2002 Abstracts
British Orthoptic Journal 2002
Editorial
Editorial stance on duplicate and salami publication
Alison Y. Firth
Sarah J. Shea
Abstract:
Aim: This review considers the value of preferential looking and grating acuity in the clinical assessment of infant visual acuity.
Methods: A literature review was conducted to identify articles relevant to the development of preferential looking and its progresssion from laboratory to clinical tool. Articles that consider the clinical value of preferential looking and grating acuity in the detection of visual disorders were also reviewed and comparisons made with other clinical tests of visual function. Special emphasis was given to acuity assessment in amblyopia.
Results: Procedural variations can have significant effects on acuity estimation and highlight the need for a high degree of objectivity when using preferential looking. More complex visual stimuli yield a more precise estimate of acuity than a grating stimulus, particularly in cases of amblyopia associated with strabismus, but grating acuity should not be dismissed in the evaluation of infant acuity.
Conclusion: Whilst they have limitations, preferential looking and grating acuity are of value in the assessment of infant visual acuity. Within a clinical department a standard preferential looking methodology with a strict threshold criterion is essential. In addition there is a need to evaluate fully the nature of the vision loss as opposed to dismissing an acuity value or test as defective.
Key Words:Preferential looking, Psycophysics, Grating acuity, Fixation preference, Recognition acuity, Vernier acuity, Acuity development, Amblyopia
The effect of aging on eye movement: a literature review
Jillian H. Davidson and Paul C. Knox
Abstract:
Aims: To present a review of the literature on the effect of aging on the eye, the neuroanatomical structures controlling eye movement and their consequent behavioural effects, from both clinical and quantitaive perspectives.
Methods: The authors examined the literature on the effects of ageing on different types of eye movement, including the clinical presentation of restrictions in ocular motility with age. As many parts of the brain play a role in the control and co-ordination of eye movement, literature on how ageing affects these structures was examined and the authors sought to relate structure and function.
Results: Brainstem oculomotor structures are remarkably well preserved into old age. However age-related effects on the cerebral cortex lead to older subjects exhibiting problems with a number of oculomotor tasks. Clinically, decreases in the range of movement are observed in the absence of pathology, particularly in upgaze.
Conclusions: The development of restrictions in eye movement with age need to be considered when examining older patients. Asymmetries remain a useful indicator of pathology. The observation that brainstem structures are preserved while oculomotor behaviour is modified in ageing, suggests that oculomotor tasks may be useful for probing the effects of ageing on structures above the level of the brainstem.
Key words: Ageing, Saccades, Smooth pursuit, Versions, Cortex, Brainstem
Diagnostic,aetiological and management considerations in accommodative insufficiency.
Veronica S. Henshall and Fiona J. Rowe
Abstract:
Aims: To review the diagnosis, differential diagnosis, aetiologies and clinical management of accommodative insufficiency.
Methods: A literature review was undertaken to address the aspects of accommodative insufficiency
Results: Accommodative insufficiency typically presents with a remote near point of accommodation and a reduction in the accommodative amplitude, and may be associated with a secondary convergence insufficiency. Differential diagnosis must be made with convergence, accommodative and refractive anolmalies, and once accommodative insufficiency is confirmed the management includes prescription of plus lenses and accommodative training.
Conclusions: Clinically it appears that young women with accommodative anomalies are seen more frequently than men and further research into this area is planned.
Key words: Accommodative insufficiency, Convergence insufficiency, Presbyopia, Systemic drugs.
Aniseikonia and its effect on binocular function: a review
Catherine Stewart and Jon Whittle
Abstract:
Aims: To describe the concepts underlying aniseikonia and discuss measurement and management techniques.
Methods: A literature review was conducted to identify articles relevant to aniseikonia with particular focus on anisometropia, aniseikonia and binocular vision.
Results: Aniseikonia is an apparent inequality in the size of the images seen with each eye. The symptoms of aniseikonia range from mild distortions of visual space, through to headaches, asthenopia and disruption of binocular vision. Aniseikonia most commonly occurs in patients with corrected anisometropia, and since the introduction of of intraocular lens implants a new population with the potential for aniseikonia has been formed. The most accurate method for measuring aniseikonia, the space eikonometer is not readily available. However, aniseikonia may be estimated and graded using modified clinical techniques.
