Search results
Results from the WOW.Com Content Network
Hemeralopia or day blindness is the inability to see clearly in bright light and is the exact opposite of nyctalopia (night blindness), the inability to see clearly in low light. [1] It is also called heliophobia. [2] It can be described as insufficient adaptation to bright light.
The opposite problem, known as hemeralopia, that is, inability to see clearly in bright light, is much rarer. The fovea is blind to dim light (due to its cone-only array) and the rods are more sensitive, so a dim star on a moonless night must be viewed from the side, so it stimulates the rods. This is not due to pupil width since an artificial ...
Other medical conditions such as keratoconus (an eye disorder that results in extreme optic sensitivity to sunlight and bright lights), migraine which can be triggered by bright light, and porphyria cutanea tarda, which causes the skin to be overly sensitive to sunlight to the point of causing blisters, can result in heliophobia if the sufferer ...
The opposite problem, the inability to see in bright light, is known as hemeralopia and is much rarer. Since the outer area of the retina is made up of more rods than cones, loss of peripheral vision often results in night blindness. Individuals with night blindness not only see poorly at night but also require extra time for their eyes to ...
Photophobia is a medical symptom of abnormal intolerance to visual perception of light. [1] As a medical symptom, photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical sensitivity of the eyes, [2] though the term is sometimes additionally applied to abnormal or irrational fear of light, such as ...
The Creation of Light by Gustave Doré. Darkness is the condition resulting from a lack of illumination, or an absence of visible light.. Human vision is unable to distinguish colors in conditions of very low luminance because the hue-sensitive photoreceptor cells on the retina are inactive when light levels are insufficient, in the range of visual perception referred to as scotopic vision.
The pupillary light reflex (PLR) or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity of light that falls on the retinal ganglion cells of the retina in the back of the eye, thereby assisting in adaptation of vision to various levels of lightness/darkness.
A mydriatic pupil will remain excessively large even in a bright environment. The excitation of the radial fibres of the iris which increases the pupillary aperture is referred to as a mydriasis. More generally, mydriasis also refers to the natural dilation of pupils, for instance in low light conditions or under sympathetic stimulation.