Functional associations of "trouble seeing"

CAPTCHA as a Visual Performance Metric in Active Macular Disease

Purpose

CAPTCHA (completely automated public turing test to tell computers and humans apart) was designed as a spam prevention test. In patients with visual impairment, completion of this task has been assumed to be difficult; but to date, no study has proven this to be true. As visual function is not well measured by Snellen visual acuity (VA) alone, we theorized that CAPTCHA performance may provide additional information on macular disease-related visual dysfunction.

Methods

This was designed as a pilot study. Active disease was defined as the presence of either intraretinal fluid (IRF) or subretinal fluid (SRF) on spectral-domain optical coherence tomography. CAPTCHA performance was tested using 10 prompts. In addition, near and distance VA, contrast sensitivity, and reading speed were measured. Visual acuity matched pseudophakic patients were used as controls. Primary outcome measures were average edit distance and percent of correct responses.

Results

70 patients were recruited: 33 with active macular disease and 37 control subjects. Contrast sensitivity was found to be significantly different in both the IRF (p < 0.01) and SRF groups (p < 0.01). No significant difference was found comparing the odds ratio of average edit distance of active disease (IRF, SRF) vs. control (OR 1.09 (0.62, 1.90), 1.10 (0.58, 2.05), p=0.77,  0.77) or percent correct responses of active disease vs. control (OR 0.98 (0.96, 1.01), 1.09 (0.58, 2.05), p=0.22, 0.51) in CAPTCHA testing. The goodness of fit using logistic regression analysis for the dependent variables of either IRF or SRF did not improve accounting for average edit distance (p=0.49,  p=0.27) or percent correct (p=0.89,  p=0.61).

Conclusions

Distance VA and contrast sensitivity are positively correlated with the presence of IRF and SRF in active macular disease. CAPTCHA performance did not appear to be a significant predictor of either IRF or SRF in our pilot study.

At the tipping point: predicting severe mobility difficulty in vulnerable older women

OBJECTIVES

To identify clinical measures that aid detection of impending severe mobility difficulty in older women.

DESIGN

Cross-sectional and longitudinal cohort study.

SETTING

Urban community in Baltimore, Maryland.

PARTICIPANTS

One thousand two community-dwelling, moderate to severely disabled women aged 65 and older in the Women's Health and Aging Study I.

MEASUREMENTS

Self-report and performance measures representing six domains necessary for mobility: central and peripheral nervous systems, muscles, bones and joints, perception, and energy. Severe mobility difficulty was defined as usual gait of 0.5 m/s or less, any reported difficulty walking across a small room, or dependence on a walking aid during a 4-m walking test.

RESULTS

Four hundred sixty-seven out of 984 (47%) had severe mobility difficulty at baseline, and 104/474 (22%) developed it within 12 months. Baseline mobility difficulty was correlated with poor vision, knee pain, feelings of helplessness, inability to stand with feet side by side for 10 seconds, difficulty keeping balance while dressing or walking, inability to rise from a chair five times, and cognitive impairment. Of these, knee pain (odds ratio (OR)=1.74, 95% confidence interval (CI)=1.05-2.89), helplessness (OR=1.87, 95% CI=1.10-3.24), poor vision (OR=2.03, 95% CI=1.06-3.89), inability to rise from a chair five times (OR=2.50, 95% CI=1.15-5.41), and cognitive impairment (OR=4.75, 95% CI=1.67-13.48) predicted incident severe mobility difficulty within 12 months, independent of age.

CONCLUSION

Five simple measures may aid identification of disabled older women at high risk of severe mobility difficulty. Further studies should determine generalizability to men and higher-functioning individuals.

Is vision function related to physical functional ability in older adults?

OBJECTIVES

To assess the relationship between a broad range of vision functions and measures of physical performance in older adults.

DESIGN

Cross-sectional study.

SETTING

Population-based cohort of community-dwelling older adults, subset of an on-going longitudinal study.

PARTICIPANTS

Seven hundred eighty-two adults aged 55 and older (65% of living eligible subjects) had subjective health measures and objective physical performance evaluated in 1989/91 and again in 1993/95 and a battery of vision functions tested in 1993/95.

MEASUREMENTS

Comprehensive battery of vision tests (visual acuity, contrast sensitivity, effects of illumination level, contrast and glare on acuity, visual fields with and without attentional load, color vision, temporal sensitivity, and the impact of dimming light on walking ability) and physical function measures (self-reported mobility limitations and observed measures of walking, rising from a chair and tandem balance).

RESULTS

The failure rate for all vision functions and physical performance measures increased exponentially with age. Standard high-contrast visual acuity and standard visual fields showed the lowest failure rates. Nonstandard vision tests showed much higher failure rates. Poor performance on many individual vision functions was significantly associated with particular individual measures of physical performance. Using constructed combination vision variables, significant associations were found between spatial vision, field integrity, binocularity and/or adaptation, and each of the functional outcomes.

CONCLUSIONS

Vision functions other than standard visual acuity may affect day-to-day functioning of older adults. Additional studies of these other aspects of vision and how they can be treated or rehabilitated are needed to determine whether these aspects play a role in strategies for reducing disability in older adults.