Visual Defects of Children in Special Educational Facilities

The limitations of the present school visual screening systems for detecting children with visual defects that may influence school learning has been well documented but the vision of children in special educational facilities has received little formal attention. The visual examination results of 43 children receiving remedial reading tuition, 43 children in a control group and 20 children in special classes for backward children, were divided into three categories: vision, ocular motility/co-ordination, and organic/colour vision. A statistically significant difference was noted between the special educational groups and the control group for the results in the ocular motility/co-ordination category. The results indicate that the components of this category, (phorias, tropias, ductions, versions and vergences) need further investigation as to the nature of the relationships to learning difficulties. It is noted that enough evidence already exists in the literature to suggest that children placed in special educational facilities should receive a full clinical visual examination.     

Eye movements and poor reading: does the Developmental Eye Movement test measure cause or effect?

The literature concerning subjects who have reading difficulties has repeatedly noted their abnormal eye movements. The Developmental Eye Movement (DEM) test was developed on the assumption that poor eye movement control is a major cause of reading difficulties. The hypothesis tested by this study was that practice in fluent reading trains the eye movements that result in a good DEM score, whilst poor readers will exhibit low DEM scores due to insufficient training. English readers (43 children, 20 adults), and Arabic readers (six children, five adults) were recruited. The DEM test was administered twice, performed once reading the horizontal section in the habitual reading direction and secondly in the opposite direction, thus enabling the subjects’ eye movements to be compared when reading in their habitual direction and when reading in a direction which is relatively unpracticed. Paired t‐tests showed that the difference in eye movements (quantified via the DEM test ratio) between the two opposing reading directions was significant in English reading adults, English reading children and Arabic reading children, but not significant in the Arabic adults, who were equally practised in reading in the two directions. The results support the hypothesis that abnormal eye movements are more likely to be an effect and not the cause of reading difficulties. The DEM test should not be used to diagnose eye movement difficulties in a patient with poor reading ability.     

The effect of time on the developmental test of visual motor integration

Studies have shown that many children with learning problems have difficulties of an integrative nature. In addition, these same children often require more time for visual information processing. In this study, the Developmental Test of Visual-Motor Integration (VMI) was given to children between the ages of 5 and 12 years, the children being categorized into normal and learning problem groups. The forms were administered with and without a time restriction. It was hypothesized that the time restriction would result in lower scores for children with visual motor perceptual deficiencies and learning problems than for those without. Results of the study showed a significant difference with time restrictions for children between ages 5 and 7 years and 9 year-1 month to 12 years. This suggests that within these age groups, timing the test items of the VMI could supply additional information relative to visual motor perceptual development. In the middle age group, the test time appears to be too complex for children with visual motor perceptual deficiencies to complete.     

Effects of wearing yellow spectacles on visual skills, reading speed, and visual symptoms in children with reading difficulties

Background

Possible beneficial effects of yellow-tinted spectacle lenses on binocular vision, accommodation, oculomotor scanning, reading speed and visual symptoms were assessed in children with reading difficulties.

Methods

A longitudinal prospective study was performed in 82 non-dyslexic children with reading difficulties in grades 3–6 (aged 9–11 years) from 11 elementary schools in Madrid (Spain). The children were randomly assigned to two groups: a treatment (n?=?46) and a without-treatment group (n?=?36). Children in the treatment group wore yellow spectacle lenses with best correction if necessary over 3 months (in school and at home). The tests were first undertaken without the yellow filter. With best spectacle correction in each subject, measurements were made of: distance and near horizontal heterophoria, distance and near horizontal fusional vergence ranges, the accommodative convergence/accommodation (AC/A) ratio, near point of convergence (NPC), stereoacuity, negative relative accommodation (NRA) and positive relative accommodation (PRA), monocular accommodative amplitude (MAA), binocular accommodative facility (BAF), oculomotor scanning, and reading speed (words per minute). The Convergence Insufficiency Symptom Survey (CISS) questionnaire was completed by all children. After the 3-month period, measurements were repeated with the yellow lenses (treatment group) or without the yellow lenses (without-treatment group) but with refractive correction if needed.

