Optic Neuropathy

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Optic neuropathy is the term used to describe damage to optic nerve (cranial nerve II) irrespective of the cause. Damage to optic nerve most often leads to reduction in the size of the nerve due to loss of some or all of its fibers. Hence, it is often referred to as optic atrophy. The end result of this condition is deterioration in color vision with or without progression to loss of vision.

The etiologies of optic nerve damage are many ranging from insufficient/lack of blood flow to the optic nerve, infections, trauma, to hereditary conditions. Thus, based on the diverse etiologies, damage to optic nerve (optic neuropathy) can be categorized under the following:

Ischemic Optic Neuropathy

This is caused by insufficient blood flow to the optic nerve and it is further classified based on the etiology of the insufficient blood flow and the location of the damage along the course of the nerve.  Risk factors for optic nerve damage are: diabetes mellitus, increased intraocular pressure, hypotension, and hyperlipidemia.

Optic Neuritis

A demyelinating inflammation of the optic nerve, optic neuritis, though can occur in isolation, is usually associated with multiple sclerosis or neuromyelitis optica. It is caused by autoimmune reaction leading to destruction of the myelin sheath of the nerves. Other causes are; infections (e.g. viral encephalitis), metastases, chemicals and drugs (lead, quinine, arsenic), diabetes, vitamin B12 deficiency, Graves’ disease, etc.

Compressive Optic Neuropathy

This is caused by the progressive compression of the optic nerve by inflammatory processes, tumors, etc.

 

Traumatic Optic Neuropathy

This may be caused by either a direct or indirect injury to the nerve. Trauma to the head involving the orbit may disrupt the structure and function of the optic nerve, while blunt injury to the forehead may transmit force to and damage the optic nerve.

 

Vitamin B12 Deficiency

This can be seen in protein-energy malnutrition, gastric bypass surgery, pernicious anemia, etc. is a well-known cause of optic nerve neuropathy.

 

Toxic Optic Neuropathy

Exposure to toxic substances may cause optic nerve damage. The most implicated substance is methanol. Others include; ethylene glycol, amiodarone, ethambutol, and tobacco.

 

Treatment

The treatment of optic neuropathy is majorly directed to the underlying cause(s). Treatment initiated before the onset of atrophy may help preserve vision, however once optic nerve atrophy sets in, it is irreversible. Thus early diagnosis and treatment of the treatable underlying cause may help prevent further optic nerve damage. Corticosteroid is a proven treatment for optic neuritis and ischemic optic neuropathy.

 

Efficacy and Safety of Acupuncture

A meta-analysis was conducted with the results of the randomized controlled trials (RCTs) on optic atrophy treatment with acupuncture. Thirteen RCTs involving 1180 eyes were included. This analysis clearly revealed that the effect of acupuncture, or when combined with medicine, was superior to medicine alone in terms of total effectiveness, visual acuity, and visual field.

In another study conducted to determine the efficacy of acupuncture in the treatment of ischemic optic neuropathy, 69 patients (93 eyes) with nerve damage were used. These patients had earlier been treated by acupuncture, performed on different acupoints related to eyes.

The qualities of vision were assessed before and after the treatment.  After 2, 4, and 8 weeks of treatment, the total effective rates of visual acuity improvement were 74.19%, 78.89%, and 81.71%, respectively, and the improvement in visual field was statistically significant.

These studies are evidences to show that acupuncture, with or without combination with medicine, is beneficial and effective in improving vision in patients with optic nerve neuropathy irrespective of the etiology.

 

References:
1) Yali Qin, Wei Yuan, Hui Deng, Ming Jin. Clinical Efficacy Observation of Acupuncture Treatment for Nonarteritic Anterior Ischemic Optic Neuropathy. Evidence-based Complementary and Alternative Medicine 2015(1):1-6 · June 2015 DOI: 10.1155/2015/713218 Link
2) Yanli Dai, Ming Liu, Yixin Zhang, Houbin Huang. Meta analysis of acupuncture in the treatment of optic atrophy.  Journal of Central South University. Medical sciences 38(3):283-90 · March 2013  DOI: 10.3969/j.issn.1672-7347.2013.03.012 Link

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