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Psychophysics of reading. VIII. The Minnesota Low-Vision Reading Test.

This is the eighth in a series of papers dealing with the role of vision in reading. In previous papers, we have evaluated the effects of stimulus and subject variables on reading rate using a drifting-text procedure. In this paper, we describe a new test of reading rate that uses static text, called the Minnesota Low-Vision Reading Test (MNread). It is microcomputer-based, and more easily set up and administered than the drifting-text procedure. It is of potential value as a standardized psychophysical test of reading and should be useful in research, clinical, and educational applications. Some types of low-vision aids rely on drifting text and others on static text. Is reading performance different for these two modes of text presentation? We measured reading rate as a function of angular character size for normal and low-vision subjects with drifting and static text. Although reading rates were highly correlated for the two modes of text presentation, normal subjects usually read static text more rapidly. The reverse was true for low-vision subjects; their reading rates for drifting text were slightly higher (average 15%) than for static text.

Adult↗

[Options and limits of visual function tests available on the internet].

BACKGROUND: The quantitative capability of the visual system can be tested using graphic presentations with defined size, form and colour. For presentations a chart projector or personal computer (PC) can be used. In the meantime the number of visual function tests on the internet is continually increasing. These tests are potentially available for over 400 million internet users with different hard- and software requirements. METHODS: From 38 on-line visual acuity tests and 19 on-line colour vision tests found by means of search engines on german language web pages, the offerer of the test, the type of chart used and the data for the test conditions, as well as hard- and software adjustment were registered. RESULTS. Various visual function tests, such as visual acuity tests, the Amsler grid, stereo and colour vision tests, can already be planned via internet. The variability of the tests ranges from a simple presentation of graphic elements to a laboriously programmed interactive input by the user to specify the test result. Most of the tests are presented by opticians and the optical industry. DISCUSSION: The analysed tests allow for a considerable variability of the test conditions, for example by missing data concerning the room lighting and lacking monitor calibration. Furthermore, problems of the web-based colour presentation were not considered or not considered sufficiently in most of the on-line colour tests. CONCLUSIONS: Because of the test deficits determined, the results of visual function tests on the internet are to be classified as doubtful. At present, most data of test offerers are not sufficient with respect to the test conditions. Standards should be defined for internet-based visual function tests and further studies should be followed to check the effectiveness of these tests for screening examinations.

Color Perception Tests↗

Visual dysfunction predicts cognitive deficits in Alzheimer's disease.

Deficits in basic visual capacities are prevalent in Alzheimer's disease (AD), raising the question of their impact on cognitive function. We examined the relation between vision and cognition in 72 patients with AD. Vision tests assessed color discrimination, stereoacuity, contrast sensitivity, and backward pattern masking. For cognitive tests of object recognition, at least 25% (up to 50%) of score variance was predicted by performance on a vision test. For tests of spatial localization, only 2 to 11% of the variance was predicted by performance on a vision test. The results indicated that: (1) visual dysfunction was a significant predictor of cognitive dysfunction in AD, and (2) visual deficits in AD may have a strong functional impact on performance in specific cognitive domains.

Aged↗

Sensitivity and specificity of tests to detect eye disease in an older population.

OBJECTIVE: To compare the ability of tests of visual function to detect the presence of eye disease. DESIGN: Cross-sectional study. PARTICIPANTS: Three thousand six hundred fifty-four of 4433 (82.4%) eligible residents of an area near Sydney aged 49 years and older had a detailed eye examination, including retinal and lens photography and subsequent grading of eye disease, tests of presenting and corrected visual acuity, contrast sensitivity, screening visual field and intraocular pressure. MAIN OUTCOME MEASURES: Receiver operator characteristic (ROC) curves were created and area under the curve compared for each vision test. Sensitivity and specificity were calculated for each test. RESULTS: No single vision test predicted the presence of eye disease with any consistency. Best-corrected visual acuity or contrast sensitivity had the highest area under the ROC curve for most eye diseases examined but had poor sensitivity and specificity. For glaucoma and diabetic retinopathy there was no difference in area under the curve for any of the tests examined, and no test had a good balance of sensitivity and specificity. Screening tests (performed with presenting correction) did not perform as well as nonscreening tests (those carried out after refraction with best correction). CONCLUSIONS: Current vision tests are not particularly good at detecting eye disease compared with the "gold standard" of a full eye examination performed by an ophthalmologist. Further work in this area should be carried out before vision screening programs can be recommended for implementation among older people.

