How to help children with neurodevelopmental and visual problems: a scoping review.

Children with visual impairment and a condition affecting their neurodevelopment (children with VND) may require extensive and specialised help but evidence on the most effective strategies for visual improvement is lacking. We defined a PICO format (Population, Intervention, Comparator, Outcome) for a scoping review and systematically searched 13 databases. Two reviewers assessed the abstracts for inclusion and a third arbitrated in cases of disagreement. We abstracted data from included studies. We found 4450 abstracts from which we identified 107 papers for inclusion. Of these, 42 related to interventions involving a change in visual input or function: 5 controlled trials, 8 before and after studies and 29 case reports. The strongest evidence supported the provision of spectacles to improve distance or near vision and the use of ultraviolet light as environmental modification for training. Less strong but suggestive evidence supported training/practice routines to improve acuity or oculomotor control. Interventions exist to help children with VND and current recommendations that they are assessed by a vision specialist are supported by the evidence. More information is needed on the effectiveness of training/practice programmes which may promote improved function, and of environmental modifications to facilitate engagement of children with VND with the surroundings.

Vision in athletes with intellectual disabilities: the need for improved eyecare.

BACKGROUND: Special Olympics provides sporting opportunities for people with intellectual disabilities (ID), and Lions Clubs International Opening Eyes GB offers vision screening for athletes at Special Olympics Games. METHODS: Opening Eyes GB screened the vision of 505 UK athletes at its inaugural event in 2001. The results were analysed and are presented here. RESULTS: Results showed that athletes do not differ from other people with ID in being at high risk of ocular and visual defects and many are not accessing eyecare. 15% reported never having an optometric eye examination, and yet 19% of these athletes had a significant refractive error, 32% had ocular anomalies and 6% were visually impaired. Overall, findings confirmed the high prevalence of refractive errors and strabismus amongst people with ID. 40% of athletes had ocular abnormalities, including 15.6% with blepharitis, a readily treatable condition that causes discomfort. 9% had lens opacities, of which half were probably impairing sight. An important finding was that many athletes have reduced vision and 14% could be classified as visually impaired (WHO definition) even when refractive errors were fully corrected. CONCLUSIONS: Special Olympics athletes should be encouraged to have regular eye examinations (as indeed, should all people with ID), and educators, carers and coaches need appropriate information about the visual status of their charges.

Heart defects and ocular anomalies in children with Down's syndrome.

AIMS: To investigate whether ocular anomalies are associated with congenital heart defects in children with Down's syndrome. METHODS: 58 children with Down's syndrome were entered into a retrospective observational study. Children were assigned to heart defect groups based on medical records. Optometric tests had previously been carried out at the homes of the children. RESULTS: A relation between congenital cardiac defects, myopia, and nystagmus was observed. Heart problems were not related to accommodative insufficiency, hyperopia, or strabismus. CONCLUSION: In children with Down's syndrome heart defects were associated with both myopia and nystagmus.

Accommodation and refractive error in children with Down syndrome: cross-sectional and longitudinal studies.

PURPOSE: To examine the relationship between defective accommodation and refractive errors in children with Down syndrome. METHODS: Children with Down syndrome aged 4 to 85 months were seen at their homes as part of an ongoing study of visual development. Seventy-five children contributed cross-sectional data and 69 children longitudinal data. Accommodation was measured using a modification of Nott dynamic retinoscopy technique, and refractive error measurements were obtained using Mohindra retinoscopy. RESULTS: Accommodation was poor, regardless of the refractive error present. The total accommodation produced by the children was related to the refractive error at the time of the test, with the degree of accommodation deficit increasing with the amount of positive refractive error. The longitudinal results showed that although children with Down syndrome did not accommodate accurately, the amount of accommodation elicited did not reflect their maximum amplitude of accommodation. Each child showed a consistent degree of underaccommodation for a given stimulus. Spectacles to correct hypermetropia did not improve the accommodative response. CONCLUSIONS: In children with Down syndrome, underaccommodation is substantial, even when there is no, or a fully corrected, refractive error. The accommodation system of children with Down syndrome may have the physical capacity to respond to a given stimulus, but the neural control of the system has an anomalous set point. Spectacles do not remedy the situation. This has important implications, especially for children in a learning environment, because near vision is consistently out of focus.

