Lori A. Lott

Vision and Driving Self-Restriction in Older Adults

Objectives: To assess driving self‐restriction (vision related and nonvision related) in relation to vision test performance of older adults.

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.

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.

Face recognition in the elderly.

Purpose. The purpose of this study was to assess face recognition ability in a large sample of elders (n = 572, mean age = 78.1 years) and to identify factors that affect performance. Methods. Face recognition was measured by presenting standardized faces of varying sizes to simulate normal-sized faces at different viewing distances. Subjects were asked to identify the name of the person and their facial expression. Threshold equivalent viewing distance (EVD) was calculated. High- and low-contrast acuity, contrast sensitivity, low-contrast/low-luminance acuity, disability glare, stereoacuity, and visual field measures (with and without an attentional task) were also measured. These vision measures, along with demographic information (age, sex, education) and cognitive status, were included in a multiple regression analysis to determine which factors predicted task performance. Results. This cross-sectional sample of elders showed significant declines in face recognition with age. Mean threshold EVD ranged from 8.0 m for participants ≤70 years of age to 2.2 meters for those over 85 years. Multiple regression analysis revealed that age, sex, years of education, spatial vision, and cognitive status were all significant predictors of face recognition, accounting for approximately 46% of the variability. Spatial vision (high-contrast acuity) and age were the best predictors. Although each spatial vision measure was significantly correlated with face recognition, adding low-contrast or contrast sensitivity measures to the regression analysis explained no more variance than age and high-contrast acuity alone. Conclusions. The marked decline in face recognition ability in elders is related to declines in spatial vision and cognitive status. All spatial vision measures have similar predictive ability for face recognition.

The Relation Between Visual Acuity and Other Spatial Vision Measures

Purpose To examine to what extent measurement of standard visual acuity allows prediction of other spatial vision measures on an individual basis when high correlations exist between visual acuity and the other measures. Methods A series of spatial vision functions were measured in a sample of 900 community-dwelling older observers. Regression analysis was performed, and correlation coefficients were calculated between standard high-contrast visual acuity and other spatial vision measures including contrast sensitivity, low-contrast acuity, low-contrast low-luminance acuity (SKILL card), and disability glare acuity. Results All measures were highly and significantly correlated with standard visual acuity (r = 0.68 to 0.91). Despite the high correlations, many predictions of the other spatial vision measures from the correlation with standard acuity fell considerably outside of acceptable ranges determined by repeatability. The influence of the range of values in correlations is emphasized. Conclusions Other spatial vision measures cannot be predicted on an individual basis from visual acuity despite high and significant correlations between the measures.

