128 results on '"Horwood, Anna"'
Search Results
2. Implementation of paediatric vision screening in urban and rural areas in Cluj County, Romania
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Kik, Jan, Nordmann, Mandy, Cainap, Simona, Mara, Mihai, Rajka, Daniela, Ghițiu, Monica, Vladescu, Alin, Sloot, Frea, Horwood, Anna, Fronius, Maria, Vladutiu, Cristina, and Simonsz, Huibert Jan
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- 2021
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3. Neonatal ocular misalignments
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Horwood, Anna M.
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618.92 - Published
- 2002
4. A population-level post-screening treatment cost framework to help inform vision screening choices for children under the age of seven.
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Horwood, Anna, Heijnsdijk, Eveline, Kik, Jan, Sloot, Frea, Carlton, Jill, Griffiths, Helen J., and Simonsz, Huibert J.
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LOW vision , *ANISOMETROPIA , *VISION testing , *MEDICAL screening , *SECONDARY care (Medicine) , *VISUAL acuity , *REFRACTIVE errors - Abstract
Visual acuity (VA) screening in children primarily detects low VA and amblyopia between 3 and 6 years of age. Photoscreening is a low-cost, lower-expertise alternative which can be carried out on younger children and looks instead for refractive amblyopia risk factors so that early glasses may prevent or mitigate the conditions. The long-term benefits and costs of providing many children with glasses in an attempt to avoid development of amblyopia for some of them needs clarification. This paper presents a framework for modeling potential post-referral costs of different screening models once referred children reach specialist services. The EUSCREEN Screening Cost-Effectiveness Model was used together with published literature to estimate referral rates and case mix of referrals from different screening modalities (photoscreening and VA screening at 2, 3–4 years and 4–5 years). UK 2019–20 published National Health Service (NHS) costings were used across all scenarios to model the comparative post-referral costs to the point of discharge from specialist services. Potential costs were compared between a) orthoptist, b) state funded ophthalmologist and c) private ophthalmologist care. Earlier VA screening and photoscreening yield higher numbers of referrals because of lower sensitivity and specificity for disease, and a different case mix, compared to later VA screening. Photoscreening referrals are a mixture of reduced VA caused by amblyopia and refractive error, and children with amblyopia risk factors, most of which are treated with glasses. Costs relate mainly to the secondary care providers and the number of visits per child. Treatment by an ophthalmologist of a referral at 2 years of age can be more than x10 more expensive than an orthoptist service receiving referrals at 5 years, but outcomes can still be good from referrals aged 5. All children should be screened for amblyopia and low vision before the age of 6. Very early detection of amblyopia refractive risk factors may prevent or mitigate amblyopia for some affected children, but population-level outcomes from a single high-quality VA screening at 4–5 years can also be very good. Total patient-journey costs incurred by earlier detection and treatment are much higher than if screening is carried out later because younger children need more professional input before discharge, so early screening is less cost-effective in the long term. Population coverage, local healthcare models, local case-mix, public health awareness, training, data monitoring and audit are critical factors to consider when planning, evaluating, or changing any screening programme. [ABSTRACT FROM AUTHOR]
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- 2023
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5. Availability of data for cost-effectiveness comparison of child vision and hearing screening programmes
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Kik, Jan, Heijnsdijk, Eveline A.M., Mackey, Allison R., Carr, Gwen, Horwood, Anna M, Fronius, Maria, Carlton, Jill, Griffiths, Helen J, Uhlén, Inger M, Simonsz, Huibert Jan, Availability of data for cost-effectiveness comparison of child vision and hearing screening programmes, Hemptinne, Coralie, Yüksel, Demet, Ophthalmology, Public Health, and UCL - SSS/IONS/NEUR - Clinical Neuroscience
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SDG 3 - Good Health and Well-being ,Health Policy ,Environmental and Occupational Health ,Public Health, Environmental and Occupational Health ,Public Health - Abstract
Objective For cost-effectiveness comparison of child vision and hearing screening programmes, methods and data should be available. We assessed the current state of data collection and its availability in Europe. Methods The EUSCREEN Questionnaire, conducted in 2017–2018, assessed paediatric vision and hearing screening programmes in 45 countries in Europe. For the current study, its items on data collection, monitoring and evaluation, and six of eleven items essential for cost-effectiveness analysis: prevalence, sensitivity, specificity, coverage, attendance and loss to follow-up, were reappraised with an additional questionnaire. Results The practice of data collection in vision screening was reported in 36% (N = 42) of countries and in hearing screening in 81% (N = 43); collected data were published in 12% and 35%, respectively. Procedures for quality assurance in vision screening were reported in 19% and in hearing screening in 26%, research of screening effectiveness in 43% and 47%, whereas cost-effectiveness analysis was performed in 12% for both. Data on prevalence of amblyopia were reported in 40% and of hearing loss in 77%, on sensitivity of screening tests in 17% and 14%, on their specificity in 19% and 21%, on coverage of screening in 40% and 84%, on attendance in 21% and 37%, and on loss to follow-up in 12% and 40%, respectively. Conclusions Data collection is insufficient in hearing screening and even more so in vision screening: data essential for cost-effectiveness comparison could not be reported from most countries. When collection takes place, this is mostly at a local level for quality assurance or accountability, and data are often not accessible. The resulting inability to compare cost-effectiveness among screening programmes perpetuates their diversity and inefficiency.
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- 2023
6. Disparity-driven vs blur-driven models of accommodation and convergence in binocular vision and intermittent strabismus
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Horwood, Anna M. and Riddell, Patricia M.
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- 2014
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7. Change in convergence and accommodation after two weeks of eye exercises in typical young adults
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Horwood, Anna M., Toor, Sonia S., and Riddell, Patricia M.
