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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.

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.

Supplemental material, sj-docx-1-msc-10.1177_09691413221126677 for Availability of data for cost-effectiveness comparison of child vision and hearing screening programmes by Jan Kik, Eveline A.M. Heijnsdijk, Allison R. Mackey, Gwen Carr, Anna M Horwood, Maria Fronius, Jill Carlton, Helen J Griffiths, Inger M Uhlén, Huibert Jan Simonsz and Country-Committees Joint-Partnership of the EUSCREEN Study Consortium in Journal of Medical Screening

Supplemental material, sj-docx-4-msc-10.1177_09691413221126677 for Availability of data for cost-effectiveness comparison of child vision and hearing screening programmes by Jan Kik, Eveline A.M. Heijnsdijk, Allison R. Mackey, Gwen Carr, Anna M Horwood, Maria Fronius, Jill Carlton, Helen J Griffiths, Inger M Uhlén, Huibert Jan Simonsz and Country-Committees Joint-Partnership of the EUSCREEN Study Consortium in Journal of Medical Screening

Supplemental material, sj-docx-3-msc-10.1177_09691413221126677 for Availability of data for cost-effectiveness comparison of child vision and hearing screening programmes by Jan Kik, Eveline A.M. Heijnsdijk, Allison R. Mackey, Gwen Carr, Anna M Horwood, Maria Fronius, Jill Carlton, Helen J Griffiths, Inger M Uhlén, Huibert Jan Simonsz and Country-Committees Joint-Partnership of the EUSCREEN Study Consortium in Journal of Medical Screening

Supplemental material, sj-docx-2-msc-10.1177_09691413221126677 for Availability of data for cost-effectiveness comparison of child vision and hearing screening programmes by Jan Kik, Eveline A.M. Heijnsdijk, Allison R. Mackey, Gwen Carr, Anna M Horwood, Maria Fronius, Jill Carlton, Helen J Griffiths, Inger M Uhlén, Huibert Jan Simonsz and Country-Committees Joint-Partnership of the EUSCREEN Study Consortium in Journal of Medical Screening

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.

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.

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.

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.

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

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.

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.

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.

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.