Color vision screening for individuals with intellectual disabilities: a comparison between the Neitz Test of Color Vision and Color Vision Testing Made Easy.

BACKGROUND: The Neitz Test of Color Vision (Neitz) and Color Vision Testing Made Easy(trade mark) (CVTME) were compared to determine which test was more effective in evaluating patients with intellectual disability (i.e., mental retardation) and developmental delay. METHODS: Two hundred eight Special Olympics floor hockey athletes were screened in San Diego, California, and 93 athletes were screened in Long Beach, California for a total of 301 athletes. Each athlete was administered the CVTME and the Neitz tests. RESULTS: The pass rate for the CVTME was 94.6% (n = 93) at Long Beach and 96.2% (n = 208) at San Diego. Every athlete was able to complete the CVTME. The pass rate for the Neitz was 38.7% at Long Beach and 56.7% at San Diego. Additionally, 10.8% of the Long Beach athletes and 12.5% of the San Diego athletes were unable to understand the Neitz. In addition, there was a low level of agreement between the results from the 2 tests with kappa = 0.081 for the San Diego data and 0.028 for the Long Beach data. CONCLUSIONS: This study suggests that the CVTME continues to be the screening test of choice in evaluating color vision in individuals with intellectual disability. The Neitz had more failing scores on the first attempt and more total failing scores leading to over-referrals, making it an inappropriate screening test for individuals with intellectual disability and developmental delay.     

Evaluation of a new color vision test: "color vision testing made easy".

PURPOSE: A new pseudoisochromatic color plate test, "Color Vision Testing Made Easy" (CVTMET) has recently been introduced. Said to be designed for all age groups, including pre-school children, it uses the identification of simple shapes and objects to detect red-green color deficiencies. We evaluated the CVTMET to determine if the test is suitable for color vision screening of young children. METHODS: Forty-one adults predetermined to be color normal (n = 20) or to have hereditary red-green color deficiency (n = 21), served as subjects. A battery of color vision tests including the Ishihara, Panel D-15, and the anomaloscope were used for diagnosis and color deficiency classification. Subjects were then tested with Part I and Part II of the CVTMET test and results were compared to the Ishihara, Panel D-15, and anomaloscope. In addition, the CVTMET was used to screen for color vision deficiency in 152 kindergarten children 5 to 7 years of age. RESULTS: The pass/fail results for the adult subjects were the same for Parts I and II and compared favorably with the anomaloscope. There were no false positives (100% specificity) and only a few (2 of 21) false negatives (90.5% sensitivity). The two color-deficient subjects who passed the CVTMET had the mildest color deficiencies (simple deuteranomaly) and also passed the Ishihara test. Testability of kindergarten children was found to be 100%. Color vision deficiency occurred in 5.06% of the boys, which is about the same frequency found in older boys of similar ethnic background. CONCLUSION: This preliminary study indicates that the CVTMET appears to be an excellent screening instrument for red-green color deficiency in adults and has been shown to be useful for examining color vision in children 5 to 7 years of age.     

Ocular and visual defects amongst people with intellectual disabilities participating in Special Olympics

PURPOSE: To analyse data from vision screening of people with intellectual disabilities from the UK participating in Special Olympics during the National Summer Games in Cardiff 2001, in order to determine visual status and access to eye care. METHODS: Athletes were invited to take part in vision screening, according to Special Olympics protocols. RESULTS: Testability rates were high. Findings confirmed the high prevalence of eye and vision defects reported in other studies of people with intellectual disabilities. In particular, visual acuity was below normal for most athletes. Significant improvement to acuity could be achieved with spectacles although correction after full refraction did not always provide normal vision. Over 40% of athletes undergoing full refraction had below normal corrected acuity. CONCLUSIONS: Athletes with intellectual disabilities were no more likely to access eye care and have adequate spectacle correction than other people with intellectual disabilities. Optometrists and carers need to be aware of the high prevalence of defects and the importance of regular eye examinations in people with intellectual disabilities.     

Sports vision testing of selected athletic participants in the 1997 and 1998 AAU Junior Olympic Games.

