Vision training for children with specific learning difficulties (dyslexia)

Research has shown that up to 70% of dyslexic individuals have a defect of the transient visual system (a magnocellular defect) (Lovegrove et al ., 1986). Clinically, the results presented have confirmed this but suggest an even higher percentage. Fortunately, these magnocellular defects can be improved or essentially eliminated with appropriate treatment and this results in a significant improvement in school work.
A combination of vision therapy and specific lenses and/or prisms are used in the clinic, plus the use of coloured overlays or tinted spectacles. Clinical results have shown that vision training is the major cause of improving or eliminating the transient defect (see below). Also, specific near vision spectacles with lenses and/or prisms which stabilize print are at least as successful, if not more so, at giving immediate relief from visual discomfort while reading, as coloured overlays or tinted spectacles. Further, it is postulated that the colour chosen may be related to the severity of the magnocellular defect (the most severe choosing an overlay in the short wavelength). The possible reasons for this will be presented. It has also been found that the favoured colour changes during the vision therapy and indeed with or without specific near spectacles.
Following improvement with treatment of the magnocellular defect up to 73% reported significant improvement with school work and over 54% of these showed marked improvement.
The results of the vision therapy treatment of some 200 youngsters are presented along with detailed analysis of an extensive questionnaire, completed prior to the first attendance. These indicate the main factors which are linked with dyslexia and the major problems complained of.
Following successful treatment, apart from habitually worn spectacles, nothing further should subsequently be required.     

Colour vision defects in children with learning difficulties

Colour is used in school classrooms to stimulate interest and attention, to increase motivation or to convey an instructional message. Teachers tacitly assume that such methodologies are inherently efficient. However, there is little research evidence to support this assumption despite its intuitive appeal. Moreover, some children with colour vision defects may be disadvantaged by a colour-oriented teaching program, particularly in the early years of school. Several studies have found an over-representation of colour defective children among those with learning difficulties. This paper reports a test of the hypothesis that such children are incorrectly diagnosed as colour defective because they cannot respond appropriately to colour vision tests, and discusses the education implications of colour defects in the classroom.     

Comparison of visual characteristics in children with and without learning difficulties

This report compares the refractive status, visual acuity, binocular status, vergence/accommodation facility, perceptual skills, and ocular health of 261 children with learning difficulties (LD) and 496 No-LD children, all between the ages of 6 and 12 years. Data reveal that among conditions diagnosed routinely by optometrists, hyperopia and perceptual skills dysfunction were more prevalent in LD children and myopia in No-LD children. No other significant between-group differences were found.     

Randomised controlled trial of the effect of coloured overlays on the rate of reading of people with specific learning difficulties

A randomised controlled trial has demonstrated that, for selected children with reading difficulties, individually prescribed coloured filters reduce symptoms of asthenopia. In the present study, we investigate the effect of individually prescribed coloured overlays on the rate of reading. Subjects were 33 children and adults who: had consulted a specific learning difficulties clinic; had received treatment to normalise any conventional optometric and orthoptic anomalies; and subsequently reported symptomatic relief from coloured filters. These subjects carried out the Wilkins Rate of Reading Test (which assesses visual rather than linguistic factors) under two conditions: with their chosen coloured overlay and with a control filter. Steps were taken to ensure that a strong placebo effect was associated with the control overlay and, when asked which they preferred, subjects were not significantly more likely to prefer their coloured overlay than the control filter (p=0.11). Nonetheless, the rate of reading was significantly faster with the coloured overlay than with the control (p=0.0019). Further analyses support the conclusion that individually prescribed coloured filters can improve reading performance for reasons that cannot be solely attributed to conventional optometric factors or to placebo effects.     

