Abstract
Purpose: The temporal modulation transfer function (TMTF) is a measure of dynamic properties of the visual system and reflects age- and disease-related changes in visual function. Whether the TMTF is impacted similarly when assessed at foveal and parafoveal loci is unknown, and was the primary question of this investigation. Given the fact that macular pigment (MP) also tends to vary with disease state and that preliminary research suggests a relation between MP density and flicker sensitivity, an ancillary goal was to relate MP density to the TMTF. Methods: A novel device (Macular Metrics) was constructed that utilized LEDs to deliver a 1-deg, 660 nm target surrounded by a 10-deg, 660 nm annulus. The target was varied sinusiodally at frequencies from 2.5–32 Hz. A 3 mm artificial pupil was used to control pupil size. 61 subjects (aged 15–84 years) adjusted the percent modulation at each frequency to threshold in the fovea and at 7-degrees of eccentricity. MP density was assessed at 30-min of eccentricity via heterochromatic flicker photometry (HFP). Results: TMTF assessment with the novel device produced a function with the expected bandpass shape in fovea and parafovea. Flicker sensitivity decreased with age in the fovea (p The bandpass shape of the TMTF and the fact that relation between TMTF and age (assessed in the fovea) followed the same trend seen in past studies suggests that that the novel device provides valid measures. Given the fact that MP density also tends to vary with disease state, the relation between MP and temporal visual function warrants further investigation.