Conclusion: The visual system is normally able to cope with 2-3% of aniseikonia but any more than this is likely to produce symptoms and reduce binocular functions. Aniseikonia is managed by prescribing contact lenses instead of spectacles or by manipulating spectacle lens parameters to reduce image size differences.
Key words: Aniseikonia, Axial anisometropia, Stereopsis, Binocularity.
Reduced adduction following lateral transposition of the vertical rectus muscles for sixth nerve palsy
Helen Murgatroyd, Irene Fleming and Caroline MacEwen
Abstract:
Aims: To discuss the role, indications and limitations of lateral transposition of the vertical rectus musles for the management of lateral rectus palsy.
Methods: The authors retrospectively reviewed the clinical notes of 6 patients undergoing this surgery and discuss the results in the context of the current literature.
Results: All the patients were operated on by the same surgeon. One patient had a partial bilateral sixth nerve palsy, 5 patients had unilateral complete palsy. All patients had had pre-operative botulinum toxin, 4 of whom had had 2 separate doses. Post operatively 3 patients had an exo deviation for near, 2 of whom had previously undergone surgery to the medial rectus. All the patients had documented mild to moderate weakness of adduction in the operated eye.
Conclusions: The lateral transposition of the vertical rectus muscles can improve the size and location of binocular single vision in patients with complete unilateral or bilateral partial lateral rectus palsy. The surgery will not allow full ocular rotation; reduced abduction and reduced adduction is to be anticipated.
Key words: Lateral rectus palsy, Vertical rectus transposition, Botulinum toxin.
The effect of Fresnel prisms on binocular vision.
Elaine S. Moreland & Helen J. Griffiths
Abstract:
Aims: The detrimental effect of Fresnel prisms on visual acuity has been well documented, whilst their effect on binocularity is less clear. The aims of this study were to assess the effect of Fresnel prisms on motor fusion and stereo acuity and to compare the results of Fresnel prisms placed over one eye with the equivalent strength split between both eyes.
Methods: Fifteen participants (mean age 25.7 +/- 7.7 years) with normal binocular single vision and minimum corrected Snellen visual acuity of 6/6 were recruited. The effect on motor fusion and stereo-acuity of Fresnel prisms of various strengths placed over one eye or split between the two eyes was assessed using a stereoscope.
Results: The deterioration in binocular functions was increasingly evident as prism strength increased and found to be significantly greater when single prisms were used
Conclusions: Fresnel prisms have been found to impair binocular functions, the effects being significantly greater when a single prism is placed over one eye compared with the equivalent strength split between the eyes. It is suggested that when using Fresnel prisms of greater than 10^ a trial with the required prismatic power split between the eyes is undertaken. This may increase the chance of diagnosing potential binocular single vision in functional cases and if used therapeutically may improve the patient's visual comfort.
Key words: Fresnel prism, Motor fusion, Stereo-acuity, Binocular function.
Is there a relationship between prism fusion range and vergence facility?
Anna C. Melville and Alison Y. Firth
Abstract:
Aim: To investigate the relationship between prism fusion range (PFR) and vergence facility (VF) measurements in subjects with normal binocular single vision.
Methods: Twenty-eight subjects (mean age 19 +/- 1 years) with normal binocular single vision (BSV) underwent measurement of the PFR and VF in a varied order, at a test distance of 1/3 m. The PFR measurements recorded were the base out (BO) range to blur and break point and the base in (BI) range to break point. The total PFR was calculated. The VF was assessed over a 1 minute time period using a 12^BO / 3^BI flip prism and recorded in cycles per minute (cpm)
Results: No correlation was demonstrable between any of the single measures of the PFR and VF results. The BO PFR to break point and the BI PFR results obtained (means 46^BO and 14^BI) were not significantly different from quoted 'normal' values. The VF results obtained (mean 12 +/- 4.2 cpm) were found to be significantly different from the reported mean value.
Conclusion: In a group of young adults with normal BSV, no correlation between PFR and VF was found. The two tests may quantify different aspects of vergence or, alternatively, results of one or both tests in this study may be unreliable.
