Confrontation visual field tests.
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Humans↗
Biomedical subjects
D B Elliott
Publications and source records attributed to D B Elliott.
Babe Ruth: with vision like that, how could he hit the ball?
Unfortunately, it is unlikely that a definitive answer will be known. We believe that it is most likely that Ruth was not amblyopic. This seems possible only if Dr. Kara had missed some amblyogenic factor such as strabismus or a significant refractive error. Our favored solution is that Ruth's unilateral vision loss was a complication of his cancer, and that Dr. Kara's examination occurred before the optic nerve damage became detectable. Of course, this is in disagreement with the ophthalmologist who examined his eyes.
Amblyopia↗
Improvements in clinical and functional vision and perceived visual disability after first and second eye cataract surgery.
AIMS: To determine the improvements in clinical and functional vision and perceived visual disability after first and second eye cataract surgery. METHODS: Clinical vision (monocular and binocular high and low contrast visual acuity, contrast sensitivity, and disability glare), functional vision (face identity and expression recognition, reading speed, word acuity, and mobility orientation), and perceived visual disability (Activities of Daily Vision Scale) were measured in 25 subjects before and after uncomplicated cataract surgery (10 first eye surgery and 15 second eye surgery) and in 10 age matched controls. RESULTS: Significant improvements were found after surgery in clinical and functional vision and perceived visual disability. Greater improvements were found after first eye surgery than after second eye surgery. However, first eye surgery did not return all scores to age matched normal levels. There were significant improvements in several of the tests measured after second eye surgery, and all postoperative values were similar to those from age matched normals. CONCLUSIONS: Significant improvements in clinical, functional, and perceived vision are obtained by cataract surgery. The improvements in objective measures of functional vision found in this study support previous findings of improvements in patients' perceived functional vision. In addition, these data provide support to the necessity of second eye surgery in some patients to improve certain aspects of visual function to age matched normal levels.
Aged↗
Demographic characteristics of the vision-disabled elderly.
PURPOSE: To profile certain demographic features of the low-vision population in Ontario, Canada. METHODS: Sixty-six optometrists or optometry centers, 8 ophthalmologists, and 23 Canadian National Institute for the Blind rehabilitation worker teams were recruited to the study. They were required to report on their low-vision examinations during a 3-year period. RESULTS: Reports from 4744 low-vision examinations were received. Of the patients examined, 71% were over age 65 (subsequently called seniors or elderly), and 55% were over age 75. Ninety percent of all the patients lived in households and 10% lived in institutions. Seniors made up 71% of the patients living in households and 88% of the patients living in institutions. Most of the seniors were women (65%), and 57% had functional limitations in addition to low vision, most commonly limitations in mobility, hearing, or agility. Age-related maculopathy was the primary diagnosis in 75% of seniors, and the most common secondary diagnosis was cataract (46%). The main objective for most elderly low-vision patients was to gain improvement in personal reading (75%). CONCLUSIONS: The vast majority of low-vision patients were elderly, the largest number being 75 to 84 years old. When older senior low-vision patients (> or = 85 years) were compared with younger seniors (65 to 74 years), the older seniors were more likely to be women, more likely to have additional functional limitations, more likely to live in an institution, and more likely to have age-related maculopathy and cataract. Whether some elderly low-vision patients may be helped by cataract surgery needs to be determined.
Adolescent↗
A comparison of sampling efficiency and internal noise level in young and old subjects.
Contrast detection in different levels of external visual noise allows a given loss in contrast sensitivity to be attributed to either an increase in the internal noise of the visual system, a decrease in sampling efficiency, or both. Sampling efficiency indicates how effectively the available stimulus information is utilized by the visual system. The aim of this study is to investigate the effect of normal ageing on sampling efficiency and internal noise. Contrast thresholds for sine-wave gratings of 6 c/deg were measured in the presence of four (including zero) levels of externally added visual noise in young and older healthy observers. Results showed that sampling efficiencies were significantly lower for the older group compared to the younger, while the internal noise showed no significant change. The implications of the data for the relative contribution of the optical and neural systems on visual function loss with ageing are discussed. Our results suggest that the neural system plays a major role in the loss of contrast sensitivity with ageing in normal, healthy eyes.
