Glaucoma

Can medicinal marijuana help patients with glaucoma manage their symptoms? Read below to find out. 

Glaucoma is the leading cause of irreversible blindness. Three million people in the U.S. and eighty million worldwide have glaucoma. It is the primary cause of adult blindness. There aren’t typically any symptoms in the early stages, which is how it gets the name “silent blinder.” However, early detection and treatment are the most critical steps to prevent loss of sight. 

Family medical history, especially siblings with glaucoma, is a risk factor for the disease. Eye pressure is the main adverse risk factor and is the target of current studies and potential treatments for glaucoma.

What is glaucoma? 

Glaucoma is a long-term and progressive eye disease caused by optic nerve damage that gradually leads to vision loss. One of the significant risk factors is eye pressure caused by a defect in the eye’s drainage system. This can cause fluid buildup and damage the optic nerve’s pressure, leading to unrecoverable loss of eyesight. The optic nerve is a bundle of nerve fibers that connects the retina to the brain. 

The vision loss due to glaucoma typically starts at the edges of the visual field and slowly moves to impact the central vision. It can take months or even years before you begin to notice symptoms. 

What are the symptoms?

People with glaucoma don’t typically notice symptoms until they begin to lose their eyesight. As glaucoma gradually damages optic nerves, small blind spots may develop in the peripheral vision. Blindness will result when the entire nerve is destroyed.

People can experience other symptoms, which include:

• Blurred or narrowed vision
• Severe eye pain
• Nausea
• Vomiting
• Headache

Who is affected by Glaucoma?

Any person could develop glaucoma. However, some are at higher risk than others. 

Glaucoma risk factors include:

• Age 40 or older
• Family history of glaucoma
• African, Hispanic, or Asian heritage
• High blood or eye pressure
• Farsighted or nearsighted
• Eye injury
• Long-term steroid use
• Thin corneas
• Thin optic nerve
• Diabetes
• Migraines
• Poor blood circulation

Types of Glaucoma

Open-angle glaucoma is the most common form of glaucoma and is caused by damage to the filter in the drainage canals of the eyes.

Angle-closure glaucoma is caused by a rapid blockage of the drainage canals due to a narrow-angle between the iris and cornea.

Low-tension or normal-tension glaucoma is defined by damage that occurs to the optic nerve without excessive eye pressure.

Congenital glaucoma occurs in infants with underdeveloped drainage canals in the eye during the prenatal period. 

Uveitic glaucoma is caused by autoimmune and inflammatory disorders.

Neovascular glaucoma is associated with uncontrolled diabetes and other conditions that damage the blood vessels.

Diagnosing Glaucoma

The following tests, along with an eye exam, may be able to diagnose glaucoma:

• A visual acuity test is a standard eye chart that measures how well you can see at various distances.
• Pupil dilation is when the pupil is widened with eye drops to allow an exam of the optic nerve and retina.
• The visual field is a test measuring peripheral vision. 
• Tonometry is a standard test that determines the fluid pressure inside the eye.
• Optic nerve imaging is photographs taken of the optic nerve to indicate areas of damage.
• Gonioscopy is when a lens is placed on the eye to determine whether the drainage angle is open or closed and if any damage has occurred. 
• Pachymetry is a measurement taken of corneal thickness.

Current Glaucoma Treatment Options

Early treatment can often control glaucoma symptoms. They often include:

• Medication. Some medicines cause the eye to produce less fluid, while other drugs can lower eye pressure by helping the fluid drain.
• Surgery. Surgery aims to create an opening for fluid to drain from the eye. 
• Laser surgery. Several types of laser surgery can be used to treat glaucoma symptoms.
• Cataract surgery: Cataract surgery typically reduces eye pressure in most patients and can often be successfully utilized as a glaucoma treatment.

Can Medical Marijuana Help Glaucoma Patients?

A person’s blood pressure directly affects if they will experience red eyes after using THC. For example, those with naturally high blood pressure need to ingest increased levels of THC to lower their blood pressure enough to cause bloodshot eyes. However, people with marijuana or smoking allergies can experience red eyes as a secondary symptom regardless of THC concentrations.

After consuming a cannabis-infused product, users typically experience increased blood pressure and heart rate due to the cannabinoids. These rises are similar to normal, moderate physical activities like exercise or sex. It generally takes up to ten minutes for heart rates to return to normal and blood pressure to decrease. Blood vessels, veins, and ocular capillaries dilate as the blood pressure drops. The dilation of ocular blood vessels and capillaries causes increased blood flow to the eyes, which causes the eyes to turn red and reduces intraocular stress.

This release can be beneficial in relieving eye pressure that can result in nerve damage and vision loss for glaucoma patients. Scientific evidence that THC can lower intraocular pressure (IOP) is a primary reason why many glaucoma patients have attempted medical marijuana use to treat symptoms.

Signs you are High on THC

After consuming marijuana, users may experience the following side effects and symptoms, especially with a high-THC strain:

• Red, bloodshot eyes
• Dizziness
• Dry Mouth
• Giggly and Laughing
• Fatigue
• Forgetfulness (short-term)
• Increased appetite (munchies)
• Slower concept of time

When you are high on THC, minutes may feel like hours as time seems to slow down. Ordinary sights, sounds, and tastes may seem attractive, funny, or different, and you could experience bouts of hunger, especially junk food. 

Summary

There are several cannabinoid receptors in the ocular tissue that are responsible for regulating eye pressure. A 1970 research project showed that THC effectively lowered eye pressure for a few hours, making glaucoma one of the first medical conditions historically treated by medical marijuana in Western culture.

THC’s short duration of effects means one would have to regularly consume it, which would likely be challenging for most due to the cognitive impacts and cost. Therefore, it is crucial to periodically follow up with an ophthalmologist to manage glaucoma and prevent severe treatment complications.