David Newsham

Ophthalmic impairment at 7 years of age in children born very preterm

Aims: To determine the prevalence of ophthalmic impairments in very preterm compared with term infants, the relation between impairments and cerebral ultrasound appearances and retinopathy, and the correlation with visual perception and motor and cognitive measures. Subjects: 279 children at 7 years of age born before 32 weeks gestation within Liverpool during 1991–92 and attending mainstream schools, and 210 term controls. Methods: Visual acuity was assessed by Snellen chart, and strabismus by the cover test. Stereopsis was determined using the TNO random dot test, and contrast sensitivity using the Cambridge low contrast gratings. Visual and motor abilities were assessed using the Developmental test of motor integration (VMI) and the Movement ABC. Intelligence was measured with the Wechsler intelligence scale for children UK. Perinatal cranial ultrasound and retinopathy data were extracted from clinical records. Results: Children born preterm were significantly more likely to wear glasses, to have poor visual acuity, reduced stereopsis, and strabismus than term controls, but they showed no significant decrease in contrast sensitivity. Ophthalmic impairments were significantly related to poorer scores on the VMI, Movement ABC, and Wechsler IQ tests, but were not significantly related to neonatal cranial ultrasound appearances. Stage 3 retinopathy was related to poorer subsequent acuity. Conclusions: Children born very preterm and without major neurodevelopmental sequelae have an increased prevalence of ophthalmic impairments at primary school age which are associated with visual perceptional, motor, and cognitive defects. The cause may be a generalised abnormality of cortical development rather than perinatally acquired focal lesions of the brain.

Parental non-concordance with occlusion therapy

BACKGROUND/AIMS Non-concordance has often been reported as a major contributor to the failure of occlusion therapy for amblyopia. In other fields of medicine the extent of a patients understanding in areas of the disease and treatment has been shown to have both a direct and indirect effect on subsequent concordance. The aims of this study were to determine the extent of parental non-concordance, to assess their level of understanding in key areas of amblyopia, occlusion therapy, critical period and prognosis, and to discover the parents own reasons for failing to concord. METHODS Parents of children aged 2–7 years receiving a minimum of 1 hour of occlusion for unilateral amblyopia were recruited. Parental concordance was monitored using a diary and their understanding and reasons for non-concordance were assessed by a questionnaire. Concordance was analysed by calculating a concordance index, determining the proportion of non-concordance, and also by classifying the non-concordance on the basis of whether the behaviour was intentional or unintentional and whether the parents were adequately or inadequately informed. RESULTS Parental non-concordance was defined as failing to occlude less than 80% of the total prescribed time. The median concordance index was 0.75 and the proportion of non-concordant parents was 0.54 (95% CI 0.41 to 0.67) (n = 57). Parental knowledge was poor in areas of the critical period with 23% of parents unaware of an age limit to the treatment. Reasons for non-concordance given by 68% of parents demonstrated poor knowledge. CONCLUSION A substantial proportion of the non-concordant parents had poor understanding in areas such as the critical period and errors also occurred in implementing the treatment regimen. Increased parental awareness of the rationale and urgency of the treatment, with reinforcement of details of the regimen, would help to reduce non-concordance with occlusion therapy.

A randomised controlled trial of written information: the effect on parental non-concordance with occlusion therapy

Background/aims: It is well documented that non-concordance with occlusion therapy is both substantial and a major factor leading to treatment failure. Parental understanding in previous work has been found to be poor in key areas such as the critical period and effect of age on prognosis. Research in other areas of medicine has shown that the level of understanding can have a direct effect on the level of concordance. The aims of this study were to assess the ability of educational material in the form of a leaflet, to improve parental understanding of amblyopia and occlusion, and subsequently increase concordance. Methods: Parents of children aged between 1 and 7 years receiving a minimum of 1 hour of occlusion for amblyopia were recruited. A randomised controlled trial was undertaken where, on inclusion, the patients were randomised into a leaflet group, whose parents were issued with written educational material, and a control group whose parents did not receive the written information. Patients were paired and matched for age (<2 years difference) and amount of prescribed occlusion (no more than 1 hour difference). Concordance was monitored by a parental diary and knowledge and parental reasons for non-concordance were assessed by a questionnaire. Concordance was analysed by means of a concordance index and by calculating the proportion of non-concordant parents by setting a threshold of concordance at 80%. Results: Parental knowledge was significantly greater in the leaflet group (88% had complete knowledge) compared to the control group (49% had complete knowledge) (p <0.001). There were also differences between the groups in the area of the treatment regimen, with errors only occurring in the control group (three patients occluded the incorrect eye), but this did not reach statistical significance. Concordance was significantly greater in the leaflet group (mean concordance index 0.85) compared to the non-leaflet group (mean concordance index (0.71) (p <0.001). Comparison of the proportion of non-concordant parents was also statistically different (p <0.005) at 0.23 (95% CI 0.13 to 0.35) for the leaflet group compared to 0.54 (95% CI 0.41 to 0.67) for the control group. Conclusion: A large proportion of patients would benefit by increasing parental knowledge in key areas such as the critical period, importance of occlusion, and potential negative consequences of not treating amblyopia. Written information is a simple, inexpensive, easy to implement, yet effective method of improving parental understanding and subsequent concordance.

