Visual Acuity and Contrast Sensitivity in Relation to Falls in an Elderly Population STEPHEN R. LORD, RUSSELL D. CLARK, IAN W. WEBSTER
Visual acuity and contrast sensitivity were measured in 95 residents of a hostel for the aged (mean age = 83 years) using a dual-contrast letter chart and the Melbourne Edge Test (MET). Vision (as measured by visual acuity, the MET, low-contrast visual acuity, and difference between high- and lowcontrast acuity) decreased significantly with age and all four measures were significantly correlated. Subjects with a clinical eye disorder had poorer vision than those without a disorder although the differences were not significant. Visual acuity and contrast sensitivity were not associated with body sway when subjects were standing on a firm base. However, when the subjects were placed in a situation which provided reduced support (standing on a compliant surface), body sway was associated with poor visual acuity and contrast sensitivity. There was also a difference in contrast sensitivity between those who fell one or more times in a year of follow-up and those who did not fall. It appears that reduced vision may be a predisposing factor to postural imbalance and falls in elderly persons.
Introduction Various studies have found that visual acuity declines with age. Despite methodological and classification discrepancies, the findings of cross-sectional studies suggest that visual acuity shows a slight improvement from early childhood up to 20 years of age, remains fairly constant up to 50 years and then steadily declines to the age of 80 years and beyond [1]. Longitudinal studies by Milne [2] and Gittings and Fozard [3] support this relationship between age and visual acuity. Gittings and Fozard's findings also suggest that, even in the absence of documented pathology, most persons experience an age-associated decline in visual acuity. Since 1978 a number of researchers have examined contrast sensitivity to different spatial frequencies, in addition to visual acuity. Contrast sensitivity is measured by determin-
ing the minimum contrast level required to detect stimuli of varied frequencies. Low spatial frequencies are optically sparse, whilst high spatial frequencies are optically dense [4]. The main types of apparatus employed have been Arden plates and oscilloscope presentations [4, 5]. The overall picture that emerges is that age differentially affects contrast sensitivities of different spatial frequencies, with high spatial frequencies affected the most, and low spatial frequencies the least. This pattern appears to be evident even when older subjects have good visual acuity, i.e. 6/6 or better. In the past few years attempts have been made to produce an easy-to-administer, standardized testing procedure for measuring contrast sensitivity applicable to clinical settings [6-8]. Verbaken and Johnston have suggested that, for general clinical practice and in the functional assessment of patients with low vision, the simple measurement of edge conAge and Ageing 1991 ;20:176-181
Downloaded from http://ageing.oxfordjournals.org/ at Aston University on September 5, 2014
Summary
176
S. R. LORD ET AL.
Methods The sample comprised 95 persons from a hostel for the aged in Sydney, Australia. The subjects were aged between 59 and 97 years—the age and sex distribution is shown in Table I. Most of the subjects were generally independent in such activities of daily living as dressing, bathing and toileting. Residents had their own 'motel style' rooms and used a common dining room. Most residents (66%) left the hostel for varying periods every day, and a number regularly used public transport. Twenty-one residents (22%) used walking sticks or frames. All residents were followed up for a period of one year (using monthly questionnaires) to determine whether the visual measures were associated with falling. Falls status was primarily determined by self reports. For residents with memory impairments (who may have fallen but did not recall doing so), a secondary check was made using reports from nursing staff and accident records. Eighty-four subjects were still living in the hostel, or in associated sections of the village complex one year after testing, seven subjects had died and four had left the village. Forty subjects reported having no falls in the year whilst 44
Table I. Age and sex distribution of the sample Age group
Men
Women
Total
59-69 70-79 80-89 90-97 Mean age (SD)
0 4 9 3
2 22 46 9
2 26 55 12
82.8 (7.4)
82.7 (6.5)
82.7 (6.6)
subjects reported one or more falls. The mean age of the fallers (84.1 years) was significantly higher than the mean age of the non-fallers (81.4 years), / = 2.16, p
Visual acuity and contrast sensitivity were measured in 95 residents of a hostel for the aged (mean age = 83 years) using a dual-contrast letter chart and the Melbourne Edge Test (MET). Vision (as measured by visual acuity, the MET, low-contrast visual acuity, and difference between high- and lowcontrast acuity) decreased significantly with age and all four measures were significantly correlated. Subjects with a clinical eye disorder had poorer vision than those without a disorder although the differences were not significant. Visual acuity and contrast sensitivity were not associated with body sway when subjects were standing on a firm base. However, when the subjects were placed in a situation which provided reduced support (standing on a compliant surface), body sway was associated with poor visual acuity and contrast sensitivity. There was also a difference in contrast sensitivity between those who fell one or more times in a year of follow-up and those who did not fall. It appears that reduced vision may be a predisposing factor to postural imbalance and falls in elderly persons.
Introduction Various studies have found that visual acuity declines with age. Despite methodological and classification discrepancies, the findings of cross-sectional studies suggest that visual acuity shows a slight improvement from early childhood up to 20 years of age, remains fairly constant up to 50 years and then steadily declines to the age of 80 years and beyond [1]. Longitudinal studies by Milne [2] and Gittings and Fozard [3] support this relationship between age and visual acuity. Gittings and Fozard's findings also suggest that, even in the absence of documented pathology, most persons experience an age-associated decline in visual acuity. Since 1978 a number of researchers have examined contrast sensitivity to different spatial frequencies, in addition to visual acuity. Contrast sensitivity is measured by determin-
ing the minimum contrast level required to detect stimuli of varied frequencies. Low spatial frequencies are optically sparse, whilst high spatial frequencies are optically dense [4]. The main types of apparatus employed have been Arden plates and oscilloscope presentations [4, 5]. The overall picture that emerges is that age differentially affects contrast sensitivities of different spatial frequencies, with high spatial frequencies affected the most, and low spatial frequencies the least. This pattern appears to be evident even when older subjects have good visual acuity, i.e. 6/6 or better. In the past few years attempts have been made to produce an easy-to-administer, standardized testing procedure for measuring contrast sensitivity applicable to clinical settings [6-8]. Verbaken and Johnston have suggested that, for general clinical practice and in the functional assessment of patients with low vision, the simple measurement of edge conAge and Ageing 1991 ;20:176-181
Downloaded from http://ageing.oxfordjournals.org/ at Aston University on September 5, 2014
Summary
176
S. R. LORD ET AL.
Methods The sample comprised 95 persons from a hostel for the aged in Sydney, Australia. The subjects were aged between 59 and 97 years—the age and sex distribution is shown in Table I. Most of the subjects were generally independent in such activities of daily living as dressing, bathing and toileting. Residents had their own 'motel style' rooms and used a common dining room. Most residents (66%) left the hostel for varying periods every day, and a number regularly used public transport. Twenty-one residents (22%) used walking sticks or frames. All residents were followed up for a period of one year (using monthly questionnaires) to determine whether the visual measures were associated with falling. Falls status was primarily determined by self reports. For residents with memory impairments (who may have fallen but did not recall doing so), a secondary check was made using reports from nursing staff and accident records. Eighty-four subjects were still living in the hostel, or in associated sections of the village complex one year after testing, seven subjects had died and four had left the village. Forty subjects reported having no falls in the year whilst 44
Table I. Age and sex distribution of the sample Age group
Men
Women
Total
59-69 70-79 80-89 90-97 Mean age (SD)
0 4 9 3
2 22 46 9
2 26 55 12
82.8 (7.4)
82.7 (6.5)
82.7 (6.6)
subjects reported one or more falls. The mean age of the fallers (84.1 years) was significantly higher than the mean age of the non-fallers (81.4 years), / = 2.16, p