Saccades reduce latency and increase velocity of ocular accommodation

Horizontal vergence can be stimulated binocularly with disparity (disparity vergence) or monocularly with accommodation (accommodative vergence). The latter results from a neural cross-coupling that causes both horizontal vergence and accommodation to respond when either one is stimulated [Alpern, M., & Ellen, P. (1956). American Journal of Ophthalmology, 42, 289-303]. The velocity of disparity and accommodative vergence is enhanced when accompanied by saccades [Enright, J. T. (1984). Journal of Physiology (London) 350, 9-31; Enright, J. T. (1986). Journal of Physiology (London) 371, 69-89]. Based upon the coupling between accommodation and vergence, we predicted that accommodation should also be facilitated by saccades. An SRI Dual Purkinje Eyetracker was used to measure left and right eye position, and the accommodation of the left eye, in response to stimulation. Horizontal saccades were stimulated by targets separated by 2-6 degrees and accommodation was stimulated monocularly over a range of +/- 2 diopters (D). When saccades occurred within 0-400 ms following a monocular step stimulus to accommodation, latency of accommodation decreased and the associated accommodative-vergence response was synchronized with the saccade. Saccades also enhanced the velocity of accommodation and accommodative-vergence, and this facilitation increased with saccade amplitude. Transient vergence responses that are normally associated with saccades [Erkelens, C. J., Steinman, R. M., & Collewijn, H. (1989). Proceedings of the Royal Society of London B. Biological Sciences, 236, 441-465; Maxwell, J. S., & King, W. M. (1992). Journal of Neurophysiology, 68 (4), 1248-1260] did not affect accommodation when it was not stimulated by defocus. Because saccades and accommodation utilize separate plants and final common pathways, the synchronization of saccades and accommodation and the enhanced velocity of accommodation and accommodative-vergence must occur at more central sites. Possibilities include the superior colliculus, which represents both accommodation and saccades [Nagasaka, Y., & Ohtsuka, K., (1998). Investigative Ophthalmology AVRO supplement], vestibular nuclei which project to regions near the oculomotor nuclei [Lang, W., Buttner-Ennever, J. A., & Buttner, U. (1979). Brain Research, 177, 3-17], and interactions between omni pause neurons and near response cells of the mesencephalic reticular formation (MRF) [Mays, L. E., & Gamlin, P. D. R. (1995a). Current Opinions in Neurobiology, 5, 763-768; Mays, L. E., & Gamlin, P. D. R. (1995b). Eye movement research: Mechanisms, processes and applications. New York: Elsevier] which represent both accommodation and vergence [Judge, S. J., & Cumming, B. G. (1986). Journal of Neurophysiology, 55, 915-930; Zhang, Y., Mays, L. E., & Gamli, P. D. R. (1992). Journal of Neurophysiology, 67, 944-960].

The Influence of Subject Instruction on Horizontal and Vertical Vergence Tracking

Previously it has been reported that horizontal disparity vergence is strongly influenced by subject instructions to vary attention or tracking effort. This paper describes experiments which compared these instruction effects on horizontal and vertical disparity vergence. Within-trial comparisons were made possible by use of oblique (combined horizontal and vertical) disparity modulation. Subjects viewed a flat, fully correlated, dynamic random noise stereogram pattern through stationary circular apertures, with a small stationary fixation cross superimposed in the center. The disparity of the noise pattern was either modulated sinusoidally or changed abruptly. Subjects were instructed either to (1) hold fixation on the cross and ignore the disparity modulation of the noise pattern; or (2) follow the movement of the noise pattern as accurately as possible. Subjects showed clear effects of instruction on the horizontal component of tracking, but showed little or no effect on the vertical component. Horizontal and vertical components of oblique vergence tracking appear to be largely independent, and vertical vergence is affected minimally, if at all, by an effort to track.

Development of refractive errors into old age

Purpose. To evaluate refractive errors in older adults. Methods. The distribution of refractive error components was evaluated in a sample of 569 older adults including 171 participants over the age of 80 years. The mean age was 75.2 years with a range from 59 to 106 years. Emphasis was placed on modern methods of analyzing astigmatic refractive errors, which convert cylindrical refractive errors into primary and oblique components. Results. The known increase in hyperopia after maturity continues into old age. The primary negative astigmatic component increases dramatically in prevalence and amount after age 70 years, whereas the oblique component remains unchanged. Significant anisometropia is common in the oldest old, suggesting failure of emmetropization mechanisms with age. Substantial gender differences exist in refractive changes with age. Conclusions. The continuing changes in all components of refractive error into old age and the surprisingly high prevalence of large amounts of astigmatism and anisometropia emphasize the importance of regular refractive evaluations among the oldest old.

Dual sensory loss: overview of problems, visual assessment, and rehabilitation.

This article provides an overview of some of the problems and possible solutions surrounding the neglected issue of combined vision and hearing deficits. The subject is treated by considering each subpopulation, ranging from those who have no residual vision or hearing to those with mild coexisting vision and hearing losses. An attempt is made to relate the different types of visual deficit to the likely problems encountered in real-life activities, such as communication and travel, among individuals who also have a hearing impairment. The assessment and appropriate referral of patients with these combined deficits is discussed, including the interpretation of visual test results and the importance of factors other than standard visual acuity. Speculation is offered on potential strategies and solutions for rehabilitation as well as the need for future research and improvements in service delivery.