GLAUCOMA: the silent thief of sight

What is Glaucoma?

Glaucoma is a group of eye conditions that damage the optic nerve, which is vital to good vision. Abnormal high pressure in the eyes is mostly the cause of this damage. Glaucoma can lead to blindness. Worldwide, glaucoma is the second-leading cause of blindness after cataracts. It occurs mostly in older adults, but can also occur in younger people.

Glaucoma  can be roughly divided into two main categories: "open-angle" and "closed-angle" glaucoma. Open-angle chronic glaucoma is painless, tends to develop slowly over time and often has no symptoms until the disease has progressed significantly.

Closed angle glaucoma is usually chronic and also symptomless but can present all of a sudden as well. This involves sudden eye pain, blurred vision, mid-dilated pupil, redness, nausea and vomiting, resulting from a sudden spike in intraocular pressure from iridotrabecular contact.

The nerve damage in glaucoma involves loss of retinal ganglion cells in a characteristic pattern. Raised intraocular pressure (above 21 mmHg or 2.8 kPa) is the most important and only modifiable risk factor for glaucoma. Some people may have high eye pressure for years and never develop damage, a condition known as "ocular hypertension".

Note: Damages caused by glaucoma can't be corrected.

Symptoms

Symptoms of glaucoma vary depending on the type and stage of the condition.

Open-angle glaucoma:

Patchy blind spots in your side (peripheral) or central vision, frequently in both eyes

Tunnel vision in the advanced stages

Close-angle glaucoma:

Severe headache

Eye pain

Oval pupil

Nausea and vomiting

Blurred vision

Halos around lights

Eye redness

Mid-dilated pupil.

Causes

There are several causes of glaucoma but ocular hypertension (i.e. increase in pressure within the eye) is the most important risk factor.

Ocular hypertension is  due to a buildup of a fluid (aqueous humor) that flows throughout your eye. This fluid normally drains into the front of the eye (anterior chamber) through tissue (trabecular meshwork) at the angle where the iris and cornea meet. When fluid is overproduced or the drainage system doesn't work properly, the fluid can't flow out at its normal rate and pressure builds up.

Medication

Patients on long-term corticosteroids have a raised risk of developing several different conditions, including glaucoma. The risk is even greater with eyedrops containing corticosteroids.

Hereditary

Glaucoma tends to run in families. In some people, scientists have identified genes related to high eye pressure and optic nerve damage.

Dietary

Caffeine increases intraocular pressure in those with glaucoma, though  does not appear to affect normal individuals.

Treatment

Since damages done by glaucoma can't be corrected, the goal of its treatment is to prevent the damages. Hence the goal of glaucoma treatment is to lower pressure in your eye (intraocular pressure) because it's one of the major risk factors for glaucoma, . Depending on the conditions options may include eyedrops, laser treatment or surgery.

Eye drops

These can help decrease eye pressure by improving how fluid drains from your eye or by decreasing the amount of fluid your eye makes.

Eye drop medications used for glaucoma treatment  include:

1.  Prostaglandins: These increase the outflow of the fluid in your eye (aqueous humor) and reduce pressure in your eye. Examples include

Latanoprost (Xalatan) and

Bimatoprost (Lumigan).

2. Beta blockers: These reduce the production of fluid in your eye, thereby lowering the pressure in your eye (intraocular pressure). Examples include
Timolol (Betimol, Timoptic) and

Betaxolol (Betoptic).

3. Alpha-adrenergic agonists: These reduce the production of aqueous humor and increase outflow of the fluid in your eye. Examples include

Apraclonidine (Iopidine) and

Brimonidine (Alphagan).

4. Carbonic anhydrase inhibitors. Rarely used for glaucoma, these drugs may reduce the production of fluid in your eye. Examples include

Dorzolamide (Trusopt) and

Brinzolamide (Azopt)

5. Miotic or cholinergic agents. These increase the outflow of fluid from your eye. An example is

Pilocarpine (Isopto Carpine).

Oral medications

Oral medications for glaucoma are  usually a carbonic anhydrase inhibitor.

Surgery and other therapies

Laser therapy and various surgical procedures are also glaucoma treatment options.

1. Laser therapy. Laser trabeculoplasty  is an option for people with open-angle glaucoma. It involves using laser beam to open clogged channels in the trabecular meshwork. It may take a few weeks before the full effect of this procedure becomes apparent.

2. Filtering surgery. With a surgical procedure called a trabeculectomy. It involves creating  an opening in the white of the eye (sclera) and removes part of the trabecular meshwork.

3. Drainage tubes. In this procedure,  a small tube is inserted  in your eye.

Reference:

http://www.mayoclinic.org/diseases-conditions/glaucoma/basics/symptoms/con-20024042

http://www.mayoclinic.org/diseases-conditions/glaucoma/basics/definition/con-20024042

https://en.m.wikipedia.org/wiki/Glaucoma

http://www.mayoclinic.org/diseases-conditions/glaucoma/basics/causes/con-20024042

http://www.mayoclinic.org/diseases-conditions/glaucoma/basics/treatment/con-20024042