A review of the management of 323 consecutive patients seen in a specific learning difficulties clinic

Visual correlates of specific learning difficulties (SpLD) include: binocular instability, low amplitude of accommodation, and Meares-Irlen Syndrome. Meares-Irlen Syndrome describes asthenopia and perceptual distortions which are alleviated by using individually prescribed coloured filters. Data from 323 consecutive patients seen over a 15 month period in an optometric clinic specialising in SpLD are reviewed. Visual symptoms and headaches were common. 48% of patients were given a conventional optometric intervention (spectacles, orthoptic exercises) and 50% were issued with coloured filters, usually for a trial period. 40% of those who were given orthoptic exercises were later issued with coloured overlays. 32% of those who were issued with coloured overlays were ultimately prescribed Precision Tinted lenses. Approximately half the sample were telephoned more than a year after the last clinical appointment. More than 70% of those who were prescribed Precision Tints were still wearing them daily, and results for this intervention compared favourably with data for non-tinted spectacles. The data suggest that many people with SpLD need optometric care and that the optometrist needs to be skilled in orthoptic techniques and cognisant of recent research on coloured filters.     

Binocular function in school children with reading difficulties

Introduction  

Prior findings suggest that poor readers tend to have poor binocular vision skills, but data on the binocular abilities of children with poor reading skills are lacking. Our aim was to characterize distance and near horizontal heterophoria, distance and near horizontal fusional vergence ranges, accommodative convergence/accommodation (AC/A) ratio, near point of convergence, and stereopsis in poor-reading school-age children without dyslexia selected from a non-clinical population.     

Accommodative function in school children with reading difficulties

Background  Prior findings suggest correlation between reading problems and accommodative function, but few studies have assessed accommodation in children with poor reading skills. Our aim was to characterize monocular accommodative amplitude, relative accommodation and binocular accommodative facility in a population of healthy, non-dyslexic primary school children with reading difficulties. Methods  We conducted a cross-sectional study on 87 poor readers and 32 control children (all between 8 and 13 years of age) in grades three to six recruited from 11 elementary schools in Madrid, Spain. In each subject with best spectacle correction, negative relative accommodation (NRA) and positive relative accommodation (PRA) were measured using a phoropter, monocular accommodative amplitude (MAA) was determined using the minus lenses method, and binocular accommodative facility (BAF) was measured using the Bernell Acuity Suppression Slide (VO/9) and a ± 2.00 D accommodative demand for a period of 1 minute. Results  Monocular accommodative amplitude was significantly lower (p < 0.001) in the group of poor readers (right eye 9.1 D ± 2.3, left eye 9.0 D ± 2.3) than in the control group (right eye 10.5 D ± 1.7, left eye 10.5 D ± 1.7). Binocular accommodative facility values were significantly lower (p < 0.05) in the poor readers (4.9 cpm ± 3.1) than controls (6.3 cpm ± 2.9). Negative and positive relative accommodation values were similar in both groups of children. Conclusions  This study provides data on the accommodative capacity of a population of children with reading difficulties. Our findings suggest a reduced monocular accommodative amplitude and binocular accommodative facility, such that this function should be assessed by an optometric clinician in children whose reading level is below average. Human subjects and informed consent  The authors confirm that this research was performed followed the tenets of the Declaration of Helsinki, and that informed consent was obtained from the subjects after having explained to them in detail the nature of the study. The study protocol was approved by the Clinical Research Ethics Committee of the School of Optometry.     

视觉诱发电位在儿童视觉发育评估中的研究进展

视觉诱发电位是视网膜受闪光或图形刺激后经视路传递,在头颅皮肤表面记录到大脑皮层视中枢对视觉刺激发生反应的一簇电信号,又称皮层视觉诱发电位。由于不受被检者认知能力及配合能力限制,可以客观反应视觉系统以及脑系统功能,适用于幼小儿童、意识丧失的患者、伪盲者以及术中检查。本研究就视觉诱发电位的理论基础、检查过程中所需参数以其在临床应用于客观视力的评估等方面进行综述。     

Errors and difficulties in the assessment of severely handicapped and blind persons