Adolescent↗
Effect of a cataract simulation on clinical and real world vision.
AIMS/BACKGROUND: Many reports have indicated that some patients with cataract can retain good visual acuity but complain of significant visual problems. This is the first in a series of papers trying to determine what causes these symptoms and whether other clinical tests can predict the real world vision loss. METHODS: The effect of a cataract simulation with a similar angular distribution of light scatter as real cataract on clinical (visual acuity, contrast sensitivity, and disability glare) and real world vision (face recognition, reading speed, and mobility orientation) was investigated. RESULTS: The simulation had a relatively small effect on visual acuity (6/6 with the simulation), but much larger effects on contrast sensitivity and low contrast acuity with and without glare. The simulation had no effect on high luminance and high contrast real world tasks, such as mobility orientation in room light and optimal reading speed. A small, but significant deterioration was found for the slightly lower contrast task of face and expression recognition. However, under low luminance conditions, substantial defects in mobility orientation were obtained (despite 6/6 acuity). CONCLUSIONS: Although the relative effect of the cataract simulation on acuity and contrast tasks is not typical of the average cataract, it can be found in those cataract patients with visual problems despite good visual acuity. This corroborates the suggestion that it is large amounts of wide angle light scatter (forward and/or backward) which are at least partly responsible for visual disability in cataract patients with good visual acuity. A patient's reported visual disability may depend on the percentage of time he or she spends under low contrast and/or low luminance conditions, such as walking or reading in dim illumination, and walking or driving at night, in fog, or heavy rain.
Adult↗
Visual acuity changes throughout adulthood in normal, healthy eyes: seeing beyond 6/6.
There are many useful longitudinal and cross-sectional epidemiological studies of how visual acuity (VA) deteriorates with age. However, few studies have evaluated age-related VA changes in normal, healthy eyes. Data from three previous studies that included VA measurements taken with logMAR charts from subjects with normal, healthy eyes were collated and additional data from 42 subjects were added. This provided VA results from 223 subjects (age range 18 to 80 years). Mean logMAR VA improved from -0.13 (Snellen equivalent 6/4.5) in 18- to 24-year-olds to -0.16 (Snellen 6/4(-1)) in 25- to 29-year-olds and then gradually became worse with age to a mean value of -0.02 (Snellen 6/6+1) for subjects over 75 years of age. The inadequacy of 6/6 as a norm value of VA is illustrated. The data show VA levels far superior to the data from the standard references of Pitts (1982) and Weale. (1975, 82) We suggest that this is because we used logMAR charts (providing nontruncated data), the subject's optimal refractive correction (rather than habitual) and strict exclusion criteria ensuring that only subjects with normal, healthy eyes were recruited for the studies.
Adolescent↗
The Waterloo Vision and Mobility Study: postural control strategies in subjects with ARM.
Binocular vision function and standing balance control was assessed in 16 subjects with age-related maculopathy (ARM) (mean age 73.9 +/- 7.4 years) and 19 controls (mean age 69.1 +/- 5.5 years). Balance control was assessed using the center of pressure signal from force plate data. It was quantified using the root mean square (RMS) error of the amplitude, sampled over a 1 min period. This was evaluated during normal standing, and while the input from the kinesthetic and/or visual systems were disrupted. The two subject groups showed significantly different RMS values across conditions (P < 0.005). The differences in RMS between ARM and control groups were only significant when the input to the kinesthetic sensory system was disrupted. Our results suggest that in the normal standing condition, the kinesthetic and vestibular systems compensated for the lack of useful information from the visual system in ARM subjects. When kinesthetic system input was disrupted, balance control of the ARM group was significantly poorer than the control. There was a weak correlation between postural control and contrast sensitivity. Various strategies for preventing falls in elderly patients with low vision are suggested.
Aged↗
Accuracy of Javal's rule in the determination of spectacle astigmatism.