The effect of age, size of target, and cognitive factors on accommodative responses of children with Down syndrome.

PURPOSE: To investigate possible factors that may be implicated in the poor accommodative responses of individuals with Down syndrome. This article evaluates the effect of age, angular size of target, and cognitive factors on accommodation. METHODS: Seventy-seven children with Down syndrome who are participating in an ongoing study of visual development were assessed. One hundred thirty-one developmentally normal children took part in a previous study and provided control data. Accommodation was measured using a modified Nott dynamic retinoscopy technique. RESULTS: Children with Down syndrome showed considerably poorer accommodative responses than normally developing children. No target used in the present study produced an improved response in children with Down syndrome. Age, angular subtense of target, and cognitive factors could not fully account for the poor accommodation in children with Down syndrome. CONCLUSIONS: Poor accommodation is a common feature of Down syndrome, regardless of the target used. The etiology of the deficit has yet to be established. It is imperative that educators and clinicians are aware that near vision is out of focus for these children.

The prevalence of ocular defects and the provision of eye care in adults with learning disabilities living in the community.

Most people with learning disabilities now live in the community rather than in institutions, and community services need to be targeted appropriately. Vision screening was carried out in community Day Care Centres for adults with learning disabilities. One hundred and fifty four subjects took part, and screening was successful in 148 subjects, using retinoscopy and standard acuity tests, including preferential looking. The previously reported high prevalence of refractive errors, strabismus and pathological defects amongst people with learning disabilities was confirmed. Over 60% of subjects had below-normal distance acuity, which in many cases was exacerbated by uncorrected refractive errors. In all, 41% of subjects could have benefited from distance spectacles, and 56% from spectacles for near tasks. The lack of adequate spectacles was particularly high amongst adults with more severe learning disabilities. The study highlights the current lack of adequate eye care for people with learning disabilities, and demonstrates that eye examinations are possible for the majority of individuals. There is a need for greater awareness amongst families/carers and amongst optometrists to address this important issue.

Investigating and managing the child with special needs.

Children with disabilities are much more at risk of eye and vision problems than are able children. These problems can take the form of 'optical' defects such as refractive errors and poor accommodation. Thus children with all forms of special needs not only have a right to Optometric services, but have a greater need than the rest of the population. This paper presents recent data on the defects found specifically in children with Down's Syndrome, (but likely to occur in other children) and provides general guidelines for Optometrists working with children with special needs.

Refractive errors in young children with Down syndrome.

Significant refractive errors are common among older children and adults with Down syndrome. We examined infants and children with Down syndrome to determine the prevalence of these errors at younger ages. Noncycloplegic retinoscopy was used to determine the refractive state of 92 infants and children with Down syndrome, aged 4 months to 12 years. The results for infants show a similar distribution of refractive errors in patients with Down syndrome and an age-matched control group. However, rather than a narrower distribution for the older age groups, as is the case with the controls, the distribution is wider, and the prevalence of refractive errors (including astigmatism) is higher among young children with Down syndrome than among controls. This high prevalence of refractive defects cannot be explained by the presence of strabismus or other pathologies.

The modified frisby stereotest.

BACKGROUND: The Frisby stereotest commonly is used in clinical practice to estimate stereoacuity. Assessment of the presence or absence of stereopsis is valuable particularly in toddlers because of the difficulties encountered in this age group with assessment of other aspects of visual function, such as monocular visual acuities. METHODS: The present study describes two modifications to the Frisby stereotest: 1) the introduction of a nonstereo practice plate; and 2) the use of an auditory "reward" for correct identification of the target. These modifications aim to increase the success rate of the test and provide a means to discriminate between testable and untestable children. Subjects were 165 children aged between 0.5 and 47 months. RESULTS: The modifications improved the age range over which results could be obtained with the Frisby test, allowing infants as young as 7 months to complete testing. By 12 months of age, more than 60% of children were able to complete testing. The modifications also allowed the examiner to distinguish untestable children from those without stereopsis. CONCLUSIONS: By simple modification of the Frisby stereotest, the authors have increased the ease with which the Frisby stereotest can be used to assess stereoacuity in infants and children and provided a means by which children unable to cooperate with testing can be distinguished from those without stereopsis.

