Critical Fusion Frequency Values Research Articles

Seeing is believing: a demonstration of critical fusion frequency and its multidimensional nature.

critical fusion frequency (CFF), or the flicker fusion threshold, is defined as the critical frequency above which a flickering light source appears steady to the observer (see [Fig. 1][1]). It is known to depend on a number of parameters, namely, intensity of the light source ([5][2], [15][3]),

A differential color flicker test for detecting acquired color vision impairment in multiple sclerosis and diabetic retinopathy

Background Optic neuritis related to multiple sclerosis and diabetic retinopathy are relatively selective post-retinal and retinal vision disorders. Vision impairment in both conditions is reliably measured by testing critical fusion frequency (CFF). Methods To examine color vision, we measured the CFF in response to red and blue stimuli, and tested CFF values in patients without evident vision impairment. To ensure that differences in CFF values in a given subject depended only on color perception we displayed red and blue flickering stimuli at equal luminance. CFF to red or blue stimuli were compared in patients with medical history of optic neuritis related to multiple sclerosis (post-retinal vision impairment), patients with diabetic retinopathy (retinal vision impairment) and healthy subjects. Results The test procedure disclosed altered CFF values for red and blue stimuli in both groups of patients studied. The comparison between the two groups disclosed a prevalent CFF impairment for red stimuli in patients with optic neuritis related to multiple sclerosis and for blue stimuli in patients with diabetic retinopathy. Conclusions The differential color flicker test appears highly accurate in detecting color vision impairment. Comparison of the two color CFFs differentiates retinal from post-retinal visual disorders.

Critical fusion frequency in the central visual field

Abstract— The critical fusion frequency (CFF) was measured across the central visual field. Stimulus parameters were adjusted to ensure an increase in CFF at the fovea. Comparison was made between the foveal and extra-foveal CFF values. The study showed that, while the CFF may be highest at the fovea when the CFF values are generally low, stimulus parameter changes that increase the CFF result in a greater increase extra-foveally. Ultimately, then, the CFF maximum shifts from the fovea to an extra-foveal area. Under the experimental conditions used in the study, the maximum occurred approximately 10° from fixation.

CRITICAL FUSION FREQUENCY IN THE CENTRAL VISUAL FIELD

The critical fusion frequency (CFF) was measured across the central visual field. Stimulus parameters were adjusted to ensure an increase in CFF at the fovea. Comparison was made between the foveal and extra-foveal CFF values. The study showed that, while the CFF may be highest at the fovea when the CFF values are generally low, stimulus parameter changes that increase the CFF result in a greater increase extra-foveally. Ultimately, then, the CFF maximum shifts from the fovea to an extra-foveal area. Under the experimental conditions used in the study, the maximum occurred approximately 10 degrees from fixation.