Aged↗

Evaluation of congenital colour vision deficiencies.

Three hundred patients who have congenital colour vision deficiencies were examined at the author's eye clinic for 3 years (1987-1990) using 5 types of colour vision tests: Hahn's, TMC's, Okuma's (new), H-R-R's colour vision tests and Double 15 Hue Test (Hahn). The results obtained from each test were quite different in type and grade, and the summarized results were considered to be the best: Type: protan 23.3%, deutan 76.0%, unclassified 0.7% Grade: mild 20.3%, medium 25.3%, strong 54.4% The frequency of coincidence both in type and grade between the summarized results and those of each test were compared, and the highest was 62.3% in Double 15 Hue Test. The efficiency of the author's colour vision test and Double 15 Hue Test were evaluated with the data in this clinical trial, and they were found to be useful for classifying the type and estimating the grade of the congenital and also acquired colour vision deficiencies.

Adolescent↗

Motorist vision policy.

BACKGROUND: The primary purpose of public policy requiring vision testing for driver license renewal is to identify individuals with functional vision impairments and, when necessary, to restrict their driving. This is based on the presumption that poor vision is causally related to poor driving and traffic crashes. METHODS: The AOA Environmental and Occupational Vision Committee performed a synthesis of relevant empirical literature on policy-based research and developed potential options for enhancing traffic safety. RESULTS: Presently, some states require vision testing for driver's license renewal and some do not. Regional and nationwide studies report that vision-related license renewal policies are associated with enhanced traffic safety. However, contemporary vision screening tests may be of limited value in identifying individuals with functional vision impairments. CONCLUSION: The most cost-effective and valid method for identifying, treating and counseling visually impaired drivers is to require a comprehensive eye examination as a condition for driver license renewal for those with a high prevalence or high probability of vision impairment.

Accidents, Traffic↗

Multifocal electroretinographic evaluation of long-term hydroxychloroquine users.

OBJECTIVES: To observe the long-term effects of hydroxychloroquine sulfate on retinal electrical activity by multifocal electroretinography (mfERG) and to evaluate the regional variation of retinal dysfunction in subjects with hydroxychloroquine retinopathy. METHODS: Multifocal ERG with 103-hexagon stimulation was performed on 19 patients (36 eyes) treated with hydroxychloroquine for systemic lupus erythematosus, rheumatoid arthritis, or localized atypical scleroderma. Visual acuity testing, Amsler grid testing, and Ishihara color vision testing were also performed. In 2 of the patients, hydroxychloroquine was discontinued due to concerns about toxicity. Both of these patients had additional mfERG performed after discontinuation of medication. RESULTS: Twelve patients (19 eyes) had a normal response density in one or both eyes, including 6 patients (12 eyes) with a low lifetime dose (< or =438 g) of hydroxychloroquine who had normal response densities in both eyes. Eleven patients (17 eyes) had abnormal response densities in one or both eyes, and 2 of these patients (4 eyes) had significant attenuation of response densities in almost the whole tested field; 4 patients had a normal mfERG result for one eye but had a slight decrease of response densities for the other eye. There were 4 patterns of abnormal mfERG amplitude change observed: (1) paracentral loss, (2) foveal loss, (3) peripheral loss, and (4) generalized loss. Implicit times were abnormal for pericentral responses in 3 patients. The results of color vision and Amsler grid testing were normal, except for one patient with a generalized loss pattern. In 2 subjects in whom hydroxychloroquine toxicity was suspected, response densities improved after termination of hydroxychloroquine. CONCLUSIONS: Long-term hydroxychloroquine use may be associated with mfERG abnormalities. The mfERG appears to detect retinal physiological change earlier than visual acuity testing, color vision testing, or Amsler grid testing can. The greatest value of the mfERG is in differentiating a retinal cause and, hence, providing important evidence for hydroxychloroquine toxicity, for whatever visual field loss is apparent on perimetry.

Adult↗

Standard measures of visual acuity do not predict drivers' recognition performance under day or night conditions.

