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Peak At Science: 2023 January 10

Peak At Science 20230110
Open Access

Peak At Science: 2023 January 10

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

Purpose

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.

Methods

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.

Results

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).

Conclusions

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.

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杆体刺激と錐体刺激によるフリッカー閾値の加齢変化

目的

桿体および錐体の視細胞特異的な検査は時間がかかることがある。新しい非侵襲的な検査について説明する。この検査は、杆体および錐体増強視覚刺激によるフリッカー変調閾値の測定に基づくもので、最小限の適応時間のみを必要とする。ここでは、杆体および錐体を介したフリッカー閾値が年齢によってどのように変化するかを検討した。

方法

健常成人140名(18-75歳)を対象に、杆体および錐体増強刺激の単眼性閾値を、窩洞()および傍窩洞(4箇所)、4象限それぞれにおいて偏心量で、5段階の適応的インターリーブ階段を用いて測定した。時間周波数、刺激サイズ、背景輝度、スペクトル構成は、杆体強調刺激と錐体強調刺激の間で感度のおよそ1対単位分離を達成するように適切に調整された。杆体強調刺激の表示輝度の適切な制御を可能にするため、スペクトル較正された「中性密度」フィルターが使用された。

結果

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)。

結論

杆体刺激と錐体刺激の閾値は、45歳以下ではほぼ不変であり、45歳以上で急速に増加する。この年齢別の標準データベースは、網膜疾患における視細胞感受性の評価に有効な機能マーカーとして利用できる。

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0232784

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