Results

Over the 3 months, the two groups showed similar mean changes in the variables used to assess binocular vision, accommodation, oculomotor scanning, and reading speed. However, mean relative changes in convergence insufficiency symptoms differed significantly between the groups (p?=?0.01).

Conclusion

No effects of wearing yellow spectacles emerged on binocular vision, accommodation, oculomotor scanning, and reading speed in children with reading difficulties. The yellow filter had no effect even in children with low MAA and BAF. The reduction in visual symptoms observed in children with reading difficulties using the yellow filters was clinically insignificant.     

地塞米松及Lat—A对人眼小梁细胞蛋白质表达的影响

目的探讨地塞米松（Dex）及latrunculin—A（Lat-A）处理后人眼小梁细胞蛋白质表达的变化。方法正常供体人眼小梁细胞培养后用Dex及Lat—A处理,经二维凝胶电泳分离小梁细胞蛋白质,分析凝胶电泳图谱,选取部分差异凝胶斑点并采用基质辅助激光解析电离飞行时间质谱（MALDI—TOFMS）鉴定蛋白质。结果采用24cm IPG胶条获得正常人眼小梁细胞对照组、Dex组、Dex＋Lat—A组以及Lat—A组的二维电泳凝胶图谱,得出不同培养条件下人眼小梁细胞蛋白质表达的差异。应用GDPi MALDI—TOFMS得出不同培养条件下差异表达的蛋白质斑点并成功鉴定出其中的24种蛋白质,主要包括细胞骨架相关的蛋白、热休克蛋白、氧化还原相关的蛋白和糖代谢相关的蛋白4类蛋白质。ADLH和Rab蛋白在Lat—A组的人小梁细胞中表达增加,但在Dex组表达减少,而热休克蛋白27（HSP27）和人CRMP2呈现相反的结果。结论成功建立Dex及Lat—A诱导人眼小梁细胞蛋白质表达图谱。Dex及Lat—A能诱导人眼小梁细胞的蛋白质表达变化,可能与青光眼致病的分子机制相关。     

Prevalence of visual impairment, cataract surgery and awareness of cataract and glaucoma in Bhaktapur district of Nepal: The Bhaktapur Glaucoma Study

Background

The present study investigates two different treatment options for convergence insufficiency CI for a group of children with reading difficulties referred by educational institutes to a specialist eye clinic in Vienna.

Methods

One hundred and thirty four subjects (aged 7-14 years) with reading difficulties were referred from an educational institute in Vienna, Austria for visual assessment. Each child was given either 8Δ base-in reading spectacles (n = 51) or computerised home vision therapy (HTS) (n = 51). Thirty two participants refused all treatment offered (clinical control group). A full visual assessment including reading speed and accuracy were conducted pre- and post-treatment.

Results

Factorial analyses demonstrated statistically significant changes between results obtained for visits 1 and 2 for total reading time, reading error score, amplitude of accommodation and binocular accommodative facility (within subjects effects) (p < 0.05). Significant differences were also demonstrated between treatment groups for total reading time, reading error score and binocular accommodative facility (between subjects effects) (p < 0.05).

Conclusions

Reading difficulties with no apparent intellectual or psychological foundation may be due to a binocular vision anomaly such as convergence insufficiency. Both the HTS and prismatic correction are highly effective treatment options for convergence insufficiency. Prismatic correction can be considered an effective alternative to HTS.     

Orthoptic Assessment of Children with Learning Difficulties

The orthoptic investigation of children with learning difficulties is discussed and a new orthoptic test for “reference eye” in central binocular vision is described. The effects of abnormal central binocular function, as shown by responses to the new test are also described. Experimental orthoptic treatment undertaken to date has shown encouraging results. It is suggested that the orthoptist can be a useful member of the diagnostic and remedial teams involved with the problem of learning difficulties.     

Is there an association between functional vision and learning to read?

