Gunilla Haegerstrom-Portnoy

Seeing into old age : Vision function beyond acuity

PURPOSEnTo provide a comprehensive description of vision function beyond acuity in older individuals.nnnMETHODSnA sample of 900 individuals between the ages of 58 and 102 years (mean age of 75.5) was binocularly tested wearing habitual correction on a battery of psychophysical tests including high and low contrast acuity, low contrast low luminance acuity, disability glare, contrast sensitivity, color vision, stereoacuity, recovery from glare, and attentional visual fields.nnnRESULTSnHigh contrast acuity is reasonably well maintained on average, even into very old ages. Spatial vision measures under conditions of reduced contrast or luminance, or glare reveal significant impairment in a large portion of the aged. Many older individuals also have greatly reduced stereopsis, poor color discrimination, and severely restricted peripheral fields under conditions of divided attention. A single exponential function relating performance to age fits all spatial vision data sets. The function for individual spatial measures lies at different positions along the age scale. The derived aging function with a time constant of approximately 15 years also fits results from other recent aging studies of acuity and contrast sensitivity.nnnCONCLUSIONSnStandard visual acuity underestimates the degree of vision function loss suffered by many older individuals under the nonoptimal viewing conditions encountered in daily life. All spatial vision functions show a similar rate of decline with age of the population, but the age at which decline begins varies among measures.

Optimum parameters for short-wavelength automated perimetry.

PurposeTo determine the optimum parameters for short-wavelength automated perimetry (SWAP) and to recommend these for standardization of the procedure. MethodsWe used a variety of stimulus and background configurations to determine the optimum background spectral distribution and luminance, and the optimum target spectral distribution, maximum luminance, and duration. We measured threshold versus intensity curves to determine which combination provided (a) the greatest isolation of the short-wavelength sensitive mechanisms and (b) the largest dynamic range for perimetry. We also evaluated the effect of lens absorption and cataract on these two factors. ResultsA broad-band yellow background at 100 candela/m2 with a narrow-band 440-nm (27-nm half-bandwidth), 1.8° diameter (Goldmann size V) stimulus presented for 200 ms was optimum at all retinal eccentricities. Specific recommendations for how to modify existing perimeters are given. ConclusionAgreement regarding the optimum parameters for SWAP should lead to standardization of the test that will facilitate comparison of results from different centers. Normative data can be collected at several sites and incorporated into statistical analysis packages currently available with various perimeters. This will greatly improve the clinical utility of this test.

The Smith-Kettlewell Institute (SKI) longitudinal study of vision function and its impact among the elderly : An overview

We present an overview of a multifaceted longitudinal study of vision function and its interaction with daily activities, health, and well-being among 900 persons aged 58 to 102 years at the first visit. Standard vision measures as well as nonconventional tests designed to assess visual performance under the nonideal conditions encountered in everyday life were used. Here we summarize a few of the findings to date, with an emphasis on a direct comparison of declines in different aspects of vision function with age. The rates of declines with advancing age vary widely for the different vision functions. Also described is the reading performance of the sample and its association with some of the vision measures. Furthermore, we describe some of the associations between vision test scores and extensive longitudinal health and functioning data collected by the Buck Center for Research in Aging. Findings show that many older people with good acuity are effectively visually impaired in performing everyday tasks involving low and changing light levels, stereopsis, glare, and low contrast. We also found that vision under nonideal conditions cannot be predicted from standard acuity on an individual basis.

Dark adaptation in age-related maculopathy

Dark adaptation was measured for patients with age‐related maculopathy (ARM) and for age‐matched controls; green and red test stimuli were flashed 15d̀ from the fovea to examine differential effects of ARM on rod and cone functions, respectively. The ARM patients showed decreases in sensitivity for both rods and cones (0.5‐ 1.5 log units) and an increased time constant of recovery for rod function. After 20 min in the dark, sensitivity to both red and green stimuli was depressed at the fovea and at 5, 10, 15 and 25d̀ eccentric to the fovea. The greatest sensitivity loss was found in the macular area (fovea and 5d̀ eccentric). Our data suggest that the ARM patients have an abnormality in both rod‐ and cone‐adaptation systems over a relatively large retinal area which extends beyond the zone of visual field abnormality.

Predictive eye movements do not discriminate between dyslexic and control children.

Pavlidis has suggested that predictive saccadic tracking eye movements distinguish between reading disabled and normal children. We have examined saccadic eye movement tracking in 34 dyslexic and 33 control subjects, between 10 and 12 yr old. The subjects were equivalent in performance IQ (WISC-R), with differences between verbal and performance IQ of less than 30 points. Children with neurological, visual or auditory deficits or histories of emotional problems and hyperactivity were excluded. There were no differences between the groups on the eye movement tracking task when scored objectively by computerized analysis of the eye movement records, or by ranking of the records by an experienced observer. Our results (and those of other recent studies) fail to support Pavlidis contention that eye movements hold the key to dyslexia.