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- 2014
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8. The effect of asymmetrical accommodation on anisometropic amblyopia treatment outcomes
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Toor, Sonia, Horwood, Anna, and Riddell, Patricia
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- 2019
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9. A comprehensive overview of vision screening programmes across 46 countries
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Carlton, Jill, Griffiths, Helen J., Mazzone, Paolo, Horwood, Anna M., and Sloot, Frea
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To describe and compare vision screening programmes and identify variance in number and type of tests used, timing of screening, personnel involved, monitoring and funding to be used as data for optimising, disinvesting or implementing future screening programmes. A questionnaire consisting of nine domains: demography & epidemiology, administration & general background, existing screening, coverage & attendance, tests, follow-up & diagnosis, treatment, cost & benefit and adverse effects was completed by Country Representatives (CRs) recruited from 47 countries. The questionnaire was sufficiently completed for 46 Countries: 42 European countries, China, India, Malawi and Rwanda. Variation of provision was found in; age of screening (0-17 years), tests included (23), types of visual acuity (VA) test used (35 different optotypes), personnel (13), number of screens per child (median 5, range 1-32), and times VA tested (median 3, range 1-30). Infant screening is offered in all countries, whereas childhood vision screening is offered at least once in all countries, but not all regions of each country. All 46 countries provide vision screening between the ages of 3-7 years. Data on screening outcomes for quality assurance was not available from most countries; complete evaluation data was available in 2% of countries, partial data from 43%. Vision screening is highly variable. Some form of VA testing is being undertaken during childhood. Data collection and sharing should be improved to facilitate comparison and to be able to optimise vision screening programmes between regions and countries.
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- 2022
10. When does Blur matter? A narrative review and commentary
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Horwood, Anna
- Abstract
Blur is the subjective awareness that the edges of a high contrast image are indistinct. T and the concept of blur is fundamental to the understanding of vision, accommodation, refractive error, concomitant strabismus and asthenopia. It is easy for clinicians to believe that blur always needs to be avoided or resolved, or that everyone responds to blur similarly.\ud This narrative review outlines the literature on blur and the accommodation to resolve it, and relates it to current clinical practice. Laboratory studies have traditionally been highly controlled, using expert observers, but more recent research using naïve participants suggests that variability and tolerance of blur is common and more widespread than often thought, especially in children and clinical groups. \ud Objective and subjective responses can differ widely, and it cannot be assumed that because we expect accommodation to have occurred, that it always has. \ud A deeper understanding of the role of blur and objective accommodation in vision, refractive error and strabismus may help us understand the variability that exists in clinical practice. We may use blur to help investigation and treatment, but also be relaxed about what is normal. Many patients are led to believe that they should always achieve constant clear vision, when this is unrealistic. Although pathological blur must be identified and treated, normal everyday blur may become medicalized into “a problem” by well-meaning professionals.
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- 2022
11. Using evidence-based psychological approaches to accommodation anomalies.
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Horwood, Anna M and Waite, Polly
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PSYCHOTHERAPY , *PSYCHOLOGICAL factors , *VISUAL perception , *DYNAMIC testing , *CLINICAL pathology , *FACIAL paralysis - Abstract
Accommodation anomalies are frequently caused or exacerbated by psychological problems such as anxiety. Patients share many features with those with other anxiety based somatic symptoms such as stomach-ache, palpitations and headaches. They can be difficult to treat, and the ophthalmic literature rarely goes beyond diagnosis and ocular treatment. This study reports characteristics and outcomes of a short case series of patients with accommodation spasms and weaknesses assessed objectively, and outlines a psychological approach to treatment 23 patients (13 severe accommodative weakness or "paralysis," 10 accommodative spasm) aged between 8–30 years, were referred to our laboratory after diagnosis by their referring clinician and exclusion of pathology or drug-related causes. Their accommodation and convergence were assessed objectively with a laboratory photorefractive method, as well as by conventional orthoptic testing and dynamic retinoscopy. All interactions with the patients used an evidence-based psychological approach, to give them insight into how stress and anxiety can cause or exacerbate eye symptoms and help them to break a vicious cycle of anxiety and risk of deterioration. 83% were female and 57% had previously diagnosed anxiety or dyslexia (with many more acknowledging being "worriers"). Inconsistency of responses was the rule and all showed normal responses at some time during their visit. Responses were poorly related to the visual stimuli presented and objective responses often differed from subjective. Dissociation between convergence and accommodation was more common, compared to our large, previously reported, control groups. No participant had true paralysis of accommodation. Responses often improved dramatically within one session after discussion and explanation of the strong relationship between anxiety and accommodative anomalies. None have returned for further advice or treatment. Our approach explicitly addresses psychological factors in causing, or worsening, accommodation (and co-existing convergence) anomalies. Many of these patients do not realize that a certain amount of blur is normal in everyday life. Ocular symptoms are often a sign of anxiety, not the primary problem. By recognizing this, patients can be helped to address the triggering issues and symptoms often subside or resolve spontaneously. Well-meaning professionals, offering only ocular treatments, can deflect attention away from the real cause and can unwittingly be making things worse. [ABSTRACT FROM AUTHOR]
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- 2023
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12. Screening for convergence insufficiency using the CISS is not indicated in young adults
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Horwood, Anna M, Toor, Sonia, and Riddell, Patricia M
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- 2014
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13. Clinical test responses to different orthoptic exercise regimes in typical young adults
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Horwood, Anna and Toor, Sonia
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- 2014
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14. Decreased accommodation during decompensation of distance exotropia
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Horwood, Anna M and Riddell, Patricia M
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- 2012
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15. Evidence that convergence rather than accommodation controls intermittent distance exotropia
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Horwood, Anna M. and Riddell, Patricia M.