Background: Controversy exists about the role of visual parameters and vision in learning to read. This study aims to determine whether ocular parameters or performance on a dynamic test of visual function differs for children of differing reading ability. Methods: Two hundred and eighty‐four children (mean age 9.9 ±1.8 years) received a vision screening emphasising binocular anomalies associated with discomfort at near (distance and near visual acuity, distance vision challenged with binocular +1 D lenses, near heterophoria, near point of convergence, stereopsis and accommodative facility). Non‐verbal mentation age and reading accuracy were assessed. One hundred and six children performed a computerised task of motion coherence detection. Children were classified as normal readers (n = 195), children with dyslexia (n = 49) or learning disabled children (n = 40) based on their mentation age and their reading age. Results: There were no statistically significant differences or correlations between visual parameters and reading performance. Over thirty per cent of the children had accommodative facilities below or equal to six cycles per minute. Children with learning disabilities performed worst on the motion coherence task but this was statistically significant only when compared to the performance of dyslexics. Discussion: The lack of association between ophthalmic parameters and poor reading ability supports the view of the Committee on Children with Disabilities. However, 39 per cent of the children might be expected to experience difficulty ‘reading to learn’, as suggested by the American Academy of Optometry, as they showed anomalies associated with visual discomfort with prolonged reading. The motion coherence test did not differentiate dyslexics from normal readers and was worst in children with learning disability. Accommodative facility testing remained the most useful predictor of potential visual discomfort.     

Learning disabilities: the role of the developmental optometrist.

The role of the optometrist in treating children experiencing learning disabilities embraces numerous areas beyond the customary optometric services. Etiological, diagnostic and therapeutic factors are discussed stressing visual functional disorders, perceptual-motor and developmental lags and cognitive style. Their effects on the learning disabled child are analyzed; and the rationale of optometric procedures frequently used in treating LD children is reviewed. The optometrist may also be helpful in counseling patients who have learning readiness problems, reading disorders, psychological difficulties and nutritional deficits.     

Patient comfort and surgeon satisfaction during cataract surgery using topical anesthesia with or without dexmedetomidine sedation

PURPOSE. To determine the safety and efficacy of perioperative dexmedetomidine (Dex) sedation on patient comfort and surgeon satisfaction during cataract surgery under topical anesthesia. METHODS. Forty-four patients having routine clear corneal phacoemulsification surgery under topical anesthesia were included in the study. Patients were randomly divided into two groups: Dex group (n=22) and control group (n=22). Patients in the Dex group were to receive intravenous Dex using an infusion pump and those in the control group were to receive 0.9% saline infusion. Primary outcome measures were patient comfort, surgeon satisfaction, and patient pain perception. RESULTS. There was no significant difference between the groups in terms of baseline characteristics including age, sex, eye side, pupil diameter, and vital signs (p>0.05 for all). Patient comfort and surgeon satisfaction in Dex group was better than in control group (p=0.042 and p=0.003, respectively). The mean pain perception score was lesser in the Dex group (1.23+-.72) than control group (3.64+/-1.43), (p<0.001). The mean surgical time and intraoperative complications were similar in both groups (p>0.05). There was no significant effect of the Dex sedation on vital signs perioperatively (p>0.05 for all). CONCLUSIONS. Dex sedation improved patient and surgeon satisfaction and decreased patients' pain perception while undergoing cataract surgery under topical anesthesia. It appears to be a safe and suitable choice of sedation for cataract surgery.     

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.     

