Peek At Science: 2023 January 10

Peak At Science 20230110
Quantum Biology

Peek At Science: 2023 January 10

Age-related change in flicker thresholds with rod- and cone-enhanced stimuli


Rod and cone photoreceptor-specific tests can be time-consuming. A new non-invasive test is described. The test is based on the measurement of flicker modulation thresholds with rod- and cone-enhanced visual stimuli, which requires only minimum adaptation time. Here, we investigated how the rod-and cone-mediated flicker thresholds vary with age.


Monocular thresholds with rod and cone–enhanced stimuli were measured in 140 healthy adults, (age range: 18–75 years), foveally (0 ̊) and at four parafoveal locations, at an eccentricity of 5 ̊ in each of the four quadrants using five, adaptive, interleaved staircases. Temporal frequencies, stimulus sizes, background luminance and spectral composition, were adjusted appropriately to achieve approximately 1 log unit separation in sensitivity between the rod- and cone-enhanced stimuli. Spectrally calibrated, ‘neutral density’ filters were used to enable adequate control of display luminance for rod enhanced stimuli.


The magnitude of central and parafoveal rod thresholds was significantly higher than the central and parafoveal cone thresholds, respectively (p < 0.001) in both the age groups. However, the rate of increase in central rod thresholds (y = 0.45x—12.79; linear regression equation) was not significantly steeper than the rate of increase in central (y = 0.29x—8.53) cone thresholds (p = 0.15). Centrally, cone thresholds showed a better correlation with rod central thresholds for the age > 45 years (Spearman correlation, ρ = 0.74, p < 0.001) compared to age 45 years (ρ = 0.41, p < 0.001).


Thresholds with rod- and cone-enhanced stimuli are largely invariant below 45 years of age and increase rapidly above this age. This age-wise normative database can be used as an effective functional-marker to assess photoreceptor sensitivities in retinal diseases.








両年齢群において、中心杆体閾値と傍鳩目閾値は中心錐体閾値と傍鳩目閾値より有意に高かった(p0.001)。しかし、中心杆体閾値の増加率(y = 0.45x-12.79; 線形回帰式)は、中心錐体閾値の増加率(y = 0.29x-8.53) に比べて有意に急峻ではなかった(p = 0.15)。中心部の錐体閾値は、45歳以上では、45歳以下(ρ0.41p0.001)に比べ、桿体中心閾値と良い相関を示した(スピアマン相関:ρ0.74p0.001)。



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