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[The clinical vision test].
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[Demonstration of a new apparatus for objective vision test].
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Capabilities of potential vision test measurements: clinical evaluation in the presence of cataract or macular disease.
PURPOSE: To determine the usefulness of a battery of potential vision tests (PVTs) including potential acuity meter (PAM), laser interferometer (LI), critical flicker/fusion frequency (CFF), superilluminated pinhole at distance (SPH(d)) and near (SPH(n)), and optimal reading speed (ORS) by their independence of the effects of cataracts and sensitivity to macular disease (MD). SETTING: Department of Optometry, University of Bradford, Bradford and Leeds General Infirmary, Leeds, United Kingdom. METHODS: Potential vision test measurements were determined in 76 patients with age-related cataract and no other eye disease, 52 patients with MD and clear ocular media, and 28 patients with normal, healthy eyes. RESULTS: Potential vision tests were independent of the degrading effects of cataract up to a visual acuity (VA) level of 20/200 or worse (CFF), 20/125 (ORS and SPH), and 20/40 (PAM and LI). A high degree of association was found between PVT scores and distance VA in the MD group for SPH(d) (r2 = 0.93), SPH(n) (r2 = 0.89), and PAM (r2 = 0.71). A moderate correlation was found for LI (r2 = 0.55), CFF (r2 = 0.50), and ORS (r2 = 0.45). CONCLUSIONS: Potential acuity meter and LI showed very limited independence to moderate/dense cataracts and inaccurate predictions in patients with MD. Superilluminated pinhole was relatively unaffected by moderate/dense cataract and yet provided accurate predictions in the presence of MD and clear ocular media. Critical flicker/fusion frequency showed the greatest ability to bypass cataracts, although its ability to predict VA in patients with early MD was limited. The ORS was relatively unaffected by moderate/dense cataract, but its poor ability to predict VA in MD may limit its clinical suitability as a PVT.
Color changes in the red-green plates of the 50-year-old AO HRR color vision test.
The original AO HRR color vision test has been considered by many as one of the best plate tests. It is still accepted by many governmental agencies for color vision certification. In their 1954 publication, Hardy, Rand, and Rittler stated that specially compounded inks were used for printing to avoid color changes with time. Fifty years later, it is both important and interesting to determine whether the wear and tear cause significant color changes. The chance finding of a never-used second edition offers an opportunity to evaluate the color changes. A GretagMacbeth Spectrolino spectrophotometer was used to measure the chromaticities of the never-used book, and an extensively used book. Four plates (#4, 7, 13, 16), selected randomly from the four red-green sections, were analyzed. The colored dots from each of the eight plates were plotted on a CIE chromaticity diagram. Isocolor lines were drawn to evaluate chromatic alignment. Chromaticities for plates #4 and 7 are significantly different between the two books. With regard to alignment with isocolor lines, the extensively used book is better than the never-used book for plate #4. There is significant misalignment on plate #7 for both books. Chromaticities for plates #13 and 16 are essentially identical between books, all with good alignment with isocolor lines. The overall comparison shows that the chromatic alignment characteristics of the extensively used book are not worse than the never-used book. Since colors in these plates have to be aligned with both the protan and deutan axes, any significant color changes would have disturbed this delicate requirement. The findings of many plates with good alignment, and the lack of differences on plates #13 and 16 between books, suggest that there are no significant color changes over time. Differences between books on plates #4 and 7 were likely the result of the original printing process.
[Exact method of testing vision in children].
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[New method of testing vision in infants].
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Repeatability and intercorrelations of standard vision tests as a function of age.
PURPOSE: We assessed repeatability and intercorrelations of five standard vision tests in subjects with normal vision. METHODS: Seventy-eight subjects (aged 21 to 68 years) completed five measurements each of high- and low-contrast visual acuity, near visual acuity and contrast sensitivity (Pelli-Robson chart). RESULTS: Except for correlations between high- and low-contrast visual acuity (r = 0.78), intercorrelations between tests were low to moderate (r < 0.5). For each measure, variability for the group was about one line on the chart (one triplet for the Pelli-Robson chart) and the minimum variability for an individual subject was about one third of this. On average, 1 to 2 lines can be expected to be lost over the normal lifespan on each test. Variability in responses did not increase significantly with age for any test. CONCLUSIONS: The criterion for judging change on commonly used clinical vision tests is about one line for subjects over a wide age range.
Vision testing of young children in the age range 18 months to 4 1/2 years.
