Abstracts 2006

British and Irish Orthoptic Journal 2006

Editorial: What’s in a title?

J.M.Woodhouse

Visual processing, fixation and eye movements in able and disabled readers: a literature review.

N.Northway

Aim: To review the literature on visual aspects of reading and how fixation and eye movements are influenced in normal reading and reading disability

Method: A literature based essay looking at the normal reading process and visual factors which affect reading in able readers and in dyslexia and Meares-Irlen syndrome (MIS).

Results: Reading using central retina results in faster more efficient reading however crowding effects may hinder reading efficiency. These effects may be more pronounced in disabled readers and may result in modifications of saccadic behaviour and fixation. Those experiencing visual stress find some text more difficult to read and this may disrupt fixation and saccadic eye movements.

Conclusions: Research has shown that many factors can affect reading such as size of font, spacing of type, contrast of text and reading is always best if central retina is used. Dyslexic readers and those with visual stress may be more easily affected by print features and this may in turn modify fixation behaviour and saccadic behaviour.

LogMAR based visual acuity measurements: limits of normality

C.E.Stewart

Aims: To review critically the literature on the use of logMAR visual acuity tests. This includes visual acuity norms for a range of different ages and tests, and repeatability values.

Method: A literature review of data on validity, age norms and repeatability of currently available logMAR tests was conducted.

Results: All the methodological discrepancies concerning the Snellen-based tests have been accounted for in the design of logMAR-based tests. Tests available for paediatric use include the crowded and uncrowded logMAR test, Kay’s linear logMAR crowded picture test, HOTV acuity test and the Lea Symbols chart. Normative acuity data has been reported for logMAR tests for children from 3 to 11 years of age and young adults. The data show that with increasing age the mean acuity improves and the range attributed to be normal narrows. The repeatability and reliability of the ETDRS and crowded logMAR tests has been determined and values reported for the detection of change.

Conclusions: Research to date remains sparse on visual acuity norms as a function of age for log-based tests and data so far tends to be on one test for a limited age group. There is a need for comparative age-specific normative data for acuity scores for logMAR tests, which could only be achieved from undertaking a large cohort study evaluating multiple tests on the same children in the age range 3 to 7 years.

Transdermal scopolamine (Hyosine): visual side effects

Alison Y Firth

Aims: To highlight the side effects of transdermal scopolamine.

Methods: Evidence from the literature is presented concerning the use of this drug and visual side effects.

Results: The main side effects are pupillary dilation and blurring of vision. These appear to be more frequently encountered with repeated use of patches and where there is local contamination between the patch and the eye.

Conclusions: Awareness of the visual side effects of transdermal scopolamine may help the clinician recognise symptomatic conditions presenting in adults; and especially in children with special needs who are unable to communicate problems.

Effects of blur on Humphrey 24-2 results

H.L.Holmes-Smith; A.Y.Firth

Aim: To determine the effects of defocus on the retinal sensitivity within central 2° and at 24°of the visual field and to compare the effect on the two areas.

Methods: Twelve normal subjects (aged 18 to 22 years) undertook three visual field tests on a Humphrey visual field analyser, one with a +3.00DS lens, one with a +4.00DS, and one with a +5.00DS. Mean threshold sensitivity was recorded in the central 2° and at 24°. Analysis of variance and paired t-tests were used for data analysis.

Results: Two participants were excluded. Analysis of the ten remaining participants showed that the strength of lens used affected sensitivity (p<0.0013), the difference occurring when the +5.00D lens was used. Each lens had a similar effect on the central 2° and at 24° (p = 0.6706).

Conclusion: Threshold sensitivity was reduced with induced blur from plus lenses, without cycloplegia.

Listening to classical music can (slightly) improve stereo-acuity in normal observers

E.E.Griffiths; D.Buckley

Aims: To test for improvements from pre-test measurements in stereo-acuity after listening to pieces of music and whether any stereo-acuity improvement tended to be made following enjoyable stimuli.

Methods: In a double-blind repeated measures study 15 participants with normal vision had their stereo-acuity measured to threshold using the Frisby Stereo-test on 5 occasions. First, prior to exposure to the test stimuli, and then on 4 subsequent occasions each time after 10 minutes of listening to a particular stimulus. Participants also rated their enjoyment of each stimulus.

Results: After listening to each of the musical stimuli stereo-acuity was improved significantly when compared to pre-test, but listening to the control white noise stimulus showed no significant improvement. There was no significant difference between any of the musical pieces in both their effect on stereo-acuity and enjoyment rating. The white noise stimulus was found to be significantly less enjoyable than all the other musical pieces. This suggested that the effect of the music was possibly due to changes in participant mood.

Conclusion: Our findings for stereo-acuity are consistent with previous studies that have shown that listening to classical music can improve performance in spatial tasks.

Refractive surgery and strabismus

Carolyn Calcutt

Aim: to evaluate the orthoptic outcome of patients with a pre-existing ocular motility defect who presented for Lasik refractive surgery.

Method: The case notes of 59 patients that had presented to two centres for Lasik refractive surgery that were judged to be at risk of post-operative symptoms because of a pre-existing ocular motility defect were reviewed. All patients had undergone a comprehensive orthoptic assessment. Factors examined in the analysis were the type of refractive error, the type of deviation, change in binocular status, change in the angle of deviation, and incidence of symptoms / diplopia post refractive surgery.