The assessment of ophthalmological examination reports in social law is usually based on subjective statements by the petitioner made towards his ophthalmologist. Insufficient consideration of objective results as well as the limited experience of the officials in charge may lead to errors. An analysis of patients for consideration as legally blind in Baden, Germany, between 1980-1999, based upon 2,265 doubtful applications resulted in 33.3% false estimates by the patient's ophthalmologist. The reason, in the vast majority of cases, was misjudgment involving visual field defects or even missing manual-kinetic Goldmann perimetry. It may be assumed that this is also true for petitions in legislation for severely handicapped persons, particularly because the officials in charge are rarely ophthalmologists.     

Treatment of children with amblyopia by perceptual learning

Recent studies have shown that perceptual learning has the potential to treat amblyopia. In this study we tested whether a recent perceptual learning technique that improved visual functions in adults can be applied to improve the vision of children after the conventional treatment of patching has failed. A prospective clinical pilot study was carried out in children who were non-compliant with patching or in whom patching had failed despite good compliance. Each child underwent a complete eye examination before and after treatment. The treatment was based on a perceptual learning technique that was similar to the adult study [Polat, U., Ma-Naim, T., Belkin, M., & Sagi, D. (2004). Improving vision in adult amblyopia by perceptual learning. Proceedings of the National Academy of Sciences of the United States of America, 101(17), 6692–6697]. Between blocks, children played a computer game to engage and maintain their attention in order to increase compliance. Each child received two treatment sessions a week, with a total of not more than 40 sessions. Each session lasted for about 1 h and included a total practice time of about 30 min. The age of the children (n = 5) was between 7 and 8 years (mean 7.3 years). For the whole group, the average improvement in visual acuity was 1.5 Snellen lines or 2.12 ETDRS lines. The training improved the contrast sensitivity, which reached the normal range after treatment. Thus, the perceptual learning technique can be successfully used to treat children with amblyopia even after the conventional treatment of patching fails.     

Diagnosis of oculomotor anomalies in children with learning disorders

This systematic review presents the existing scientific evidence for oculomotor anomalies in children with three different types of learning disorders – namely, dyslexia, dyspraxia and attention deficit-hyperactivity disorder (ADHD). This review was registered in the PROSPERO database (registration number: 139317). The QUADAS-2 tool was used to systematically evaluate the quality of the diagnostic tests used in the evaluated studies and to confirm whether the oculomotor alterations observed in the different groups of children with various learning disorders had a consistent diagnostic basis. Using this tool, the design of the articles was well elaborated, although concerns exist regarding the selection of patients and the diagnostic criteria for the binocular conditions. All the studies reviewed conclude that a pattern of oculomotor anomalies exist in the groups of children with these three types of learning disorders compared to healthy children. However, there is a concern regarding the diagnostic methodology, as no clear range of normality for the parameters used to characterise ocular motility was identified and no gold standard or reference test has been defined. In future studies, this range of normality must be developed for different oculomotor skills, and a reference test (possibly video-oculography) for the measurement of these skills must be established.     

A new protocol for the optometric management of patients with reading difficulties

Research by Evans et al . ( Ophthal. Physiol. Opt. 15 , 481–487, 1995⁶) has demonstrated a correlation between visual processing and ocular motor factors in people with specific reading difficulties (dyslexia). In addition, research by Wilkins et al. ( Ophthal. Physiol. Opt. 14 , 365–370, 1994) has shown that some people with dyslexia will benefit from a reduction of perceptual symptoms of discomfort and distortion if they use individually prescribed coloured filters. Three examples of the dyslexic patients who attend at the Institute of Optometry clearly demonstrate the importance of full investigation of ocular function, including the assessment of the effect of colour on visual perception. All three patients presented with similar symptoms of asthenopia when reading. Symptoms were alleviated for the first patient by use of orthoptic treatment of an exotropia with intermittent suppression. With the second patient, ocular motor functions were found to be within acceptable limits and relief of symptoms was obtained by the prescribing of lenses of a specific chromaticity. For the third patient, both orthoptic intervention and the use of specifically tinted lenses were necessary to relieve the visual difficulties that were being experienced. By taking advantage of recent research and developments in optometric instrumentation, it is possible for some of those with dyslexia to receive considerable benefit from optometric intervention.     

