Glaucoma does not refer to one disease but rather a group of conditions resulting in optic nerve damage. Abnormally high pressure inside your eye (intraocular pressure) is often the cause of this damage. However one person can suffer from intraocular pressure for years with no effects while another may have low pressure and suffer nerve damage.

Glaucoma can be divided roughly into two main categories, "open angle" or chronic Glaucoma and "closed angle" or acute glaucoma. Closed angle or acute glaucoma appears suddenly and often with painful side effects and so is usually diagnosed quickly, although damage and loss of vision can also occur very suddenly. Open angle, chronic glaucoma tends to progress more slowly and so the patient may not notice it until the disease has progressed quite significantly.

Glaucoma is the second leading cause of blindness. Sometimes called the silent thief of sight, glaucoma can damage a person's vision gradually so no notice of loss of vision is taken until the disease is at an advanced stage.

Early diagnosis and treatment can minimize or prevent optic nerve damage and limit glaucoma-related vision loss.

Glaucoma (symptoms)

The most common types of glaucoma ??" primary open-angle glaucoma and acute angle-closure glaucoma ??" have different symptoms.

Primary open-angle glaucoma signs and symptoms include:

• Gradual loss of peripheral vision often in both eyes
• Tunnel vision in the later stages

Acute angle-closure glaucoma signs and symptoms include:

• Severe eye pain
• Nausea and vomiting (accompanying the severe eye pain)
• Sudden onset of visual disturbance, often in low light
• Blurred vision
• Halos around lights
• Reddening of the eye

Both open-angle and angle-closure glaucoma can be primary or secondary conditions. They're called primary when the cause is unknown and secondary when the condition can be traced to a known cause, such as eye injury, inflammation, tumour, advanced cataract or diabetes. In secondary glaucoma, the signs and symptoms can include those of the primary condition as well as typical glaucoma symptoms.

Because there are few noticeable signs of glaucoma it is recommended that a person go for regular eye check-ups.

There are a number of different methods to treat glaucoma. In essence they all try to reduce the intraocular pressure by improving the aqueous outflow, reducing the production of aqueous or both. Aqueous is a thick watery substance that is between the lens and the cornea. Glaucoma can never be totally cured nor can the damage be reversed. But treatment and regular checkups can prevent further damage.

Eyedrops
Glaucoma treatment often starts with medicated eye drops. The types of most commonly prescribed eye drops include:

• Beta blockers. Reduction of the production of aqueous humor. Examples include levobunolol (Betagan), timolol (Betimol, Timoptic), betaxolol (Betoptic) and metipranolol (OptiPranolol).
• Alpha-agonists. These reduce the production of aqueous humor and increase drainage. Examples include apraclonidine (Iopidine) and brimonidine (Alphagan)..
• Carbonic anhydrase inhibitors. These also reduce the production of aqueous humor. Examples include dorzolamide (Trusopt) and brinzolamide (Azopt).
• Prostaglandin-like compounds. These eyedrops increase the outflow of aqueous humor. Examples include latanoprost (Xalatan), bimatoprost (Lumigan) and travoprost (Travatan).
• Miotic or cholinergic agents. These also increase the outflow of aqueous humor. Examples include pilocarpine (Isopto Carpine, Pilopine) and carbachol (Isopto Carbachol
• Epinephrine compounds. These compounds, such as dipivefrin (Propine), also increase the outflow of aqueous humor. Possible side effects include red eyes, allergic reactions, palpitations, increased blood pressure, headache and anxiety.

Oral medications
If eye drops alone don't bring the eye pressure down to the desired level an oral medication may be recommended. Commonly prescribed medications are carbonic anhydrase inhibitors, such as acetazolamide (Diamox Sequels) and methazolamide (Neptazane), for glaucoma

Neuroprotective drugs
Lowering the intraocular pressure provides only a partial solution when it comes to preserving vision in people with glaucoma. Ongoing clinical trials are evaluating certain drugs, such as brimonidine (Alphagan) and memantine (Namenda), to determine if they may help protect the optic nerve from damage associated with glaucoma.

Surgery
Surgery is also used to treat glaucoma. Surgeries used to treat glaucoma include:

• Laser surgery. Trabeculoplasty has an increasing role in treating open-angle glaucoma. After administering an anaesthetic eye drop, the doctor uses a high-energy laser beam to open clogged drainage canals and help aqueous humour drain more easily from the eye. After time, however, intraocular pressure may begin to increase.
• Filtering surgery. If eye drops and laser surgery are not effective in controlling eye pressure, a filtering procedure may be needed, usually in the form of a trabeculectomy (the rremoval part of the eye's trabecular meshwork and adjacent structures).
• Drainage implants. Another type of operation, called drainage implant surgery, may be an option for people with secondary glaucoma or for children with glaucoma. It consists of a doctor inserting a small silicone tube in your eye to help drain aqueous humour.

Treating acute angle-closure glaucoma

Acute angle-closure glaucoma is a medical emergency. The doctor may administer several medications to reduce eye pressure as quickly as possible. An iridotomy (a laser procedure that creates a small hole in your iris so that aqueous humour can pass into the trabecular meshwork) may also be necessary.

• Learn about glaucoma
• Glaucoma conditions
• Facts about glaucoma
• Glaucoma association

Page Updated: 11 March 2013