What is glaucoma?
Glaucoma is a group of eye conditions that damage the optic nerve, whose health is essential for good vision. Optic nerve damage occurs due to abnormally high pressure in your eyes.
Glaucoma is one of the most prominent causes of blindness for people over the age of 60. The disease can appear at any age, but it occurs more commonly in older adults.
Many forms of glaucoma do not show any signs. The effect is so gradual that you may not notice a change in vision until the condition has reached an advanced stage.
Since vision loss caused by glaucoma cannot be treated, it is important to have eye exams that include regular eye pressure measurements so that the diagnosis can be made in its early stages and treated appropriately. If glaucoma is detected early, it may be possible to slow or prevent vision loss. If you have the condition, you will need treatment for the rest of your life.
What are the types of glaucoma?
Open-angle glaucoma is the most common form of glaucoma. The drainage angle formed by the cornea and iris remains open, but the trabecular meshwork remains partially closed. This causes pressure inside the eye that gradually increases. This pressure damages the optic nerve. It happens slowly you may lose your vision before you even realize the scale of the problem.
Angle-closure glaucoma occurs when the iris protrudes forward to narrow or block the drainage angle formed by the cornea and iris. This prevents the fluid from circulating through the eye, and causes the pressure to increase. Angle-closure glaucoma may occur suddenly (acute angle-closure glaucoma) or gradually (chronic angle-closure glaucoma).
Normal pressure glaucoma
In normal pressure glaucoma, the optic nerve is damaged, even though the pressure in your eye is less than normal. You may have a sensitive optic nerve, or the blood that feeds on that nerve may be less than the amount needed for it. This can result from reduced blood flow due to atherosclerosis – a build-up of fatty deposits (plaques) in the arteries – or other conditions that block blood circulation.
Glaucoma in children
Infants and children can develop glaucoma. They may be born with it or contract it during the first few years of their lives. Damage to the optic nerve may be caused by either a blocked tear duct or an underlying disease.
In pigmentary glaucoma, pigment granules in the iris build-up in the drainage channels of eye fluid, slowing or blocking the exit of that fluid from the eye. Activities such as jogging sometimes stir the pigment beads and send them onto the trabecular meshwork, causing an intermittent rise in eye pressure.
What are the symptoms of glaucoma?
The signs of symptoms of glaucoma may vary depending on its type and stage.
- Scattered blind spots in the lateral (peripheral) or central part of the field of vision, often affecting the eyes
- Tunnel vision in advanced stages
Acute angle-closure glaucoma
- Severe headache
- Eye pain
- Nausea and vomiting
- Blurred vision
- Halos around light
- Redness of the eye
Glaucoma will eventually lead to blindness if left untreated.
What are the causes of glaucoma?
Glaucoma occurs when the optic nerve is damaged. When the optic nerve degenerates, blind spots begin to appear in your field of vision. This nerve damage is related to elevated intraocular pressure.
High intraocular pressure results from the accumulation of fluid (aqueous humor) that flows into the eye. This internal fluid usually drains through a tissue called the trabecular meshwork at the angle where the iris and cornea meet. When this fluid is produced profusely, it does not drain sufficiently, the fluid does not flow out at the normal rate, and the eye pressure increases.
How to diagnose glaucoma?
The doctor will review your medical history and conduct a comprehensive eye examination. They may perform several tests, including:
- Intraocular pressure measurement (tonometry)
- A test to detect damage to the optic nerve with a dilated pupil fundus and x-rays
- Checking for areas of vision loss (visual field test)
- Corneal thickness measurement (ichthyosis)
- Drainage angle examination (gonioscopy)
How to treat glaucoma?
Even though the damage caused by glaucoma can not be treated, regular check-ups and treatment can help slow or prevent vision loss, especially if glaucoma is detected in its early stages.
Treatment may include eye drops, oral medications, laser treatment, surgery, or a combination of these treatments.
Treatment for glaucoma often begins with prescribing eye drops. This helps reduce eye pressure by improving fluid drainage from the eye or reducing the amount of fluid that the eye excretes.
If the eye drops alone do not lower the eye pressure to the required level, your doctor may prescribe an oral medication, usually a carbonic anhydrase inhibitor. Possible side effects include frequent urination, numbness in the fingers and toes, depression, stomach upset, and kidney stones.
The following treatments aim to improve the drainage of the fluid inside the eye, thereby reducing pressure:
- Laser treatment. Laser trabeculoplasty is an option if you have open-angle glaucoma. In this outpatient procedure, your doctor uses a precise laser beam to open the blocked channels in the trabecular meshwork. It may take a few weeks to see the full result of this procedure.
- Filtering surgery. Your surgeon makes an incision in the white part (sclera) of the eye and removes part of the trabecular meshwork, through a procedure called laser trabeculoplasty.
- Minimally invasive glaucoma surgery. Your doctor may suggest minimally invasive glaucoma surgery to lower your eye pressure. This procedure generally requires less immediate postoperative care than a trabeculectomy. It is often combined with cataract surgery. There are several minimally invasive glaucoma techniques available, and your doctor will discuss which operation may be right for you.