Preliminary report: Examination of young children with Lea symbols

BACKGROUND. Lea symbols are highly sensitive for detection of amblyopia in cooperative patients. They are favorable for visual acuity assessment in childhood. Therefore, we assessed age-related normal values and interocular differences of Lea symbol visual acuity. METHODS/PATIENTS. We reexamined 50 out of 193 children aged 21 months to 7 years who came for a routine pediatric examination between January and November 1999. Lea symbol acuity (Lea Symbols Single Symbol Book (LS) and Lea 15-Line Folding Distance Chart (CLS)) and Landolt-C acuity (single (LC) and crowded with 2.6' inter-optotype distance (LC 2.6 )) were measured. A three out of four criterion was used. Strabismus and any organic eye disease were excluded by orthoptic and ophthalmologic examination, consisting of biomicroscopy, ophthalmoscopy, retinoscopy or refractometry, cover test or Hirschberg test and Lang Stereotest. RESULTS. Only 26% of the parents (50 out of 193) accepted an examination in our hospital. In 35 (32) of the 50 children, visual acuity could be measured in both eyes seperately with single (crowded) Lea symbols, while 26 (25) children could be examined in both eyes monocularly with the Landolt-C with single (crowded) optotypes. Except for one 3-year-old boy, all of the children older than 30 months could be tested with single Lea symbols. Lea acuity surpassed Landolt acuity. The difference was about 1.5 lines (1.5 dB) for both the single and the crowded optotypes. In 63% (69%) of the children who could be tested monocularly, LS acuity (CLS acuity) was higher than 0.8 (0.63). 89% (83%) of the children had an interocular difference of maximum 1 line for single (crowded) Lea symbols. CONCLUSIONS. The youngest child whose visual acuity could be assessed with Lea symbols was 23 months old. Almost every child older than 30 months could be tested with Lea symbols. Lea acuity higher than 1 and an interocular difference less than 2 lines is not suspect for amblyopia. Children with a difference of more than one line should be reexamined.     

知觉学习对于间歇性外斜视儿童视功能影响的研究

目的 观察知觉学习训练对于儿童间歇性外斜视双眼视功能的影响.方法 42例间歇性外斜视患儿,行知觉学习训练.训练前及训练1个月、2个月、3个月后应用同视机检测Ⅰ级、Ⅱ级、Ⅲ级视功能,Titmus立体视觉检查图观察近立体视,同时进行间歇性外斜视斜视角检查.并对数据进行统计学分析.结果 42例患儿中,经同视机检查训练前Ⅰ级视功能20例,训练后1个月、2个月、3个月分别增加到24、27、32例,训练前与训练3个月后比较,差异有统计学意义(P＜0.05);训练前Ⅱ级视功能20例,训练后1个月、2个月、3个月分别增加至23、26、30例,训练前与训练3个月后比较,差异有统计学意义(P＜0.05);训练前Ⅲ级视功能18例,训练后1个月、2个月、3个月分别增加至23、25、30例,训练前与训练3个月后比较,差异有统计学意义(P＜0.05);Titmus立体视觉检查图发现,训练前近立体视19例,训练后增加至21、23、29例,训练前与训练后3个月后比较,差异有统计学意义(P＜0.05).训练前远方斜视角为28.33△±11.15△,训练1个月、2个月、3个月后分别为27.81△±10.87△,27.98△±11.28△,27.69△±11.56△,与训练3个月后比较,差异有统计学意义(P＜0.05).结论 知觉学习训练治疗有助于间歇性外斜视患儿双眼视功能的重建,减少斜视度,对于未达到手术指证患者可以应用.