不同程度视力残疾儿童应用助视器康复的研究

目的对有残余视力的视力残疾儿童在给予光学和电子助视器康复后进行远、近视力的分析和效果评估,探讨不同程度视力残疾患儿有效的康复手段及其对低视力康复对象范围界定的影响。方法对盲校及低视力门诊共206名4～14周岁（含14岁）视力残疾儿童按视力残疾的程度进行分组,比较应用国产4倍、6倍望远镜前后远视力和应用国产眼镜式助视器、国产简易电子助视器后两种助视器间阅读成功率的差异。远视力康复结果采用秩和检验,近视力康复结果采用卡方检验进行统计学分析。结果视力0．05以下至眼前指数的盲童组和0．3以下至0．05的低视力组应用远用助视器前后远视力差异均有统计学意义（P〈0．05）;视力0．05以下至光感的肓童和低视力儿童分别使用眼镜式近用助视器与简易电子助视器后,两种助视器间阅读成功率的差异均有统计学意义,使用简易电子助视器的阅读成功率均明显高于使用眼镜式近用助视器。结论助视器康复的对象可以从低视力范围扩展到0．01甚至以下的盲童。低视力助视器是视力残疾儿童视觉康复有效和必要的手段,早期视觉康复特别是使用简易电子助视器进行近视力阅读的康复,对视力残疾儿童提高学习认知能力、促进身心健康成长和回归社会具有重要意义。     

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.     

不同年龄人群的立体视觉检查与比较

目的：了解不同年龄人群的立体视觉现状与规律，为开展立体视觉检查与评价提供参考；提出一种新的立体视觉检查工具与方法。方法：选用全息立体视觉检查仪，用相同方法，对四组不同年龄人群进行立体视觉的检查和分析。结果：共检查1039人，立体视锐度总正常率为82.6%。其中，学龄前儿童组立体视觉正常率是86.9%；学生组最高为98.0%；青壮年组次之为94.7%；老年组的立体视觉正常率明显降低为35.4%，立体视盲的比例明显增加。结论：年龄与立体视觉之间明显相关（P＜0.001)；各年龄组立体视觉正常率与近视力关系密切；全息立体视觉检查仪可作为一种新的、可靠的检查工具在临床上推广使用。     

表没食子儿茶素没食子酸酯抑制地塞米松体外诱发兔白内障的作用

目的:观察表没食子儿茶素没食子酸酯(EGCG)对抑制地塞米松(Dex)诱导体外培养兔晶状体上皮细胞(LEC)凋亡的作用。方法:采用体外培养正常家兔晶状体,随机将家兔晶状体分为3组:空白对照组(A);Dex(10μmol/L)处理组(B);Dex+EGCG(10mmol/L)实验组(C)。分别于3,5,7d培养结束后观察各组晶状体的透明度,并进行相关比较及统计学分析。TUNEL法检测EGCG对Dex诱发的兔LEC凋亡细胞数量的影响,并进行相关比较及统计学分析。结果:EGCG实验组晶状体透明性均低于空白对照组,但高于Dex处理组,差异有显著统计学意义(P<0.01);Dex处理组LEC凋亡率显著高于空白对照组(P<0.01);Dex处理组与EGCG实验组比较,有显著性差异(P<0.01)。结论:EGCG可抑制Dex损伤所诱导兔LEC调亡,具有明显抑制激素性白内障形成的作用。     

Coloured overlays in schools: orthoptic and optometric findings

In two studies, the first in a school in Peterborough and the second in a school in Norwich, more than 233 children aged 8-12 years received either an orthoptic examination, or an optometric examination, together with an examination using coloured overlays and a test of reading fluency. In both studies more than one-third of the children reported visual symptoms. More than one-third of the children chose to use an overlay, and they read more quickly with it than without. The colour of the overlay chosen was weakly related to the binocular amplitude of accommodation: overlays reflecting greater energy at long wavelengths were chosen more frequently by children with a higher amplitude of accommodation. Although the visual symptoms were strongly related to the use of an overlay, in neither study was the benefit from an overlay strongly related to the orthoptic or optometric findings. Nevertheless, children who used an overlay had slightly, but significantly, reduced mean binocular amplitude of accommodation and fusional reserves. On average, children with 'sensory' or 'motor' instability of the nonius strips of the Mallett unit read more slowly than others, as did those with poor stereopsis. However, 60% of those demonstrating sustained overlay use gave a normal response on the Mallett aligning prism test, compared with 80% of those who did not use an overlay for a sustained period. Another indicator of decompensated heterophoria, Sheard's criterion, did not differentiate subjects who used overlays from those who did not. Although binocular and accommodative anomalies do not appear to be the underlying mechanism for the benefit from coloured filters in most cases, there may be some individuals who respond to coloured filters and in whom these ocular motor factors require treatment. Children with visually precipitated symptoms and/or reading difficulties need both a careful evaluation of their accommodative and binocular status, and an investigation of the effect of coloured filters.     

