CONTRAST SENSITIVITY & AGING

Contrast Sensitivity & Aging 1 | 2 |

Summary from: "Retrospective Evaluation of Alternative Vision Screening Criteria for Older and Younger Drivers." (In references, see: Decina LE, et al. Retrospective Evaluation of Alternative Vision Screening Criteria for Older and Younger Drivers.)

Visual examinations of 12,400 drivers in Pennsylvania were conducted at the time of their license renewal. Static binocular tests of visual acuity, horizontal visual field, and contrast sensitivity at varying spatial frequencies were given to license renewal operators who were unaware that their vision would be tested when they arrived at the facility where license photographs are processed. Examination results were correlated with involvement in selected crash categories over a 3.67 year period, taking self-reported mileage into account. Neither visual acuity nor horizontal visual field measures in isolation were significantly related to crash involvement. The combination of visual acuity, horizontal visual fields, and broad contrast sensitivity criteria was significantly related to increasing crash involvement for drivers aged 66-75 and 76 and over. The implications of including contrast sensitivity measures in driver vision screening protocols are considered.

Contrast sensitivity measurements show that the ability to see targets of low spatial frequency is statistically independent of the ability to see high spatial frequency targets, such as those presented in routine static visual acuity testing. It has been found that contrast sensitivity changes systematically with age and does so in ways not predictable from changes observed in the commonly administered tests of static visual acuity. Specifically, contrast sensitivity performance in the high and middle spatial frequency range is found to decline with age, especially over age 40 (Schieber 1988).

Research from the early 1980s (Ginsburg et al. 1982; Ginsburg, Esterly, and Evans 1983), examined the relationship of contrast sensitivity function with the detection of targets by pilots. They found that high spatial frequency contrast sensitivity predicted high levels of real-world visual detection performance and that low spatial frequency sensitivity was useful in predicting detection performance under suboptimal viewing conditions, such as adverse weather conditions. Evans and Ginsburg (1985) examined the relationship between contrast sensitivity and the ability to discriminate highway traffic signs. They found that age-related decreases in the ability to discriminate between highway signs were predicted by diminished contrast sensitivity levels.

Contrast Sensitivity & Aging 1 | 2 |

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