Development of a critical flicker/fusion frequency test for potential vision testing in media opacities

Abstract

Purpose: To determine whether critical flicker/fusion (CFF) thresholds fulfill the criteria for a potential vision test (PVT) by being unaffected by media opacity yet affected by retinal disease.

Methods: CFF thresholds for three different stimulus sizes (0.5, 1.0, and 1.5 degrees ) were measured in 72 patients (mean age, 78.43 +/- 7.07 years) comprising 31 subjects with media opacity, 21 with macular disease, and 20 with pseudophakia.

Results: There were no statistically significant differences between CFF values from the media opacity and the pseudophakia groups for any target size (p > 0.10). However, CFF values were significantly lower in patients with macular disease for all the target sizes (p < 0.05). Analysis of a subset of six subjects with media opacity and seven subjects with macular disease and visual acuity of 20/200 or worse showed the media opacity group still had similar CFF values as the pseudophakia group and had significantly higher CFF than the macular disease group.

Conclusions: CFF testing is shown to fulfill the requirements for a PVT and may prove to be particularly useful for patients with dense media opacity.