PURPOSE: This study investigated whether visual acuity or contrast sensitivity, measured under a range of luminance conditions, could predict drivers' recognition performance under real-world day and night road conditions. METHODS: Twenty-four participants, comprising three age groups (younger, mean = 21.5 years; middle-aged, mean = 46.6 years; and older, mean = 71.9 years), drove around a 1.8-km closed road circuit under day and nighttime conditions. At night, headlight intensity was varied over 1.5 log-units by ND filters mounted on the headlights. Participants drove around the circuit under five light conditions (daytime and four at night) and were asked to report relevant targets, including road signs, large low-contrast road obstacles, and pedestrians who wore retroreflective markings on either the torso or the limb joints (creating "biological motion"). Real-world recognition performance was measured as percent correct recognition and, in the case of low-contrast road obstacles, avoided. Clinical vision tests included high-contrast visual acuity and Pelli-Robson letter contrast sensitivity measured at four luminance levels. RESULTS: Real-world recognition performance of all age groups was significantly degraded under low light conditions, and this impairment was greater for the older participants. These changes in drivers' recognition performance were more strongly predicted by contrast sensitivity than visual acuity measured under standard photopic conditions. Interestingly, contrast sensitivity was highly correlated with visual acuity measured under low-luminance conditions. Further analyses showed that recognition performance while driving is better predicted by combinations of two tests: either 1) photopic visual acuity and photopic contrast sensitivity, or 2) photopic and mesopic visual acuity. CONCLUSIONS: These findings confirm that visibility is seriously degraded during night driving and that the problem is greater for older drivers. These changes in real-world recognition performance were better predicted by a standard test of contrast sensitivity than by visual acuity. Still better predictions can be obtained by the use of two vision tests. The implications of these findings for driver licensing standards are discussed.

Adult↗

The night vision threshold test is a better predictor of low serum vitamin A concentration than self-reported night blindness in pregnant urban Nepalese women.

This study was conducted to validate the night vision threshold test (NVTT) as an indicator of night blindness. A total of 1401 pregnant women from the National Maternity Hospital participated in this study. Women were queried about night blindness and took the NVTT using standardized procedures after 10 min of dark adaptation. Sixteen percent failed the NVTT, but only 6.4% reported having night blindness. Blood samples from women who failed the NVTT (cases) and matched controls indicated the serum vitamin A (SVA) concentration was lower (P < 0.05) in cases (1.19 +/- 0.03 micromol/L) than in controls (1.29 +/- 0.03 micromol/L). The SVA concentrations did not differ between women who reported and did not report night blindness. The SVA concentration was correlated (r = 0.22, P < 0.001) with the NVTT scores. Twenty-five percent of women with an SVA < 0.35 micromol/L reported night blindness while 100% failed the NVTT. Nineteen percent of women with an SVA < 0.70 micromol/L reported night blindness while 73% failed the NVTT. A receiver operating characteristics analysis indicated that the NVTT had greater sensitivity (0.73 vs. 0.19) and less specificity (0.51 vs. 0.87) compared with reported night blindness for women with SVA < 0.70 micromol/L and greater sensitivity (100.0 vs. 0.73) and similar specificity (0.51 vs. 0.50) for women with SVA < 0.35 micromol/L. The NVTT identified women with low SVA and self-reported night blindness was misleading. We provide a preliminary algorithm to predict the population of women with low SVA concentrations.

Adult↗

Who fails lantern tests?

A battery of clinical colour vision tests was given to a group of 100 observers with abnormal colour vision who were also tested on the Farnsworth lantern and the Holmes-Wright lanterns types A and B. It was found that clinical colour vision tests are imperfect predictors of lantern test performance. However, observers classified as having a 'severe' colour vision defect were found to fail the lantern tests but only one half to two-thirds of those who fail the lantern tests can be identified in this way. It is not possible to identify with certainty any of the people likely to pass the lantern tests: about one-third to two-thirds of observers classified as being mildly affected fail the lantern tests. The Farnsworth D-15 and City University tests were found to be the best predictors of lantern test performance but other tests such as the Nagel anomaloscope, the H-16, L'Anthony's desaturated test can also be used. The lack of a strong correlation between clinical tests and the recognition of the small coloured stimuli presented by the lantern tests suggests that clinical tests do not test the same aspect of colour vision that is important to the recognition of signal lights. For this reason lantern tests should be retained for occupational testing of colour vision.

Adaptation, Ocular↗

[A new apparatus for testing binocular vision (author's transl)].