BACKGROUND: Sports vision researchers have attempted to establish the need for vision care services for athletes and the relationship between visual skills and athletic success. METHODS: Data collected from sports vision screenings at the 1997 and 1998 Amateur Athletic Union AAU Junior Olympic Games was compiled for analysis. Four hundred forty-nine athletes, ranging in ages from 5 to 19 years old and representing 12 sports, were part of the sports vision epidemiology project conducted by the American Optometric Association Sports Vision Section. Protocols from the AOA Sports Vision Section were used to assess the visual systems of athletes participating in the games. The history included evaluation of the use of vision care services, refractive correction type, and symptomology. The screening assessed visual acuity, contrast sensitivity, ocular alignment, eye-hand dominance, handspeed, footspeed, speed of stereopsis, speed of recognition, eye movements, hand-eye coordination, anterior-segment health, and posterior-segment health. Performance testing was analyzed by age group and sport. RESULTS: In this population of athletes, eye care was under-utilized. The performance testing indicated an increase in performance with increasing age for most tests. With increasing age, there was a decrease in the number of fixation losses, an increase in footspeed, and a decrease in handspeed. The norms for the performance tests are reported by age group and by sport. CONCLUSIONS: The results of this study imply that athletic populations at all levels are in need of eye care services. The norms derived from this investigation act as a standard for the evaluation of vision performance using the AOA Sports Vision Testing Battery.     

Comparison on testability of visual acuity,stereo acuity and colour vision tests between children with learning disabilities and children without learning disabilities in government primary schools

Context:

Children with learning disabilities might have difficulties to communicate effectively and give reliable responses as required in various visual function testing procedures.

Aims:

The purpose of this study was to compare the testability of visual acuity using the modified Early Treatment Diabetic Retinopathy Study (ETDRS) and Cambridge Crowding Cards, stereo acuity using Lang Stereo test II and Butterfly stereo tests and colour perception using Colour Vision Test Made Easy (CVTME) and Ishihara''s Test for Colour Deficiency (Ishihara Test) between children in mainstream classes and children with learning disabilities in special education classes in government primary schools.

Materials and Methods:

A total of 100 primary school children (50 children from mainstream classes and 50 children from special education classes) matched in age were recruited in this cross-sectional comparative study. The testability was determined by the percentage of children who were able to give reliable respond as required by the respective tests. ‘Unable to test’ was defined as inappropriate response or uncooperative despite best efforts of the screener.

Results:

The testability of the modified ETDRS, Butterfly stereo test and Ishihara test for respective visual function tests were found lower among children in special education classes (P < 0.001) but not in Cambridge Crowding Cards, Lang Stereo test II and CVTME.

Conclusion:

Non verbal or “matching” approaches were found to be more superior in testing visual functions in children with learning disabilities. Modifications of vision testing procedures are essential for children with learning disabilities.     

Color vision screening: a comparison of the AO H-R-R and Farnsworth F-2 tests

Vision screening tests should include a simple, reliable, and valid test of color vision defects. In this investigation the single plate Farnsworth F-2 test and the AO H-R-R pseudoisochromatic plates were compared as primary screening tests for red-green color defective vision. The tests were administered to 2827 children, kindergarten through high school grades. Both tests failed a higher percentage of children than expected in the lower grades (kindergarten through 3). In grades 4 through high school, however, 4.16% failed the F-2 test and 4.02% failed the AO H-R-R, compared to a predicted 4.2% of the general population with inherited red-green deficiencies. The failure rates of the F-2 test for 1171 high school boys and girls were 7.3 and 0.89%, respectively, very close to the expected incidence of red-green defects in males and females. Although the F-2 test passed a few pupils who failed the AO H-R-R test, their defects were categorized as mild or borderline on the AO H-R-R test and therefore not likely to be of practical significance. Less than 0.5% of the children in grades 4 through high school failed the F-2 test after passing the AO H-R-R. Some children with normal color vision, particularly very young children, may fail the F-2 test because of difficulty picking out the less obvious blue square. Nevertheless, for screening purposes the F-2 test is comparable to the AO H-R-R test and except for kindergarten and grade 1 pupils is an excellent single plate color vision screening test.(ABSTRACT TRUNCATED AT 250 WORDS)     

Random Dot E stereotest: Testability and reliability in 3- to 5-year-old children

