Six Tests for Glaucoma:

1. Tonometry

Tonometry is a very common test to measure the pressure inside the eye, also known as intra-ocular pressure (IOP). Having eye pressure higher than normal places a person at a higher risk for glaucoma. It is important to understand that having higher pressure than normal does not mean a definite diagnosis of glaucoma.

2. Ophthalmoscopy

Ophthalmoscopy is used to examine the inside of the eye. Ophthalmoscopy can be performed on a dilated or undilated eye. An eye doctor uses special magnifying lenses and medical devices to view the optic nerve. The color, shape and overall health of the optic nerve is important in glaucoma assessment. The doctor may also use a digital camera to photograph the optic nerve.

3. Gonioscopy

Gonioscopy is a test that uses a special mirrored device to gently touch the surface of the eye to examine the angle where the cornea meets the iris. Whether this angle is open or closed can tell the doctor what type of glaucoma is present, and how severe the glaucoma may be.

4. Visual Field Testing

Visual field testing, also known as perimetry, is a test that measures how sensitive a person's vision is. During a visual field test, you will look straight ahead at a small light or other target and will be asked to let the examiner know when you see a light flash off to the side in your peripheral vision. Most visual field testing today is computerized.

5. Nerve Fiber Analysis

Nerve fiber analysis is a newer method of glaucoma testing in which the thickness of the nerve fiber layer is measured. Thinner areas may indicate damage caused by glaucoma. This test is especially good for patients who may be considered to be a glaucoma suspect and also to indicate if a person’s glaucoma is progressively becoming worse.

6. Pachymetry

Pachymetry is the method of measuring the thickness of the cornea. Although research is still being conducted on the importance of corneal thickness, pachymetry is starting to play a larger role in glaucoma testing. The thickness of the cornea seems to influence the eye pressure reading when tonometry is performed.

           primary open angle glaucoma

Primary open-angle glaucoma (POAG), sometimes referred to as chronic wide-angle glaucoma, comprises about 70-80% of all cases of glaucoma. Primary open angle glaucoma is referred to as the "sneak thief of sight" because it usually has no symptoms until it is too late and vision is lost. Open angle glaucoma is the leading cause of blindness among adults.

                         In "open angle" glaucoma, you may experience progressive loss of optic nerve fibers, decreased visual field and elevated eye pressure even though the angle of the eye is wide open. Thus, the "angle" is a very important part of glaucoma care.

Glaucoma is a family of diseases in which the optic nerve atrophies -- usually, but not always, due to high intraocular eye pressure. In some eyes, the eye cannot withstand the force that this elevated eye pressure causes and it begins to put pressure on the nerves in the eye. As the optic nerve (the nerve cable that connects the eye to the brain) becomes sick or damaged, vision begins to deteriorate. Peripheral vision is usually affected first, but glaucoma patients can definitely suffer central vision loss if the glaucoma is severe enough.

Drainage system and glaucoma:understand glaucoma, one must learn about how the eye's fluid, called the intraocular fluid, is manufactured by the eye and how it flows through the eye’s angle. The muscle that controls the way the eye focuses is called the ciliary body. Another job of the ciliary body is to produce intraocular fluid. This fluid cycles through the eye by first passing through the pupil to the anterior chamber, or front part of the eye. Then the fluid circulates through the anterior chamber and then out of the drainage canal in the angle of the eye where the cornea meets the iris. The drainage canal in the angle is called the trabecular meshwork. The trabecular meshwork is a filter through which the fluid travels. The fluid is then carried out and away from the eye through vessels.

Primary open angle glaucoma:

In some types of glaucoma, the drainage system can be plugged up and the fluid is not able to be filtered out. In other types, the anatomy is just different. The angle that the corneamakes with the iris can be so narrow that the fluid can't get to the drainage system very easily. When this occurs, pressure rises and the eye cannot handle it. Optic nerve damage then occurs. When this happens and the angle is wide open, the glaucoma is characterized as primary open angle glaucoma.

High pressure but no glaucoma:

An important point is that just because eye pressure is elevated, it does not mean that you have open angle glaucoma. Increased eye pressure is a risk factor associated with glaucoma and is not the disease itself. Some patients have optic nerve damage without increased eye pressure. These patients have a condition called low tension or normal tension glaucoma. They usually have all the characteristics of glaucoma but the eye pressure seems to be unusually high. Patients that have high pressure but no damage or visual field loss have a condition called ocular hypertension.