The Optometer can be used in a binocular manner if the loupe-lens is replaced by a concave mirror of appropriate size and form. The concave mirror or the plane mirror connected to it can be partially transparent. With an appropriate arrangement of these elements the test field can be seen in free space. The image can be adjusted from infinity to 35 cm by displacement of the test object. Choice of the test object makes possible testing the stereoscopic vision under natural conditions. Other test objects can be used to test further functions of the eyes-monocular, binocular or separately.

Optometry↗

The Night Vision Threshold Test (NVTT): a simple instrument for testing dark adaptation in young children.

It is estimated that 41 per cent of the population aged under 5 in the developing world has an inadequate vitamin A dietary intake resulting in increased morbidity and mortality. Half a million children go blind each year as a result of vitamin A deficiency. Thirteen and a half million have night blindness, the first sign of vitamin A deficiency. Unfortunately, there is no simple, sensitive and inexpensive means to identify the child who has marginal levels of vitamin A and thus institute means to prevent their development of severe deficiency. A low cost, simple, easy-to-use instrument designed to detect a young child's ability to adapt to darkness was tested in children admitted to the Mwanamugimu Nutrition Unit at Makerere Medical School in Kampala, Uganda. Despite the severe degree of malnutrition found in these children, Night Vision Threshold Test results and serum retinol levels were related (r = 0.41, p < 0.05). Further efficacy trials for this instrument are planned at community sites in Nepal.

Adaptation, Ocular↗

[A study of para-foveal color vision in normal-tension and primary open angle glaucoma eyes].

A perimetric color vision test developed by Iijima et al. for evaluating parafoveal color vision provides information regarding local retinal function which can not be evaluated by other color vision tests. Using this method, we investigated para-foveal color sensitivity in normal-tension glaucoma (NTG) and primary open angle glaucoma (POAG) eyes whose glaucomatous visual field change determined with the central 30-2 program of the Humphrey visual field analyzer was confined to either the upper or the lower hemifield. The examined eyes had no abnormalities in ocular media with best corrected visual acuity of 1.0 or higher, and age, refraction, mean deviation, and extent of visual field loss were matched between NTG and POAG eyes. In the para-foveal area of the spared hemifield, acquired blue-yellow dyschromatopsia was detected in 52.3% of the POAG eyes and in 11.3% of the NTG eyes (p < 0.02, chi 2-test), and in damaged hemifield, it was found in 76.1% of the POAG eyes and 80.7% of the NTG eyes. We suggest that visual function is more diffusely damaged in POAG than in NTG and that the perimetric color vision test is useful for detecting glaucomatous damage which cannot be detected with conventional light threshold measurements.

Adult↗

Visual acuity and stereopsis between the ages of 5 and 10 years. A cross-sectional study.

The development of visual acuity and stereopsis was studied in 321 boys and 340 girls aged between 5 and 10 years. Visual acuity was assessed by the E test and a modified version of the STYCAR test, stereo acuity by the Lang-Stereo test [17]. Both vision tests showed an increase in the median visual acuity between the ages of 5 and 10 years. The E test indicated an increase from 1.2 between 5 and 6 years to 1.5-1.7 between 7 and 10 years. The values obtained with the STYCAR test were 0.6-1.3 higher, depending on the test rating used. Visual acuity norms between 5 and 10 years are presented as empirical centile curves. No significant differences were observed in visual acuity between the left and right eyes, nor between the sexes. The right eye was found to be the leading eye in 54.8% of the boys and 54.5% of the girls (P less than 0.001). The Lang-Stereo test was passed by 87.9%-94.3% of all children, and there were no significant differences with respect to age and sex. Children who failed the test had a significantly lower visual acuity than those who passed it. In the former group a significant interocular difference in visual acuity was present (P less than 0.01).

Age Factors↗

Evaluation of the visual system in multiple sclerosis: a comparative study of diagnostic tests.

In 22 patients with clinically definite multiple sclerosis (MS) who were without visual symptoms and had a visual acuity of at least 1.0 in both eyes at the time of measurement, the following tests were performed to detect subclinical lesions in the visual system: visual evoked potential (VEP), contrast sensitivity test (CS), flight of colours test (FOC), colour vision test (Ishihara plates) (CV) and the pupillary light reflex (PLR). VEP was abnormal in 81.8%, CS in 72.7%, FOC in 36.4%, CV in 31.8%, and PLR in 52.3% of the patients. VEP and CS together were most sensitive: combining these techniques subclinical lesions of the visual system were detected in 90.9% (20/22) of these asymptomatic patients.

Adult↗