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Glaucoma is one of the main causes of blindness worldwide. In the United States, primary open-angle glaucoma (POAG) is the most common form. More than 3 million Americans suffer from POAG.
Glaucoma occurs when the fluid in your eye cannot drain properly and the intraocular pressure (IOP) gets too high. Primary open-angle glaucoma is when the opening of the eye’s drainage channel is clear and working, but the fluid is still not draining properly. It is blocked somewhere in the drainage canal. (Learn More)
POAG is diagnosed through an eye exam that measures your IOP, as the condition usually doesn’t have many noticeable early symptoms. (Learn More) Often, there aren’t any early signs of glaucoma, and the condition can progress very slowly over years. It can impact vision as POAG progresses, leading to a loss of peripheral vision and blurriness. (Learn More)
Primary open-angle glaucoma is the most common form of glaucoma, but there are other less common forms as well, such as angle-closure glaucoma and normal-tension glaucoma. (Learn More)
When caught early, primary open-angle glaucoma can be managed through medications. (Learn More) Vision loss that results from advanced glaucoma cannot be reversed. Medications, laser treatments, and surgery can help to keep eye pressure lower, which keeps the disease from progressing. (Learn More)
Primary Open-Angle Glaucoma Explained
Glaucoma is a common condition. Globally, it is the second leading cause of blindness behind only cataracts.
Primary open-angle glaucoma (POAG) is the most common form of the disease. POAG, also called chronic open-angle glaucoma due to its continuous nature, can lead to optic nerve damage, which can negatively impact vision and cause blindness.
Glaucoma is generally the result of high intraocular eye pressure (IOP) when the fluid in your eyes doesn’t drain properly. With open-angle glaucoma, the opening of your drainage channel is clear, but there is a blockage further down the channel. Much like a clogged pipe, this can cause a backup of fluid and therefore raised IOP.
When your IOP gets too high, it can put pressure on your optic nerve. This is when you can start to have vision problems.
Primary open-angle glaucoma is a chronic, or long-lasting, and progressive disease. Treatments can help to keep the condition from getting worse and slow its progression. This is particularly important since vision loss related to glaucoma is not reversible.
Since POAG is both progressive and chronic, it is important to catch it as early as possible. The disease usually progresses very slowly, often over a period of years. If you manage it early, you can maintain healthy eyes and vision.
Primary open-angle glaucoma often does not have many early warning signs. You may not notice any visual symptoms or issues with your eyes in the early stages. Therefore, it is important to keep getting regular eye exams, so your doctor can monitor any potential vision changes and rising IOP.
Glaucoma is often the result of high IOP. Measuring IOP is part of regular eye exams, to ensure that eye pressure remains at normal levels.
During an exam, the angle of your anterior chamber will be measured since it is open with open-angle glaucoma. The optic disk is also checked because POAG can cause changes to it.
Visual field changes, such as distortions, reduced peripheral vision, and blurriness, can also be signs of late-stage POAG. These symptoms can be used to help diagnose the condition.
Signs & Symptoms of POAG
Again, primary open-angle glaucoma develops slowly, often over a period of several years. You may not notice any vision changes or problems with your eyes in the early stages. Regular eye exams are the best way to detect the condition and minimize damage to your eyes and vision.
Vision issues related to primary open-angle glaucoma usually start on the sides of your eyes, so peripheral vision is typically one of the first things to be impacted. Blurriness and a feeling of a narrowed field of vision are also signs of POAG.
This condition can occur differently in each eye. One eye can compensate for vision issues in the other, so you may not notice any changes in your vision until the late stages of the disease. Regular eye exams can help screen for POAG and treat the condition as early as possible.
Risk Factors for Primary Open-Angle Glaucoma
High IOP is not the only risk factor for POAG. In fact, there are several things to consider, including:
- Race. People of African American decent have a higher rate of POAG than other races.
- Family history. If someone in your immediate family suffers from POAG, you have a higher chance of developing the condition as well.
- Age. POAG develops slowly and is more common in older adults.
- Myopia (nearsightedness). This form of vision impairment can be a risk factor for developing POAG.
- Thin central cornea. The thickness of your cornea can contribute to poor drainage and therefore POAG.
- Other medical conditions. Conditions like diabetes and high blood pressure can also put you at risk for developing POAG.
Your eye doctor will do a thorough screening to determine if you have any specific risk factors, such as the ones above, that can contribute to the likelihood of developing primary open-angle glaucoma.
Types of Glaucoma
Primary open-angle glaucoma is the most common form of glaucoma, but there are other forms as well.
Another less common form of glaucoma occurs when the drainage canal is blocked due to a closed or narrow angle between the cornea and the iris. This is angle-closure glaucoma. Unlike POAG, it develops quickly and has noticeable symptoms.
Other forms of glaucoma include:
- Secondary glaucoma. This condition is the result of another medical issue.
- Traumatic glaucoma. This occurs because of an injury to the eyes.
- Congenital glaucoma. This happens when drainage canals in the eye don’t form properly during the prenatal period. Babies are born with this condition.
- Normal-tension glaucoma (NTG). With this form, damage to the optic nerve occurs without high IOP.
Treatment Options for POAG
The main goal in treating primary open-angle glaucoma is to keep the IOP within healthy ranges to decrease damage to the optic nerve and stabilize vision.
Medications are often the primary treatment option for glaucoma to maintain IOP levels. These can be in the form of eye drops, oral medications, or both. By keeping the pressure in your eyes normalized, the optic nerve isn’t as stressed and the progression of the condition can be managed.
The best way to manage POAG is to catch it as early as possible and follow your doctor’s treatment plan as directed. Take any and all medications as prescribed, and continue to get regular eye exams to monitor your eye pressure and check on your visual field. Your doctor can ensure that your medication is working properly and your IOP stays in the target range with the fewest side effects.
Medication types for managing POAG include:
- Prostaglandin analogs.
- Alpha 2 adrenergic agonists.
- Beta blockers
- Carbonic anhydrase inhibitors.
Medications can be very effective in regulating IOP and keeping glaucoma and vision loss from progressing. Additional treatments for POAG include laser therapies and surgeries.
- Laser trabeculoplasty: This procedure can increase the drainage of the aqueous fluid in the eyes and therefore be successful in lowering IOP and treating POAG. It is an alternative to medications as an initial therapy or an option when medications are either not an option or not working as intended. Laser therapies are minimally invasive, and results are often long term.
- General surgery for POAG: This is usually the last resort when other methods are not working. Traditional trabeculoplasty can lower IOP, but the success rate is lower than with laser therapies. The results often don’t last long.
- Eye surgery: This is surgery to place aqueous shunts. It can help to lower IOP, but this is a more invasive type of surgery. It has more risk factors and possible complications.
Your doctor is your best resource in determining how best to manage your primary open-angle glaucoma. Keep getting regular eye exams, monitor your IOP, and report any changes in your vision to your eye doctor.
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Primary Open-Angle Glaucoma. (June 2019). American Academy of Ophthalmology (AAO).
Primary Open Angle Glaucoma (Or Chronic Glaucoma). (2019). International Glaucoma Association (IGA).
Primary Open Angle Glaucoma. (March 2009). New England Journal of Medicine (NEJM).
Types of Glaucoma. (October 2017). Glaucoma Research Foundation (GCF).
Primary Open-Angle Glaucoma. (September 2018). American Academy of Ophthalmology (AAO).