Glaucoma is a condition that causes damage to the nerve at the back of the eye (optic nerve), resulting in loss of eyesight, especially peripheral (side) vision. If glaucoma is not treated, loss of vision may continue, leading to total blindness over time.
The causes of glaucoma are not well understood, but in many cases it is related to a buildup of pressure inside the eye. Most types of glaucoma develop slowly over time without causing noticeable symptoms, but one type (narrow or closed-angle glaucoma) develops quickly and usually causes severe eye pain. Any type of glaucoma can lead to blindness if not treated. Glaucoma can be easily detected during regular eye exams. It usually responds well to treatment with medication.
There are several glaucoma tests that can be carried out by your optometrist. They are painless and quite quick. The tests should be carried out during the same appointment to ensure results are as accurate as possible.
These tests are explained below.
An eye pressure test (tonometry) uses an instrument called a tonometer to measure the pressure inside your eye. Tonometry can diagnose ocular hypertension (OHT – raised pressure in the eye), which is a risk factor for chronic open-angle glaucoma.
A visual field test (perimetry) checks for missing areas of vision. You will be shown a sequence of light spots and asked which ones you can see. Some dots will appear in your peripheral vision (around the sides of your eyeball), which is where glaucoma begins.
If you cannot see the spots in your peripheral vision, it may indicate the glaucoma has damaged your vision.
Your optic nerve connects your eye to your brain. The optometrist will examine your eyes using a slit lamp (a microscope with a very bright light) and assess whether your optic nerve has been damaged by the glaucoma.
If your optometrists suspects glaucoma, they will refer you to an ophthalmologist for further tests. Your ophthalmologist will confirm your diagnosis and find out:
They will then be able to advise on treatment.
In some cases, your ophthalmologist will continue to treat you. But if you have chronic open-angle glaucoma, you may be referred back to your optometrist who will continue your treatment.