Glaucoma is a group of eye conditions that damages your eye’s optic nerves and is the second leading cause of blindness. It is further divided into types such as Congenital, Secondary, and Open-angle Glaucoma.

Out of all the types, Open-angle Glaucoma is the most common. In the US alone, more than 80% of Glaucoma cases are classified as Open-angle Glaucoma (OAG), with Primary Open-angle Glaucoma (POAG) being the most prevalent subtype. It is recognized as a vision-threatening condition, mainly for older people.

Early diagnosis and treatment are crucial to safeguard your eyesight since it is a chronic, progressive, and irreversible condition. This article will help you understand everything you need about OAG in depth.

We will discuss its symptoms, diagnosis, and treatments to help you understand this eye condition and protect your eyes from its adverse effects. So, let’s learn more about it!

What is Open-angle Glaucoma?

Open-angle Glaucoma is a chronic (long-term), progressive, and irreversible damage to the optic nerve that ultimately causes blindness. The exact cause of Open-angle Glaucoma is not known. However, to understand how a person may develop it, it is important to understand the role of fluid in eye health. 

Our eyes have fluids to maintain their overall shape and health. The main fluids in our eyes are:

  • Aqueous humor: A watery fluid filling the front chamber of the eyes, i.e., between the cornea and iris
  • Vitreous humor: A gel-like substance filling the back chamber of the eyes (between lens and retina) 

Our body maintains a balance between the production and the drainage of these fluids within the eyes. As new aqueous humor is produced, an equal amount of previous aqueous humor must be drained out through the drainage angle to maintain the balance.

The area through which the fluid drains out is called the drainage angle. A disruption in this angle can lead to a change in intraocular (eye) pressure. Open-angle Glaucoma occurs when the drainage channels are wide open but do not drain the fluid properly. It results in a rise in eye pressure; if left untreated, it can cause irreversible blindness.

Fact
The normal intraocular pressure of the eyes lies between 10 to 21 mm Hg. Generally, 20-30 mm Hg pressure causes optic damage for several years, and 40-50 mm Hg pressure can cause rapid visual loss.

Symptoms of Open-angle Glaucoma

According to the American Academy of Ophthalmology, OAG is asymptomatic in the early stage of the condition. However, many people notice changes in their eyesight once the condition becomes severe. Therefore, it is also called the ‘silent thief of sight.’

As the disease progresses, a blind spot (the areas through which you cannot see) develops at the periphery (side) of your eyes. If left untreated, the condition can worsen, and you may permanently lose your eyesight. 

Therefore, it is important to have routine eye examinations to detect the condition early and  stop its progression.

Risk factors of Open-angle Glaucoma

According to NCBI, multiple risk factors of OAG have been proposed, such as:

  • Intraocular pressure: Elevated intraocular pressure is the main risk factor for OAG
  • Ocular blood flow: The blood flow to the optic nerve is determined by Ocular Perfusion Pressure (OPP). Low OPP is a risk factor for Open-angle Glaucoma
  • Myopia: It is stated that the optic nerve head in the Myopic eyes is more sensitive to Glaucomatous damage because of the changes in tissue arrangement
  • Central Corneal Thickness (CCT): CCT can cause Ocular Hypertension, and thinner CCT (<40 micrometers) can increase the risk of OAG by 70%  
  • Optic disc hemorrhage (bleeding around the optic disk): It is also one of the risk factors for the development and progression of OAG

Moreover, a few other underlying risk factors that contribute to developing Open-angle Glaucoma are:

  • Age: Glaucoma increases with age and is prevalent in people above 40 years of age
  • Blood pressure: Elevated blood pressure can cause high IOP, but lower BP may cause a drop in Ocular Perfusion Pressure (OPP) and injury
  • Atherosclerosis: It is the build-up of fats and cholesterol in the arteries, which can cause autoregulatory dysfunction in several vascular beds, leading to changes in Ocular blood flow and, hence, OAG
  • Ethnicity: African-Caribbean and Hispanic people are more likely to develop OAG and also have a faster disease progression in comparison to others

If you suspect any of these risk factors, you can consult your doctor, ensure routine eye checkups for early detection of OAG, and seek treatment to stop its progression.

Careprost for gluacoma

Open-angle Glaucoma diagnosis

As OAG is asymptomatic in its early stages, it can be difficult to detect changes in one’s eyesight. Therefore, a complete eye examination is the only possible way to diagnose OAG.

You can visit your doctor, who can perhaps detect the change in your eye, such as:

  • Measuring intraocular pressure
  • Inspecting the eye’s drainage angle
  • Damage in the optic nerves
  • Checking blind spot in the side vision
  • Measuring the thickness of your cornea
  • Checking your optic nerve with a computer

Your doctor may use tests such as eye pressure tests, Gonioscopy (looking at the front part of the eye to see if the angle is open or closed), visual field tests (checking areas of missing vision), and optic nerve assessment to examine your eye. 

These can help the doctor detect the early signs of developing OAG and prescribe medications to stop the progression. An early diagnosis and Glaucoma treatment can eventually save your eyesight!

