Glaucoma - What is it? Symptoms, Causes, Types, Treatment & Diagnosis

Glaucoma is a condition that affects your optic nerve. The condition worsens over time and is often linked to pressure buildup inside the eye. It mostly affects people in the later part of their life and often tends to run in families. The extra pressure on the eye, also known as intraocular pressure, can damage the optic nerve that sends images to the brain. Left untreated can lead to total blindness or permanent vision loss within a few years.

Most people living with glaucoma don’t show any symptoms or experience pain. Get yourself checked regularly if you are at risk of developing glaucoma. This is essential because once you lose your vision, you cannot get it back. However, lowering the eye pressure will allow you to keep your sight.

Different Types of Glaucoma

Glaucoma can be classified into five major types. These include:

• Open-angle Glaucoma (Chronic): Chronic, or open-angle, glaucoma does not show any symptoms apart from gradual vision loss. This process can be so slow that you may not notice any signs till your vision undergoes irreparable damage.
• Angle-closure Glaucoma (Acute): When the flow of aqueous humour is blocked, it may lead to a rapid buildup of fluid in the eyes. This can result in pain and a severe increase in eye pressure. This is an emergency and requires immediate medical attention.
• Congenital Glaucoma: Some children are born with congenital glaucoma, which causes a defect in the visual angle. It often displays symptoms such as excessive tearing, cloudy eyes, and sensitivity to light.
• Secondary Glaucoma: This is often a side-effect of eye conditions like eye tumours and cataracts. It may also be caused due to medications like corticosteroids.

Symptoms of Glaucoma

In many cases, glaucoma does not show any symptoms, especially in the case of open-angle glaucoma. On the other hand, acute-angle glaucoma requires immediate medical attention. Some common symptoms of this condition include:

• Severe eye pain
• Redness in the eyes
• Sudden blurred vision
• Sudden vision disturbance
• Seeing coloured rings around the lights
• Nausea 
• Vomiting

Common Causes of Glaucoma

Your eyes continually produce a clear fluid known as aqueous humour. This fluid fills the front of the eyes and leaves the eyes through channels in the iris and cornea. In case these channels get obstructed or blocked, the intraocular pressure increases in the eyes. This pressure can also damage the optic nerve and lead to vision loss.

Though the exact cause of this increase in pressure is not clear, the following factors are believed to play an important role:

• High internal eye pressure, is called intraocular pressure.
• Diabetes: Diabetic retinopathy is a common side-effect of diabetes that causes the growth of abnormal blood vessels. This can lead to blockage of fluids draining out of your eyes, resulting in glaucoma. 
• High blood pressure: Elevated blood pressure can increase intraocular pressure by boosting the production of aqueous humour. Due to this, long-term uncontrolled BP can lead to glaucoma.
• Migraines: Migraine attacks lead to a temperature reduction in your ocular blood perfusion. As a result, frequent bouts of migraines can also lead to the development of glaucoma.
• Sickle cell anaemia: Sickle cell anaemia often leads to the development of hyphema — a blood clot in the front chamber of your eyes. Even a tiny hyphema can increase your intraocular pressure significantly, resulting in glaucoma.
• Poor blood flow to the optic nerve
• Dilating eye drops
• Medications like corticosteroids
• Blockage in the drainage channels in your eyes

How is Glaucoma Diagnosed?

Glaucoma is diagnosed using a combination of tests. These tests are non-invasive, quick, and painless. The following tests are used for diagnosing glaucoma:

• Angle exam: Also called gonioscopy, this test checks the angle where your cornea meets your iris. If the test detects a closed angle, your eye’s drainage system is blocked.
• Corneal thickness measurement: This test measures your cornea’s thickness to determine your risk of glaucoma.
• Dilated eye exam: This test requires eye drops to dilate your pupils. A special tool shines light into the back of the eye to magnify your optic nerve and retina. After this, your ophthalmologist can properly check your optic nerve and retina, including its shape, size, colour, and blood vessels, to detect any damage.
• Eye pressure check: This test involves using a tiny instrument to touch your eye and flatten the cornea, which then measures the pressure.
• Optic nerve imaging: This test is done to take pictures of your optic nerve and retina using a special digital camera. This test may also be done using a special machine known as optical coherence tomography.
• Visual field test: This test checks if you have lost vision in specific areas to understand the severity of your glaucoma. Doctors may use certain tools to conduct the test, such as automated static perimetry. You may need to look at a line pattern and report if any parts look blank or blurry.
• Blood sugar test: If you have been experiencing symptoms of glaucoma without knowing about the underlying cause, your doctor may check your blood sugar levels to understand if you are living with diabetes which may be causing your glaucoma.
• Haemoglobin electrophoresis: Suppose your glaucoma is caused due to sickle cell anaemia. Then your doctor may check if you are a carrier of a particular sickle cell trait using a blood test known as haemoglobin electrophoresis.

Treatment Options for Glaucoma

Open-angle glaucoma is mostly treated using a combination of microsurgery, eye drops, and laser trabeculoplasty. Usually, the doctor starts with medication, but microsurgery or early laser surgery may be recommended to some people depending on their condition.

The standard treatment options for glaucoma include:

• Eye drops: Eye drops are often prescribed for treating glaucoma to reduce fluid buildup and encourage the eyes to drain out. This lowers its pressure. However, eye drops can have certain side effects, such as allergies, blurred vision, stinging, redness, and irritation of the eyes.
• Oral medications: Your doctor may also prescribe certain oral medicines. These include carbonic anhydrase inhibitors or beta-blockers for your conditions. These medicines can help boost fluid drainage or slow down production.
• Laser surgery: This treatment option is mostly recommended in case of open-angle glaucoma. The surgery can help increase fluid flow from the eyes and alleviate the fluid blockage. 

Some of the common procedures performed for glaucoma using laser surgery include:

• Iridotomy: This procedure involves making tiny holes in the iris to allow fluids to flow freely from the eyes.
• Trabeculoplasty: This procedure opens the drainage area to allow fluids to flow.
• Cyclophotocoagulation: This procedure treats parts of the eye's middle layer to reduce fluid production.
• Microsurgery: This procedure, known as trabeculectomy, involves creating new channels to drain fluids from the eyes and reduce eye pressure. This type of surgery may need to be performed multiple times to work properly. The doctor may also implant a tube in the eyes to facilitate fluid draining.
• Minimally Invasive Glaucoma Surgeries: MIGS is a new form of surgery that involves making tiny openings with the help of devices that cannot be seen with your naked eye. It is a safer and faster procedure but does not reduce pressure drastically. It is often performed simultaneously with other procedures, such as cataract surgery.

Conclusion 

Though there is no cure for glaucoma, treatment options are available to manage eye pressure. These treatments, if done on time, can prevent vision loss. Get yourself tested regularly by your ophthalmologist to detect glaucoma early. If you are at a higher risk of developing the condition, check with your doctor how often you should get screened. On the other hand, if you are living with glaucoma, make sure to use your eye drops daily or as prescribed by your doctor. With proper care, you can prevent the condition from worsening and causing irreparable damage to your eyes.