Abstract
Purpose :
To study if the contrast range of uncertainty around a flicker detection thresholds was enlarged in patients with retinitis pigmentosa (RP).
Methods :
We used a psychophysical procedure based on a temporal contrast sensitivity procedure combined with the silent substitution paradigm in a group of RP patients and in a normal control group. We examined 17 normal subjects (27±8 years, 7 females, 10 males) and 21 RP subjects with different genetic backgrounds (45±15 years, 6 females, 15 males). The subjects had to indicate the presence or absence of perceived flicker. The stimuli were created with a dedicated LED stimulator. Parafoveal L-cone, M-cone, S-cone and Rod-isolating stimuli at different temporal frequencies, between 1 and 4 Hz (low frequencies) and 12 and 20 Hz (high frequencies), were generated using triple silent substitution. Two randomly interleaved staircase procedures were used to determine psychometric curves. The thresholds and slope values of the psychometric curves were extracted. The slope values correspond to the range of uncertainty towards the tested condition. The shallower the slope value (i.e. smaller value), the larger is the range of uncertainty. These slope values were compared between normal subjects and RP patients using Wilcoxon-signed-rank tests.
Results :
At high frequencies, the slope values were not significantly different between the two groups and a large slope variability was found especially at high frequencies for M-cone isolating stimuli. At low temporal frequencies, there were significantly shallower slopes for the L-cone, M-cone and for Rod isolating stimuli in RP patients compared to the normal subjects (p < 0.05).
Conclusions :
RP patients display a larger range of uncertain flicker perception at low temporal frequency for Rod isolating stimuli and at low temporal frequencies for L- and M-cone isolating stimuli where the parvocellular pathway mediates flicker detection. The larger uncertainties in RP patients are possibly related to the area of retinal degeneration and can possibly be used to diagnose and monitor the disease.
This is a 2021 ARVO Annual Meeting abstract.