PURPOSE: To determine the proportion of preschoolers testable with the Random Dot E (RDE) stereotest and the between-tester reliability. METHODS: Subjects were 1257 3- to 5-year-olds who were participants in Head Start programs in five communities. The sample was over-weighted with children who failed the routine Head Start vision screening (58% failures; 42% nonfailures). Each child had stereotesting attempted by two licensed eye care professionals using the RDE test, first in a screening setting and later in a comprehensive eye examination. Pretesting was performed at 50 cm. Children who discriminated between the nonstereo E and blank cards on 4 of 4 or 4 of 5 presentations were considered testable. Stereotesting was conducted at 50, 100, and 150 cm corresponding to 504, 252, and 168 arcsec disparity). Extent of agreement beyond chance between the screening and examination test results was assessed using the kappa (kappa) and weighted kappa (kappa(w)) statistics. RESULTS: Testability increased with age at both the first (86% of 3-, 89% of 4-, and 93% of 5-year-olds; p = 0.02) and the second (90% of 3-, 94% of 4-, and 98% of 5-year-olds; p = 0.0001) sessions. Overall, stereopsis was better at the second session. Agreement between sessions was moderate (kappa(w) = 0.43; 59% identical scores). While identical scores increased with age (53% of 3-, 59% of 4-, and 63% of 5-year-olds), kappa(w) statistics did not differ with age (p = 0.49). CONCLUSIONS: Child testability on the RDE stereotest was significantly better for older than younger preschool-age children. Overall, test-retest agreement was moderate and did not differ according to age. Testability rates of 98% and higher have been achieved in the same population with other screening tests including another random dot stereotest.     

Negative predictive value of a population-based preschool vision screening program.

BACKGROUND: The Enhanced Vision Screening Program is a population-based vision screening program that has, at present, examined 59,782 children. Its main goal is to detect amblyopia, strabismus, and high refractive errors. An average of 11,910 4 1/2- to 5 1/2-year-old children are screened yearly. The current study determines the negative predictive value of the screening program: For a subject having passed the vision screening test, what is the probability of not having amblyopia, strabismus, or high refractive errors? METHODS: Of the 11,734 subjects who passed the vision screening, 200 were randomly chosen to undergo a strictly defined gold standard examination by an orthoptist and an ophthalmologist. RESULTS: Of the 200 randomly chosen subjects, 157 underwent the gold standard evaluation. The negative predictive value of the Enhanced Vision Screening Program was 97.6% for any potentially vision-threatening ocular condition. It was 98.7% if we considered only the visually significant ocular problems that the test was designed to detect. CONCLUSION: Because the negative predictive value of the Enhanced Vision Screening Program is not 100%, some children with amblyopia, strabismus, or refractive errors are missed. Occasionally, a rare, potentially vision-threatening condition may go undetected. Parents should be made aware of this when they receive the results of the vision screening.     

The Ohkuma's test: an evaluation

Ohkuma's pseudoisochromatic test was evaluated in 147 subjects including 130 cases with hereditary dyschromatopsias, and compared with the color vision tests of Ishihara, the HRR, the Farnsworth Panel D-15 and the City University Color Vision Test. Qualitatively, Ohkuma's test was more exact for the diagnosis of the axis of the dyschromatopsia (protan or deutan); quantitatively, Ohkuma's test was of good efficiency for screening, but the quantitative gradation was mediocre, indicating dichromatism in only 3/4 of the cases.     

Testability of preschoolers on stereotests used to screen vision disorders.

OBJECTIVE: The purpose was to determine whether preschool children aged 3 years 0 months through 3 years 6 months could be tested with the Random Dot E, Stereo Smile, and Randot Preschool stereoacuity tests, which are random dot stereotests marketed for use with preschoolers. METHODS: A total of 118 children from five Vision In Preschoolers Study Clinical Centers participated. Strabismic children, as determined by the cover test at distance and near, were excluded from this study. Stereopsis was tested on each child using each of the three tests in a variable, balanced order. A child's testability for each test was determined by the ability to complete the nonstereo task (pretest) and the gross stereo task for each stereotest. Proportions of children able to perform each test were compared using statistical methods accommodating multiple measurements per child. RESULTS: Testability of children on the pretest was greater for the Stereo Smile test (91%) than for the Random Dot E test (81%; p = 0.007) or the Randot Preschool test (71%; p < 0.0001) and greater for the Random Dot E test than for the Randot Preschool test (p = 0.02). For all children, testability on the gross stereo task was greater for the Stereo Smile (77%; p < 0.0001) and Random Dot E (74%; p = 0.005) tests than for the Randot Preschool test (56%) but did not differ significantly between the Stereo Smile and Random Dot E tests (p = 0.19). There were no significant differences among the proportion of children able to complete the gross stereo task among those who were testable on the pretest (p > 0.12, all comparisons). CONCLUSIONS: Among preschoolers aged 3 years 0 months through 3 years 6 months, testability differs significantly across the three commercially available random dot stereotests evaluated. The results suggest that two-choice procedures increase testability of young preschoolers.     

