What is Glaucoma?
The name glaucoma
belongs to a group of eye diseases that damage the optic nerve in the back of
the eye. It tends to worsen gradually over time.
Most commonly, this
is due to increased pressure inside the eye — known as intraocular pressure
The front of the
eye produces what is known as the ‘aqueous humor’, a fluid that is continuously
drained from the eye.
If this fluid
doesn’t circulate out of the eye properly, it builds up — causing increased
pressure within the eyeball.
Glaucoma may also be caused by poor blood supply to the optic nerve fibers or a weakness in the nerve structure of the eye [
4]. There are Different Types of
Most cases of glaucoma are due to IOP with two common
1. Open-Angle Glaucoma
(OAG) is the most common type of glaucoma, accounting for at least 90% of all
glaucoma cases .
OAG happens when
the aqueous humor (the clear liquid that lubricates and nourishes the inside of
the front of the eye) becomes blocked and doesn’t drain properly. This causes
pressure to rise in the eye, eventually damaging the optic nerve.
Often there are no
warning signs, with loss of vision occurring gradually over several years
without pain or discomfort.
With early detection, you can treat and slow down the
condition. 2. Angle-Closure Glaucoma
glaucoma (ACG) is different from OAG in that the eye pressure can rise rapidly.
It’s a rare form of the disorder.
ACG happens when
the peripheral part of the iris — the colored part of the eye — becomes blocked
over the drainage canals. The pupil will enlarge too much or too quickly.
Symptoms of Glaucoma Blurry vision Seeing “halos” in the eyes under bright lights Headaches Nausea Vomiting
Not all patients
with glaucoma will have elevated intraocular pressure, but what’s been found is
that for every mmHg(a measurement of
pressure) that intraocular pressure is lowered, it reduces the risk of the
disorder by 10% .
Anyone can get
glaucoma, however, some people are more at risk than others. Risk Factors for Glaucoma Family history of glaucoma Diabetes Aged 40 years and over Previous injuries to the eye Hypertension High eye pressure Myopic or “near-sighted” If you experience any of the following symptoms you
should see your eye specialist as soon as possible. Vision loss Halos in bright lights Redness in the eye Eye pain Blurred vision Nausea and vomiting
It’s important to
note that symptoms can vary greatly between individuals, you may have some or
none of the symptoms mentioned.
This is why it is
important to have regular visits with your eye specialist to ensure the
condition is detected in its early stages.
How is Glaucoma Detected?
initially causes peripheral vision loss (side vision) undetectable to the
patient, regular eye check-ups — especially after the age of 40 — are essential
to screen for glaucoma, assessing if further examination is needed.
A Glaucoma Test Usually Includes
the Following: Optic nerve check with an
ophthalmoscope Eye pressure check (tonometry) Visual field assessment if needed
— this tests the sensitivity of the peripheral vision, where glaucoma initially
starts. Standard Treatments for Glaucoma
Most treatments for
open-angle glaucoma are aimed at lowering and controlling eye pressure or
decreasing the production of fluid in the eye. The most common treatment is
specialized eye drops — an ophthalmologist decides on which treatment to use or
a combination of therapies.
1. Eye Drops
This is the most
common initial form of treatment and are classified by their active chemical
ingredient. These include prostaglandins, beta-blockers, alpha agonists, and
rho kinase inhibitors.
Common Side Effects of Eye Drops: Eye drops that contain prostaglandins can
cause stinging, burning, and eye color change. Beta-blocker medications used in a variety of
glaucoma eye drops can cause reduced heart rate and adverse side effects in
individuals with heart and lung problems such as emphysema, diabetes, and
depression. Alpha agonist-based eye drops can cause
burning, stinging, fatigue, headache, and drowsiness. 2. Oral Medications
Medications such as
Carbonic Anhydrase Inhibitors (CAIs) can be used in conjunction with eye drops.
CAIs can cause systemic side
effects such as transient myopia (short-sightedness), frequent urination,
tingling of the extremities, and lightheadedness. 3. Selective Laser
are performed if eye drops have failed to control deterioration in vision. The
effects of laser treatment are often not permanent, and many patients will need
to return to medications.
Side Effects of Selective Laser Trabeculoplasty (SLT) May Include: Mild side effects include soreness, redness, and
blurring of vision. Elevated Eye Pressure — In some cases the eye pressure can increase after the
procedure. This increase in eye pressure is usually temporary and may be
treated with additional eye drops or oral medications. Very rarely this
increase in eye pressure can persist and require more invasive surgical procedures
to be performed. Peripheral Anterior Synechiae — adhesion of the iris to the cornea. Inflammation
& Swelling — In rare cases,
selective laser trabeculoplasty (SLT) can lead to persistent inflammation
within the eye. This is a potentially serious complication that can lead to
other problems in the eye. 4. Surgery
performed if eye drops, medications or laser has failed to control the pressure
in the eye. Surgery can be effective, however, there are risks involved.