Four hundred and twenty-five normal children in the age range 18 months to 4 1/2 years have been studied to determine the percentage of children according to age who can be expected to cooperate in a letter-matching vision test using a key card; to see whether the use of plastic letters to replace the key card lowers the age at which a letter-matching test can be achieved, and to show that children in this age range can do a vision test at 20ft (6m). Acceptance of occlusion using a patch occluder was also examined. The study shows that children effectively begin to cooperate in letter-matching vision tests using a key card from 33 months of age. Replacement of the key card with plastic letters lowers the age to 30 months and thereafter there is a gain of some 25% of children up to 39 months. All children were successfully tested at 20ft (6m). The most difficult age for occlusion was in the age group around the second birthday.
Predicting components of closed road driving performance from vision tests.
PURPOSE: Mild cataracts can interfere with visually dependent everyday activities, although they only minimally affect static visual acuity. This study compared the effects of simulated cataracts with that of optical blur on driving performance and determined the extent to which acuity could account for variations in driving performance either alone or in combination with supplementary vision tests. METHODS: Closed road driving performance was measured in 24 young, normally sighted subjects under five binocular acuity levels, four produced by different levels of optical blur (6/4.5, 6/12, 6/30, 6/60) and one by frosted lenses simulating mild cataracts (6/12c). Driving measures included gap perception, total driving time, sign recognition, road hazard avoidance, maneuvering time, and errors. Subjects were also tested with the Pelli-Robson chart, SKILL card, and Berkeley Glare Test under comparable acuity levels. RESULTS: Total driving time, sign recognition, and hazard avoidance were linearly related to the acuity degradation produced by blur; performance in the 6/12c condition was similar to that in the 6/60 blur condition. Static acuity predicted 30% to 60% of the variance in these driving measures when the 6/12c condition was excluded from analysis; this proportion was reduced by a factor of two to three when the 6/12c condition was included. However, using any one of the three supplementary tests with visual acuity in a multiple regression analysis recaptured much of the lost variance. CONCLUSIONS: Static acuity can only predict variations in closed road driving performance measured under degraded conditions that include simulated mild cataracts when it is combined with supplementary vision tests.
A new contrast sensitivity vision test chart.
A new contrast sensitivity vision chart has been tested and compared to an automated video-based vision tester on 83 observers whose ages ranged from 9 to 75 years. Good agreement was found between the contrast sensitivity measurements obtained from the vision chart and the automated tester for similar population and age variations. These results suggest that vision test charts can be developed to provide useful contrast sensitivity psychometric functions and yet be as simple to use as present eye charts.
Evaluation of mid-term stability of night vision tests.
BACKGROUND: Dark adaptation rate, scotopic retinal sensitivity and contrast sensitivity under mesopic conditions, but not visual acuity, have been shown to be directly related to the ability to identify military targets at night. These parameters can be used to select personnel for specific military tasks demanding excellent night vision, as well as to assess pharmacological effects on night vision. PURPOSE: To evaluate the mid-term (2 to 6-week period) stability of night vision tests based on assessment of the above parameters. METHODS: Dark adaptation rate, scotopic retinal sensitivity and contrast sensitivity under mesopic conditions were studied in 16 young volunteers during a 6-week period. RESULTS: Tests of scotopic retinal sensitivity (after 30 min of dark adaptation) exhibited high reproducibility and a low fluctuation rate, with a high correlation between values at week 0 and at 2-week intervals during the following 6 weeks of the study (rs (week 0 to week 6) = 0.81, p = 0.0001). The reproducibility of mesopic contrast sensitivity tests (average of 1.5, 3, 6 and 12 cycles per degree, (cpd)) was fair (rs (week 0 to week 2) = 0.67, p = 0.0045), whereas that of dark adaptation rate tests was poor. CONCLUSIONS: In view of the reproducibility characteristics of these night vision tests, assessment of night vision ability in pilots and military personnel, as well as assessment of pharmacological effects on night vision, may be based on scotopic retinal sensitivity (after 30 min of dark adaptation) and contrast sensitivity under mesopic conditions (average of 1.5, 3, 6 and 12 cpd).
Color vision testing with a computer graphics system: preliminary results.
