Medical Cannabis and Intraocular Pressure in Glaucoma

Glaucoma needs eye pressure kept down around the clock, and that is where medical cannabis for glaucoma falls short: in human studies, THC taken under the tongue lowered eye pressure for only about four hours ^[1]. So cannabis does not replace your drops. Smoke and vapor can add red, dry eyes, and any form with THC can lower blood pressure, change how you feel and affect driving. Decide with your eye doctor.

This overview draws on small trials in people, a genetic study of hundreds of thousands of people, patient records, reviews of the research, and animal and laboratory work on how cannabinoids act in the eye.

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Last updated October 29, 2026 · Medically reviewed by the Dr. Weedy medical team · Educational summary of published research, not medical advice

What Is Glaucoma? Definition, Pronunciation and Types

Glaucoma is a group of eye diseases that damage the optic nerve, the cable that carries what the eye sees to the brain, most often in connection with raised intraocular pressure (IOP), the fluid pressure inside the eye ^[2]. The damage is slow and silent at first, and it starts at the edges of your vision, which is why many people do not notice it until a routine eye exam finds it.

How to pronounce it: glaw-KOH-muh.

Glaucoma is not one disease but a family of them. The type you have shapes how fast it can move, what it feels like, and what your eye doctor watches for at each visit.

Open-angle glaucoma

The most common form in the U.S. ^[2]. The eye’s drainage angle looks open, but fluid drains too slowly, pressure creeps up, and the optic nerve is damaged over years. There is no pain and no early warning, so regular eye exams are the only way to catch it.

Angle-closure glaucoma

The colored iris blocks the drainage angle, and fluid cannot leave the eye. It can build slowly, or strike suddenly as an acute attack with severe eye pain, headache, blurred vision and nausea. An acute attack is a medical emergency ^[3].

Normal-tension glaucoma

The optic nerve is damaged even though eye pressure measures in the normal range. Doctors think poor blood flow to the nerve and a nerve that is more sensitive to pressure may both play a part. Treatment still aims to lower pressure further ^[2].

Secondary glaucoma, including drug-induced

Pressure rises because of something else: an eye injury, inflammation, diabetes-related blood vessel growth, or medicines such as long-term steroid drops, pills or inhalers. Glaucoma caused by a medicine has its own diagnosis code.

Is glaucoma acute or chronic?: Most glaucoma is chronic: open-angle glaucoma develops over years and is managed for life. Angle-closure glaucoma can be acute, coming on over hours, and needs emergency treatment.
Is glaucoma cancer?: No. Glaucoma is damage to the optic nerve, not a growth or tumor, and it does not spread to other parts of the body.
Can glaucoma be cured?: Not yet. There is no cure, but treatment can slow or stop further damage, and many people keep useful vision for life when pressure stays controlled ^[2].

What causes glaucoma, and does it run in families?

What Causes Glaucoma? Is It Hereditary or Genetic?

Glaucoma is caused by damage to the optic nerve, and the most common driver of that damage is pressure. The front of the eye constantly makes a clear fluid and drains it away. When fluid is made faster than it drains, pressure rises and slowly squeezes the nerve fibers at the back of the eye ^[2]. In some people the nerve is damaged at normal pressure, which tells doctors that blood flow and nerve sensitivity matter too.

How do you get it?

Nobody catches glaucoma, and it is not caused by reading or screen time. It develops when several risk factors add up over the years.

Age

Risk climbs after 60, and earlier, after 40, for Black Americans ^[2].

Does glaucoma run in families?

Yes. A parent, brother or sister with glaucoma raises your own risk ^[2].

High eye pressure

The best-known risk factor, and the only one treatment can change ^[2].

Steroid medicines

Long-term steroid eye drops, pills or inhalers can raise eye pressure in some people.

An eye injury

A blow to the eye can damage the drainage system, sometimes years before pressure rises.

Diabetes and high blood pressure

A large U.S. national health survey looked at diabetes among glaucoma risk factors ^[4].

Is glaucoma hereditary or genetic?

Glaucoma does run in families, and several genes have been linked to it, but inheriting a higher risk does not mean you will get it. What it does mean is timing: if a close relative has glaucoma, tell your eye doctor and ask how often you should be checked. Catching pressure changes early is the single most useful thing you can do with that family history.

