
Helen J Griffiths
Aim: To review evidence from the literature of the effect of concomitant strabismus on saccadic eye movements and saccade adaptation. To consider how analysis of such eye movements may provide information about the link between the coordination of saccades and binocular vision.
Method: A literature-based review of saccades in strabismus is presented.
Results: Saccade characteristics are in general unaffected by the presence of concomitant strabismus in the absence of amblyopia. The literature also documents no significant change to saccade performance following surgical intervention to the extraocular muscles despite evidence of altered velocity profiles. The main effect on saccades in strabismus is disconjugacy, which is significantly increased. There is evidence that disconjugate saccade adaptation, however, is intact in strabismus, suggesting that fusion may not be necessary for activating the adaptive mechanism.
Conclusion: Measurement of eye movement characteristics may help to give an understanding of mechanisms involved in sensory and motor adaptations to strabismus.
Amblyopia Treatment: from research to practice
Marie Cleary
Aims: To review recent literature on occlusion treatment, focussing on the issues of dosage, factors affecting outcome including compliance, and the age-limit for treatment. The piloted virtual-reality based treatment developed in Nottingham will be discussed.
Methods: A literature-based review was conducted to produce a summary of evidence-based guidelines, which can be applied in clinical practice.
Results: There is mounting evidence for the beneficial effects of occlusion treatment in amblyopia. A period of at least 18 weeks of spectacle adaptation is indicated before implementation of occlusion. An initial daily dose of occlusion of 2 to 6 hours should be effective for most children: full-time occlusion should be reserved for those who fail to respond to part-time occlusion. Treatment effect is greatest within the first 400 hours or 6 months of occlusion wear.
Conclusions: It is vital that clinicians use the best possible evidence-base in selecting appropriate treatment. This can be used to inform patients, and provide them with choice as to how their treatment is to be implemented.
Visual Perception and Visual Dysfunction in Autism Spectrum Disorder: A Literature Review
Elizabeth Milne and Helen J Griffiths
Aim: To describe autistic spectrum disorder (ASD), and to review the evidence for associated visual dysfunction in the disorder.
Method: An initial literature search was performed using Web of Science with the key words: autism and sensory; autism and vision; autism and visual; and autism and oculomotor. Papers which reported investigation of basic vision in autism were obtained, and any additional references listed in these articles that referred to other relevant data but didn’t emerge from the original search were followed up.
Results: There is evidence that basic visual function may be affected in individuals with ASD, however the mixed nature and limited number of empirical studies conducted make it difficult to draw clear conclusions as to specific deficits and areas of spared visual function in ASD.
Conclusion: It is likely that patients with ASD may present to the orthoptic department. Specific vision screening of this population may be indicated, and further study based on large well defined samples would be of significant value.
Interdisciplinary aspects of vision and communication deficits following stroke
Sonia MacDiarmid, Fiona Rowe and F. Parsons
Aim: To review the relationship between visual and communication impairments following the occurrence of stroke.
Methods: A literature review was undertaken which involved a Medline and manual search of relevant journals and transactions.
Results: Information was gathered on visual consequences of stroke, communication difficulties including expressive and receptive dysphasia, dyspraxia and dysarthira, associated anatomical areas plus assessment and treatment options for communication impairment and the visual requirements associated with these options.
Conclusions: Vision is a major requirement in the assessment and management of communication difficulties and visual impairment thus impacts on the rehabilitation process. Appropriate relay of visual information to the multi-disciplinary team is vital to making appropriate decisions for individual rehabilitation programmes.
The importance of cognitive function in driving following stroke.
Nicola R Morris
Aim: To review the published standards for driving and consider the importance of an assessment of cognitive function in determining suitability to resume driving after a stroke.
Methods: A literature based essay, using articles relating to driving after stroke and cognitive function and driving.
Results: The DVLA has guidelines on driving following a stroke and the visual standards required to drive. There are no standards for the level of cognitive function required to resume driving. Cognition is difficult to evaluate in relation to driving and there is no one test that can clearly predict if a patient is safe to drive. Currently, where a decision cannot be made on the basis of medical reports the gold standard for fitness to drive is an on road assessment.
Conclusion: Cognitive function makes a significant contribution to the ability to drive and evaluation of visual function alone is not sufficient when determining if a patient is fit to drive.
Ocular motility disturbances in Multiple Sclerosis
Nicola Morris
Aim: To review the pathophysiology of multiple sclerosis and the resultant ocular motility impairment.
Methods: A literature review was undertaken to ascertain potential ocular motility involvement in cases of multiple sclerosis. This involved a Medline and manual search of relevant journals and transactions.
Results: This review provides background information on the pathophysiology of multiple sclerosis, environmental and genetic factors, ocular motility disturbances at cortical, cerebellar and brainstem level plus mechanisms of remyelination and relevance to recovery.
