Summary
The circadian clock drives pronounced rhythms in rod-mediated vision at mesopic light levels, with peak rod responses occurring at night due to increased gap junction coupling between photoreceptors — an effect abolished by the gap junction blocker meclofenamic acid. This means that lighting environments operating in the mesopic range (typical of evening/nighttime indoor settings) will be processed differently by the visual system depending on time of day, with amplified sensitivity at night that may inform optimal lighting levels for evening environments.
Key Findings
- Rod-mediated visual responses at mesopic light levels were highly rhythmic across the circadian cycle, peaking in amplitude during the subjective night.
- This circadian rhythm in rod vision was abolished by intravitreal injection of the gap junction blocker meclofenamic acid, implicating circadian variation in electrical coupling strength between photoreceptors.
- Cone-mediated responses were arrhythmic across mesopic-to-photopic backgrounds when adapted to background irradiance.
- Combined rod-plus-cone responses showed a stable contrast-response relationship during the circadian day, but were significantly amplified at lower (mesopic) light levels during the night.
- Results support the conclusion that the circadian clock anticipatorily adjusts the relative rod/cone contribution to vision to match the expected visual environment at each time of day.
Categories
The Science of Light: Investigates circadian regulation of rod and cone photoreceptor contributions to mesopic vision, with mechanistic findings on gap junction coupling and spectral sensitivity.
Eye Health & Vision: Provides insight into how time-of-day modulates visual sensitivity and contrast responses across mesopic-photopic light levels, relevant to visual comfort and lighting design.
Author(s)
AE Allen
Publication Year
2022
Related Publications
The Science of Light
- Phototransduction by retinal ganglion cells that set the circadian clock
- Color appearance models
- The mammalian circadian timing system: organization and coordination of central and peripheral clocks
- Diminished pupillary light reflex at high irradiances in melanopsin-knockout mice
- Melanopsin is required for non-image-forming photic responses in blind mice
Eye Health & Vision
- Diminished pupillary light reflex at high irradiances in melanopsin-knockout mice
- Genetic reactivation of cone photoreceptors restores visual responses in retinitis pigmentosa
- Melanopsin and rod–cone photoreceptors play different roles in mediating pupillary light responses during exposure to continuous light in humans
- Characteristic patterns of dendritic remodeling in early-stage glaucoma: evidence from genetically identified retinal ganglion cell types
- Intrinsically photosensitive melanopsin retinal ganglion cell contributions to the pupillary light reflex and circadian rhythm