Search results
Results from the WOW.Com Content Network
The first symptoms most people notice are difficulty reading fine print, particularly in low light conditions, eyestrain when reading for long periods, blurring of near objects or temporarily blurred vision when changing the viewing distance. Many extreme presbyopes complain that their arms have become "too short" to hold reading material at a ...
The term comes from the Greek skotos, meaning 'darkness', and -opia, meaning 'a condition of sight'. [2] In the human eye , cone cells are nonfunctional in low visible light . Scotopic vision is produced exclusively through rod cells , which are most sensitive to wavelengths of around 498 nm [ 3 ] and are insensitive to wavelengths longer than ...
A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction.The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiation) into signals that can stimulate biological processes.
Picture of the back of the eye showing intermediate age-related macular degeneration: Specialty: Ophthalmology, optometry: Symptoms: Blurred or no vision in the center of the visual field [1] Complications: Visual hallucinations [1] Usual onset: Older people [1] Types: Early, intermediate, late [1] Causes: Damage to the macula of the retina [1 ...
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.
Spectral sensitivity is the relative efficiency of detection, of light or other signal, as a function of the frequency or wavelength of the signal. In visual neuroscience , spectral sensitivity is used to describe the different characteristics of the photopigments in the rod cells and cone cells in the retina of the eye .
At moderate to bright light levels where the cones function, the eye is more sensitive to yellowish-green light than other colors because this stimulates the two most common (M and L) of the three kinds of cones almost equally. At lower light levels, where only the rod cells function, the sensitivity is greatest at a blueish-green wavelength.
The basic light-processing unit of eyes is the photoreceptor cell, a specialized cell containing two types of molecules bound to each other and located in a membrane: the opsin, a light-sensitive protein; and a chromophore, the pigment that absorbs light. Groups of such cells are termed "eyespots", and have evolved independently somewhere ...