Symptoms depend on which type of glaucoma you may have. Although there are several varieties of glaucoma, there are two main types – open angle glaucoma and angle-closure glaucoma.
The most common type of glaucoma is called open-angle glaucoma. It usually progresses slowly and can often go unnoticed for many months or years, causing a gradual deterioration in vision.
There are two types of angle-closure glaucoma:
1. Acute angle-closure glaucoma, which has a sudden onset.
2. Chronic angle-closure glaucoma, which has a more gradual onset.
Angle-closure glaucoma is one type of glaucoma, although uncommon, that does produce noticeable symptoms. The outside edge of the iris (coloured part of eye) blocks off the drainage angle at the front of the eye, causing a sudden increase in the IOP in the acute form (much slower increase in IOP in the chronic form). This type of glaucoma is more common in older patients who are longsighted, and those of Asian background. The raised IOP causes the cornea to swell and become waterlogged. The swollen cornea then acts like a prism, causing light to be broken up into separate colours.
Symptoms of acute angle-closure glaucoma include:
This type of glaucoma is serious and can rapidly lead to blindness. It is most important that you contact your eye care practitioner, GP or eye doctor immediately if you have any of these symptoms.
Glaucoma can only be detected through a comprehensive eye exam.
A thorough history is taken to identify any risk factors.
A special instrument called a tonometer is used to measure the IOP. A small pressure-sensitive plastic tip is gently placed on the eye after a drop of anaesthetic has been used.
A special contact lens is placed on your eye to examine the drainage angle. This helps to see if it is blocked.
After eye drops have been used to dilate your pupil, the ophthalmologist examines the optic nerve for damage. This is done on the slit-lamp (the special microscope used for the general eye examination) with a lens which gives a 3-D colour view.
This is a simple, quick, painless test to measure the thickness of the central part of your cornea. This test can help your doctor better understand your IOP reading.
Computerised visual field testing, or perimetry, is an important part of assessing the health and function of your optic nerve. During these tests, you will be asked to look into a computer screen and push a button when you see a light flash or a row of black lines appear. White-on-white, blue-on-yellow (SWAP), Frequency Doubling Perimetry (FDP), Heidelberg Retinal Tomography (HRT), are all used at Vision Eye Institute and are the most advanced tests available.
Stereoscopic (3-dimensional) colour photographs are taken of your optic disc at your initial visit. This is done with a retinal camera and digitally downloaded into a computer. There are no X-rays involved, and the painless test only takes a few minutes. These images are used as a baseline, and the appearance of your optic nerve is compared to them at each visit. In this way, early changes, or progression, of glaucoma can be detected. Optic disc photography can also be obtained by a sophisticated apparatus called an OCT (Optical Coherence Tomography) which records the optic nerve head with various measurements to assist with follow up comparisons.
It may not be necessary for you to have all these tests each visit. If glaucoma is suspected, or your glaucoma worsens, more tests may be added or the tests repeated more frequently.