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Glaucoma 1
Glaucoma
Jodi McQueen
Stephen F. Austin University
Glaucoma
(glah-KOH-muh) Pathological condition. Group of diseases characterized by increased
intraocular pressure resulting in damage to the optic nerve and retinal
nerve fibers, with typical visual field defects and increased size of optic
cup. A common cause of preventable vision loss.
What is Glaucoma?
Glaucoma is a group of diseases that can steal sight without warning or symptoms. Over three million Americans have it and only half of them know it.
Glaucoma refers to a category of eye disorders associated with a intense buildup of internal eye pressure (IOP) which can damage the eye's optic nerve that transmits visual information to the brain. Elevated pressure in the eye is a risk factor, but even people with normal pressure can lose vision to glaucoma.
The Eye With Glaucoma
In most types of glaucoma, the eye’s drainage system becomes clogged so the intraocular fluid cannot drain properly. As the fluid builds up, it causes pressure to build within the eye. This inner pressure of the eye (intraocular pressure or IOP) depends upon the amount of fluid in the eye. If your eye’s drainage system is working correctly then the fluid can drain out properly and this will prevent a buildup. Proper drainage helps keep eye pressure at a normal level.If the pressure is high it damages the sensitive optic nerve and results in vision loss. With untreated or uncontrolled glaucoma, you might eventually notice decreased ability to see at the edges of your vision (peripheral vision). Progressive eye damage could then lead to blindness.
Types of Glaucoma
The two main types of glaucoma are Primary Open Angle Glaucoma (POAG), and Angle Closure Glaucoma. These are marked by an increase of intraocular pressure (IOP), or pressure inside the eye. When optic nerve damage has occurred despite a normal IOP, this is called Normal Tension Glaucoma. 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. There are five types of Secondary Glaucoma: Pseudoexfoliative Glaucoma, Pigmentary Glaucoma, Traumatic Glaucoma, Neovascular Glaucoma, and Irido Corneal Endothelial Syndrome (ICE).
Primary Open Angle Glaucoma: This is the most common form of glaucoma. It happens when the eye’s drainage canals become clogged over time. The inner eye pressure (also called intraocular pressure or IOP) rises because the correct amount of fluid can’t drain out of the eye. A clogging problem occurs deep inside the drainage canals. No painful, red eye is seen and the eye pressure is only moderately elevated. If open angle glaucoma is not diagnosed and treated, it can cause a gradual loss of vision. It responds well to medication, especially if caught early and treated.
Angle Closure Glaucoma:This type of glaucoma is a rare form known as acute glaucoma or narrow angle glaucoma. The eye pressure rises very quickly and causes a painful red eye. This happens when the drainage canals get blocked or covered over. Symptoms include headaches, eye pain, nausea, rainbows around lights at night, and very blurred vision.
Normal Tension Glaucoma (NTG):Normal tension glaucoma is also known as low-tension glaucoma or normal pressure glaucoma. The optic nerve is damaged even though intraocular pressure (IOP) is not very high. Studies conclude that eye drops can be used to lower intraocular pressure. Most doctors treat it by keeping normal eye pressures as low as possible with medicines, laser surgery, or filtering surgery.
Secondary Glaucoma: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 may be mild or severe. The type of treatment will depend on whether it is open angle or angle closure glaucoma.
Pediatric Glaucoma and Childhood Glaucoma
Pediatric glaucomas consist of congenital glaucoma (present at birth), infantile glaucoma (appears during the first three years), juvenile glaucoma (age three through the teenage or young adult years), and all the secondary glaucomas occurring in the pediatric age group. Childhood glaucoma—also referred to as congenital glaucoma, pediatric, or infantile glaucoma—occurs in babies and young children. It is usually diagnosed within the first year of life. This is a rare condition that may be inherited, caused by incorrect development of the eye’s drainage system before birth. This leads to increased intraocular pressure, which in turn damages the optic nerve. Symptoms of childhood glaucoma include enlarged eyes, cloudiness of the cornea, and photosensitivity (sensitivity to light).
Functional Problems
Glaucoma can be congenital and it is progressive. Individuals with this condition will have problems with a reduced to total loss of vision acuity and field loss
Treating Glaucoma
Depending upon the type of glaucoma, treatment may include medication, usually prescription eyedrops, or surgery to lower the pressure in the eye and prevent further damage to the optic nerve. While there is no cure as yet for glaucoma, early diagnosis and continuing treatment can preserve eyesight.
Four Key Facts About Glaucoma
1. Glaucoma is a leading cause of blindness. 2. There is no cure (yet) for glaucoma. 3. Everyone is at risk for glaucoma. 4. There may be no symptoms to warn you
Sources:
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2. Dictionary of Eye Terminology 5th Ed., Barbara Cassin and Melvin Rubin, MD, Editor, 2006, Gainsville, FL., pg. 120
3. Opthamology Made Ridiculously simple., Stephen Goldberg, M.D. 1991, Miami, FL., pg 4, 25
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