The effect of recent amblyopia research on current practice in the UK.

Background/aims Several studies have recently provided insights into how amblyopia may be most effectively managed. Despite the new evidence, a US study reported that a recent randomised controlled trial had made little influence on clinical practice. The aims of this research are to assess current practice of amblyopia management in the UK and to determine the comparability with the evidence-based recommendations. Methods A questionnaire was constructed to assess current amblyopia management practice, particularly in relation to areas investigated by recent research and emailed to every head orthoptist within the UK. Results There was a great deal of variability in the amount of occlusion that was prescribed for moderate and severe amblyopia. Sixty per cent of clinicians indicated that the maximum they would prescribe was in excess of the 6 h recommended by research. Atropine was rarely recommended as a first-line treatment, with occlusion generally being considered to be more effective. Despite recommendations regarding education as a means of reducing non-compliance, only 39% of clinicians always gave written information, although various other methods of enhancing compliance were used. A period of refractive adaptation was allowed by most clinicians but often far less than recommended. Conclusion The uptake of recent research evidence into clinical practice is sporadic and incomplete with one-third of respondents indicating that following the studies, they had made no changes whatsoever to their practice. This is similar to other areas of medicine; the reasons are likely to be varied, and is an area that would benefit from greater attention.

A Pilot Study Examining Density of Suppression Measurement in Strabismus

Abstract Purpose: Establish whether the Sbisa bar, Bagolini filter (BF) bar, and neutral density filter (NDF) bar, used to measure density of suppression, are equivalent and possess test-retest reliability. Determine whether density of suppression is altered when measurement equipment/testing conditions are changed. Methods: Our pilot study had 10 subjects aged ≥18 years with childhood-onset strabismus, no ocular pathologies, and no binocular vision when manifest. Density of suppression upon repeated testing, with clinic lights on/off, and using a full/reduced intensity light source, was investigated. Results were analysed for test-retest reliability, equivalence, and changes with alteration of testing conditions. Results: Test-retest reliability issues were present for the BF bar (median 6 filter change from first to final test, p = 0.021) and NDF bar (median 5 filter change from first to final test, p = 0.002). Density of suppression was unaffected by environmental illumination or fixation light intensity variations. Density of suppression measurements were higher when measured with the NDF bar (e.g. NDF bar = 1.5, medium suppression, vs BF bar = 6.5, light suppression). Conclusions: Test-retest reliability issues may be present for the two filter bars currently still under manufacture. Changes in testing conditions do not significantly affect test results, provided the same filter bar is used consistently for testing. Further studies in children with strabismus having active amblyopia treatment would be of benefit. Despite extensive use of these tests in the UK, this is to our knowledge the first study evaluating filter bar equivalence/reliability.