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- 2012
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16. Hypo-accommodation responses in hypermetropic infants and children
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Horwood, Anna M and Riddell, Patricia M
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- 2011
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17. Differences between naïve and expert observersʼ vergence and accommodative responses to a range of targets
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Horwood, Anna M and Riddell, Patricia M
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- 2010
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18. The use of cues to convergence and accommodation in naïve, uninstructed participants
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Horwood, Anna M. and Riddell, Patricia M.
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- 2008
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19. Gender differences in early accommodation and vergence development
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Horwood, Anna M. and Riddell, Patricia M.
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- 2008
20. Typical and atypical development of ocular alignment and binocular vision in infants – the background
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Horwood, Anna M.
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genetic structures ,sense organs ,eye diseases - Abstract
These pages cover the outcomes of research into the typical motor aspects of development of binocular vision in very early childhood. Separate pages on the clinical Examination of Ocular Alignment and Binocular Vision in Infants under six months of age deals with the their clinical assessment and the recognition of atypical signs. The development and assessment of visual acuity, stereopsis, refraction and the process of emmetropization has a large literature, are only covered here where they affect motor systems. Specific ocular motor anomalies such as esotropia, exotropia, incomitant strabismus, congenital dysinnervation syndromes and paralytic strabismus are also not be covered as their management extends well beyond infancy.
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- 2019
21. Clinical examination of ocular alignment and binocular vision in infants under six months of age
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Horwood, Anna
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genetic structures ,eye diseases - Abstract
These pages outline the clinical assessment of ocular alignment and binocular vision, as well as the factors which might influence them, in typical and atypical infants. Visual acuity testing and fundus and media examination are not covered in these pages.\ud A companion set of pages covers the research evidence on typical and atypical development upon which these clinical methods are based.
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- 2019
22. The 13th Bielschowsky lecture: accommodation and convergence – ratios, linkages, styles and mental somersaults
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Horwood, Anna
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genetic structures ,eye diseases - Abstract
A relatively fixed relationship between convergence and accommodation appears to be fundamental to binocular vision and its disorders. The accommodative convergence to accommodation ratio (AC/A) has traditionally been considered a major explanatory factor, but it fits only a small number of clinical diagnoses and fails to explain others. An alternative model, based on the different weights the visual system places on the main cues to target position in depth, fits concomitant strabismus, heterophoria and convergence and accommodation anomalies more comprehensively. Typical accommodation can be surprisingly variable and many intermittently-strabismic people still use binocular disparity as their primary visual cue, with blur and proximal/looming cues having less weight. The convergence-accommodation to accommodation (CA/C) linkage is therefore more important than the AC/A relationship in the majority of typical and atypical cases. Between-diagnosis style differences in the relative balance between these relationships can explain many clinical findings.\ud Instead of “accommodation drives convergence”, or “convergence drives accommodation”, we should instead think of the visual and non-visual cues which drive both systems more independently and flexibly.
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- 2019
23. Costs and effectiveness of two models of school-entry visual acuity screening in the UK.
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Horwood, Anna, Lysons, Deborah, Sandford, Victoria, and Richardson, Greg
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COST effectiveness , *VISUAL acuity , *SENSITIVITY & specificity (Statistics) , *DATA integrity , *HOSPITAL records , *OPTICIANS - Abstract
Cost effectiveness of different visual screening modalities cannot be calculated without long-term outcome data. This paper reports detailed outcomes from a gold-standard UK recommended orthoptist-delivered screening (ODS) at 4–5 years in school, compared to a neighboring school-nurse delivered screening (SNDS), both feeding into the same treatment pathway. The target condition was reduced visual acuity (VA) of worse than logMAR 0.2 in either eye. Available records from screening databases and hospital records were analyzed, comparing the two services wherever possible. More screening data was available from the ODS. ODS: 5706 screened, 3.5% referred. False positives 6.5%, PPV 91.4%, sensitivity 97.9%, and specificity 99.8% for reduced VA. Cost per child with reduced vision detected £195.22, and per amblyope detected £683.28. The mean treatment cost per child with reduced VA was £331.68 and for amblyopia treatment was £458.65. SNDS: 5630 screened and 3.8% referred (plus some referrals to local optometrists lost to follow up). False positives 34%, PPV 53.2%, sensitivity and specificity estimated as 89.3% and 98.67%. Costs to secondary services of false positives were seven times greater. The cost per child with confirmed reduced vision seen at the hospital was 46% more; and per amblyope detected was 39% more. Outcomes for treatment post referral in both groups were similar and excellent. 86% of genuine referrals improved to within normal limits with glasses alone. Of 221 genuine referrals with final outcome data, all now have better than 0.2logMAR acuity in the better eye and only two (0.9%) have residual amblyopia in one eye worse than 0.4logMAR. About 14–18% of children with reduced VA would have passed AAPOS photoscreening referral criteria. An orthoptist-delivered single VA screen at 4–5 years is highly cost effective with good outcomes. The main contributing factors to success appear to be training and experience in accurate VA testing, the opportunity to rescreen equivocal results, and monitoring, audit, and feedback of outcomes. [ABSTRACT FROM AUTHOR]
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- 2021
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24. Asymmetrical accommodation in hyperopic anisometropic amblyopia
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Toor, Sonia, Horwood, Anna M., and Riddell, Patricia
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genetic structures - Abstract
Background/Aims: To investigate the presence of asymmetrical accommodation in hyperopic anisometropic amblyopia.\ud Methods: Accommodation in each eye and binocular vergence were measured simultaneously using a PlusoptiX SO4 photorefractor in 26 children aged 4 to 8 years with hyperopic anisometropic amblyopia and 13 controls (group age-matched) whilst they viewed a detailed target moving in depth. \ud Results: Without spectacles, only 5 (19%) of anisometropes demonstrated symmetrical accommodation (within the 95%CI of the mean gain of the sound eye of the anisometropic group), whereas 81% demonstrated asymmetrical accommodation. Of those, 15 (58%) showed aniso-accommodation and 6 (23%) demonstrated “anti-accommodation” (greater accommodation for distance than for near). In those with anti-accommodation the response gain in the sound eye was (0.93 ±0.20) whilst that of the amblyopic eye showed a negative accommodation gain of (-0.44 ±0.23). Anti-accommodation resolved with spectacles. Vergence gains were typical in those with symmetrical and asymmetrical accommodation.\ud Conclusion: The majority of hyperopic anisometropic amblyopes demonstrated non-consensual asymmetrical accommodation. Approximately one in four demonstrated anti-accommodation.
