What is Glaucoma ?

Glaucoma is caused by a number of different eye diseases, which in most cases produce increased pressure within the eye. This elevated pressure is caused by the drainage of the fluid produced by the eye that is not enough. This will cause damage to the optic nerve. This damage will become noticeable through the apparition of blind spots in the visual field. If glaucoma is not treated, a gradual vision loss and sometimes-even lead to blindness.

Who's at special risk?

Everyone is at risk for glaucoma, however, certain groups are at higher risk than others. It is recommended that people at high risk for glaucoma receive a complete eye exam that includes eye dilatation every one to two years. This is important because early detection, diagnosis and treatment are the only way to prevent vision impairment and blindness.

People at greater risk are:

• People over the age of 45. While glaucoma can develop in younger patients, it occurs more as we get older.
• People who have family history of glaucoma.
• People with abnormally high intraocular pressure.
• People of African descent.
• People who have diabetes, myopia, regular Steroid/Cortisone use.
• People who have suffered from previous eye injury.

Different types of Glaucoma

There are a variety of different types of glaucoma. The two main types of glaucoma are primary open angle glaucoma and angle closure glaucoma.

1) Primary Open Angle Glaucoma

This is the most common form of glaucoma. 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. This type of glaucoma develops slowly and sometimes without noticeable sight loss for many years.

2) Angle Closure Glaucoma

This type of glaucoma is much more rare and differs from open angle glaucoma as the eye pressure usually goes up very fast. This happens when the drainage canals get blocked or covered over. Symptoms of angle closure glaucoma may include headaches, eye pain, nausea, seing halo's around lights at night, and a very blurred vision. Treatment of angle closure glaucoma usually involves surgery to help to unblock the drainage canals so that extra fluid can drain.

3) Normal Tension Glaucoma

In this type of glaucoma, the optic nerve is damaged even though intraocular pressure is not very high. In this case, the optic nerve is probably suffering less from high intraocular pressure than from an insufficient irrigation by the surrounding fessels.

Other forms of secondary glaucoma also exist and may result of an eye injury, inflammation, tumor or in advanced cases of cataract or diabetes. It can also be caused by taking certain drugs as for example steroids.

Diagnosing glaucoma

Early detection, through regular and complete eye exams, is the key to protecting your vision from damage caused by glaucoma. Regular glaucoma check-ups include four main tests.

1) Tonometry

The Tonometer measures the intra-ocular pressure. If the applanation is used , your eye first has to be topically anesthetized. Dr. Rynerson use an instrument that is called air tonometry, a puff of air is sent onto the to take the measurement. Since this instrument does not come in direct contact with your eye, no anesthetic eye drops are required.

2) Opthalmoscopy

Ophthalmoscopy is used to examine the inside of the eye. The eye doctor will look through the pupil at the optic nerve. Its shape and color can indicate whether or not damage from glaucoma is present and how extensive it is. A dilated retinal exam allows for an even more thorough evaluation of the internal eye.

If the eye pressure is not within the normal range, or if the optic nerve looks unusual, then other special glaucoma tests will be done.

3) Visual field test

In computerized visual field testing you will be asked to look at a fixed point on a special screen and then to press a button each time a light flash is seen. At the end of this test the doctor will receive a printout of your field of vision. This test measures a patient's entire range of vision, including peripheral or side vision.

In patients with glaucoma, typically the side or peripheral vision is lost first, characterized by a narrowing of what is seen outside of center focus.

4) Gonioscopy

Gonioscopy is a painless eye test that checks if the angle where the iris meets the cornea is open or closed, showing if either open angle or closed angle glaucoma is present. This exam is carried out by means of a contact lens placed on the patient's eye.

5) Optical coherence tomography (OCT)

This is a recently developped method which allows to picture the retina. This technique is far superior to the echography and is mostly used to study macular affections. The OCT instrument utilizes a technique called optical coherence tomography which creates images by use a special beams of light. The OCT machine can create a contour map of the optic nerve , optic cup and measure the retinal nerve fiber thickness. This technique is far more occurate than echography.

Treating glaucoma

Because damage to the optic nerve cannot be reversed, treatment is aimed at preventing or slowing further damage caused by glaucoma. The whole purpose of treatment is to lower the internal pressure of the eye and prevent any loss of vision, or any further deterioration in vision. Options include medicine given as eye drops, laser treatment and surgery.

1) Eye drops

Eye drop lower the internal eye pressure by either decreasing fluid production or increasing fluid outflow through drainage. They must be appliedregularly and continuously. The effect of a medication only lasts a certain number of hours after which time the eye pressure may rise again, resulting in damage to the optic nerve. Therefore, a number of drops used at specific intervals will be required.

There are several types of drugs available in drop and tablet form for treating glaucoma.

2) Laser surgery

When medication does not achieve the desired results, or when it causes intolerable side effects, your ophtalmologist may suggest laser treatment. The type of laser surgery used depends on the type of glaucoma and the general health of the eye.

The most common glaucoma laser surgeries are:

Laser trabeculoplasty

Used in people with primary open angle glaucoma. This procedure is painless and can be performed in either a doctor's office or in a one-day-clinic. The laser beam is focused upon the eye's drain. The intense heat of the laser causes some areas of the eye's drain to shrink, resulting in adjacent areas stretching open and permitting the fluid to drain more easily.

After this procedure, many patients are eventually able to stop some of their medications. This, however, is not true in all cases. Your doctor is the best judge to determine whether or not medication is still necessary for you.

Laser peripheral Iridotomy

Often used in people with narrow-angle glaucoma. Narrow-angle glaucoma occurs when the angle between the iris and the cornea in the eye is too small. This causes the iris to block fluid drainage, which makes the inner eye pressure increase. Laser peripheral Iridotomy makes a small hole in the iris. This will allow fluid to pass from behind your iris to the trabecular meshwork. Then fluid can drain out of your eye and help decrease your eye pressure.

3) Traditional surgery

Surgery is an option when medicines and/or laser treatment have failed to adequately lower pressure in the eye. The most common of these operations is called a trabeculectomy. In this procedure, the surgeon removes a small section of the trabecular meshwork. This allows the aqueous humor to drain more easily, reducing the pressure in the eye. Patients usually leave the hospital on the day of the surgery and are followed up closely in a practice after the operation. It is important to note that your eyes may not have their normal visual acuity for several weeks following this procedure.