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The optic radiation contains feedforward tracts that transmit visual information (from the retina of the eye) from the geniculate nucleus to the visual cortex, and also feedback tracts from the visual cortex to the neurons in the LGN that project to them. [2] The function of the feedback from the visual cortex back to the LGN is unknown.
Optical radiation is the part of the electromagnetic spectrum with wavelengths between 100 nm and 1 mm. [1] [2] This range includes visible light, infrared light, and part of the ultraviolet spectrum. [3] Optical radiation is non-ionizing, [4] and can be focused with lenses and manipulated by other optical elements.
This is most commonly the result of exposure to the sun at high altitude, and in areas where shorter wavelengths are readily reflected from bright surfaces, such as snow, water, and sand. UV generated by a welding arc can similarly cause damage to the cornea, known as "arc eye" or welding flash burn, a form of photokeratitis. [52]
The eye is usually patched on the day of surgery and use of an eye shield at night is often suggested for several days after surgery. [52] In all types of surgery, the cataractous lens is removed and replaced with an artificial lens, known as an intraocular lens, which stays in the eye permanently. Intraocular lenses are usually monofocal ...
This may cause long-term changes in the structure and function of cerebral blood vessels. The brain's mechanism for maintaining constant blood flow despite changes in systemic blood pressure, known as cerebral autoregulation, can be impaired by sleep apnea. This impairment results in periods of both reduced and excessive cerebral blood flow ...
Radiation is a moving form of energy, classified into ionizing and non-ionizing type. [4] Ionizing radiation is further categorized into electromagnetic radiation (without matter) and particulate radiation (with matter). [4] Electromagnetic radiation consists of photons, which can be thought of as energy packets, traveling in the form of a wave ...
Other factors can cause glaucoma, known as "secondary glaucoma", including prolonged use of steroids (steroid-induced glaucoma); conditions that severely restrict blood flow to the eye, such as severe diabetic retinopathy and central retinal vein occlusion (neovascular glaucoma); ocular trauma (angle-recession glaucoma); plateau iris; and ...
Despite the term posterior, this form of damage to the eye's optic nerve due to poor blood flow also includes cases where the cause of inadequate blood flow to the nerve is anterior, as the condition describes a particular mechanism of visual loss as much as the location of damage in the optic nerve.