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- 2018
25. Children’s accommodation to a variety of targets –\ud a pilot study
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Ludden, Siobhan M., Horwood, Anna M., and Riddell, Patricia M.
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Background: Previous research indicates that a significant proportion of children underaccommodate\ud at 1/3 m. Accommodation may vary with task demand, so children may accommodate\ud appropriately if required, for example, when reading small print. This study explores the range\ud of accommodative responses elicited in typical children, under naturalistic conditions, to a range\ud of targets.\ud Method: We identified 24 typically developing children from the University of Reading Child\ud Database. Primary-school children attending UK Year 2 (age 6-7 years) or Year 6 (age 10-11\ud years) with minimum distance visual acuity of 0.200 logMAR and near visual acuity of 0.100\ud logMAR were recruited for participation. A remote haploscopic photorefractor was used to assess\ud naturalistic, sustained, binocular accommodative responses to a variety of targets. At 33 cm,\ud accommodative targets included individual letters, age-appropriate text in large print equivalent\ud to early primary-school books, small N5 equivalent print, a visual search task (“Where’s Wally?”), a\ud clown picture containing a range of spatial frequencies, and a children’s cartoon. Participants were\ud given minimal instructions for task completion. The target presentation order was counterbalanced.\ud The results reported in this study were obtained during a longer testing session involving\ud different target types and fixation distances.\ud Results: The accommodative response observed with each target varied across participants to\ud both the clown target and single letters of a size used in school reading books the accommodative\ud responses were 2.4±0.48 D (range 0.85-2.97 D) and 2.47±0.37 D (range 1.48-3.09 D), respectively.\ud The accommodative response to N5 print (3.06±0.52 D) was statistically better than all\ud other targets other than the visual search and larger print tasks (P
- Published
- 2017
26. Plusoptix photoscreener use for paediatric vision screening in Flanders and Iran.
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Bostamzad, Parinaz, Horwood, Anna M., Schalij‐Delfos, Nicoline E., Boelaert, Kristel, de Koning, Harry J., and Simonsz, Huibert J.
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EYE examination , *VISION testing , *ANISOMETROPIA , *STRABISMUS , *REFRACTIVE errors , *VISUAL acuity , *AMBLYOPIA - Abstract
Purpose: Photoscreening assesses risk factors for amblyopia, as an alternative to measurement of visual acuity (VA) to detect amblyopia, on the premise that its early correction could prevent development of amblyopia. We studied implementations of Plusoptix photoscreening in existing population‐based screening in Flanders and Iran. Methods: In Flanders, VA is measured at age 3, 4 and 6, photoscreening was added to existing screening at age 1 and 2.5 years in 2013. In Iran, VA is measured at ages 3–6 years, photoscreening was added at ages 3–6 years between 2011 and 2016. Plusoptix use was analysed in the literature for detection of risk factors for amblyopia and amblyopia itself, for ages 0–3 and for 4–6. A questionnaire, containing seven domains: existing vision screening, addition of photoscreening, implementation in screening program, training, attendance, diagnosis and treatment, and costs was distributed. In Iran, screening procedures were observed on site. Results: Implementation of Plusoptix photoscreening was mainly analysed from questionnaires and interviews, its effectiveness from literature data. In Flanders, of 56 759 children photoscreened at age one (81% of children born in 2013), 9.2% had been referred, 13% of these were treated, mostly with glasses, resulting in an increase of 4‐year‐old children wearing glasses from 4.7% to 6.4%. In Iran, 90% of children aged 3–6 years participated in vision screening in 2016, but only those who failed the vision test were subjected to photoscreening. Conclusions: In Flanders, the use of Plusoptix photoscreening at ages 1 and 2.5 resulted in an increase of children wearing glasses, but it remains unknown how many cases of amblyopia have been prevented. Studies are needed to determine the relation between size and sort of refractive error and strabismus, and the increased chance to develop amblyopia. [ABSTRACT FROM AUTHOR]
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- 2020
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27. Intermittent exotropia: are we underminusing by not overminusing?
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Brodsky, Michael C., Horwood, Anna M., and Riddell, Patricia M.
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genetic structures ,sense organs ,eye diseases - Abstract
In this invited commentary, the authors discuss whether the use of minus lenses to aid control of intermittent exotropia has an alternative method of action. Conventional theory suggests that the lenses induce accommodation and therefore accommodative convergence to reduce the angle of deviation. We discuss evidence which suggests that convergence is induced to control the primary deviation and that the minus lenses allow this control by correcting refractive blur caused by additional vergence accommodation.
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- 2015
28. Convergence and accommodation development is pre-programmed in premature infants
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Horwood, Anna M., Toor, Sonia, and Riddell, Patricia M.