Visual acuity and accommodation in infants and young children with Down's syndrome.

Accommodation and visual acuity were measured in 53 children with Down's syndrome aged between 12 weeks and 57 months. Results were compared with data for 136 control (typically developing) children aged between 4 weeks and 48 months. Whereas the control children accommodated accurately on near targets, accommodation was defective in 92% of the children with Down's syndrome, and there was no change in accommodative ability with age. On the other hand, visual acuity lay within normal limits for the younger children. Children over the age of 2 years showed a below-normal visual acuity, which is not explained either by refractive error or by the effect of poor accommodation. The data suggest a sudden change in the rate of development of visual acuity which may be associated with physiological changes in the visual cortex. Previously reported defects of accommodation and visual acuity in older children and adults with Down's syndrome are confirmed by our findings in infants and young children.

Emmetropisation in human infancy: rate of change is related to initial refractive error.

Animal studies show that the rate of recovery from experimentally induced refractive errors is related to the level of ametropia induced. The present study examined the rate of emmetropisation occurring in a sample of 22 human infants refracted by near retinoscopy during the first six months of life and then again between 12 and 17 months old. None of the subjects were myopic. Regression analysis revealed that emmetropisation occurred more rapidly in the presence of high refractive errors (P < 0.005 and P = 0.001 for hyperopia and astigmatism respectively). These data confirm the findings of the animal studies and suggest that non-reducing hyperopia and astigmatism in the second year of life may require correction.

The Cardiff acuity test used for measuring visual acuity development in toddlers.

The Cardiff acuity test was used in estimating the binocular and monocular visual acuity norms of 231 toddlers between 12 and 36 months. Mean binocular acuity increased from 4.5 to 1.2 min arc and monocular acuity from 4.5 to 1.4 min arc over the age range. Interocular acuity difference was not significant and for 99% of the children, the difference in acuity estimate was < or = 1/3 octave. Success rates ranged from 96 to 100% for binocular tests but fell to a range of 41-91% for monocular testing. Acuity assessment was fast and the intraobserver reliability was high. Age norms of visual acuity useful in clinical settings are presented for toddlers between the ages of 12 and 36 months.

Facial characteristics in children with Down's syndrome and spectacle fitting.

Significant refractive error is very common among children with Down's syndrome so the requirement for spectacles for this group is high. The aim of this study was to measure the facial characteristics of children with Down's syndrome and to compare them with two previous studies which have aided the design of children's spectacle frames. The study was carried out in two schools in South Wales, measuring 20 children between the ages of 3.6 and 14.4 years. The results show that between the ages of 7 and 14 years, facial characteristics of children with Down's syndrome do not change with age and rarely coincide with those of other children, either of a similar age or younger. Thus children with Down's syndrome cannot be fitted satisfactorily with conventional children's frames, and it would be desirable for a specially designed range of frames to be made available.

Reduced accommodation in children with Down syndrome.

PURPOSE: To examine the accommodative accuracy and amplitude in children with Down syndrome. Accommodation is usually assumed to be good in children and is rarely measured. METHODS: A dynamic retinoscopy technique was developed that allows rapid and reliable measures of accuracy and amplitude of accommodation in infants and children. RESULTS: Use of the dynamic technique with a small sample of schoolchildren with Down syndrome shows that 80% have reduced amplitude of accommodation, in comparison to a control group of developmentally normal children. CONCLUSIONS: Optometric management of children with Down syndrome should include consideration of accommodation.

Reading performance with low vision aids: relationship with contrast sensitivity.