Javal's rule and Grosvenor's simplification of it are commonly used formulas for predicting spectacle astigmatism from keratometric measurements. We assessed the accuracy of these two rules. Spectacle astigmatism was estimated using both rules from measurements of corneal astigmatism on 100 eyes of 100 subjects. These estimates were then compared to the subjectively determined spectacle astigmatism. Grosvenor's simplification of Javal's rule gave slightly more accurate assessments than the original rule. However, only 66% of results gave estimates within 0.50 D, and 7% differed by more than 1.00 D. This can be compared to previous reports on the accuracy of autorefractors, where approximately 95% of cylinder results were within 0.50 D of the spectacle astigmatism. These results indicate that using Javal's rule or Grosvenor's simplification of it to determine spectacle astigmatism from corneal cylinder readings is of limited clinical value.
Adult↗
Waterloo Vision and Mobility Study: gait adaptations to altered surfaces in individuals with age-related maculopathy.
Walking is an extremely complex task that can become seriously challenged if one of the sensory systems which provides input to the motor system is compromised. The present study evaluated gait adaptations to altered surface characteristics and high and low ambient light conditions by subjects with age-related maculopathy (ARM). Twenty subjects with ARM and 20 control subjects walked along a 6 m path, along which they met 1 of 3 altered surfaces (compliant, uneven, or shiny). Kinematic data and ground reaction forces information were analyzed to discern gait adaptation strategies used by the ARM group. Ten trials on each surface were collected under both high and low ambient light levels. The ARM subjects were found to be generally more cautious when walking on the altered surfaces. For example, they walked more slowly, with a longer swing time. However, gait adaptations in the ARM group were not merely scaled versions of normal gait but were adjustments to adapt to environmental changes. Gait was modified to avoid tripping over a surface edge, to prevent slipping at heel contact, and to balance during stance. These adaptations enabled subjects to maintain safe mobility when walking in a challenging environment.
Adaptation, Physiological↗
Age-related effects of glare on luminance and color contrast sensitivity.
PURPOSE: To determine the effect of disability glare (DG) upon luminance and color contrast sensitivity for young and elderly subjects. METHODS: DG was defined as the difference in contrast sensitivity with and without the presence of a glare source. Isoluminant color gratings were modulated either along a red-green (R-G) or blue-yellow (B-Y) axis. RESULTS: Without glare the effect of age on sensitivity to both luminance and R-G color-modulated gratings was small and did not reach statistical significance (P > 0.1). However, the reduction in sensitivity for B-Y color modulation was highly significant (P < 0.01). For both age groups, DG was greatest for the R-G stimulus and least for the B-Y. DG in the elderly increased relative to the young observers for both R-G and luminance-modulated gratings (P < 0.01) but not for B-Y (P > 0.01). CONCLUSIONS: The precise effect of a glare source on color discrimination depends upon a complex interaction between the chromaticity of the glare source and that of the stimulus. In certain circumstances, such as in our R-G stimulus, glare can dramatically reduce chromatic discrimination ability by desaturating the component colors.
Adult↗
Factors affecting light-adapted pupil size in normal human subjects.
PURPOSE: To investigate the effect of age, gender, refractive error, and iris color on light-adapted pupil size in humans. METHODS: Pupil diameters of 91 subjects (age range, 17 to 83 years) with normal, healthy eyes were measured using an objective infrared-based continuous recording technique. Five photopic ocular illuminance levels were used (2.15 to 1050 lumens m-2), and the accommodative status of each subject was precisely controlled at a constant level. RESULTS: Pupil size decreased linearly as a function of age at all illuminance levels. Even at the highest illuminance level, there was still a significant effect of age upon pupil size. The rate of change of pupil diameter with age decreased from 0.043 mm per year at the lowest illuminance level to 0.015 mm per year at the highest. In addition, the variability between pupil sizes of subjects of the same age decreased by a factor of approximately two as luminance was increased over the range investigated. Pupil size was found to be independent of gender, refractive error, or iris color (P > 0.1). CONCLUSIONS: Of the factors investigated, only chronologic age had a significant effect on the size of the pupil. The phenomenon of senile miosis is present over a wide range of ocular illuminance levels.
Accommodation, Ocular↗
Confirmation of the validity of the psychophysical light scattering factor.