智障儿童眼部筛查结果与分析

目的 通过对温州地区特殊学校就读的智障儿童进行眼部健康筛查,了解智障儿童的眼部健康问题,分析相关因素,以提供相应的视觉矫正和治疗措施,及探索如何为智障儿童的眼部健康提供有效的服务.方法 调查研究.对在温州地区特殊学校就读的342名智障儿童进行眼部健康筛查,内容包括：一般信息、视力检查、眼位检查、色觉检查、眼前段检查、内眼检查以及屈光不正检查.采用Excel软件对数据进行整理、归纳和求百分比.并针对存在的视觉问题作出相应的分析和医学处理.结果 筛查患儿智力残疾为轻度至中度,心理与情绪等适应能力轻度或中度障碍,能参与部分社区活动.眼科检查发现,正视眼占46.6%,屈光不正均以低度屈光不正状态为主,大部分能通过眼镜矫正达到5.0 眼位检查显示正位眼占67.2%,隐斜视占12.9% 色觉正常者占81.9%,色觉存在明显异常者占6.4% 外眼及眼前段检查未发现明显异常者占92.7% 内眼检查未发现明显异常者占81.1%.这些患儿眼部的异常主要是眼球震颤（占50.0%）和白内障（占28.3%）.结论 智障儿童的眼部问题现患率比普通儿童高,但还是以屈光不正、眼球震颤、白内障等为主,大多为可矫正和可康复的,可以通过眼镜、手术或视觉康复等提高视功能.     

Chromatic and achromatic transient VEPs in adults with Down syndrome

Oculo-visual abnormalities such as strabismus and high refractive error are common in people with Down syndrome, and account in large part for reduced visual function in this group. In the absence of such abnormalities, however, some spatial vision deficits persist, probably reflecting abnormal function of the neural visual pathway in this population. In addition, colour vision abnormalities are reportedly common in subjects with Down syndrome. We recorded transient visual evoked potentials in response to black-white and chromatic stimuli, in seven subjects with Down syndrome and 33 controls, to investigate function of the visual pathways underpinning spatial and chromatic visual function in Down syndrome. Our findings indicate, in agreement with previous studies, that retino-striate achromatic and chromatic processing in Down syndrome are abnormal. We find, however, that abnormal retino-striate processing of chromatic signals in this group may not give rise to colour vision deficits detected by the Colour Vision Test Made Easy or the City University test.     

Neurophysiological basis and clinical tests for assessment of X-linked color vision deficiencies in school children

Vision screening of school children at 5-6 years of age must include color vision screening. X-linked dyschromatopsia is the most frequent disorder affecting 8% of boys and 0.4% of girls. This paper presents the physiology of these deficiencies caused by an alteration of the spectral absorption properties of one of the cone pigments (protanomalous or deuteranomalous trichromats) or the absence of one of the pigments (protanopia or deuteranopia), the most frequent. Absence of two of the pigments (blue cone monochromacy) is very rare and differs from achromatopsia. The physiological basis of the main tests for easy clinical screening are presented. Testing methods designed for children are reviewed. The Ishihara test is the most widely used screening test specific for congenital color defects. If the plates are correctly read, the child has normal color vision. If not, arrangement tests such as Panel D 15 and desaturated Panel D 15 tests can be used to diagnose the type of the defect (protan or deutan) and grade the degree of color deficiency according to a strategy adapted to children. Examples of results are presented for each axis along which caps are confused, providing a quick and easy preliminary diagnosis. Early detection of color vision malfunction in children allows parents and teachers to make necessary adjustments to the teaching methods for appropriate learning.     

Visual acuity testability and comparability in Australian preschool children: the Sydney Paediatric Eye Disease Study

Purpose

To establish standardised protocols for vision screening, testability and comparability of three different vision tests were examined in a population-based, cross-sectional sample of preschool children (Sydney Paediatric Eye Disease Study).

Methods

Measurement of presenting monocular distance visual acuity (VA) using the Amblyopia Treatment Study (ATS) HOTV protocol, was attempted by all (1774) children aged≥24 months. In addition, in children aged≥60 months (576), VA was also tested using the logMAR retro-illuminated HOTV or Early Treatment Diabetic Retinopathy Study (ETDRS) linear charts (CSV 1000). Children able to have both eyes tested monocularly were considered.

