Glaucoma: Signs, Symptoms, Treatments
Glaucoma is the term for serious eye conditions typically referring to elevated pressure inside the eye, potentially leading to optic nerve damage, loss of vision, and blindness.
Glaucoma is nearly always the result of excessive pressure within the eye, but a rare form of the disease called “normal-tension glaucoma” not caused by eye pressure can occur.
During your eye exam, your eye doctor looks for signs of possible glaucoma damage by carefully evaluating the optic nerve. Tests showing the intraocular pressure or IOP also help your doctor determine if you may have glaucoma.
Glaucoma risk rises with age, and both black and Hispanic persons have a higher risk of developing it. However, glaucoma can strike anyone, any race, or any age at any time. Even small children may have developmental glaucoma, and it can even be present at birth.
Glaucoma is a threat to sight, but it’s also amenable to treatment if caught early. It’s entirely possible for early intervention and prompt treatment, usually with eye drops, to prevent any vision loss. However, treatment must happen before any damage has occurred, as damage is typically permanent.
Glaucoma and the Anatomy of the Eye
When the IOP is elevated, eye doctors call this ocular hypertension. Just as high blood pressure within the body’s blood vessels can cause damage to the heart and kidneys, elevated pressure within the eye can damage the optic nerve. The optic nerve transmits images to the brain from the retina and makes sight possible.
The fluid inside the eye is called aqueous humor. In this context, humor refers to bodily fluids. The aqueous humor gives the eyeball its shape and helps to nourish the interior of the eye. Because this aqueous humor is constantly being produced, it must drain out to maintain normal eye pressure.
Glaucoma is essentially an eye disease that prevents normal drainage of the aqueous humor. To understand this further, you need to know more about the structure of the eye relating to this condition.
Behind the iris, the colored part of the eye, there is a structure called the ciliary body that produces aqueous humor. The ciliary body also helps the lens to focus.
A normal eye will drain this fluid through the trabecular meshwork because it resembles a mesh-like channel. The trabecular meshwork is located where the eye’s cornea and iris meet.
Glaucoma conditions often refer to angles, such as closed-angle glaucoma. The angle involved is the one formed by the iris and cornea.
If the eye maintains a balance between aqueous humor produced and drained, glaucoma is highly unlikely. If more aqueous humor is produced than can be drained, the most common type of glaucoma may result. This is called open-angle glaucoma.
Typically, the open-angle form is the result of IOP that’s been too high for too long. As its name suggests, the angle between the iris and the cornea isn’t closed; it’s just not draining from the eye properly.
Glaucoma may take several years to damage sight, but it can also happen much faster. There are often no symptoms until vision is quite impaired. If symptoms do occur, it’s often in the form of reduced peripheral vision.
Causes of Glaucoma
Causes and risk factors for this condition include:
1. Trauma to the eye
2. Underlying conditions like diabetes or hypertension
3. Chronic steroid use and other medications
4. Thin corneas
5. High myopia or hyperopia
This refers to a very high degree of either nearsightedness or farsightedness. High myopia begins at prescriptions of -6 and above and is typically inherited.
6. Being over the age of 60
7. Family history and genetic risk
These are only possible causes. Some people with glaucoma have no known risk factors at all.
Glaucoma Symptoms
1. Headaches, nausea, and vomiting
2. High IOP
3. Cloudy eyes and blind spots in your vision
There are often no symptoms, so you cannot use them to warn you of a problem. Only your eye care professional can diagnose glaucoma before the condition damages your eyesight. Lost eyesight cannot be restored. At that point, treatment would focus on preserving the remaining vision.
Types of Glaucoma
Angle-closure glaucoma
Also called closed-angle glaucoma, this rare form of the disease occurs when the iris bulges forward, closing off the angle where the aqueous humor must drain.
The acute form occurs suddenly with eye redness, nausea, and severe eye pain. It’s a medical emergency, and only immediate medical treatment may preserve vision. The chronic form has the same cause but develops gradually, with IOP rising steadily over time. This is far more likely to occur in persons who happen to have narrow drainage angles.
Because of this, angle-closure glaucoma may also be referred to as narrow-angle glaucoma.
Open-angle glaucoma
The most common form is also known as POAG for primary open-angle glaucoma. The angles are not closed, but the aqueous humor still doesn’t drain from the eye properly. IOP rises out of the normal range, and damage to the optic nerve may occur. POAG is treatable with eye drops.
Secondary glaucoma
This simply means that the condition results from an underlying condition like diabetes and is not directly caused by the eye itself. This form can be either open-angle or narrow-angle and may also be caused by an injury.
Developmental glaucoma
This type is also called congenital, childhood, or pediatric glaucoma. Like other forms, it may be caused by another underlying disease or injury.
Normal-tension glaucoma
Although this type is not as common, this form of glaucoma occurs even though the IOP is within the normal range. It’s not well understood, but it’s thought to be related to restricted blood flow to the optic nerve. It may be linked to other conditions causing impaired circulation.
Glaucoma Diagnosis
An important part of your eye exam involves a test called tonometry. This measures your IOP. There are two basic types:
Applanation tonometry: this uses a small device that resembles a penlight. Your doctor will place a numbing drop into your eye and then place the device briefly against your eye, measuring the internal pressure. You will feel nothing.
Non-contact tonometry: this uses a gentle puff of air onto the eye’s surface to determine your IOP but may not be as accurate as applanation tonometry. The puff may be startling, but the test is painless. Young children and even teenagers are often highly amused by this procedure and may even ask the doctor to do it again!
These tests are essential but only reveal part of the picture. It’s up to your eye doctor to examine your optic nerve for an accurate diagnosis.
Other tests may include gonioscopy to inspect the drainage angle, visual field tests, and cornea thickness measurements.
Treatment
This may consist of eye drops, laser therapy, and surgery, but most people with glaucoma receive very good results from their glaucoma treatment.
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