Assessment of the Density of Suppression to Identify Risk of Intractable Diplopia in the United Kingdom

ABSTRACT Background/Aims: Occlusion used to treat amblyopia towards the end of the developmental component of the critical period gives a risk of inducing intractable diplopia. In the United Kingdom, the density of suppression is assessed via the Sbisa/Bagolini filter bar, but there is very little research evidence to guide clinical practice or interpretation of the tests used. The aims of this study were to determine current practice and estimate the incidence of intractable diplopia following amblyopia treatment. Methods: Current practice and incidence of intractable diplopia following amblyopia were determined via a questionnaire distributed to head orthoptists in every eye department in the United Kingdom. The questionnaire explored testing and test conditions, interpretation of the test results, and cases of intractable diplopia over the last 5 years. Results: There was considerable variation in clinical practice of the measurement of the density of suppression and interpretation of the results to guide the treatment of amblyopia. The minimum age of patients taking the test ranged from 2 to 8 years and the minimum filter considered still safe to continue treatment ranged from 4 to 17. It is estimated there were 24 cases of intractable diplopia over the last 5 years. Conclusion: The issue of intractable diplopia and amblyopia treatment is likely to become increasingly important as there appears to be greater plasticity and scope to treat amblyopia in teenagers and adults than was previously thought. Lack of knowledge of how to evaluate the risk may lead to more cases of intractable diplopia or alternatively treatment being withheld unnecessarily.

Oculomotor control in a group of very low birth weight (VLBW) children.

VLBW infants are at risk of lesions including intraventricular haemorrhage and periventricular leucomalacia. Those with normal IQ still present with reading difficulties. Oculomotor performance was assessed on 14 VLBWs (IQ > 85) and 15 full-term age-matched controls. Anti-saccade errors were significantly higher for the VLBWs (78%) compared to full terms (62%) (P = 0.02). Smooth pursuit latency was longer for the VLBWs compared to the full terms. Greater anti-saccade errors may be indicative of a lesion affecting the frontal cortex or developmental delay. Oculomotor deficits in VLBW children may be associated with the higher incidence of reading difficulties that have been reported.

Use of atropine penalization to treat amblyopia in UK orthoptic practice.

PURPOSE To compare clinical practice patterns regarding atropine penalization use by UK orthoptists to the current evidence base and identify any existing barriers against use of AP as first-line treatment. METHODS An online survey was designed to assess current practice patterns of UK orthoptists using atropine penalization. They were asked to identify issues limiting their use of atropine penalization and give opinions on its effectiveness compared to occlusion. Descriptive statistics and content analysis were applied to the results. RESULTS Responses were obtained from 151 orthoptists throughout the United Kingdom. The main perceived barriers to use of atropine penalization were inability to prescribe atropine and supply difficulties. However, respondents also did not consider atropine penalization as effective as occlusion in treating amblyopia, contrary to recent research findings. Patient selection criteria and treatment administration largely follow current evidence. More orthoptists use atropine penalization as first-line treatment than previously reported. CONCLUSIONS Practitioners tend to closely follow the current evidence base when using atropine penalization, but reluctance in offering it as first-line treatment or providing a choice for parents between occlusion and atropine still remains. This may result from concerns regarding atropines general efficacy, side effects, and risk of reverse amblyopia. Alternatively, as demonstrated in other areas of medicine, it may reflect the inherent delay of research findings translating to clinical practice changes.

Incidence, risk factors and management of intractable diplopia

Aims There is a paucity of literature concerning intractable diplopia. The aims of this study were to determine the incidence of intractable diplopia in the UK, identify the causes and any associated risk factors, establish how cases are managed and if the treatment is successful and tolerated. Methods A 1-year prospective observational study was undertaken via the British Ophthalmological Surveillance Unit (BOSU). This involved implementation of a reporting mechanism, which then triggered distribution of an incident questionnaire to explore clinical details concerning each case and a follow-up questionnaire 6 months later to explore how the case had been managed. Results The incidence of intractable diplopia was 53 cases per year. The most common preceding events were strabismus surgery (32%), no known preceding event, that is,spontaneous (25%), severe head trauma (8%), cataract surgery (6%) and vitrectomy (6%). In the at-risk age group of 7 years and above, the incidence of intractable diplopia following strabismus surgery is 1 in 494 (95% CI; 1 in 296 to 790) cases. A total of nine different treatments were used in the management, with many patients receiving between two and four different methods. The overall success rate was poor, but most effective were opaque intraocular lenses (IOLs) (86%) and opaque contact lenses (50%). Conclusion Intractable diplopia is a relatively rare but important condition. The main risk factor is a pre-existing strabismus, and careful counselling is needed when planning surgical correction in patients with no demonstrable binocular function. Treatment success of intractable diplopia is high when using opaque IOLs, although with additional risk, but is often disappointing via other methods where it can be difficult to eradicate the diplopia successfully.