Critical flicker fusion frequency in age‐related macular degeneration

Abstract

Purpose To discuss the influence of AMD on critical flicker fusion frequency (CFF) Methods CFF was measured centrally for red, green and blue signal and in 10° excentricity with a red signal. 33 patients with non exsudative AMD and a visual acuity (VA) of 20/100‐20/20, 12 patients with exsudative AMD (VA: 20/100‐20/25) and 45 age‐matched healthy eyes (VA: 20/32‐20/20) were included. Results CFF decreased in eyes with non exsudative AMD (red 1,6Hz p=0,01, green 1,6 Hz p=0,04, blue 2,1 Hz p=0,01). The difference between central and peripher CFF increased (red‐red 10°, 1,0 Hz p=0,01). Differences between different colours were low and reached no significance. In eyes with exsudative AMD CFF showed lower values (red 2.2 Hz p=0.02, green 3.3 Hz p=0.001, blue 2,9 Hz p=0.02, but in spite of increased difference between central and peripher CFF had no statistical significance. (red‐red 10° , 1,3 Hz p=0,25). Eyes with exsudative AMD showed a 1.0 Hz (p=0.02) higher difference between CFF with a red and a green signal than healthy eyes. Sub‐group analysis of patients with non exsudative AMD and visual acuity better than 20/32 (n=20) and healthy eyes showed no difference. Patients with non exsudative (n=13) and eyes with exsudative AMD (n=7) and VA between 20/200 and 20/40 reached equal CFF values. Conclusion CFF was decreased in non exsudative and exsudative AMD. The difference between central and peripher CFF increased in exsudative and nonexsudative AMD. Exsudative AMD has a stronger impact on a green than on a red signal. CFF is not able to distinguish between groups of equal visual acuity and therefore not applicable as a diagnostic test.

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

“…blue) visual stimuli [31,32]. Confirming previous knowledge, using the differential color flicker test in healthy subjects in a wide age range we found that the bCFF deteriorates with age, and does so mainly from 50 years onwards whereas rCFF, remains almost unchanged with age [31,32]. Our study therefore suggests that the age-related chromatic impairment preferentially involves blue light, leaving chromatic sense for red light relatively unaffected.…”

“…In these patients, some evidence suggests a preferential impairment of the visual pathway conveying short-wavelength (i.e. blue) visual stimuli [31,32]. Confirming previous knowledge, using the differential color flicker test in healthy subjects in a wide age range we found that the bCFF deteriorates with age, and does so mainly from 50 years onwards whereas rCFF, remains almost unchanged with age [31,32].…”

“…The significant differences in CFF value we found in patients with diabetic retinopathy and healthy volunteers could depend on preferential tritanotopic degeneration [26]. Age-related macular degeneration could also aggravate the deficit in patients and in healthy volunteers [32,[40][41][42]. Conversely, multiple sclerosis related color vision impairment cannot depend on light scattering and even if disk edema is present, visual testing is unlikely to find selective retinal degeneration patterns.…”

“…Our study therefore suggests that the age-related chromatic impairment preferentially involves blue light, leaving chromatic sense for red light relatively unaffected. Some evidence suggests that the major cause of the age-related deterioration in color vision is crystalline lens degeneration, a change that mainly affects the short-wave rays [37][38][39], insofar as age-related macular degeneration has a more widespread effect on visual acuity [32,40].…”

“…The CFF is influenced by physical variables including properties of the light source and of the background illumination and biological variables, including pupil size, body temperature, and metabolic condition [28][29][30]. The CFF is also influenced by age [31,32].…”