Conclusions: This is a practical review of common and uncommon ocular motility disturbances that arise from multiple sclerosis. Recovery relates to inflammatory changes and the remyelination process of damaged nerve axons.
Visual Outcomes and Conservative Management Options for Infantile Idiopathic Nystagmus and Manifest Latent/ Latent Nystagmus
Meritxell Cristino-Amenos and Anna R O’Connor
Aim: To critically evaluate the literature on the visual outcome in patients with Infantile Idiopathic Nystagmus (IIN) and Manifest Latent/Latent Nystagmus (MLN/LN) and appraise the factors that influence the acuity outcome.
Method: A literature review was undertaken to determine visual outcomes and a common prognosis for this population. The implications of the waveform evolution were considered as well as the importance of test parameters. Also the conservative management options were evaluated.
Results: The best and the worst binocular VA recorded for IIN subjects was -0.3 and 1.2 and for MLN/LN was -0.1 and 0.8 respectively. This variation was attributable to factors such as test type, test distance, type of occluder used in monocular assessment and contour interaction. In addition the most effective management options appear to be the use of contact lenses. Although prisms did reduce the oscillations there was little increase in acuity. In terms of amblyopia management a variety of treatment options have been suggested, but no optimum protocol was identified.
Conclusion: This review has highlighted the inconsistency in outcomes in these patients, in particular when evaluating the outcome there are a large number of variables in the assessment of visual acuity. Standardisation in visual assessment would allow more effective evaluation and comparison between studies of treatment modalities.
The role and clinical implications of rectus extraocular muscle pulleys.
Sandeep Virdee
Aim: To review the clinical implications of rectus extraocular muscle (EOM) pulleys in normal subjects and those with incomitant strabismus.
Methods: A literature-based review of EOM pulleys in normal and abnormal ocular motility is presented.
Results: Rectus EOM pulleys stabilise EOM path and support the dynamic role of the direction of muscle pull in ocular motility. The coronal plane location of each rectus pulley in relation to the orbital wall is highly uniform and stable across normal subjects when the eyes move from primary into secondary gaze positions. Studies of incomitant strabismus associated with advancing age, alphabet patterns, high myopia or dysfunction of oblique extraocular muscles, have provided evidence that resultant patterns of strabismus and /or abnormal ocular motility may depend on static pulley positions, pulley instability, and co-existing globe translation.
Conclusion: EOM pulleys are fundamental to ocular motility and should be considered in differential diagnosis of patients with incomitant deviations.
Retrospective Study To Investigate The Long Term Sustainability Of Amblyopia Treatment
Pamela King, Sarah C. Turner, Catherine Kidals, Elizabeth Clarke, Diana Ward, Helen Wortley, Victoria Chapman and Said Mohamoud
Aim: To determine whether the level of visual acuity achieved after occlusion for amblyopia was maintained for at least five years post cessation of treatment.
Methods: Patients whose amblyopia had been successfully treated and in whom at least five years had elapsed since treatment were recalled for assessment of their present level of visual acuity. The types of occlusion used, duration of treatment and the treatment regimes were recorded. The patient’s comments with regard to their hospital visits were assessed using a questionnaire.
Results: 400 patients met the inclusion criteria and were recalled for assessment. Seventy-six patients attended the recall appointment. Two cases were excluded from data analysis due to complications with repeated episodes of occlusion treatment, leaving 74 cases for analysis. Sixty-four patients had maintained their level of visual acuity and 10 showed a reduction in their acuity. The average vision reduction was 2.6 lines on Snellen. The reduction ranged from 1 to 4 lines for 7 cases with strabismus, 3 lines for 2 cases of anisometropia and 5 lines for 1 case who had developed keratoconous..
Conclusion: Occlusion treatment can be beneficial and the improvement in visual acuity is more likely to be maintained than to regress.
Incidence and nature of Orthoptic problems found in children previously screened for retinopathy of prematurity – an argument for Orthoptic follow up?
Hannah Bullock, Jeremy M. Butcher, Chris Burrows, Karen Hordern, Linda Smith and Sheila Clegg
Aim: To determine the incidence and type of visual and/or binocular defects in infants previously screened for and found to have insignificant or no retinopathy of prematurity (ROP).
Methods: The case notes of a consecutive cohort of children who had passed screening for ROP were reviewed retrospectively. Details of attendance, orthoptic assessments, related investigations, and outcome were documented with particular attention to the incidence and type of ocular defect.
Results: 108 cases were reviewed; 78 cases met the inclusion criteria. 19patients had an ocular defect that required treatment or ongoing orthoptic review. Eleven children had strabismus, of whom 8 had constant esotropia and 3 intermittent exotropia. Other defects were refractive error (without strabismus), congenital idiopathic nystagmus, and a case of an upper lid haemangioma.