Effects of Surgery Include: Postoperative infection Drooping eyelid Double vision Swelling Bleeding Developing a hole near the operation site Scarring Low IOP (hypotony) In severe cases, some people experience: Hemorrhaging inside the affected eye Choroidal detachment Vision loss Loss of the eye itself
If treated and monitored, glaucoma will usually not lead to blindness.
5% of patients with glaucoma experience vision
loss. While it isn’t a condition that can be cured, there are many options
available to maintain IOP at normal levels. These options include medication,
laser, and surgery. How Could Cannabis Help with
glaucoma have used medicinal marijuana for decades to help ease symptoms.
back in the 1970s found that smoking marijuana can indeed lower IOP,
but it has a short duration, only lasting for three to four hours at a time.
If you have
glaucoma, it’s important to maintain lower eye pressure 24 hours a day, so
smoking marijuana multiple times a day is not a practical solution.
Studies have shown
that THC is the molecule that lowers IOP. CBD, on the other hand, works against
THC. Therefore, if you’re thinking of using cannabis oils to treat glaucoma,
it’s best to use high-THC oil instead of high-CBD oil.
There is a lot of
debate about this, however.
THC Has Two Key Advantages: It reduces intraocular pressure (IOP) It supports nerve health
7, 8] )
So, what does this
The two major
cannabinoids found in cannabis, tetrahydrocannabinol (THC) and cannabidiol
(CBD), are both compounds that influence the body’s
endocannabinoid system (ECS) but have very different effects.
Now, when people
talk about marijuana they’re usually thinking of the effects of THC, which is
the part of the cannabis plant that gives us the euphoric feelings or of being
“high”. While it also has other side effects, such as dizziness, loss of
coordination, anxiety, paranoia, and increased heart rate, THC is strongly
linked to reducing IOP in
studies. 1. THC Reduces Intraocular
There are many
receptors for cannabinoids in the ECS. THC interacts with them, though the
mechanics are still unknown. What is known is that this interaction reduces IOP
while CBD, the other type of cannabinoid found in cannabis, interferes with THC
It’s theorized that
there is a high concentration of the CB1-type cannabinoid receptors in the eye.
This is why smoking marijuana or consuming THC oils and edibles can help lower
2. THC Supports Optic Nerve
reducing intraocular pressure isn’t always enough to prevent vision loss.
Something known as
glutamate-induced neurotoxicity also
appears to play a significant role in glaucoma.
Sufferers tend to
have an elevated level of glutamate – the major neurotransmitter found in the
eye – the excess glutamate accumulates in the retinal ganglion cells and
New research has
found that CBD and THC
can protect against this glutamate-induced
cell death since they are both antioxidants. What CBD Can Help With: Glaucoma
While CBD may not help with glaucoma directly,
it can help with other issues that may aggravate existing IOP issues. Let’s
take a look at them:
1. CBD and High Blood Pressure
CBD oil has been
shown to reduce blood pressure and manage stress due to its ability to increase
blood flow during times of stress .
CBD acts as a
vasodilator — it allows the blood to flow more freely by relaxing the smooth
muscle cells within blood vessels and taking away pressure placed on the
2. CBD and Diabetes
Diabetes is a major
cause of two specific types of glaucoma known as
open-angle glaucoma (the most common form of the disease), and neovascular glaucoma.
There are several
theories as to why this happens — including such processes as inflammation in
the eye, retinal cell death from high blood sugar levels, and the development
of dysfunctional blood vessels in the eye.
due to insulin resistance is a key factor in developing type 2 diabetes.
Researchers have found that the anti-inflammatory properties of CBD treat this
inflammation, thus improving the body’s metabolism and glycemic control .
What does this
CBD can reduce inflammation that leads
to developing type 2 diabetes, which may reduce the chances of diabetic-induced
glaucomas. 3. CBD and Inflammation
been shown to be anti-inflammatory and immunosuppressive agents — largely due
to their interactions with the ECS.
They do this by
inhibiting cell proliferation, and suppressing inflammatory cytokines .
What does this
Simply put, CBD can reduce inflammation and influencing
certain immune system cells. Tips on Using Cannabis Oils With
When using cannabis for glaucoma, there are
three main things to remember:
Oils high in CBD are not recommended if you have glaucoma — THC is the only cannabinoid backed by research to be a potential treatment for glaucoma Always follow the advice of a medical practitioner — be open about your interest in trying cannabis products to support your symptoms When it comes to dosing, the key is to start low and go slow
There are different
methods for treating glaucoma with cannabis. You can try topical eye drops or
take in the form of oral drops, pastes, capsules, or in tea or lozenges.