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Purpose This study investigated whether vergence and accommodation development in pre-term infants is pre-programmed or is driven by experience.\ud Methods 32 healthy infants, born at mean 34 weeks gestation (range 31.2-36 weeks) were compared with 45 healthy full-term infants (mean 40.0 weeks) over a 6 month period, starting at 4-6 weeks post-natally. Simultaneous accommodation and convergence to a detailed target were measured using a Plusoptix PowerRefII infra-red photorefractor as a target moved between 0.33m and 2m. Stimulus/response gains and responses at 0.33m and 2m were compared by both corrected (gestational) age and chronological (post-natal) age. \ud Results When compared by their corrected age, pre-term and full-term infants showed few significant differences in vergence and accommodation responses after 6-7 weeks of age. However, when compared by chronological age, pre-term infants’ responses were more variable, with significantly reduced vergence gains, reduced vergence response at 0.33m, reduced accommodation gain, and increased accommodation at 2m, compared to full-term infants between 8-13 weeks after birth. \ud Conclusions When matched by corrected age, vergence and accommodation in pre-term infants show few differences from full-term infants’ responses. Maturation appears pre-programmed and is not advanced by visual experience. Longer periods of immature visual responses might leave pre-term infants more at risk of development of oculomotor deficits such as strabismus.
- Published
- 2015
29. Alternative treatments: bogus or bona fide?
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Archer, Steven, Merrill, Kimberly, Fredrick, Douglas, Whitecross, Sarah, DeYoung Smith, Mary, Horwood, Anna, Heinmiller, Laura, Haider, Kathryn, Henson, Karl, and Boden, Brenda
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- 2019
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30. Accommodation and convergence—ratios, linkages, styles and mental somersaults
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Horwood, Anna
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- 2018
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31. Accommodation and vergence response gains to different near cues characterize specific esotropias
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Horwood, Anna and Riddell, Patricia
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genetic structures ,eye diseases - Abstract
Aim. To describe preliminary findings of how the profile of the use of blur, disparity and proximal cues varies between non-strabismic groups and those with different types of esotropia.\ud Design. Case control study\ud Methodology. A remote haploscopic photorefractor measured simultaneous convergence and accommodation to a range of targets containing all combinations of binocular disparity, blur and proximal (looming) cues. 13 constant esotropes, 16 fully accommodative esotropes, and 8 convergence excess esotropes were compared with age and refractive error matched controls, and 27 young adult emmetropic controls. All wore full refractive correction if not emmetropic. Response AC/A and CA/C ratios were also assessed.\ud Results. Cue use differed between the groups. Even esotropes with constant suppression and no binocular vision (BV) responded to disparity in cues. The constant esotropes with weak BV showed trends for more stable responses and better vergence and accommodation than those without any BV. The accommodative esotropes made less use of disparity cues to drive accommodation (p=0.04) and more use of blur to drive vergence (p=0.008) than controls. All esotropic groups failed to show the strong bias for better responses to disparity cues found in the controls, with convergence excess esotropes favoring blur cues. AC/A and CA/C ratios existed in an inverse relationship in the different groups. Accommodative lag of >1.0D at 33cm was common (46%) in the pooled esotropia groups compared with 11% in typical children (p=0.05). \ud Conclusion. Esotropic children use near cues differently from matched non-esotropic children in ways characteristic to their deviations. Relatively higher weighting for blur cues was found in accommodative esotropia compared to matched controls.
- Published
- 2013
32. Developmental changes in the balance of disparity, blur and looming/proximity cues to drive ocular alignment and focus
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Horwood, Anna and Riddell, Patricia
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sense organs - Abstract
Accurate co-ordination of accommodation and convergence is necessary to view near objects and develop fine motor co-ordination. We used a remote haploscopic videorefraction paradigm to measure longitudinal changes in simultaneous ocular accommodation and vergence to targets at different depths, and to all combinations of blur, binocular disparity, and change-in-size (“proximity”) cues. Infants were followed longitudinally and compared to older children and young adults, with the prediction that sensitivity to different cues would change during development. Mean infant responses to the most naturalistic condition were similar to those of adults from 6-7 weeks (accommodation) and 8-9 weeks (vergence). Proximity cues influenced responses most in infants less than 14 weeks of age, but sensitivity declined thereafter. Between 12-28 weeks of age infants were equally responsive to all three cues, while in older children and adults manipulation of disparity resulted in the greatest changes in response. Despite rapid development of visual acuity (thus increasing availability of blur cues), responses to blur were stable throughout development. Our results suggest that during much of infancy, vergence and accommodation responses are not dependent on the development of specific depth cues, but make use of any cues available to drive appropriate changes in response.
- Published
- 2013
33. What Do We Expect New Graduate Orthoptists to Do?
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Horwood, Anna M.
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ORTHOPTICS ,MEDICAL education ,MEDICAL students ,CURRICULUM ,PHYSICIAN practice patterns - Abstract
Aims: To validate the content of an updated orthoptic curriculum for the British & Irish Orthoptic Society (BIOS), BIOS members were surveyed about their views on what an orthoptist should be able to do soon after entering the profession. Methods: An online survey of all practicing members of BIOS was carried out. In 35 questions across 5 domains (professional behaviour, foundation knowledge and theory, investigation, management and research and literature skills) covering the range of orthoptic practice, orthoptists were asked about the breadth and depth of knowledge required. Results were analysed by the respondents' working environment, experience, geographical region and teaching involvement. Results: 325 orthoptists (27% of the membership) provided useable data, and 265 provided a full dataset. Orthoptists are frequently required to exercise considerable autonomy and responsibility for patient care from very early in their careers across many domains, often in the least-supervised environments. There was broad agreement across most core topics but wider variation in opinion in more peripheral domains. More experienced orthoptists value the wider medical aspects of orthoptic practice more highly. Conclusions: The survey confirmed that there is generally a good match between current undergraduate teaching and clinicians' expectations of newly graduated orthoptists. It is clear that training must prepare graduates for a high level of professional autonomy from the earliest stages of their careers. There may be a place for targeting CPD provision for professionals at different stages in their careers. [ABSTRACT FROM AUTHOR]
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- 2018
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34. Accommodation in children and young people -- an alternative outlook.
