Glaucoma is a group of eye disorders associated with optic nerve damage. It may lead to permanent blindness if not well managed.
A healthy optic nerve is vital for proper vision. The nerve is typically a set of fibers that connect the retina to the brain. Damage to this crucial part of the eye could mean complete loss of vision. Glaucoma, the condition responsible for the damage is therefore dangerous. This is especially because it is asymptomatic in the early stages and can easily be missed. The condition persists for a long time but is manageable with early diagnosis and a proper treatment plan.
There are two main types of glaucoma:
- Open-angle glaucoma
- Narrow angle/angle-closure glaucoma
Causes and Risk Factors
The cause of glaucoma depends on the type of the disease. It is broadly categorized as open-angle and angle closure but may further be classified as follows:
1. Open-angle glaucoma. Also referred to as wide angle, this is the most common type of glaucoma. The optic nerve gets damaged in spite of the angle being open. The subtypes include:
- Primary open-angle glaucoma - This happens when the rate at which the eye drains is slow. As a result, pressure builds in the eye (intraocular pressure) and can eventually damage the optic nerve. It mostly occurs due to aging of the drainage channel.
- Normal-tension glaucoma - This kind of glaucoma is not associated with build up of pressure. The cause is not well established but it is believed to be related to poor blood supply to the optic nerve.
- Pigmentary glaucoma - Occurs when the drainage angle is obstructed by pigment shedding off from the iris. As a result, intraocular pressure (IOP) builds up.
- Pseudoexfoliation glaucoma - Just like in pigmentary, the drainage angle in this case is blocked. The obstruction arises from the shedding off of the internal structure of the eye when excess material is produced.
- Secondary glaucoma - This type comes about due to other medical eye conditions. They include inflammation, cataracts, tumors, and enlargement of the lens.
2. Narrow-angle glaucoma (angle-closure glaucoma) - Glaucoma of this kind arises from closure or narrowing of the drainage angle. The various subtypes include:
- Acute angle-closure glaucoma - Occurs when the closed angle leads to build up of fluid inside the eyes. As a result, the optic nerve is damaged. The symptoms occur at the onset and are quite dramatic.
- Chronic angle-closure glaucoma - This is an asymptomatic type of glaucoma. The cause is similar to the acute form but the symptoms do not show until later. It is very serious, known to result in blindness.
- Neovascular glaucoma - This is caused by development of new abnormal vessels which close the drainage angle. The result is a build up of pressure and optic nerve damage.
Those at the highest risk of developing glaucoma are individuals over 40 years and those with a family history of the disease. Diabetes patients are also believed to be at great risk.
Signs & Symptoms
It is in most cases asymptomatic. However, signs and symptoms to watch out for include:
- Blurred vision
- Peripheral vision (side vision)
- Vomiting and nausea
- Halos around lights
Diagnosis checks for high IOP, thickness of cornea, vision defects and optic nerve anatomy. The tests may include:
- Dilated eye exam
- Visual field and acuity tests
Treatment is geared towards reducing internal eye pressure and preventing loss of vision.
Eye doctors will in most cases issue eye drops and/pills to lower the eye pressure. Side effects may include burning, redness, and stinginess.
In some cases, doctors may have to perform a laser trabeculoplasty to help drain the aqueous fluid of the eye. A conventional surgery (trabeculectomy) can also be done to create a new opening for proper drainage.
The condition can be controlled with a good treatment plan and regular eye examinations. However, if left untreated, permanent blindness may occur.
Although not preventable, eye care practitioners recommend regular check-ups for early diagnosis and treatment. The latter is necessary to avoid progression of the disease or loss of vision. Research also shows that an active lifestyle plus a healthy diet reduces the chances of developing glaucoma. Those already diagnosed should also adhere to treatment plans and go for frequent tests.