Results

Testability significantly increased with age for all VA tests. The ATS HOTV with an overall testability of 80% (females: 82%, males: 78%) was the most testable of the VA tests (P<0.0001). In children aged <3 years testability was low (≤47%) rising to≥80% in children aged≥3. In children≥60 months, testability was higher for the HOTV (94%) than the ETDRS (59%) chart. In those that did two VA tests, mean difference of the ATS HOTV compared with the HOTV(CSV) was −0.1, and compared with ETDRS was −0.12 (P<0.0001).

Conclusions

Children aged <3 years had poor VA testability, whereas those 3 years and above were highly testable using the ATS HOTV. The HOTV (CSV) retro-illuminated test was appropriate for children aged >5 years, and may be possible in younger children with early educational exposure. When comparing VA measures using these tests, the higher VA attained using the ATS HOTV, needs to be taken into account.     

色盲角膜接触镜的临床应用

目的 :探讨红绿色盲患者戴色盲角膜接触镜后辨色力的改变状况和色盲角膜接触镜的实用性。方法 :色觉正常对照组 (Gn组 )和红绿色盲实验组 (Gc组 )各 10例 ,年龄匹配 ,矫正视力 1.0。两组在使用色盲角膜接触镜前后 ,针对色调图片 (红、黄、绿、蓝、绛、褐、灰 )、《色觉检查图》、《色盲检查D 15色彩排列盒》 ,比较戴镜前后不同的色觉变化。结果 :色觉检查图中的第一、第二组类型的假同色图 ,Gc组戴镜前读不出 ,戴镜后能读出 ;Gn组戴镜前后均能读出 ;第三组类型的假同色图Gc组戴镜前后不能读出 ,Gn组戴镜前能读出 ,戴镜后不能读出。D 15色彩排列检查Gc组戴镜前后均不能正确排列色调顺序 ;Gn组戴镜前排列正确 ,戴镜后排列错误。结论 :红绿色盲患者戴色盲角膜接触镜后能提高对某些假同色图的分辨能力 ,使原来混淆的色调有了深浅的变化 ,但不能改善其对自然环境中的色彩分辨     

Color vision in epilepsy patients treated with vigabatrin or carbamazepine monotherapy

PURPOSE: To investigate color vision in epilepsy patients treated with vigabatrin or carbamazepine monotherapy and to evaluate the association between vigabatrin-induced visual field defects and dyschromatopsia. DESIGN: Nonrandomized comparative trial. PARTICIPANTS: Thirty-two epilepsy patients treated with vigabatrin monotherapy, 18 patients treated with carbamazepine monotherapy, and 47 age-matched healthy controls were examined. MAIN OUTCOME MEASURES: Color vision was examined with Standard Pseudoisochromatic Plates 2 (SPP2) screening test, Farnsworth-Munsell 100 (FM 100) hue test, and Color Vision Meter 712 anomaloscope. RESULTS: Abnormal color perception was found in 32% of the epilepsy patients treated with vigabatrin monotherapy and 28% of the epilepsy patients treated with carbamazepine monotherapy. The total error score in the Farnsworth-Munsell 100 hue test was abnormally high in the vigabatrin monotherapy patients who had concentrically constricted visual fields and a statistically significant correlation was found between the temporal visual field extents and the age-adjusted Farnsworth-Munsell 100 total error score in vigabatrin monotherapy patients (R = .533, P = 0.003 in the right eye, R = .563, P = 0.001 in the left eye). Four of 31 (12%) vigabatrin monotherapy patients, and 1 of 18 (6%) carbamazepine monotherapy patients had a blue axis in Farnsworth-Munsell 100 hue test. In the anomaloscope, there were a few pathologic findings in both groups. In the SPP2 screening test, a few plates were not seen in both groups. CONCLUSIONS: Both examined antiepileptic drugs, vigabatrin and carbamazepine, cause acquired color vision defects. The abnormal color perception seems to be associated with constricted visual fields in the vigabatrin monotherapy patients. The duration of carbamazepine therapy correlates with high FM100 total error score. The best method for detecting dyschromatopsia in patients treated with vigabatrin or carbamazepine was the Farnsworth-Munsell 100 hue test. The SPP2 screening test does not seem to be useful in clinical practice.     