Results: Forty-four patients were considered suitable for refractive surgery. Of these, 39 proceeded to surgery; data were incomplete for 12 cases leaving 27 cases for analysis. No patient experienced diplopia or a change in binocular status post refractive surgery. Five patients with an accommodative type esotropia had a reduction in the angle of deviation of between 9^Δ to 20^Δ. There was a small reduction in angle of 5^Δ to 6^Δ in three cases with exo deviations and a reduction of 12^Δ BO and 15^Δ BI for two cases of myopic anisometropia.

Conclusion: Full orthoptic assessment of binocular status prior to refractive surgery is essential for patients with a pre-existing ocular motility defect, in order to identify those who are at risk of postoperative symptoms / diplopia and provide advice on the possible consequences of proceeding with the surgery.

The effectiveness of inferior transposition of the horizontal recti in improving symptoms in patients with a deficit of downgaze – a case series of nine patients.

Karen Russell, Shadrokh Nabili and Caroline J. MacEwen

Aim: To evaluate the outcome of inferior transposition of the horizontal recti in patients with reduced downgaze in one eye.

Methods: The cases of nine patients who underwent inferior transposition of horizontal recti were retrospectively reviewed. The pre and post-operative orthoptic findings are presented and the outcome of surgery discussed.

Results: Indication for surgery was a reduction in downgaze, caused by trauma in five cases, fourth nerve palsy in three cases and in one case decompensated congenital fourth nerve palsy in association with a facial fracture. The median vertical deviation in the primary position was 14^Δ pre-operatively (range 4 -25^Δ) reducing to 3^Δ post-operatively (range 0 – 13^Δ). No patient was overcorrected in downgaze. Pre and post-operative Hess charts scores indicated a reduction in vertical displacement for all patients. Binocular single vision (BSV) scores demonstrated a more centralised field of BSV in all but one patient.

Conclusions: Inferior transposition is useful in patients with poor depression in one eye. It improves downgaze, centralises the field of BSV and relieves symptoms of diplopia.

Silent Sinus Syndrome: two cases presenting with sudden onset vertical diplopia

C.MacIntosh; C.E.Riddell; S.Hague

Aim: To report the clinical signs of silent sinus syndrome, and raise orthoptic awareness of this condition, which may present with vertical diplopia.

Method: With informed patient consent, to describe 2 cases of silent sinus syndrome who attended the Orthoptic department within a 2 year period, presenting with sudden onset vertical diplopia. Orthoptic findings with Hess charts are documented, along with photographs and CT imaging for one case. Investigation and management are discussed, and the literature on silent sinus syndrome is reviewed.

Results: Both patients were male, aged 44years and 54 years respectively, were of good general health, and had no history of orbital trauma or disease. A small vertical deviation was found in primary position, with slight limitation of one eye on upgaze and slight hypoglobus. Following Ct scanning the diagnosis in each case was silent sinus syndrome. Both patients underwent maxillary sinus washout, and one patient had an orbital floor implant. Diplopia resolved post operatively in both cases.

Conclusion: Silent sinus syndrome is an uncommon condition associated with asymptomatic maxillary sinus disease, and should be considered in the differential diagnosis of vertical diplopia.

Case report of acquired Brown’s Syndrome due to a mucocoele

Margaret .A E Lye

Aim: To present a case of acquired Brown’s syndrome, subsequently found to be caused by the presence of a left fronto-ethmoidal mucocoele.

Method: Documentation of clinical details of a female patient aged 56 years with sudden onset diplopia from initial presentation to final results.

Results: An apparent acquired Brown’s syndrome was found to be due to a mucocoele in the left fronto-ethmoidal sinus. Surgery to remove the mucocele was undertaken. A small prism was incorporated into reading glasses for use in the evenings when required.

Conclusion: Binocular single vision (BSV) was restored following excision of the mucocoele.

A case of childhood multiple sclerosis

Liz Gaccon

Aim: To describe a case of Multiple Sclerosis (MS) which presented with sudden onset esotropia.

Method: A case is documented with history, ophthalmic and neurological findings and management. Multiple sclerosis is discussed in relation to paediatric onset.

Results: A previously healthy boy aged 2 years 10 months presented with malaise, fever and sudden onset right esotropia, which followed a urinary tract infection 4 weeks earlier. Ophthalmic examination revealed bilateral papillodeama. Magnetic resonance imaging (MRI) showed multiple areas of high signal in the basal ganglia and sub-cortical white matter in the occipital and right frontal lobes. Steroid medication was commenced and resulted in a reduction in signs and symptoms. The provisional diagnosis was acute demyelinating encephalomyelitis (ADEM). Following two further similar episodes a diagnosis of Multiple Sclerosis (MS) was made based on the variation of neurological signs and resolving demyelination on MRI brain scans.

Conclusion: Multiple Sclerosis is very rare in childhood. This was not a typical case of esotropia in a 2 year-old child, as the presence of bilateral papillodeama was indicative of urgent investigation.

A case of benign intracranial hypertension

Sarah J Shea

Aim: To describe a case of longstanding fully accommodative esotropia who developed benign intracranial hypertension.

Method: A case is documented with history, orthoptic, ophthalmological, and neurological findings. The diagnosis of benign intracranial hypertension is discussed in relation to the child’s symptoms and when further investigation is required.

Results: An unexplained temporary decompensation of a previously well-controlled deviation followed by several episodes of blurred vision and occasional headache six months later prompted the orthoptists to press for further investigations. Subsequent neurological investigation led to a diagnosis of benign intracranial hypertension.

Conclusion: The orthoptic team were responsible for the long-term management of this child. The onset of symptoms that could not be easily accounted for were the key elements in the orthoptists’ requesting further investigation.