Concentrations vary greatly between products and how it is prepared.
As we are all different, the dosage will vary with each
individual. We recommend starting with a small dose,
such as 10 mg of extract per day, and see how you react.
responds to cannabis differently it may take some trial and error to get the
right dose for you.
Keep a daily
journal of dosages, timings and any symptoms. This will help you to find your
personal optimal dose.
It’s important to
higher doses (>40 mg) of
CBD increase IOP. So it is extremely important to read the label of the
product you are using.
Use cannabis oils,
do not smoke marijuana. Smoking marijuana long-term is not recommended as a
treatment for glaucoma due to its short duration of action and risk of lung
damage over time.
Is CBD Oil Safe? You can’t overdose on CBD.
According to the
World Health Organisation (WHO) CBD oil, in its pure state, does not cause harm
or have the potential for abuse even at high doses .
The research we
have discussed here is based on using high-quality CBD. It’s important you make
sure you use a high-quality CBD product that is free from contaminants and
Final Verdict: Using Cannabis for
Most of the
research up until this point shows that THC is effective in reducing IOP, while
CBD interferes with THC activity. For the small percentage of people who suffer
continued vision loss even after controlling their IOP, THC is an antioxidant
that can help prevent retinal ganglion cell apoptosis.
since CBD does not relieve IOP, one would need to find an oil that is high in
THC and avoid CBD specific oils. Of course, you should also continue with the
medication schedule ordered by your ophthalmologist. To prevent any drug
interactions, always check with your doctor before beginning any supplemental
References Tham, Y. C., Li, X., Wong, T. Y., Quigley, H. A., Aung, T., & Cheng, C. Y. (2014, November 1). Global prevalence of glaucoma and projections of glaucoma burden through 2040: A systematic review and meta-analysis. Ophthalmology. Elsevier. https://doi.org/10.1016/j.ophtha.2014.05.013 Glaucoma Treatment, Symptoms & Diagnosis. (n.d.). Retrieved December 12, 2018, from https://www.lei.org.au/services/eye-health-information/glaucoma/ Lederer C. M. (2012). The use of marijuana to treat glaucoma. Missouri medicine, 109(2), 95. Retrieved August 22, 2019, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6181747/ Weinreb, R. N., Aung, T., & Medeiros, F. A. (2014). The pathophysiology and treatment of glaucoma: a review. JAMA, 311(18), 1901–1911. doi:10.1001/jama.2014.3192 Types of Glaucoma | Glaucoma Research Foundation. (n.d.). Retrieved December 13, 2018, from https://www.glaucoma.org/glaucoma/types-of-glaucoma.php Cairns, E. A., Baldridge, W. H., & Kelly, M. E. M. (2016, January 12). The Endocannabinoid System as a Therapeutic Target in Glaucoma. Neural Plasticity. Hindawi. https://doi.org/10.1155/2016/9364091 Tomida, I., Pertwee, R. G., & Azuara-Blanco, A. (2004). Cannabinoids and glaucoma. The British journal of ophthalmology, 88(5), 708–713. doi:10.1136/bjo.2003.032250 Philpott, H. T., OʼBrien, M., & McDougall, J. J. (2017). Attenuation of early phase inflammation by cannabidiol prevents pain and nerve damage in rat osteoarthritis. Pain, 158(12), 2442–2451. doi:10.1097/j.pain.0000000000001052 Kokona, D., Georgiou, P.-C., Kounenakis, M., Kiagiadaki, F., & Thermos, K. (2016). Endogenous and Synthetic Cannabinoids as Therapeutics in Retinal Disease. Neural Plasticity, 2016, 8373020. https://doi.org/10.1155/2016/8373020 Jadoon, K. A., Tan, G. D., & O’Sullivan, S. E. (2017). A single dose of cannabidiol reduces blood pressure in healthy volunteers in a randomized crossover study. JCI Insight, 2(12). https://doi.org/10.1172/jci.insight.93760 Horváth, B., Mukhopadhyay, P., Haskó, G., & Pacher, P. (2012). The endocannabinoid system and plant-derived cannabinoids in diabetes and diabetic complications. The American Journal of Pathology, 180(2), 432–42. https://doi.org/10.1016/j.ajpath.2011.11.003 Mecha, M., Feliú, A., Iñigo, P. M., Mestre, L., Carrillo-Salinas, F. J., & Guaza, C. (2013). Cannabidiol provides long-lasting protection against the deleterious effects of inflammation in a viral model of multiple sclerosis : A role for A2A receptors. Neurobiology of Disease, 59, 141–150. https://doi.org/10.1016/j.nbd.2013.06.016 World Health Organization. (2017). WHO | Cannabidiol (compound of cannabis). WHO. Retrieved from http://www.who.int/features/qa/cannabidiol/en/