What glaucoma feels like, and when it is an emergency

Glaucoma Symptoms: Eye Pain, Headaches, Blurry Vision and Halos

Open-angle glaucoma usually causes no symptoms for years, which is why eye pressure checks matter so much. Acute angle-closure glaucoma is the opposite: it comes on fast, with eye pain, headache and blurred vision, and needs emergency care ^[3].

Which kind of glaucoma were you told you have?

Your eye doctor names the type in your diagnosis or visit notes, often as “open-angle” or “angle-closure”. Not sure? Pick the last tile.

Open-angle

Eye pain?: Usually none. The pressure rises slowly, and the eye does not hurt.
Headaches or dizziness?: Not a typical sign. Headaches are common for many other reasons and do not tell you how your glaucoma is doing.
Blurry vision, halos, light sensitivity?: Usually not early on. The first loss is at the edges of vision, and the brain fills the gaps, so it goes unnoticed. Floaters and seeing things that are not there are not typical of glaucoma; mention them to your eye doctor.
How fast vision is lost: Slowly, over years, if pressure stays high. Treatment that keeps pressure at your target can stop or slow the loss.
What to do now: Keep every pressure check and use your drops exactly as prescribed. Ask what your target pressure is and how your visual field test has changed.

Angle-closure

Eye pain?: In an acute attack, yes: sudden, severe pain in or around the eye, often with a red eye.
Headaches or dizziness?: A strong headache on the same side, sometimes with nausea and vomiting, can come with an attack.
Blurry vision, halos, light sensitivity?: Sudden blurred vision and rainbow-colored rings around lights are classic warning signs ^[3]. Floaters and seeing things that are not there are not typical; tell your doctor about them anyway.
How fast vision is lost: An acute attack can damage the optic nerve within hours to days if pressure is not brought down. A slower, chronic form behaves more like open-angle glaucoma.
What to do now: If the warning signs below appear, go to an emergency room now. If you have had laser treatment for narrow angles, ask whether any medicines you take could narrow them again.

Normal-tension

Eye pain?: Usually none.
Headaches or dizziness?: Not a typical sign. Dizziness on standing or very low blood pressure is worth mentioning, because blood flow to the optic nerve matters in this type.
Blurry vision, halos, light sensitivity?: Usually not early on; the first loss is at the edges of vision. Floaters and seeing things that are not there are not typical of glaucoma and should be checked.
How fast vision is lost: Often slowly, though it varies from person to person. Your doctor follows it with visual field tests and nerve scans.
What to do now: Keep your follow-ups. Tell your eye doctor about blood pressure medicines and fainting spells, since anything that lowers blood pressure, THC included, is relevant to you.

Not sure yet

Eye pain?: Open-angle and normal-tension glaucoma usually do not hurt. Sudden severe eye pain points to an angle-closure attack.
Headaches or dizziness?: Not typical of the slow forms. A headache with eye pain, nausea and blurred vision is an emergency sign.
Blurry vision, halos, light sensitivity?: The slow forms take side vision first, without halos. Halos around lights with pain are an emergency sign. Floaters and seeing things that are not there are not typical; get them checked.
How fast vision is lost: Slowly over years in the common forms; within hours to days in an untreated acute attack.
What to do now: At your next visit, ask which type you have and write it down. It changes what to watch for and what to ask about medicines.

Red flags: go to the emergency room now

Sudden, severe pain in one eye
Rainbow-colored rings around lights
Nausea or vomiting together with eye pain
Vision that suddenly turns blurry or dim

If any of these happen, call 911 or go to an emergency room. Do not wait for your next appointment, and do not try to treat it at home with anything, cannabis included.

Does glaucoma lead to blindness?

Does Glaucoma Cause Blindness? How Long Before Vision Loss?

It can, if it is not found and treated. With treatment, most people with glaucoma do not go blind ^[2]. That fear brings many readers to this page, so it is worth saying plainly: the outcome depends far more on how early glaucoma is caught and how well pressure is controlled than on the diagnosis itself.

How long before blindness?

There is no single timeline. Open-angle glaucoma usually takes years to cause noticeable vision loss, and the pace depends on your type, how high your pressure is, how early treatment began and how steadily you use it. An untreated acute angle-closure attack is different and can harm the optic nerve quickly. Your eye doctor tracks your own pace with repeated visual field tests and scans of the nerve; ask to see how your results have changed over time.

Does glaucoma go away?

No. Glaucoma does not go away on its own, and vision already lost to it cannot be restored ^[2]. Treatment protects what you still have. That is why stopping drops because your eyes “feel fine” is risky: the disease is silent whether it is controlled or not.