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Horwood, Anna
- Subjects
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CONTACT lenses , *CONVERGENT strabismus , *OPTOMETRY , *ORTHOPTICS , *BINOCULAR vision - Published
- 2018
35. Independent and reciprocal accommodation in anisometropic amblyopia
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Horwood, Anna Mary and Riddell, Patricia Mary
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genetic structures ,eye diseases - Abstract
Accommodation is considered to be a symmetrical response and to be driven by the least ametropic and nonamblyopic eye in anisometropia. We report the case of a 4-year-old child with anisometropic amblyopia who accommodates asymmetrically, reliably demonstrating normal accommodation in the nonamblyopic eye and antiaccommodation of the amblyopic eye to near targets. The abnormal accommodation of the amblyopic eye remained largely unchanged during 7 subsequent testing sessions undertaken over the course of therapy. We suggest that a congenital dysinnervation syndrome may result in relaxation of accommodation in relation to near cues and might be a hitherto unconsidered additional etiological factor in anisometropic amblyopia.
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- 2010
36. 2016 International Orthoptic Congress Burian Lecture: Folklore or Evidence?
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Horwood, Anna M.
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STRABISMUS , *VISUAL accommodation , *CONVERGENCE insufficiency , *VISUAL training , *PATIENTS - Abstract
The theme of the 2016 Burian Lecture is how our understanding of strabismus has been changed by the research carried out in our laboratory in Reading over the years. Accommodation and convergence are fundamental to orthoptics, but actual responses have often been very different compared to what we had expected. This paper outlines how our laboratory’s understanding of common issues such as normal development of accommodation and convergence, their linkage, intermittent strabismus, anisometropia, orthoptic exercises, and risk factors for strabismus have changed. A new model of thinking about convergence and accommodation may help us to better understand and predict responses in our patients. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
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37. Binocular convergence babies, children and adults.
- Author
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Horwood, Anna
- Subjects
- *
OPTOMETRY , *BINOCULAR vision , *VISUAL perception , *OPTOMETRISTS , *OPTICIANS - Published
- 2018
38. Binocular Visual Acuity in Intermittent Exotropia: Role of Accommodative Convergence
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Firth, Alison Y., Davis, Helen, and Horwood, Anna M.
- Published
- 2013
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39. The effect of effort and exercise on convergence and accommodation
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Horwood, Anna M., Toor, Sonia S., and Riddell, Patricia M.
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- 2013
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40. Accommodation and Vergence Response Gains to Different Near Cues Characterize Specific Esotropias.
- Author
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Horwood, Anna M. and Riddell, Patricia M.
- Subjects
- *
CONVERGENT strabismus , *OPTICAL instruments , *BINOCULAR vision , *VISUAL accommodation , *YOUNG adults - Abstract
Aim: To describe preliminary findings of how the profile of the use of blur, disparity, and proximal cues varies between non-strabismic groups and those with different types of esotropia. Design: This was a case control study. Methodology: A remote haploscopic photorefractor measured simultaneous convergence and accommodation to a range of targets containing all combinations of binocular disparity, blur, and proximal (looming) cues. Thirteen constant esotropes, 16 fully accommodative esotropes, and 8 convergence excess esotropes were compared with age- and refractive error-matched controls and 27 young adult emmetropic controls. All wore full refractive correction if not emmetropic. Response AC/A and CA/C ratios were also assessed. Results: Cue use differed between the groups. Even esotropes with constant suppression and no binocular vision (BV) responded to disparity in cues. The constant esotropes with weak BV showed trends for more stable responses and better vergence and accommodation than those without any BV. The accommodative esotropes made less use of disparity cues to drive accommodation ( p = 0.04) and more use of blur to drive vergence ( p = 0.008) than controls. All esotropic groups failed to show the strong bias for better responses to disparity cues found in the controls, with convergence excess esotropes favoring blur cues. AC/A and CA/C ratios existed in an inverse relationship in the different groups. Accommodative lag of >1.0 D at 33 cm was common (46%) in the pooled esotropia groups compared with 11% in typical children ( p = 0.05). Conclusion: Esotropic children use near cues differently from matched non-esotropic children in ways characteristic to their deviations. Relatively higher weighting for blur cues was found in accommodative esotropia compared to matched controls. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
41. Developmental changes in the balance of disparity, blur, and looming/proximity cues to drive ocular alignment and focus.
- Author
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Horwood, Anna M. and Riddell, Patricia M.
- Abstract
Accurate coordination of accommodation and convergence is necessary to view near objects and develop fine motor coordination. We used a remote haploscopic videorefraction paradigm to measure longitudinal changes in simultaneous ocular accommodation and vergence to targets at different depths, and to all combinations of blur, binocular disparity, and change-in-size (‘proximity’) cues. Infants were followed longitudinally and compared with older children and young adults, with the prediction that sensitivity to different cues would change during development. Mean infant responses to the most naturalistic condition were similar to those of adults from 6–7 weeks (accommodation) and 8–9 weeks (vergence). Proximity cues influenced responses most in infants of less than 14 weeks of age, but sensitivity declined thereafter. Between 12 and 28 weeks of age infants were equally responsive to all three cues, while in older children and adults manipulation of disparity resulted in the greatest changes in response. Despite rapid development of visual acuity (thus increasing availability of blur cues), responses to blur were stable throughout development. Our results suggest that, during much of infancy, vergence and accommodation responses are not dependent on the development of specific depth cues, but make use of any cues available to drive appropriate changes in response. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
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42. The Clinical Near Gradient Stimulus AC/A Ratio Correlates Better With the Response CA/C Ratio Than With the Response AC/A Ratio.