Reading performance and contrast sensitivity were measured in 30 subjects with low vision due to a variety of pathologies. The Pepper test was used to quantify reading rate and accuracy with the subject's own prescribed optical reading low vision aid. It was found that both reading rate and accuracy were repeatable measures. Reading rates were found to be correlated with contrast sensitivity at 0.5 c/deg (r = 0.62). Multiple regression analysis also showed that the best predictor of reading rate was contrast sensitivity at 0.5 c/deg and that no other components of the contrast sensitivity function helped to explain more of the variance. This indicates that primarily low spatial frequencies are necessary for reading with optical low vision aids, as has been found previously for reading with a close circuit TV system.

The Cardiff Test: a new visual acuity test for toddlers and children with intellectual impairment. A preliminary report.

We have developed a new test for acuity measurements specifically designed for the hard to test group of toddlers and children with intellectual impairment. The test uses vanishing optotypes and the preferential looking technique. Comparison studies with established acuity tests, Snellen, Cambridge and Teller cards show that the test provides a realistic acuity measure. It is highly successful for toddlers and children with intellectual impairment and quicker to administer for the toddler age group.

Problems measuring contrast sensitivity in children.

A preliminary study measured the contrast sensitivity function (CSF) in 30 children (aged 3 months-5 years). Preferential looking techniques were used to assess CSF to sine wave gratings displayed on one of two screens. To find a meaningful contrast sensitivity procedure we compared the results with a shorter procedure using an edge stimulus. The following problems were encountered: measuring the contrasts required to detect four or five different spatial frequencies took time, resulting in boredom and loss of attention in our subjects; there was poor correlation between CSF and edge detection; an interesting artefact resulted in a plateau rather than a low frequency fall-off in the CSF of five of the children greater than 30 months old. This artefact may have resulted from peripheral rather than central retinal responses and/or motion artefacts in the stimulus onset. A follow up study with 41 additional children aged 3-36 months limited the contrast testing to that of the spatial frequency corresponding to the peak of the CSF. The shortened procedure, plus a lot of encouragement, resulted in higher contrast sensitivities in all but the oldest age group and successful monocular contrast measurements. In order to avoid artefacts arising from peripheral vision, children were encouraged to look at each screen before responding.

New acuity test for toddlers.

Preferential looking is the technique of choice for measuring visual acuity in infants and young children. Most workers agree that the toddler age group, 1 to 3 years, is the most difficult to test. This is because of their short attention span and restlessness, but mostly because they find the grating target used in the test, frankly boring. The concept of the vanishing optotype chart offers alternative test targets, while utilizing the technique of preferential looking. We have designed a test which comprises a familiar shape (house, car etc.) on the upper or lower part of a neutral grey card. The shape is computer generated, and designed to fade completely when beyond the resolution limit. Acuity is determined by the width of the white lines making up the shape. As with conventional preferential looking, the observer notes the child's eye movements to determine the position of the target shape. Although picture naming is not required, the shapes help to maintain the child's interest in the test. The test is quick, and is successful with the toddler age group and older patients with intellectual impairment.

Visual fitness to drive after stroke or head injury.

The visual requirements for driving in Britain are outlined and how they might be compromised following stroke or head injury examined. The role of the optometrist in assessing such patients who wish to resume driving is discussed. Topics discussed include legal considerations, the relationship between visual problems and driving ability and the vision-testing techniques that are most appropriate for use with the brain injured. An illustrative case history is presented.

Success rates in testing monocular acuity and stereopsis in infants and young children.

This study demonstrated how success in stereopsis and monocular acuity testing in the under-fives changes with age. Monocular testing was least successful with 1-2-year olds, while success with stereopsis testing increased linearly to 100% by 3 years. The differing patterns mean that a reasonable degree of success with one test or the other is likely whatever a child's age. Since the demonstration of either stereopsis or normal monocular acuities rules out the presence of any gross visual anomaly, the age-appropriate use of the two types of testing will facilitate the early detection of any abnormality.