Check what your own answers suggest

Glaucoma ICD-10 Codes

ICD-10 codes are the short labels doctors use on forms, insurance claims and medical records. You may see one on a visit summary or need it when you bring records to a medical cannabis evaluation. The main glaucoma codes are below; the exact code adds digits for the eye and the stage.

Main ICD-10-CM codes for glaucoma
Code	What it means
H40.1x	Open-angle glaucoma, the common chronic form
H40.2x	Primary angle-closure glaucoma
H40.6x	Glaucoma secondary to drugs, such as steroids
H40.9	Unspecified glaucoma

Source: ICD-10-CM code set, National Center for Health Statistics, CDC ^[6]. Codes are updated every year; check the current code set or ask your doctor’s office.

See whether your situation fits a medical card

Living With Glaucoma: Why Patients Look for Alternatives

Glaucoma rarely hurts, yet it asks a lot of you. The treatment is daily, it lasts for life, and you never feel it working. Many people tell their eye doctors some version of the same thing: “I do everything right, and I still worry at every visit.”

Drops every day, for life

One to several bottles, at set times, every day. Miss doses and pressure can drift up without any sign that it has.

Drops that sting or redden the eyes

Burning, redness and dry, gritty eyes are common complaints, and some drops change eyelash growth or eye color over time ^[3].

Cost and refills

Brand-name drops, pharmacy runs and insurance rules for refills add up over years of treatment.

Worry before every pressure check

Each visit can feel like a test you may fail, and the fear of losing sight is hard to put down between them.

It is natural to look for something that feels more in your control, and cannabis comes up often because of decades of headlines about eye pressure. Here is the honest frame for everything below: drops, laser and surgery remain the foundation of glaucoma care. Cannabis is something some patients discuss as an addition, and only with their doctors, not as a way out of treatment.

How glaucoma is treated today

How to Treat Glaucoma: Eye Drops, Laser and Surgery

Every glaucoma treatment does the same job: it lowers eye pressure to a target your doctor sets for you, and keeps it there day and night ^[2]. The tools differ in how they get there.

Eye drops

Usually the first step. Different families of drops either help fluid drain out of the eye or make the eye produce less of it: prostaglandin analogs, beta-blockers, alpha agonists, carbonic anhydrase inhibitors and rho kinase inhibitors. Side effects depend on the family: stinging and redness are common, prostaglandins can darken the iris and lengthen lashes, and beta-blocker drops can slow the heart or tighten the airways in some people ^[3]. Tell your doctor about any side effect; there is usually another option.

Laser treatment

A short office procedure. For open-angle glaucoma, laser trabeculoplasty helps the drainage meshwork work better and can reduce or delay the need for drops. For narrow angles, laser iridotomy makes a tiny opening in the iris so fluid can reach the drain ^[3].

Surgery and implants

When drops and laser are not enough, a surgeon creates a new drainage route. In a trabeculectomy, a small flap lets fluid leave the eye under the outer layer; drainage implants, also called tubes or shunts, carry it out through a fine tube. Newer minimally invasive procedures place tiny stents during cataract surgery or on their own ^[2].

Is glaucoma curable or treatable?

Treatable, not curable. Treatment cannot bring back lost vision, but it can protect what remains, and most people need some form of it for life ^[2]. That makes the long view important when you weigh any added option.

Herbal and plant remedies are often asked about alongside cannabis. A review of herbal medicines in glaucoma found interesting laboratory leads but no plant remedy ready to replace standard treatment ^[7].

See if a card fits your situation

Can You Prevent Glaucoma? Home Remedies, Foods and Lifestyle

Nothing has been shown to prevent glaucoma itself, but there is a reliable way to prevent most of the vision loss it causes: finding it early ^[2]. Everyday habits support eye health; none of them replaces a prescribed treatment.

Regular eye exams

What can help
A dilated eye exam finds glaucoma before you notice any loss, especially with family history or after 60.

What it can’t do
It cannot stop glaucoma from starting; it makes sure treatment starts in time.
Exercise and blood pressure

What can help
Regular moderate activity is good for your heart and circulation, which the optic nerve depends on.

What it can’t do
It does not replace drops. Ask before head-down yoga poses or heavy straining if you have glaucoma.
Foods to eat and avoid

What can help
A balanced diet supports general health and helps manage diabetes and blood pressure, both linked with eye disease.