PURPOSE: To reevaluate the validity of the light scatter factor (LSF) formula of Paulsson and Sjöstrand, LSF = L/E (M2/M1-1), where L is the target luminance, E is the illuminance of the glare source at the eye, and M2 and M1 are modulation contrast thresholds measured with and without the glare source, respectively. This equation has recently been deemed invalid by Yager, Yuan, and Mathews. METHOD: Ratios of contrast thresholds with and without glare were measured for three glare illuminance levels for each of three stimulus luminances. This results in five different ratios of L/E, spanning a range of 1.60 log units. RESULTS: The data show an excellent fit to the Paulsson and Sjöstrand equation, and the LSF scores conform well to previously published normative values. CONCLUSION: The light scatter factor equation of Paulsson and Sjöstrand is confirmed as valid without resorting to the need for correction factors based on variables such as pupil size.
Adult↗
Ultraviolet-induced lenticular fluorescence: intraocular straylight affecting visual function.
Ultraviolet radiation (UVR) excitation of fluorophores within the crystalline lens results in intraocular straylight. These fluorescent emissions are known to increase with age. The visual effect of this increase in fluorescent straylight has not previously been published. In this study, the visual deficit associated with UV-induced lenticular fluorescence was measured for 61 normal subjects between the ages of 21 and 80 yr of age using the Regan visual acuity charts at varying levels of contrast. UVR was shown to decrease low contrast acuity and this loss increased linearly with age.
Adult↗
Evaluating visual function in cataract.
This paper reviews recent research on the evaluation of visual function in cataract. Visual impairment in cataract is principally caused by increased intraocular forward light scatter. It is assumed that visual acuity (VA) measurements assess the impact of narrow angle light scatter. This also makes the measurement of high spatial frequency contrast sensitivity (CS) unnecessary. However, VA measurements alone are an inadequate assessment of visual impairment in some patients with cataract. In addition, it is suggested that a measurement of wide-angle light scatter is required. This can be evaluated directly using the van den Berg Straylightmeter, or indirectly using low spatial frequency CS or disability glare (DG) tests. The following are discussed: (1) the relative usefulness of these tests; (2) how they can be incorporated into the decision as to when to extract a cataract; and (3) the importance of considering binocular visual function.
Cataract↗
Light scatter in the normal young, elderly, and cataractous eye demonstrates little wavelength dependency.
The purpose of the study was to investigate whether light scatter in normal young, elderly, and cataractous eyes exhibits significant wavelength dependency. Straylight was quantified by calculating light scatter factors (LSF's) based upon the reduction in contrast sensitivity produced by a glare source. The angle of the glare source relative to fixation was varied (3.25 to 26 degrees), as was its wavelength (460 to 660 nm). LSF's increased as a function of age an especially in the presence of media opacities. However, the relation between LSF and glare angle remained approximately the same for each group. Our results suggest that wavelength dependency in normal young, elderly, or cataractous eyes is rather unimportant relative to other factors.
Adult↗
Relative sensitivity of clinical tests to hydrophilic lens-induced corneal thickness changes.
The relative sensitivity of the van den Berg Straylightmeter, slitlamp biomicroscopy, a modified optical pachometer, Bailey-Lovie logMAR visual acuity (VA), and two glare tests (The Brightness Acuity Tester used with 10% contrast VA and Pelli-Robson contrast sensitivity) to hydrophilic contact lens-induced edema was assessed in 19 subjects (mean age 25.9 +/- 4.5 years). After baseline assessments, subjects wore thick hydrogel lenses on one eye which was patched tightly for 3 h. Assessments were repeated at frequent intervals after lens removal to assess recovery. None of the pachometer measurements returned to baseline within the 2-h monitoring period, although the majority were within 2% of baseline corneal thickness. The average time for the Straylightmeter scores to recover to baseline values after the lens removal was 90 min, which was similar to the time when visible edema at the slitlamp disappeared. The average time for return to baseline of logMAR VA and the two glare tests was consistently two to three times shorter than the time for the Straylightmeter score. The Straylightmeter therefore provided assessments of corneal edema similar to slitlamp examination and was more sensitive than VA or glare testing.
Adult↗