Glaucoma is a disease that gradually steals sight, without warning, and symptoms. It is a condition in which pressure inside the eye rises when the aqueous humour fluid, which normally flows in and out of the eye is unable to drain properly. As the fluid collects, It increases pressure whichdamage's the optic nerve. This results in loss of vision.
The risk of developing glaucoma in the general population is 2% per year. Having a genetic predisposition such as family history of glaucoma increases the risk. However, not everyone with a family history will develop glaucoma. Conversely, lack of family history does not mean that someone will not develop glaucoma.
There are several types of glaucoma:
- Ocular Hypertension
- Open-angle glaucoma
- Normal-tension glaucoma
- Closed-angle glaucoma (or Narrow-angle glaucoma or Angle-closure glaucoma)
- Congenital glaucoma
- Secondary glaucoma
The most common form of glaucoma is called primary open-angle glaucoma. It occurs when the trabecular meshwork of the eye gradually becomes less efficient at draining fluid. As this happens, the eye pressure, called intraocular pressure (IOP), rises. Raised eye pressure leads to damage of the optic nerve. Your ophthalmologist determines the maximum IOP which is safe for you. This varies from patient to patient since each person's optic nerve can tolerate different amounts of IOP.
Typically, open-angle glaucoma has no symptoms in its early stages and vision remains normal. As the optic nerve becomes more damaged, blind spots begin to appear. These can be detected by visual field testing. Patients usually do not notice these blind until the optic nerve is significantly damaged and these spots become large. If glaucoma progresses, unchecked, it leads to blindness.
Half of patients with glaucoma do not have high IOP when first examined. The IOP can fluctuate between normal and high at different times during the day. Some such individuals will only occasionally have high eye pressures on repeat testing; thus, a single eye pressure test misses many with glaucoma. In addition to routine eye pressure testing, it is essential that the optic nerve be examined by an ophthalmologist for proper diagnosis.
Some people have a type of glaucoma called normal-tension, or low-tension glaucoma. Their IOP is not elevated, but optic nerve damage and visual field loss still occur. Normal-tension glaucoma is typically treated in the same way as open-angle glaucoma.
Ocular hypertension is a condition where the eye pressure is high but does not cause optic nerve damage. Individuals with ocular hypertension are at higher risk for developing glaucoma and need to be closely monitored by an ophthalmologist. Once optic nerve damage is detected, the condition has progressed to glaucoma.
Closed-angle glaucoma, narrow-angle glaucoma or angle-closure glaucoma
A less common form of glaucoma is closed angle (or narrow-angle glaucoma or angle-closure glaucoma). Closed-angle glaucoma occurs when the drainage opening in the eye becomes blocked. Unlike open-angle glaucoma, IOP rises very rapidly. The pressure rises because the iris, which is the colored part of the eye, partially or completely blocks off the drainage opening resulting in a closed-angle glaucoma attack.
Symptoms of an attack include:
- Severe eye or brow pain or headache
- Redness of the eye
- Decreased or blurred vision
- Seeing colored rainbows or halos
- Nausea or vomiting
A closed-angle glaucoma attack is a medical emergency and needs to be treated immediately. Unfortunately, people at risk for developing closed-angle glaucoma often have few or no symptoms before the attack.
People at risk for closed-angle glaucoma should avoid over-the-counter decongestants and other medications where the packaging states not to use these products if you have glaucoma. They should also be treated before undergoing general anesthesia.
Secondary glaucoma is glaucoma that results from another eye condition or disease or medications, such as tumors or steroids.
Congenital glaucoma is a rare type of glaucoma that develops in infants and young children and can be inherited. While uncommon relative to the other types of glaucoma, this condition can be devastating, often resulting in blindness when not diagnosed and treated early.
Treatment for Glaucoma (medication, lasers, and surgery)
Medicated eye drops are the most common way to treat glaucoma. These medications lower your eye pressure either by slowing the production of aqueous humor or by increasing its outflow from the eye.
These eye drops must be taken every day. Just like any other medication, it is important to take them regularly as prescribed.Never change or stop taking your medications without talking with your doctor.
If you have glaucoma, it is important to tell your ophthalmologist about your other medical conditions and medications you currently take.
- Bring a list of your medications with you to your eye appointment. Also it is very important that your primary care doctor and any other doctors caring for you be informed about the glaucoma medication you take.
- Some drops are contraindicated for patients with asthma, congestive heart failure, and certain types of arrhythmia.
A laser treatment called selective laser trabeculoplasty, (SLT), is often used to treat glaucoma.
SLT, A low energy laser is applied to the drainage channels lowering eye pressure by increasing the outflow of aqueous humour.
Laser iridotomy is recommended for treating people with closed-angle glaucoma and those with small or narrow drainage openings. The laser creates a small hole about the size of a pinhead through the iris to allow the aqueous fluid to reach the opening for the drainage system in the eye.
There are several different procedures available for glaucoma that cannot be controlled with medication and laser treatment
Important things to remember about glaucoma:
There are a number of ways to treat glaucoma. While some people may experience side effects from glaucoma medications or glaucoma surgery, the risks of side effects should always be balanced with the greater risk of leaving glaucoma untreated and losing vision.
Preserving vision requires strong teamwork between doctor and patient. A doctor can prescribe treatment, but the patient has to follow the treatment plan closely by taking medications and keeping follow up appointments to monitor the status of the optic nerve. Like most medical disorders, the disease can progress and requires constant monitoring. The key to success is early detection and treatment because the optic nerve damage that occurs is permanent and irreversible.