Key words: Prism fusion range, Fusional amplitudes, Fusional vergences, Vergence facility.
The relationship between the strength of sensory fusion and motor fusion amplitude.
Gemma E. Hocking and Joanne E. Gage.
Abstract:
Aims: To determine the strength of sensory fusion in a normal population at 1/3m and 6m testing distances, and to investigate whether a correlation exists between the strength of sensory fusion and motor fusion amplitude.
Methods: The presence and strength of binocular vision was investigated in 36 participants at 1/3m and 6m. The Sbisa bar was used to test the strength of sensory fusion and Gulden prism bars were used to test motor fusion amplitude.
Results: The strength of sensory fusion at 1/3m was found to be 11.01 filters +/- 3.37 and at 6m was found to be 11.25 filtes +/- 3.06. There was no significant correlation between the strength of sensory fusion and motor fusion amplitude at 1/3m or 6m (p>0.05). There was no significant correlation between the strength of sensory fusion at 1/3m or 6m (p>0.05). Correlation between motor fusion amplitude at 1/3m and 6m was statistically significant (p<0.0001).
Conclusions: Despite being two components of fusion, sensory and motor fusion were not found to correlate. No statistically significant difference was found in the strength of sensory fusion at 1/3m and 6m. This sugests that, in subjects with normal binocular single vision, the strength of sensory fusion need be tested at only one distance.
Key words: Sensory fusion, Motor fusion, Sbisa bar.
Detection of Glaucoma: the role of visual fields.
Gillian E. Coyle, John D. Ellis and Caroline MacEwen
Abstract:
Aims: To evaluate the effectiveness of visual field testing performed by optometrists in the community for the detection of glaucoma.
Methods: Case records were reviewed on all patients with visual field assessment by community optometrists as part of their referral criteria. The total number of patients included was 87. Referrals were divided into four categories: subgroup 1, visual field defect + raised intraocular pressure (IOP) + pathological disc cupping; subgroup 2, visual field defect + pathological disc cupping; subgroup 3, visual field defect + raised IOP; subgroup 4 visual field defect alone. Each patient attending the hospital eye service had visual fields plotted with the Humphrey automated perimeter using the Central 24-2 Fastpac programme. Full ophthalmological examination followed over a number of visits and the diagnosis of glaucoma was confirmed or excluded.
Results: The positive predictive value (PPV) for the diagnosis of each patient subgroup was as follows: subgroup 1, 75%; subgroup 2, 63%; subgroup 3, 25%; and subgroup 4, 0%.
Conclusions: This study demonstrates that patients suspected of having glaucoma who are referred to the hospital eye service with a suspected visual field defect are highly unlikely to have glaucoma unless the defect is accompanied by other disease indicators, in particular pathological disc cupping.
Key words: Glaucoma, Screening, Visual fields.
Use of LogMAR charts for the measurement of visual acuity in orthoptic departments throughout the UK
Catherine Stewart
Abstract:
Aims: To establish the dissemination of logMAR testing of visual acuity in orthoptic deartments throughout the UK, and to establish the main reasons given for not using logMAR tests.
Methods: This questionnaire-based study audited current usage of LogMAR visual acuity testing in orthoptic deartments throughout the UK. Questionnaires were sent to all BOS members but results were analysed per department.
Results: One hundred and six of 288 orthoptic departments returned the questionnaire (37%). Of these departments only 21% are currently using logMAR tests. Departments not using logMAR-based were not doing so due to insufficient undersatnding of logMAR tests (64 departments, 73%), insufficient funds (45 departments, 51%), Snellen tests providing adequate visual acuity measurements (38 departmens, 43%), other health professionals being reluctant to change (32 departments, 36%), test charts being too bulky (19 departments, 21%) and other reasons (5 departments, 6%).
Conclusions: The majority of departments not using logMAR tests acknowledge that these tests have potentialbenefits for improving visual acuity testing. The major issues which need to be overcome are that health professionals have insufficient understanding and information provided on logMAR tests, in addition to insufficient funds at present to change acuity tests throughout their eye department.