明水县农村居民10030人色觉调查与分析

目的 了解黑龙江省明水县农村居民的色觉情况.方法 以人群为基础,采用整群随机抽样方法,包括全体年龄阶段的人接受检查.采用人民卫生出版社俞自萍色盲检查图,对黑龙江省明水县10030人农村居民色觉情况进行检查.用logistic回归及单因素卡方检验分析年龄、性别与色盲及色弱患病率的关系.结果 共有11391人入选调查,10030人参加检查了色觉检查,应答率88.05%(范围:86%～91%).其中男性色盲患病率为2.56%(2.13%～2.99%),女性为0.842%(0.582%～1.00%),男、女色盲患病率有显著性差异(x2=34.773,P＜0.05).男性色弱患病率为2.30%(1.9%～2.7%),女性为0.657%(0.44%～0.88%),男、女色弱患病率有显著性差异(x2=45.885,P＜0.05).年龄对色盲及色弱的患病率没有影响,(P＞0.05).结论 本地区色盲患病率男性明显低于其他国家和地区,女性没有明显差别.男性色盲的患病率已经显著下降.

Abstract：

Objective To estimate the prevalence of Color Vision Defects by a population-based survey in a rural Chinese population.Methods Cluster sampling was used to select samples.Residents' sense of color with the color vision plate drawing by Ziping Yu was examined.The associations of Color Vision Defects by age and gender were calculated through multiple logistic regression.Results Among the 11,391 people entered in the project,10,030 were examined(88.05%),and of these 5,162(51.46%)were men.The prevalence of color blindness and color weakness was 1.72%(95% confidence interval CI:1.47%～1.97%)and 1.51%(95% CI:1.28% to 1.74%),respectively.We found that gender was associated with color anomalopia.Of the 251 cases of defective color vision in males,132 cases(2.56%)involved color blindness,119 cases(2.30%)involved color weakness; Of the 73 cases of defective color vision in females,41 cases(0.842%)involved color blindness,32 cases(0.657%)involved color weakness; men had a higher abnormal rate than women.Significant difference was found in the above results according to the statistics.Conclusions The male prevalence of color deficiencies in this area has already fallen down.No significant difference is found in females.     

The validity of the University of Waterloo Colored Dot Test for Color Vision Testing in adults and preschool children.

PURPOSE: Most color vision tests require a high level of cognitive ability and as such are problematic for preschool children and multiply challenged individuals. Our goal was to design a color vision test for these groups and evaluate the clinical utility for preschool children. METHODS: The University of Waterloo Colored Dot Test (UWCDot) for Color Vision Testing requires the subject to distinguish a colored disc from seven gray discs. The target disc was a Munsell color along the deutan, protan, or tritan confusion line with gray. The first phase estimated the sensitivity and specificity of the test for adults. Thirty-one adults with normal color vision and 21 adults with congenital red-green defects participated. In the second phase, the utility of the UWCDot test for screening preschool children was determined. Subjects were 281 males and 269 females aged 2.5 to 5 years with normal vision. Their color vision was also assessed with the Standard Pseudoisochromatic Plates, Part 1 (SPP1). RESULTS: The sensitivity and specificity of UWCDot for adults approached the values for the desaturated D-15 when subjective responses were scored. Monitoring fixational eye movements produced sensitivity and specificity values that were similar to the anomaloscope. After adjusting the scoring criterion for the preschool children by using the females as a control, 2.9% of the males were identified as red-green deficient, 1.8% were blue-yellow deficient, and 3.2% had an unclassified deficiency. By definition, 1% of the females failed the test. Counting fixational eye movements was not a useful scoring method in the preschool children. Comparisons with SPP1 indicated that the UWCDot uncovers approximately 35% of the individuals with definite red-green color vision defects. CONCLUSIONS: Our results indicate that the UWCDot is capable of detecting approximately 35% of the preschool children who have a congenital red-green color vision defect. These individuals are likely to have a more severe deficiency.     

The mentally handicapped patient: a perspective

The patient exhibiting decreased cognitive abilities (mental retardation) requires full scope optometric care, but may often receive little or no vision care whatsoever. This paper will provide the optometrist with a review of the history of exceptionality, Public Law 94-142, the educational classification of mental retardation, and various examination techniques appropriate for this population. The optometrist should contribute his/her knowledge and skill as a member of the patient's rehabilitation team and provide those services required by this unique population.