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Optic Neuritis Case Studies

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Optic Neuritis
Introduction
Optic neuritis (ON) is a disease related to the eye that causes visual impairment. ON arises due to the inflammation and demyelination of the optic nerve, affecting interpretation of visual signals causing blurred, grey or dim vision. More often than not, ON is monocular in scope however there are cases where both eyes are affected. ON has been known to be highly associated with Multiple Sclerosis (MS) however an individual does not have to have MS to be diagnosed with ON.  81
Epidemiology and Pathology
Optic Neuritis has been found to persist more commonly in young healthy adults, with females having a higher incidence rate than males. ON is the most common optic neuropathy in individuals under the age of 50 years …show more content…

The optic nerve is the second cranial nerve (CN II) in the eye which is tasked to transfer visual information in the form of electrical impulses from the retina to the brain for interpretation. Typically, a human optic nerve is around 0.3-0.4mm in diameter and is protected by a nerve sheath, is surrounded by cerebrospinal fluid (CSF). Visual acuity and contrast sensitivity are two highly important functions that the optic nerve specialises in, and as a result, are the common issues affected by ON. Damage to the optic nerve inhibits proper functioning at the optic chiasm which, depending on the damage, causes specific problems depending on the extent of damage. Patients with MS are often revealed to develop ON as their first symptom. MS is a common central nervous system (CNS) disease that develops through issues relating to inflammatory demyelinating white matter lesions. There have been suggestions that the onset of ON is immune-mediated; activated T cells release cytokines as well as other inflammatory mediators when migrating across the blood-brain barrier and essentially degrade the axons around the optic nerve causing cell death, and thus leading to impaired visual functioning.  …show more content…

Acute ON usually involves a singular eye being affected whereby 90% of ON cases take place; the other 10% of cases occurring in both eyes is found to occur more frequently in children under the age of 15. The Optic Neuritis Treatment Trials (ONTT) identified vision loss and eye pain as the most common symptoms found in patients with acute unilateral ON. Vision loss was found to occur steadily over a period of a few hours to a few days, with a peak in between 1-2 weeks, whilst eye pain occurred in 92% of those affected and would worsen through eye movement. These visual defects however would usually resolve itself with care, with the ONTT presenting 56% of participants being clear after one year and 73% cleared after 10 (Cleary et al., 1997). In other cases, a patient may become affected with papillitis (intraocular ON) causing hyperemia leading to the swelling of the optic disc; a point of exit for optic ganglion cells. This area is important for the major blood vessels to supply the retina and thus aid in interpreting visual signals to be passed through the optic nerve into the brain. 

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