glaucoma

Glaucoma   "silent thief of sight"

Glaucoma is a complicated disease in which damage to the optic nerve leads to progressive, irreversible vision loss.  (The optic nerve receives light-generated nerve impulses from the retina and transmits these to the brain, where we recognize those electrical signals as vision. Glaucoma is characterized by a particular pattern of progressive damage to the optic nerve that generally begins with a subtle loss of side vision ).

 If glaucoma is not diagnosed and treated, it can progress to loss of central vision and blindness.
Glaucoma is theThe second leading cause of blindness.

It is often, but not always, associated with increased pressure of the fluid in the eye aqueous humour( which provides nourishment to the structures in the front of the eye ).
The term 'ocular hypertension' is used for cases having constantly raised intraocular pressure (IOP) without any associated optic nerve damage. But mostely,  this elevated eye pressure  leads to damage of the eye (optic) nerve.


 In some cases, glaucoma may occur in the presence of normal eye pressure. This form of glaucoma is believed to be caused by poor regulation of blood flow to the optic nerve.

 Glaucoma affects 1 in 200 people aged fifty and younger, and 1 in 10 over the age of eighty. If the condition is detected early enough it is possible to arrest the development or slow the progression with medical and surgical means.

Types of Glaucoma

Glaucoma is actually a group of diseases. The most common type is hereditary.

• Primary Open-Angle Glaucoma
• Angle-Closure Glaucoma
• Normal-Tension Glaucoma
• Other Types of Glaucoma



1. Primary Open-Angle Glaucoma
   This is the most common form of glaucoma .

With open-angle glaucoma, the entrances to the drainage canals are clear and should be working correctly. The clogging problem occurs further inside the drainage canals, similar to a clogged pipe below the drain in a sink.

 Most people have no symptoms and no early warning signs. If open-angle glaucoma is not diagnosed and treated, it can cause a gradual loss of vision. The subsequent loss of side vision (peripheral vision) is usually not recognized. That's why it  has been nicknamed the "silent thief of sight"
This type of glaucoma is usually responds well to medication, especially if caught early and treated.

 A slow chronic increase in eye pressure is probably not painful. In contrast, there is discomfort and pain when the eye pressure increases rapidly during an acute onset or with the rapid return of glaucoma following unsuccessful glaucoma surgery. Lowering high eye pressure relieves these painful symptoms quickly.

2. Angle-Closure Glaucoma   ( closed-angle glaucoma)

This type of glaucoma is also known as acute glaucoma or narrow angle glaucoma. It is much more rare and is very different from open-angle glaucoma in that the eye pressure usually rises very quickly.
This happens when the drainage canals get blocked or covered over, like a sink with something covering the drain.
With angle-closure glaucoma, the iris is not as wide and open as it should be. The outer edge of the iris bunches up over the drainage canals, when the pupil enlarges too much or too quickly. This can happen when entering a dark room.

Symptoms of angle-closure glaucoma may include:

• Hazy or blurred vision
• The appearance of rainbow-colored circles around bright lights
• Severe eye and head pain
• Nausea or vomiting (accompanying severe eye pain)
• Sudden sight loss

In contrast with open-angle glaucoma, symptoms of acute angle-closure glaucoma are very noticeable and damage occurs quickly. If you experience any of these symptoms, seek immediate care from an ophthalmologist.


3. Normal-Tension Glaucoma  (normal-pressure glaucoma)

Normal-tension glaucoma (NTG) is a form of glaucoma in which damage occurs to the optic nerve without eye pressure exceeding the normal range. In general, a "normal" pressure range is between 10-20 mm Hg.
 The causes of NTG are still unknown. For some reason, the optic nerve is susceptible to damage from even the normal amount of eye pressure.
Those at higher risk for this form of glaucoma are:

• people with a family history of normal-tension glaucoma
• people of Japanese ancestry
• people with a history of systemic heart disease such as irregular heart rhythm.

4. Other Types of Glaucoma

Secondary Glaucom

Secondary glaucoma refers to any case in which another disease causes or contributes to increased eye pressure, resulting in optic nerve damage and vision loss.
Secondary glaucoma can occur as the result of an eye injury, inflammation, tumor, or in advanced cases of cataract or diabetes. It can also be caused by certain drugs such as steroids. This form of glaucoma may be mild or severe. The type of treatment will depend on whether it is open-angle or angle-closure glaucoma.