Effects of ocular functioning and time upon reading proficiency

We hypothesize that children with fusional and/or accommodative abnormalities will tend to tire more readily when reading than will children with normal vision and that, consequently, they will show a greater decrement in reading proficiency over time on a task requiring reading. Forty-five subjects who passed the New York State Optometric Association Vision Screening Battery and 32 who failed were given a "maze" reading test developed for the study. The abnormal vision group made significantly more errors than did the normal vision group on the reading test. The abnormal vision group also made progressively more errors than did the normal vision group at the end of each segment of the reading test. The differences, however, were not statistically significant. While the correlations between speed and accuracy reversed over time, the abnormal vision group began and ended at the most extreme levels, having undergone a significantly more radical shift in this regard.     

视知觉学习对早期老视症状的改善作用

目的探讨视知觉学习对早期老视者临床症状的改善作用。方法前瞻性对照研究。选取来本院就诊的有早期老视症状者80例,年龄40～45岁,平均（42.3±2.5）岁,负镜片法测量双眼调节幅度,选取调节力差的眼为受检眼（80眼）,随机数字表法分为2组,一组进行为期3个月,每周3次,每次12～15 min的视知觉学习训练（治疗组）;另一组为对照组。评估治疗组训练前和训练3、6、9、12周后的主观感受,2组训练前和训练3、6、9、12周后的单眼远视力、调节幅度、阅读视力、最大阅读速度、临界字体、眼前节光学相干断层扫描仪（AS-OCT） 检查晶状体调节变化幅度。采用重复测量资料方差分析对各项指标不同时间点的数据进行统计分析。结果训练前和训练3、6、9、12周后,治疗组各项主观感受评分：视近困难、阅读疲劳、暂时性视物模糊、眼部酸痛、久视头晕评分训练前后差异均有统计学意义（F=283.9、482.7、160.9、198.3、126.7,P均<0.05）。治疗组和对照组单眼远视力、调节幅度、晶状体调节变化幅度训练前后变化趋势的差异均无统计学意义;但阅读视力、最大阅读速度、临界字体训练前后变化趋势的差异均有统计学意义（F=30.3、4.6、41.5,P均<0.05）。结论视知觉学习训练可有效改善有早期老视症状者的近距离阅读能力。     

Investigation of accommodative and binocular function in dyslexia

The visual correlates of dyslexia are the subject of controversy, and much evidence suggests that they may include some aspects of binocular and accommodative function. These factors were investigated in 43 control and 39 dyslexic children, who were matched for age, sex and performance intelligence quotient. The dyslexic group exhibited significantly lower positive and negative vergence reserves, and vergence instability when the eyes were dissociated at near. Their amplitudes of accommodation also were significantly reduced. However, other measures including dissociated and associated heterophoria and accommodative lag and facility were similar in both groups. The stability of motor ocular dominance, as assessed with a modified Dunlop test, was similar in both groups. The results of a simulated reading visual search task suggested that the vergence and accommodative dysfunction were not a major cause of the dyslexia. Further analyses, using reading-age matched groups, suggested that these ocular motor correlates were not attributable to the better reading performance in the control group. The most likely remaining explanation is that they are, in most cases, non-causal correlates of the dyslexia.     

A review of the role of visual problems in reading disabilities

In this review we discuss the etiology of reading disturbances in children and adults. The majority of reading problems in children are either due to primary causes (dyslexia) or secondary to a variety of nonophthalmologic disorders or diseases. In adults the nature of reading difficulties is different to that in children and is defined as asthenopia. Asthenopia can develop as a result of uncorrected refractive errors or due to an imbalance of extraocular muscle action. The therapeutic approach to reading problems is reviewed and it will be seen to be different in children and in adults.