Glaucoma is the term used to describe a group of incurable eye diseases. Its origins are unknown and it is the leading cause of irreversible blindness worldwide. In this article I will define glaucoma, describe the symptoms, discuss risk factors, and treatment options, including medical cannabis.
The most prevalent symptom is an increase in eye pressure, known as intraocular pressure (IOP), which speeds up the progression of the disease. However, those with normal or low eye pressure can also get the disease. Scientists are realizing that they must look beyond the eye pressure factor for other treatment options. This has led them to investigate neuroprotection, something cannabis researchers recognized over a decade ago.
Early treatment intervention is crucial. It may stop further damage and protect your vision. While glaucoma is thought to be a hereditary condition, anyone is at risk of developing glaucoma. Ophthalmologists advise everyone to have an eye exam every 2-3 years. For those in high risk groups, the recommendation is yearly or every 1-2 years.
- Patchy blind spots
- Tunnel vision
- Severe eye pain
- Nausea and vomiting
- Blurred vision
- Halos around lights
- Eye redness
Types of Glaucoma
90% of Americans with glaucoma have open-angle, the most common form of the disease. With this type, the eye is kept inflated and healthy by a clear fluid, the aqueous humor. If there is a drainage blockage, pressure inside the eye becomes too high. This may crush the cells of the optic nerve which carries images from the retina to the brain.
A type of open-angle glaucoma, it occurs in people with normal eye pressure. 1 in 3 people with open-angle glaucoma has this type.
Risk Factors Include:
- Low blood pressure
- Heart problems, especially irregular heartbeat
- Family history of normal-tension glaucoma
- Japanese ancestry
Also known as narrow-angle or acute glaucoma, this type occurs when the iris bulges forward which narrows or blocks the drainage angle formed by the cornea and iris. This stops the fluid from circulating throughout the eye, increasing the pressure. Some people are born with narrow drainage angles, increasing their risk of this type of glaucoma. It requires emergency medical treatment. It can cause the following symptoms:
- Blurred vision
- Red eyes
- Intense eye pain
- Severe headache
- Halos around lights
Slow/Chronic Angle-Closure Glaucoma
This type happens more slowly and it is not uncommon for there to be no symptoms. Treatment options include medication, laser treatments or surgery.
About 1 in 10,000 American infants is born with this type. The symptoms are very obvious. They include:
- Sensitivity to light
- Cloudy eyes
- Production of more tears than normal
- Larger eyes than normal
There are several other types of glaucoma that affect children known as pediatric glaucoma. Early intervention surgical treatment usually will prevent permanent vision loss.
Higher Risk Factors
- Over age 60
- High blood pressure, heart disease, sickle cell anemia, diabetes
- Higher eye pressure
- African Americans/Latinos over age 40
- Family history of glaucoma
- Corneas that are thin in the center
- Extreme nearsightedness or farsightedness
- Previous eye injury or certain types of eye surgery
- Long term corticosteroid medication usage, especially eye drops
Dilated Eye Exams
In this exam, your eyes are dilated by drops which enables the doctor to check for problems inside your eye by allowing more light into it. Your doctor will check for glaucoma and other problems such as diabetic retinopathy, cataracts and age-related macular degeneration.
- Visual field test for peripheral vision assessment
- Visual acuity test to check how clearly you can see
- Eye muscle function test to check the status of your eye muscles
- Pupil response test to check how your pupils react to light
- Tonometry test measures the pressure in your eyes. This test involves the use of a machine to blow a puff of air onto your eye or the use of a special tool to touch your eye.
Other Facts About Glaucoma
- Glaucoma can occur in one or both eyes
- Not everyone with high eye pressure gets glaucoma
- Normal eye pressure varies by person
The FDA has just approved a few new different eye drops, the first new advances in 20 years. These new drugs, designed to be used once a day, improve the outflow of the aqueous humor from drainage tissue at the base of the cornea. However, they may produce adverse side effects such as bloody eyes and blurred vision.
Scientists are also working on eye drops used to act as a neuroprotectant which would aid in protecting the optic nerve from damage.
Lasers can be used to aid in the drainage of eye fluid which lowers the pressure. It is a simple procedure that takes place in the doctor’s office. It does have risks as does surgery.
- Glaucoma Implant Surgery
- Minimally Invasive Glaucoma Surgery (MIGS)
Cannabis research, begun in the 1970s, sought to investigate the effects of medical cannabis on IOP. The results indicated that smoking cannabis did reduce the IOP by 30% for 3-4 hours, peaking at the 2 hour mark.
Cannabis researchers now believe that glaucoma is a neurodegenerative disease. This was the focus of a Canadian 2007 study, conducted by N. Gupta and YH Yucel at the Department of Ophthalmology at St. Michael’s Hospital at the University of Toronto. They concluded that it is likely that there are other factors at play besides elevated eye pressure. Researchers observed similarities between glaucoma and other neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases. These include neuron loss, cell injury and death, and degeneration of the synapses in which the disease spreads from injured neurons to connected neurons.
Cannabis researchers are currently at work on producing eye drops containing cannabinoids, not only to treat the disease but to stop its progression which would be a game-changer for glaucoma patients.
nei.nih.gov, Types of Glaucoma, updated June 26, 2019
nei.nih.gov, Get a Dilated Eye Exam, updated Aug 2, 2019
apothecarium.com, Cannabis and Glaucoma, Cameron Klar, May 14, 2018
knowablemagazine.org, Putting the Squeeze on Glaucoma, Chris Woolston, June 4, 2019