Key words: logMAR tests, Visual acuity, Current use, Orthoptic departments, Repeatability
Concomitant esotropia following sixth cranial nerve palsy
Fiona J. Rowe and Carmel P. Noonan
Abstract:
Aims: To discuss the aetiological and recovery aspects of two cases of sixth nerve palsy onset in older children.
Methods: The authors present two cases of sixth nerve palsy onset at age 11 years in patients with previously documented binocular vision but who subsequently developed concomitant esotropia and suppression.
Results: At such an age the visual system is considered to have reached a mature level and maintenance of binocular vision would be the expected sensory outcome in these children. Literature reports of adults with acquired suppression responses or with the ability to 'ignore' diplopia implicate a degree of plasticity in the mature visual system.
Conclusions: risk factors associated with such poor sensory outcome may include loss of visual function (acuity and field)
Key words: Sixth nerve palsy, Concomitant esotropia, Suppression, Visual function
A case of intraorbital injury
Marion Logan
Abstract:
Aims: To report the risk of orbital cellulitis following intraorbital trauma and to highlight the difficulty of diagnosing foreign bodies with CT scanning.
Methods: A case is discussed of an 8-year-old girl who presented with orbital cellulitis after sustaining a facial injury while playing. It was discovered after CT scanning and examination under anaesthetic that an intraorbital foreign body was the cause. Once the foreign body was removed she was left with residual restriction of movement and diplopia.
Results: The patient recovered well and regained excellent binocular single vision. She was left with only slight residual weakness of depression in the affected eye.
Conclusions: Urgent investigation and treatment of orbital cellulitis is crucial to prevent loss of sight.
Key words: Orbital cellulitis, Intraorbital wooden foreign body, Diplopia
A case of Moebius syndrome with vertical muscle involvement, not well recognised by the literature
Gemma C. I. Bates
Abstract:
Aims: To present a case of Moebius syndrome with unusual ocular motility and compare it with the relevant literature.
Methods: Documaentation of the case in relation to its history, orthoptic assessment and photographic illustrations is presented.
Results: Limitation ofthe right eye was present and this unusual feature of the syndrome is compared with similar published cases.
Conclusions: Moebius syndrome has been recognised as a multi-system disorder of VIth and VIIth nerve involvement and various associated features. The case presented shows a complex of ocular motor abnormalities with unusual vertical involvement of limited elevation that highlights the variability of the syndrome.
Key words: Moebius syndrome, Sixth nerve palsy, Seventh nerve palsy, Limited elevation.
Spasmus nutans: a case review
Sarah E. Ashurst
Abstract:
Aims: To describe a case of spasmus nutans and to comment on the implications of the condition.
Methods: A seven month-old female who presented with a large angle esotropia, titubation, torticollis and nystagmus on attempted convergence is discussed. After a full ophthalmic and neurological review, the diagnosis of spasmus nutans was confirmed.
Results: CT scan and ultrasound results were normal. Spasmus nutans was still demonstable at the age of 11 months.
Conclusion: The clinical presentation of spasmus nutans can vary a great deal, and some form of neuroimaging is advocated to eliminate the possibility of any anterior visual pathway abnormality.
Key words: Spasmus nutans, Titubation, Torticollis, Nystagmus.
Isolated abducens nerve palsy without diplopia occuring in ophthalmoplegic migraine.
Gail Horne, Ronnie Bhola, Sundeep Kheterpal
Abstract:
Aim: To present a case of ophthalmoplegic migraine with recurring lateral rectus palsy in a child.
Method: Details are reported of a young girl who was examined several times over a 9 year period. During this time she was found to demonstrate a variable degree of esotropia and lateral rectus underaction which increased significantly after a migraine attack.
Results: No other abnormal neurological signs were found on investigation and the deviation became permanent with suppression due to the early onset of the condition. The aetiology was pesumed to be ophthalmoplegic migraine.
Conclusion: Ophthalmolplegic migraine was diagnosed following exclusion of other causes. Repeated episodes led to a constant esotropia with permannt loss of lateral rectus function and suppression.
Key words: Ophthalmoplegic migraine,Diplopia, Esotropia, Lateral rectus palsy.