Measuring the Temporal Contrast Sensitivity Function and Macular Pigment Optical Density in Older Adults with and Without Cognitive Impairment

Abstract

Introduction: Reduced temporal processing speed is characteristic of age-related neurodegenerative diseases, such as age-related macular degeneration and Alzheimer's disease, and may be a useful indicator of disease status. Whether or not the full temporal contrast sensitivity function (tCSF) can be accurately measured in adults with cognitive impairment (CI) is unknown. The purpose of this study is 1) to determine whether or not the tCSF and macular pigment optical density (MPOD), a measure of retinal lutein and zeaxanthin, also known to vary with temporal processing speed, can be accurately measured in subjects with CI, and 2) to determine whether MPOD and tCSF differ in patients with CI. Methods: 28 subjects (65–89 years), including 7 patients with CI, were tested. tCSF was measured psychophysically using a custom-built device. MPOD was measured using heterochromatic flicker photometry. Psychophysical techniques were adapted for MCI patients. Results: High-frequency portions of the tCSF were significantly reduced in impaired individuals (p < 0.03). MPOD was not significantly different in impaired vs. unimpaired individuals. Variability on both measures was not significantly different from young subjects and did not differ between impaired and unimpaired elders. Conclusions: tCSF and MPOD can be assessed using adapted psychophysical techniques in older adults with CI.