- Author
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Horwood, Anna M. and Riddell, Patricia M.
- Subjects
- *
EDUCATIONAL tests & measurements , *EXOTROPIA , *STRABISMUS , *LENS testing , *CONVERGENT evolution , *DIAGNOSIS , *THERAPEUTICS - Abstract
Aim: To provide evidence that a near clinical gradient AC/A ratio could instead reflect the CA/C relationship (the accommodation driven by response to disparity). Design: Case control study. Methodology: 27 emmetropic participants with heterophoria <4 PD, 19 with intermittent distance exotropia, and 17 with near exophoria >6 PD were tested. A remote haploscopic photorefractor, which can measure simultaneous convergence and accommodation to a range of targets containing all combinations of presence or absence of binocular disparity, blur, and proximal (looming) cues, was used to assess response AC/A and CA/C relationships. These were compared with clinical gradient AC/A ratios at near and distance fixation using alternate prism cover test and plus or minus lenses. Results: Although the near and distance clinical AC/A ratios correlated weakly with each other ( p = 0.03), neither clinical method correlated with the more accurate response AC/A ratio from the laboratory method ( p = 0.88 and p = 0.93, respectively). The laboratory CA/C ratio correlated strongly with the near clinical AC/A ratio ( p = 0.004) but only very weakly with the distance ratio ( p = 0.16). Conclusions: The 'near gradient AC/A ratio' may actually reflect the CA/C linkage as the dissociation of the prism cover test disrupts vergence accommodation. If the near deviation diverges more with plus lenses, it may be because the lenses allow clear near vision without needing to recruit convergence accommodation to achieve it. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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43. Receding and disparity cues aid relaxation of accommodation.
- Author
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Horwood AM, Riddell PM, Horwood, Anna M, and Riddell, Patricia M
- Published
- 2009
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44. A Novel Experimental Method for Measuring Vergence and Accommodation Responses to the Main Near Visual Cues in Typical and Atypical Groups.
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Horwood, Anna M. and Riddell, Patricia M.
- Subjects
- *
VERGENCE (Binocular vision) , *BINOCULAR vision , *EYE movements , *VISION , *PANUM'S fusional area - Abstract
Binocular disparity, blur, and proximal cues drive convergence and accommodation. Disparity is considered to be the main vergence cue and blur the main accommodation cue. We have developed a remote haploscopic photorefractor to measure simultaneous vergence and accommodation objectively in a wide range of participants of all ages while fixating targets at between 0.3 and 2 m. By separating the three main near cues, we can explore their relative weighting in three-, two-, one-, and zero-cue conditions. Disparity can be manipulated by remote occlusion; blur cues manipulated by using either a Gabor patch or a detailed picture target; looming cues by either scaling or not scaling target size with distance. In normal orthophoric, emmetropic, symptom-free, naive visually mature participants, disparity was by far the most significant cue to both vergence and accommodation. Accommodation responses dropped dramatically if disparity was not available. Blur only had a clinically significant effect when disparity was absent. Proximity had very little effect. There was considerable interparticipant variation. We predict that relative weighting of near cue use is likely to vary between clinical groups and present some individual cases as examples. We are using this naturalistic tool to research strabismus, vergence and accommodation development, and emmetropization. [ABSTRACT FROM AUTHOR]
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- 2009
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45. Variations in accommodation and convergence responses in a minimally controlled photorefractive setting.
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Horwood, Anna M., Turner, Judith E., Houston, Sheila M., Riddell, Patricia M., Horwood, A M, Turner, J E, Houston, S M, and Riddell, P M
- Published
- 2001
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46. Hyperopic children systematically under-accommodate in naturalistic conditions
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Horwood, Anna and Riddell, Patricia
- Published
- 2010
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47. Availability of data for cost-effectiveness comparison of child vision and hearing screening programmes.
- Author
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Kik J, Heijnsdijk EA, Mackey AR, Carr G, Horwood AM, Fronius M, Carlton J, Griffiths HJ, Uhlén IM, and Simonsz HJ
- Subjects
- Child, Humans, Cost-Benefit Analysis, Early Detection of Cancer, Hearing Tests methods, Hearing, Vision Screening, Amblyopia diagnosis
- Abstract
Objective: For cost-effectiveness comparison of child vision and hearing screening programmes, methods and data should be available. We assessed the current state of data collection and its availability in Europe., Methods: The EUSCREEN Questionnaire, conducted in 2017-2018, assessed paediatric vision and hearing screening programmes in 45 countries in Europe. For the current study, its items on data collection, monitoring and evaluation, and six of eleven items essential for cost-effectiveness analysis: prevalence, sensitivity, specificity, coverage, attendance and loss to follow-up, were reappraised with an additional questionnaire., Results: The practice of data collection in vision screening was reported in 36% (N = 42) of countries and in hearing screening in 81% (N = 43); collected data were published in 12% and 35%, respectively. Procedures for quality assurance in vision screening were reported in 19% and in hearing screening in 26%, research of screening effectiveness in 43% and 47%, whereas cost-effectiveness analysis was performed in 12% for both. Data on prevalence of amblyopia were reported in 40% and of hearing loss in 77%, on sensitivity of screening tests in 17% and 14%, on their specificity in 19% and 21%, on coverage of screening in 40% and 84%, on attendance in 21% and 37%, and on loss to follow-up in 12% and 40%, respectively., Conclusions: Data collection is insufficient in hearing screening and even more so in vision screening: data essential for cost-effectiveness comparison could not be reported from most countries. When collection takes place, this is mostly at a local level for quality assurance or accountability, and data are often not accessible. The resulting inability to compare cost-effectiveness among screening programmes perpetuates their diversity and inefficiency.
