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Cataracts can arise as an effect of exposure to various types of radiation. X-rays, one form of ionizing radiation, may damage the DNA of lens cells. [21] Ultraviolet light, specifically UVB, has also been shown to cause cataracts, and some evidence indicates sunglasses worn at an early age can slow its development in later life. [22]
It occurs when exposure to a substance – specifically, a neurotoxin or neurotoxicant– alters the normal activity of the nervous system in such a way as to cause permanent or reversible damage to nervous tissue. [1] This can eventually disrupt or even kill neurons, which are cells that transmit and process signals in the brain and other ...
At some point—usually as you enter middle age—most people develop this eye condition, which is a clouding of the eye’s lens that can get progressively worse and impair your vision.
Long-term contact lens use can lead to alterations in corneal thickness, stromal thickness, curvature, corneal sensitivity, cell density, and epithelial oxygen uptake. . Other structural changes may include the formation of epithelial vacuoles and microcysts (containing cellular debris), corneal neovascularization, as well as the emergence of polymegethism in the corneal endoth
Visual impairment can also be caused by problems in the brain due to stroke, premature birth, or trauma, among others. [12] These cases are known as cortical visual impairment. [12] Screening for vision problems in children may improve future vision and educational achievement. [13] Screening adults without symptoms is of uncertain benefit. [14]
In both types of PION, decreased blood flow leads to the death of optic nerve cells. Ischemic injury to the optic nerve causes inflammation and swelling. Because the posterior optic nerve passes through the optic canal, a bony tunnel leading to the brain, swelling in this rigid space causes compression of the optic nerve. This compression ...
When considering the possible causes for spontaneous NAION, the list includes other conditions like arteritic anterior ischemic optic neuropathy (associated with inflammation of arteries), optic neuritis (inflammation of the optic nerve), infiltrative and compressive types of optic neuropathy (where the optic nerve is invaded or pressed upon by ...
Cortical blindness-Cortical blindness is the total or partial loss of vision in a normal-appearing eye caused by damage to the brain's occipital cortex. [7] Retrobulbar neuritis- Retrobulbar neuritis cause of visual loss with normal fundus but there will be relative afferent pupillary defect (RAPD) and abnormal visually evoked responses. [8]