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Light sensitivity or photosensitivity refers to a notable or increased reactivity to light. Apart from vision , human beings have many physiological and psychological responses to light. In rare individuals an atypical response may result in serious discomfort, disease, or injury.
Humans have three classes of cones (L, M, S) that each differ in spectral sensitivity and 'prefer' photons of different wavelengths (see graph). For example, the peak wavelength of the S-cone's spectral sensitivity is approximately 420 nm (nanometers, a measure of wavelength), so it is more likely to absorb a photon at 420 nm than at any other ...
In humans, cones are normally one of three types: S-cones, M-cones and L-cones, with each type bearing a different opsin: OPN1SW, OPN1MW, and OPN1LW respectively. These cones are sensitive to visible wavelengths of light that correspond to short-wavelength, medium-wavelength and longer-wavelength light respectively. [3]
Photosensitivity is the amount to which an object reacts upon receiving photons, especially visible light. In medicine, the term is principally used for abnormal reactions of the skin, and two types are distinguished, photoallergy and phototoxicity .
The human eye contains three types of photoreceptors, rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs). Rods and cones are responsible for vision and connected to the visual cortex. ipRGCs are more connected to body clock functions and other parts of the brain but not the visual cortex.
An ipRGC, shown here as a complied image of the retina from proximal inner nuclear layer to the ganglion cell layer with fluorescent labeling of melanopsin Spectral sensitivities of the photoreceptors in the human eye. [4] Compared to the rods and cones, the ipRGCs respond more sluggishly and signal the presence of light over the long term. [5]
Visual phototransduction is the sensory transduction process of the visual system by which light is detected by photoreceptor cells (rods and cones) in the vertebrate retina.A photon is absorbed by a retinal chromophore (each bound to an opsin), which initiates a signal cascade through several intermediate cells, then through the retinal ganglion cells (RGCs) comprising the optic nerve.
Distribution of rods and cones along a line passing through the fovea and the blind spot of a human eye [1]. A blind spot, scotoma, is an obscuration of the visual field.A particular blind spot known as the physiological blind spot, "blind point", or punctum caecum in medical literature, is the place in the visual field that corresponds to the lack of light-detecting photoreceptor cells on the ...