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- 2023
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48. Effectiveness of early spectacle intervention on visual outcomes in babies at risk of cerebral visual impairment: a parallel group, open-label, randomised clinical feasibility trial protocol.
- Author
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Bullaj R, Dyet L, Mitra S, Bunce C, Clarke CS, Saunders K, Dale N, Horwood A, Williams C, St Clair Tracy H, Marlow N, and Bowman R
- Subjects
- Child, Early Intervention, Educational, Eyeglasses adverse effects, Feasibility Studies, Humans, Infant, Infant, Newborn, Randomized Controlled Trials as Topic, Vision Disorders etiology, Vision Disorders therapy, Brain Diseases complications, Mydriatics
- Abstract
Introduction: Hypoaccommodation is common in children born prematurely and those with hypoxic ischaemic encephalopathy (HIE), with the potential to affect wider learning. These children are also at risk of longer-term cerebral visual impairment. It is also well recognised that early intervention for childhood visual pathology is essential, because neuroplasticity progressively diminishes during early life. This study aims to establish the feasibility and acceptability of conducting a randomised controlled trial to test the effectiveness of early near vision correction with spectacles in infancy, for babies, at risk of visual dysfunction., Methods and Analysis: This is a parallel group, open-label, randomised controlled (feasibility) study to assess visual outcomes in children with perinatal brain injury when prescribed near vision spectacles compared with the current standard care-waiting until a problem is detected. The study hypothesis is that accommodation, and possibly other aspects of vision, may be improved by intervening earlier with near vision glasses. Eligible infants (n=75, with either HIE or <29 weeks preterm) will be recruited and randomised to one of three arms, group A (no spectacles) and two intervention groups: B1 or B2. Infants in both intervention groups will be offered glasses with +3.00 DS added to the full cycloplegic refraction and prescribed for full time wear. Group B1 will get their first visit assessment and intervention at 8 weeks corrected gestational age (B1) and B2 at 16 weeks corrected gestational age. All infants will receive a complete visual and neurodevelopmental assessment at baseline and a follow-up visit at 3 and 6 months after the first visit., Ethics and Dissemination: The South-Central Oxford C Research Ethics Committee has approved the study. Members of the PPI committee will give advice on dissemination of results through peer-reviewed publications, conferences and societies., Trial Registration Number: ISRCTN14646770, NCT05048550, NIHR ref: PB-PG-0418-20006., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2022
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49. A Comprehensive Overview of Vision Screening Programmes across 46 Countries.
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Carlton J, Griffiths HJ, Mazzone P, Horwood AM, and Sloot F
- Abstract
Purpose: To describe and compare vision screening programmes and identify variance in number and type of tests used, timing of screening, personnel involved, monitoring and funding to be used as data for optimising, disinvesting or implementing future screening programmes., Methods: A questionnaire consisting of nine domains: demography & epidemiology, administration & general background, existing screening, coverage & attendance, tests, follow-up & diagnosis, treatment, cost & benefit and adverse effects was completed by Country Representatives (CRs) recruited from 47 countries., Results: The questionnaire was sufficiently completed for 46 Countries: 42 European countries, China, India, Malawi and Rwanda. Variation of provision was found in; age of screening (0-17 years), tests included (23), types of visual acuity (VA) test used (35 different optotypes), personnel (13), number of screens per child (median 5, range 1-32), and times VA tested (median 3, range 1-30). Infant screening is offered in all countries, whereas childhood vision screening is offered at least once in all countries, but not all regions of each country. All 46 countries provide vision screening between the ages of 3-7 years. Data on screening outcomes for quality assurance was not available from most countries; complete evaluation data was available in 2% of countries, partial data from 43%., Conclusion: Vision screening is highly variable. Some form of VA testing is being undertaken during childhood. Data collection and sharing should be improved to facilitate comparison and to be able to optimise vision screening programmes between regions and countries., Competing Interests: At the time of submission, Dr Carlton was the Editor of British and Irish Orthoptic Journal. She had no role in the peer-review process of this article., (Copyright: © 2022 The Author(s).)
- Published
- 2022
- Full Text
- View/download PDF
50. When Does Blur Matter? A Narrative Review and Commentary.
- Author
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Horwood AM
- Subjects
- Accommodation, Ocular, Child, Convergence, Ocular, Humans, Asthenopia, Refractive Errors, Strabismus
- Abstract
Blur is the subjective awareness that the edges of a high contrast image are indistinct. The concept of blur is fundamental to the understanding of vision, accommodation, refractive error, concomitant strabismus, and asthenopia. It is easy for clinicians to believe that blur always needs to be avoided or resolved, or that everyone responds to blur similarly. This narrative review outlines the literature on blur and the accommodation to resolve it, and relates it to current clinical practice. Laboratory studies have traditionally been highly controlled, using expert observers, but more recent research using naïve participants suggests that variability and tolerance of blur are common and more widespread than often thought, especially in children and clinical groups. Objective and subjective responses can differ widely, and it cannot be assumed that because we expect accommodation to have occurred, that it always has. A deeper understanding of the role of blur and objective accommodation in vision, refractive error and strabismus may help us understand the variability that exists in clinical practice. We may use blur to help investigation and treatment but also be relaxed about what is normal. Many patients are led to believe that they should always achieve constant clear vision, when this is unrealistic. Although pathological blur must be identified and treated, normal everyday blur may become medicalized into "a problem" by well-meaning professionals.
- Published
- 2022
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