Open-angle Glaucoma treatment

Open-angle Glaucoma is an irreversible eye condition, but the following ways can stop further progression and preserve your eyesight:

Medications

Woman using eyedrop
Woman using eyedrop

Open-angle Glaucoma is usually treated with a prescribed first line of treatment, i.e., eye drops. These eye drops work effectively by lowering eye pressure. It can be achieved by improving the flow of fluid through the drainage angle or by reducing the aqueous fluid produced by the eyes.

The different Glaucoma eye drops prescribed by the doctor include:

  • Carbonic anhydrase inhibitors: These reduce the amount of fluid produced in the eyes, hence intraocular pressure. Examples include Dorzolamide
  • Alpha-adrenergic agonists: These reduce fluid production and promote fluid outflow to reduce eye pressure. One example is Apraclonidine
  • Rho Kinase Inhibitors: These are known to lower intraocular pressure and effectively treat Primary Open-angle Glaucoma. One such example is Netarsudil
  • Miotic or cholinergic agents: Agents such as Pilocarpine are the third-line treatment for Glaucoma, which works by promoting eye fluid drainage

Laser surgery

Glaucoma can be treated with Laser Trabeculoplasty, which drains the aqueous humor from the eyes. In this, the surgeon uses a laser to reduce eye pressure. It helps properly function the drainage angle, and the fluid flows out properly. Moreover, a doctor can advise you on other invasive surgical treatments to treat the progression of severe conditions. 

Other surgeries and devices

Some other options to treat Open-angle Glaucoma include minimally invasive procedures, tube shunts, and Trabeculectomy. 

Minimally Invasive Glaucoma Surgery (MIGS) is a relatively newer procedure that intends to improve fluid drainage and minimize the risk of complications like hemorrhage associated with traditional surgeries. On the other hand, Trabeculectomy is a traditional surgery for Glaucoma that lowers eye pressure by creating a hole in the wall of the eye to drain excess fluid. It is the gold standard for treating POAG.

Another option is tube shunts, a device fitted through Glaucoma surgery to drain excess fluid from inside the eye to external reservoirs. 

Warning
Do not ignore early signs of Glaucoma, like blind spots in the side vision. Get an immediate eye checkup done via a trusted Ophthalmologist to rule out the possibility of Glaucoma or seek timely treatment in case of Glaucoma to avoid progression. 

When to see a doctor

It is necessary to seek medical guidance from an eye care specialist for Glaucoma on any of the underlying causes:

  • Changes in vision
  • If you have Diabetes
  • A family history of Glaucoma
  • You are an elderly citizen

Early diagnosis can stop its progression. So, it is important to get your eyes checked to detect any symptoms.

Conclusion

Open-angle Glaucoma is the most common form of Glaucoma, a group of eye conditions. It occurs when the eye’s intraocular pressure increases, which, if left untreated, may lead to permanent blindness. 

In the condition’s early stages, you may not see any changes in the vision. However, as OAG progresses, a blind spot develops at the side of the eye.

According to NCBI, elevated eye pressure, Myopia, thin cornea, and optic disc bleeding are the main risk factors of OAG. Simultaneously, a few systematic factors, such as age, genetic factors, blood pressure, Diabetes, and vasospasm, are other risk factors.

Consulting an eye care specialist is recommended to diagnose OAG through a complete eye examination. After detecting it, your doctor can prescribe eye drops or recommend laser surgeries to avoid further progression.

If you notice any changes in your vision, visit your doctor immediately to detect and treat the condition early, which will eliminate the risks of its progression and preserve your vision.

Frequently Asked Questions

What are the risk factors of Open-angle Glaucoma?

Open-angle Glaucoma has multiple risk factors, such as elevated intraocular pressure, change in corneal thickness, Myopia, Diabetes, and patient’s age. Genetic factors, along with blood pressure and vasospasm, also contribute to the development of this eye condition.

How bad is Open-angle Glaucoma?

Open-angle Glaucoma is a common form of Glaucoma and is the second leading cause of blindness worldwide. If the condition is left untreated, it can cause loss of peripheral vision and then complete eyesight. Therefore, it is recommended that an eye examination be performed early to detect the condition. 

Who is at risk for Open-angle Glaucoma?

Older people with Myopic eyes, diabetic patients, and a family history of Atherosclerosis are at a high risk of developing this condition. You can consult your eye care specialist and ensure routine eye examinations to avoid progression. 

How is Open-angle Glaucoma diagnosed?

A complete eye examination is needed to diagnose OAG. You can visit your doctor and have your eyes checked for changes in intraocular pressure, eye drainage, optic nerve damage, etc. After examining your eyes, your doctor can recommend treatment such as Careprost eye drops or surgery if necessary. 

Is Open-angle Glaucoma asymptomatic?

In the early stages of the condition,  Open-angle Glaucoma is asymptomatic, and the patient can not even see any possible changes in the vision. However, as the condition progresses, they can notice blind spots in the periphery (side) vision. If left untreated, it can cause blindness.

Citations:
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