Conclusions: The review confirmed a higher prevalence of strabismus and visual/binocular defects in patients who had previously passed screening for ROP compared to the normal population.
Constant esotropia was the most common form of strabismus found.
Prism Fusion Range: Gulden v Clement Clarke Plastic Prism Bar
Jagdeep K. Bath and Alison Y. Firth
Aim: To determine the degree of error induced when measuring the prism fusion range by using the Clement Clarke plastic prism bar in the frontal position rather than its calibrated position of use, the Prentice position, and to compare this with a previous model of induced error and to assess the level of agreement with the Gulden prism bar.
Method: The base out blur, break and recovery points of the near and distance prism fusion range were recorded in 20 normal participants (aged 18-28 years), using the Clement Clarke plastic prism bar and Gulden prism bar in the frontal position.
Results: At near, each measure was shown to be larger when using the Clement Clarke plastic prism bar (p<0.05). The median blur point was 25∆ base out (range:14-75∆) with the Clement Clarke bar and 18∆ base out (range:12-65∆) with the Gulden bar. Median break point was 62∆ base out (range:25-85∆) with Clement Clarke and 43∆ base out (range:16-80∆) with Gulden. The median recovery was 54∆ base out (range:16-80∆) with Clement Clarke and 38.5∆ base out (range:14-70∆) with Gulden. In the distance there was no statistically significant difference between blur or break point with either bar but the median recovery point was significantly overestimated (p<0.05), measuring 20∆ base out (range:8-85∆) with Clement Clarke and 18∆ base out (range:8-70∆) with Gulden.
However, after application of a correction formula to Clement Clarke measurements, the limits of agreement between these and the Gulden measurements showed, with a few exceptions, results lying within ± 2 standard deviations.
Conclusions: Using the Clement Clarke plastic prism bar in the frontal position rather than the calibrated Prentice position overestimates the measurement of the prism fusion range at near. Practical measures are similar to those that may be calculated mathematically for the error induced due to the use of the bar in a position for which it is not calibrated.
Visual function measurement using a laptop computer: does the screen angle matter?
Anna R O’Connor, Paul C Knox, James Bridson and Rebecca Tompkin
Aims: Computerised vision assessment on a laptop provides increased portability and flexibility. However, when a laptop screen is tilted it can alter the visibility of information on the screen. This study evaluated the effect of changing the laptop screen angle on visual acuity (VA) and contrast sensitivity (CS) measurements and compared the results to those obtained using standard clinical tests.
Methods: VA and CS were measured with the screen at 5 angles (80-100°), with 5° intervals in a randomised order. The ETDRS chart and Pelli Robson chart were used as standard clinical tests.
Results: VA laptop scores were not affected by tilting the screen and were comparable with the ETDRS scores. CS measurements were directly proportional to the screen angle with a mean increase of 0.11logCS units for every 5° increase. The laptop CS measurement was closest to the Pelli Robson result at an angle of 100°; but the laptop measurement was still on average 0.44logCS units lower and analysis showed considerable variability between the two tests.
Conclusions: The variability between the CS tests means that they are not interchangeable. VA measurements were not affected by the screen angle and produced measurements within normal limits compared to the standard clinical test.
A pilot study of ocular symptoms experienced by visual display unit users
Jignasa V. Mehta and Anna R. O’Connor
Aims: In recent years there has been a marked increase in computer use and while they bring many benefits they are also associated with an increase in health risks, including visual disorders. The aim of this pilot study was to begin to examine the relationship between a wide range of ergonomic factors, work routine and ocular symptoms reported by VDU users and to inform future research.
Methods: Questionnaires were distributed to 84 VDU users and workstations were analysed for illumination, viewing distance, temperature and relative humidity on a subset of 45 VDU users. The questionnaire was used to determine age, gender, working conditions, work routine and ocular symptoms experienced. Each VDU user had to indicate from a list of 10 ocular symptoms whether they experienced each symptom ‘before’, ‘during’ or ‘after’ VDU use.
Results: 83% of the VDU users reported at least one ocular symptom during or after VDU use, with headaches as the most frequent complaint. Ergonomic factors; illumination, temperature, relative humidity and viewing distance were not associated with increased number of symptoms experience by VDU users. However, females experienced almost twice as many symptoms as their male counterparts and younger subjects reported more symptoms.
Conclusions: A high proportion of VDU users experienced ocular symptoms which were not related to environmental factors. Age and gender proved to be significant factors associated with VDU related symptoms. The findings of the pilot study have highlighted the need to explore these significant factors and to include confounding variables such as psychosocial factors and employment status. Further work will also incorporate full ocular assessment of VDU users to identify why particular VDU users have a predisposition to ocular symptoms.