The Glenn A. Fry Award Lecture 2003: Vision in elders--summary of findings of the SKI study.

Purpose. To assess a broad range of vision functions in a large older population, to investigate the impact of vision function loss on visual performance measures, and to determine whether low contrast vision measures can predict future loss of visual acuity. Methods. A large battery of vision functions, including spatial vision measures, glare tests, visual fields, stereopsis, color vision, temporal sensitivity, reading performance, and face recognition, was administered to a population of 900 community-living older observers (mean age, 75.5 years; SD, 9.3 years; range, 58 to 102 years). A subsample (N = 596) was retested on average 4.4 years later (SD, 1.0 years). Results. Each vision function is affected differentially by aging. Some functions show little change with age (e.g., standard clinically measured high contrast visual acuity), whereas others demonstrate drastic losses with increasing age. For the oldest age group (>90 years), vision function losses ranged from 1.2 times worse than young observers (critical flicker/fusion frequency) to 18 times worse than young observers (low contrast acuity in glare). Visual performance measures, such as reading or face recognition, are also significantly affected by aging even in those with intact visual acuity. The results demonstrate that low contrast vision functions can successfully predict subsequent loss of high contrast visual acuity. Conclusion. Nonstandard vision function measures show significant losses with age that cannot be predicted by standard clinical measures. Measures of low contrast vision function allow clinicians to identify and monitor those patients at high risk for future vision loss.

Contribution of vision variables to mobility in age-related maculopathy patients.

ABSTRACT Can mobility performance be predicted from measures of vision function? This study addressed this question by measuring a series of vision variables including visual acuity, visual fields, and differential motion sensitivity in a group of patients with age‐related maculopathy (ARM) and a group of age‐matched normals. Mobility performance at three adaptation levels was determined objectively on an indoor course. The results indicate that for the patients with ARM, mobility variables can be predicted from measures of vision function, including differential velocity sensitivity, and that simple variables such as time taken to complete the course and average speed are those which relate best to vision.

Night driving self-restriction : Vision function and gender differences

Purpose. The purpose of this study was to evaluate gender differences in the relationship between night driving self-restriction and vision function in an older population. Methods. Night driving self-restriction patterns (assessed by questionnaire) were examined cross-sectionally in relation to age, gender, health and cognitive status, depression, and vision function in a sample of 900 elders (mean age, 76 years) living in Marin County, California. Results. Of the total sample, 91% of men and 77% of women were current drivers. The mean age of the drivers was 73.3 years (range, 58–96 years). Among current drivers, women had slightly better vision function than men on most measures (low-contrast acuity, contrast sensitivity, low-contrast acuity in glare, low-contrast, low-luminance acuity, and glare recovery) but were twice as likely as men to restrict their driving to daytime. Men showed significant associations with avoidance of night driving on four spatial vision measures (high- and low-contrast acuity, low-contrast, low-luminance acuity, and contrast sensitivity). For women, in addition to these measures, a significant association was seen for low-contrast acuity in glare. Neither men nor women showed significant associations between driving restriction and performance on the other vision measures examined (glare recovery time, attentional field integrity, or stereopsis). The vision measures most predictive of self-restriction were contrast sensitivity for men and low-contrast acuity in glare for women. Conclusions. Including both cessation and self-restriction, men over age 85 years are 6.6 times more likely than women to be driving at night. For both genders, vision plays a significant role in the self-restriction decision. A higher percentage of men than women continue to drive at night with poor vision. Men’s night-driving cessation was associated with contrast sensitivity and depression, whereas women’s night-driving cessation was associated with low-contrast acuity in glare as well as age.

Reading performance in older adults with good acuity.

Purpose. This study evaluated factors affecting reading performance in a sample (N = 544) of older adults (mean age 72.8 years, range 58 to 102) with good high-contrast acuity (≥20/32). Methods. Using the Pepper Reading Test, the relationship between reading rate and several vision measures was assessed. Results. Mean corrected reading rate fell substantially over the age range tested despite the fact that these individuals all had good acuity. However, multiple regression analysis indicated that when other measures were taken into account (most notably, low-contrast vision, motor ability, and attentional field integrity), age was not a significant independent predictor of corrected reading rate. Conclusion. Reading is an important skill, and ways of enhancing reading performance should be explored. Good high-contrast acuity does not assure that older individuals can read satisfactorily.

Tracking Eye Movements Are Normal in Dyslexic Children

ABSTRACT We measured saccadic and smooth eye tracking movements in 34 dyslexic and 35 control subjects and were unable to show differences in any of the tasks or parameters measured. Subjects were carefully screened for neurological, optometric, audiological, and behavioral problems before admission to the study. We suggest that differences between our results and those of previous investigators are based on sampling differences. We conclude that while there may be children with reading disorders secondary to visual or oculomotor deficits, dyslexia can and does exist independent of such deficits. Because, in this and other studies, we have ruled out peripheral involvement, we feel that dyslexia is primarily a deficit of central information processing of written or spoken material.