We report a method for computer enhancement of color vision tests. In our graphics system 256 colors are selected from a much larger range and displayed on a screen divided into 768 x 288 pixels. Eight-bit digital-to-analogue converters drive a high quality monitor with separate inputs to the red, green, and blue amplifiers and calibrated gun chromaticities. The graphics are controlled by a PASCAL program written for a personal computer, which calculates the values of the red, green, and blue signals and specifies them in Commité Internationale d'Eclairage X, Y, and Z fundamentals, so changes in chrominance occur without changes in luminance. The system for measuring color contrast thresholds with gratings is more than adequate in normal observers. In patients with mild retinal damage in whom other tests of visual function are normal, this method of testing color vision shows specific increases in contrast thresholds along tritan color-confusion lines. By the time the Hardy-Rand-Rittler and Farnsworth-Munsell 100-hue tests disclose abnormalities, gross defects in color contrast threshold can be seen with our system.
Practical color vision tests for air traffic control applicants: en route center and terminal facilities.
BACKGROUND: Two practical color vision tests were developed and validated for use in screening Air Traffic Control Specialist (ATCS) applicants for work at en route center or terminal facilities. The development of the tests involved careful reproduction/simulation of color-coded materials from the most demanding, safety-critical color task performed in each type of facility. METHODS: The tests were evaluated using 106 subjects with normal color vision and 85 with color vision deficiency. The en route center test, named the Flight Progress Strips Test (FPST), required the identification of critical red/black coding in computer printing and handwriting on flight progress strips. The terminal option test, named the Aviation Lights Test (ALT), simulated red/green/white aircraft lights that must be identified in night ATC tower operations. Color-coding is a non-redundant source of safety-critical information in both tasks. RESULTS: The FPST was validated by direct comparison of responses to strip reproductions with responses to the original flight progress strips and a set of strips selected independently. Validity was high; Kappa = 0.91 with original strips as the validation criterion and 0.86 with different strips. The light point stimuli of the ALT were validated physically with a spectroradiometer. The reliabilities of the FPST and ALT were estimated with Chronbach's alpha as 0.93 and 0.98, respectively. CONCLUSIONS: The high job-relevance, validity, and reliability of these tests increases the effectiveness and fairness of ATCS color vision testing.
Architecture and design of a computerised stereogram generator for vision test.
A new microcomputer-based stereogram generator was designed and implemented to generate various visual stimuli that are used for testing the binocular vision system. The system is capable of generating static and dynamic stereoscopic stereograms that can be varied in size, shape, speed and disparity. It can also be used to generate a luminous stimulus on a dark background which, except for the depth parameters, can be varied in a similar way to the stereoscopic stimulus. A 16/32-bit microprocessor has been employed for the overall control of the stereogram parameters, which provides flexibility, versatility, compactness and speed at reduced cost. We have applied this system to the measurement of eye movement and computer vision.
[Color vision test for detection and evaluation of dyschromatopsia].
METHODS: The color vision test for diagnosis and evaluation of the dyschromatopsias consists of a set of 92 colored test charts of the pseudochromatic type, a lamp and a test report giving a graphic image of the sensitivity to color deficiency. RESULTS: The test makes it possible to identify each neutral zone of all types of dyschromatopsia, places the neutral zone within the color spectrum and establishes its extent according to 6 axes (Protan, Deutan, Tritan, Tetartan, Scotopic and Monochromatic) and 10 levels. The visual sensitivity to color is measured on a 10 point scale, just as visual acuity is. Between a normal sensitivity to color, which is marked 1, and an anopia (i.e complete lack of visual sensitivity to color along one axis), marked 0, there are 9 intermediary levels marked 0.9; 0.8: 0.7; 0.6: 0.5; 0.4; 0.3; 0.2 and 0.1. CONCLUSION: Testing is important for all kinds of eye diseases or common diseases which affect eyesight making possible not only early diagnosis of a disease but also treatment follow-up.
Optimal reading speed in simulated cataract: development of a potential vision test.
Previous studies suggest that optimal reading speed is unaffected by cataract, yet is significantly reduced in age-related macular disease. This raises the question of whether a reading speed test could be developed to assess potential vision after cataract surgery. In this study, 20 young subjects, with and without a simulation of dense cataract, read aloud Bailey-Lovie word charts. From the results, critical print size, optimal reading speed and word acuity were calculated. The simulated cataract reduced word acuity and increased the critical print size, yet optimal reading speed remained unchanged. Measurements were also taken with the charts in reversed contrast polarity. Reversing the contrast polarity of the charts improved the word acuity and optimal reading speed with the cataract simulation. The results suggest that optimal reading speed could be used as a potential vision test. Further investigations using patients with cataract and ARMD are required.