Inferior rectus recession (IRR): outcome of surgery
G Cormack , K Russell and C MacEwen
Aims: Inferior rectus recession (IRR) surgery has been reported to be unstable, with particular concerns about progressive overcorrection. This study reviews the vertical outcomes following inferior rectus recession surgery in order to observe post-operative stability.
Methods: The authors present a retrospective review of all IRR surgery from Jan 1996- March 2006 by a single surgeon.
Results: A total of 42 cases were included with adjustable sutures used in 40. The mean follow-up was 9 months. The mean (median) pre-operative vertical deviation in the primary position was 19.8D (20D) pre-operatively, reducing to 5.2D (2D) at final post-op visit. The aim of a small undercorrection within the patient’s vertical fusion range was achieved in all cases, after adjustment if necessary. By the end of follow-up, 35 (83%) patients retained a satisfactory result, 5 (12%) were overcorrected and 2 (5%) were undercorrected. Twenty five (60%) remained orthophoric or undercorrected , 17 (40%) progressed from a planned undercorrection to an overcorrection. Overcorrection was significantly more common in thyroid eye disease (TED) patients (12/20) than the non-thyroid patients (5/22) (p=0.014. chi-square). Three cases (7%) demonstrated progressive overcorrection – all patients with TED.
Discussion: In this study, aiming for a small undercorrection within the patient’s vertical fusion range allowed for resolution of symptoms in most cases. TED was more susceptible to overcorrection. Progressive overcorrection did occur, but was uncommon.
Case Report: Orbital Foreign Body Causing Temporary Diplopia
Sue Elliott and Rick Collyer-Powell
Aims: To report an interesting case of diplopia, caused by an initially undiagnosed intra-orbital foreign body, which resolved following its removal.
Methods: A case is discussed of a 16-year old boy who injured his right eye by riding a quad bike into a hedge. Ophthalmic and orthoptic findings with Hess charts are documented, with a photograph of the orbital foreign body. Investigation and management are described.
Results: The boy presented to the accident and emergency department reporting a twig had poked his right eye following the accident. Chloromphenicol was prescribed and the boy was discharged. Four days later the boy presented with orbital swelling with vertical and torsional diplopia. Examination revealed restriction of ocular movement and X-ray revealed no orbital or foreign body. The orbital swelling and restriction of ocular movement increased and 18 days post injury a 12mm long thorn was removed from the upper nasal conjunctiva. Full recovery of ocular movement and swelling occurred in the weeks following removal of the foreign body.
Conclusion: Careful investigation and follow-up of such cases is needed as intraorbital foreign bodies are difficult to detect and a high level of suspicion is needed.
Two Cases Of Kabuki Syndrome
Cynthia Everett-Allen and Scot Wilton
Aims: To describe two cases of Kabuki syndrome (KS) and the relevant signs which aid in the diagnosis.
Method: The cases are documented with details of history, orthoptic and ophthalmic findings and the criteria by which Kabuki syndrome is identified.
Results: Kabuki syndrome is rare. The five main criteria used to define the syndrome are characteristic facial features, skeletal anomalies, dermatoglyphic anomalies, mental retardation and short stature. Five facial features are a key element in the diagnosis. Both children reported had the characteristic facial features. In addition they were of short stature, had hearing loss, learning difficulties, and speech and language problems. Thirty to fifty percent of children with KS will have ophthalmic involvement. One child presented to the eye clinic with ocular problems the other child was seen via the child development team.
Conclusion: Ocular problems are common in children with KS and these children will present to orthoptic departments for assessment. It is important for orthoptists to be aware of this syndrome.
Literature Review and Case Presentation of the Use of Botulinum Toxin in the case of Acquired Nystagmus
Sarah L Poulton
Aim: To review the literature on the use of Botulinum Toxin (BT) in the treatment of symptoms associated with acquired nystagmus and to present a case report of a patient who experienced relief of symptoms with an injection of only one horizontal rectus muscle.
Method: A literature-based review on the use of BT in acquired nystagmus. A case is presented of a 40-year old woman with multiple sclerosis who had BT injection to relieve symptoms of reduced vision and oscillopsia due to horizontal nystagmus. Orthoptic findings pre- and post injection are documented and the management of the case described.
Results: It has been reported that BT can be injected into both the horizontal recti of one eye, or the retrobulbar space of one eye to alleviate the symptoms of oscillopsia associated with acquired nystagmus. Numerous detrimental side effects associated with the injections have been reported. In the case presented the patient reported an improvement in vision and oscillopsia following a BT injection into the left lateral rectus muscle. This was substantiated by an objective improvement in the visual acuity, with few side effects.
Conclusion: BT injections into selected extra ocular muscles can temporarily reduce the amplitude of nystagmus and relieve the symptom of oscillopsia. The case presented shows that a subjective improvement in symptoms can be achieved by a BT injection of only one horizontal rectus muscle