Pigmentary Glaucoma

Pigmentary Glaucoma is a form of secondary open-angle glaucoma. It occurs when the pigment granules that are in the back of the iris (the colored part of the eye) break into the clear fluid produced inside the eye. These tiny pigment granules flow toward the drainage canals in the eye and slowly clog them. This causes eye pressure to rise. Treatment usually includes medications, laser surgery, or conventional surgery.

Pseudoexfoliative Glaucoma

This form of secondary open-angle glaucoma occurs when a flaky, dandruff-like material peels off the outer layer of the lens within the eye. The material collects in the angle between the cornea and iris and can clog the drainage system of the eye, causing eye pressure to rise. Pseudoexfoliative Glaucoma is common in those of Scandinavian descent. Treatment usually includes medications or surgery.

Traumatic Glaucoma

Injury to the eye may cause secondary open-angle glaucoma. Traumatic glaucoma can occur immediately after the injury or years later. It can be caused by blunt injuries that bruise the eye (called blunt trauma) or by injuries that penetrate the eye.
In addition, conditions such as severe nearsightedness, previous injury, infection, or prior surgery may make the eye more vulnerable to a serious eye injury.

Neovascular Glaucoma

The abnormal formation of new blood vessels on the iris and over the eye's drainage channels can cause a form of secondary open-angle glaucoma.
Neovascular glaucoma is always associated with other abnormalities, most often diabetes. It never occurs on its own. The new blood vessels block the eye's fluid from exiting through the trabecular meshwork (the eye's drainage canals), causing an increase in eye pressure. This type of glaucoma is very difficult to treat.

Irido Corneal Endothelial Syndrome (ICE)

This rare form of glaucoma usually appears in only one eye, rather than both. Cells on the back surface of the cornea spread over the eye's drainage tissue and across the surface of the iris, increasing eye pressure and damaging the optic nerve. These corneal cells also form adhesions that bind the iris to the cornea, further blocking the drainage channels.
Irido Corneal Endothelial Syndrome occurs more frequently in light-skinned females. Symptoms can include  hazy vision upon awakening and the appearance of halos around lights. Treatment can include medications and filtering surgery. Laser therapy is not effective in these cases.

Congenital Glaucoma (Childhood Glaucoma)

Childhood Glaucoma refers to the presence of glaucoma in a child, and occurs in 1 out of every 10,000 births in the United States. Congenital glaucoma is the common term used for a glaucoma diagnosed in infancy or early childhood.
This glaucoma is caused by abnormal intraocular fluid drainage from the eye as a result of a blocked or defective trabecular meshwork (the mesh-like drainage canals in the eye). Congenital glaucoma may be due to an hereditary defect or abnormal development during pregnancy.
In other cases, an abnormal drainage system may be the result of some other disease in the eye which results in secondary glaucoma. In these cases, the glaucoma may be associated with recognizable iris (the colored part of the eye), corneal, or other eye problems.
In an uncomplicated case of congenital glaucoma, microsurgery can often correct the structural defects. Other cases are treated with medication and surgery.

Symptoms of childhood glaucoma

• light sensitivity (photophobia)
• corneal opacification (hazy gray cornea)
• enlarged eye and cornea
• epiphora (overflow of tears)
• vision loss

A cloudy cornea is the earliest and most common sign of childhood glaucoma. The healthy cornea is transparent. The loss of this transparency is caused by edema, or swelling of tissue from excess fluid. This occurs in the corneal epithelium (outermost layer of the cornea) and in the corneal stroma (middle layer of the corneal tissue). Careful inspection of the cornea may also reveal defects in its inner layer, which is further proof of a raised eye pressure (IOP).

In most cases of glaucoma affecting children under three years of age, the cornea and eye enlarges. Review of early photographs of your child may reveal the presence of glaucoma months before the diagnosis was actually made.

In addition to eye problems, secondary systemic (body) symptoms may occur. These secondary symptoms are especially common with acute glaucoma. Examples include irritability, loss of appetite, and vomiting. These symptoms may be misunderstood before the glaucoma is recognized. Young children with glaucoma are often unhappy, fussy, and poor eaters.