Glaucoma describes damage to the optic nerve and retina that is most commonly caused by a higher than normal build-up of pressure in the eye.
It is essential for the eyes to maintain a constant and firm shape for light to focus accurately within them. The body does this by pumping a clear fluid called aqueous into the eye, which also provides the eye with essential nutrients from the blood. The aqueous drains in and out of the eye against a resistance which sustains a pressure that is higher than air but lower than blood pressure.
Damage through higher than normal pressure can result if there is a blockage in the circulation or drainage of aqueous fluid.
Damage may also be caused by poor blood supply to the optic nerve fibres, a weakness in the structure of the nerve, or a problem in the health of the nerve fibres.
During a routine eye examination your optometrist will test for glaucoma by measuring the pressure within the eye as well as examining the optic nerve at the back of the eye. If any abnormality is detected or if there is a family history of glaucoma, your optometrist will perform a visual field check to further rule out the possibility of glaucoma. A visual field allows the optometrist to assess for loss of sensitivity to light or even a loss of sight in parts of the retina, this usually commencing in the peripheral vision in glaucoma.
As the peripheral vision is often the first to be affected by elevated eye pressure, there is generally no symptoms for an individual in the early stages of the most common form of glaucoma, which is why monitoring of intraocular pressure is very important, generally being checked every two years in persons over 40 years of age, or annually if there exists a family history of glaucoma or if previous tests have been suspicious.
Should an elevated eye pressure or visual field loss be detected the optometrist will refer to an Ophthalmologist for treatment.
Glaucoma is controlled most commonly by the use of eye drops which help to maintain an acceptable pressure in the eye. More acute forms of glaucoma may be treated by laser surgery.