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Many variations occur, but scintillating scotoma usually begins as a spot of flickering light near or in the center of the visual field, which prevents vision within the scotoma area. It typically affects both eyes, as it is not a problem specific to one eye. [5] [6] The affected area flickers but is not dark. It then gradually expands outward ...
Blue–red contrast demonstrating depth perception effects 3 Layers of depths "Rivers, Valleys & Mountains". Chromostereopsis is a visual illusion whereby the impression of depth is conveyed in two-dimensional color images, usually of red–blue or red–green colors, but can also be perceived with red–grey or blue–grey images.
A stye, also known as a hordeolum, is a bacterial infection of an oil gland in the eyelid. [4] This results in a red tender bump at the edge of the eyelid. [1] [5] The outside or the inside of the eyelid can be affected.
Photopsia is the presence of perceived flashes of light in the field of vision. It is most commonly associated with: [4] posterior vitreous detachment; migraine aura (ocular migraine / retinal migraine) migraine aura without headache; scintillating scotoma; retinal break or detachment; occipital lobe infarction (similar to occipital stroke)
The human eye can function from very dark to very bright levels of light; its sensing capabilities reach across nine orders of magnitude. This means that the brightest and the darkest light signal that the eye can sense are a factor of roughly 1,000,000,000 apart. However, in any given moment of time, the eye can only sense a contrast ratio of ...
Protanopia is a severe form of red-green color blindness, in which the L-cone is absent. It is sex-linked and affects about 1% of males. Colors of confusion include blue/purple and green/yellow. [2] Deuteranopia is a severe form of red-green color blindness, in which the M-cone is absent. It is sex-linked and affects about 1% of males.
Blue cone monochromacy (BCM) is an inherited eye disease that causes severe color blindness, poor visual acuity, nystagmus, hemeralopia, and photophobia due to the absence of functional red (L) and green (M) cone photoreceptor cells in the retina. BCM is a recessive X-linked disease and almost exclusively affects XY karyotypes.
A chalazion may occur following a stye or from hardened oils blocking the gland. [2] The blocked gland is usually the meibomian gland, but can also be the gland of Zeis. [8] A stye and cellulitis may appear similar. [2] A stye, however, is usually more sudden in onset, painful, and occurs at the edge of the eyelid. [2] Cellulitis is also ...