What it can’t do
No food or supplement has been shown to prevent glaucoma or lower pressure enough to treat it.
Home and herbal remedies

What can help
Wearing eye protection during sports and yard work prevents the injuries that can lead to glaucoma later.

What it can’t do
Herbal remedies have not been shown to control glaucoma ^[7]; some interact with prescribed medicines.

Home remedies do not replace your prescribed drops, and cannabis does not belong on a list of home treatments for glaucoma. Whether it has any place in your care is a medical question, and the next sections lay out what the research actually shows.

How cannabinoids interact with the eye

Understanding the Endocannabinoid System and Ocular Health

Your body makes its own cannabis-like messengers, called endocannabinoids, and the network that uses them is the endocannabinoid system. It works through receptors called CB1 and CB2, which are like docking stations on cells: when a cannabinoid docks, the cell changes what it does. These receptors sit in the tissues that make and drain eye fluid and in the retina ^[1].

Plant cannabinoids such as THC dock on the same receptors, which is why researchers began asking about eye pressure decades ago. CBD is different: it does not switch CB1 on, and in some settings it even dampens it ^[1]. That is why results for THC cannot simply be applied to CBD, or the other way around.

To see where cannabinoids might act, it helps to follow the eye’s fluid from where it is made to where it drains.

Ciliary body

Fluid is made

What cannabinoids may change: less fluid made ^[1]^[8].
Front of the eye

Fluid flows

What cannabinoids may change: no direct effect described here.
Drainage meshwork

Fluid drains

What cannabinoids may change: more fluid drains ^[1]^[8].

Mostly shown in animal and lab studies

The same system is also present in the retina, the light-sensing layer whose nerve cells form the optic nerve. In laboratory and animal work, cannabinoids have been studied for protecting those cells from stress and inflammation ^[1]. Whether that happens in people with glaucoma has not been shown.

What the studies found

What Does the Research Say? Clinical Evidence on Cannabis and Glaucoma

The short version: THC can lower eye pressure in people, but only for a few hours, and no study has shown that cannabis keeps glaucoma under control over months or years.

How strong is the evidence?

Trials in people: Shown in a trial: a controlled test in a small group, usually a single dose.
Genetic studies and patient records: Linked with, not proof of cause: they show what goes together in large groups.
Animal and lab studies: Not applied to people: they point to where to look next.

Who was studied?

Results in animals often do not hold in people. Filter to see what was tested in humans.

Showing all 11 rows of the table

Table 1. Studies on cannabinoids and the eye
Study (type, year)	Who	What was tested	What happened
Crossover randomized trial, 2026 People	23 people with glaucoma	One oral dose of dronabinol (prescription THC) and placebo, each person trying both	Blood flow to the optic nerve head rose 10.8% at 10 mg; the effect was seen for about 4 hours ^[9]
Genetic study, 2023 People	Genetic data on 16,677 people with open-angle glaucoma and 199,580 without it	Whether an inborn tendency toward cannabis use changes glaucoma risk	No link found, either for lifetime use or for cannabis use disorder ^[5]
Patient records study, 2025 People	24,774 people who use cannabis, compared with people who don’t	How often eye inflammation and its complications appeared in health records	Uveitis, scleritis and, at ages 18-45, cataracts were recorded more often; a link, not proof of cause ^[10]
Population cohort, 2022 People	Adults in the UK Biobank health study	Cannabis smoking and recorded glaucoma	Mixed findings that do not settle whether smoking cannabis changes glaucoma risk ^[11]
Retrospective gene analysis, 2022 People	Adults with genetic and eye pressure data	Whether the GAS7 gene changes how eye pressure responds to cannabis	Variation in this gene may change the pressure response, so effects could differ between people ^[12]
Eye clinic survey, 2025 People	134 eye clinic patients, most of them treated for glaucoma	How many use cannabis and what they believe about it	15.7% had used marijuana in the past month; 44.2% of glaucoma patients were interested in using it for glaucoma ^[13]
Animal study, 2026 In animal studies	90 mice bred to develop glaucoma	Eye drops with WIN 55,212-2, a lab-made cannabinoid	Eye pressure 11.5 mmHg vs 22 mmHg in untreated mice at the same point; nerve function better preserved ^[14]
Animal study, 2025 In animal studies	8 healthy horses	One oral dose of CBD oil	Eye pressure was tracked through the day; the horses did not have glaucoma ^[15]
Randomized animal trial, 2024 In animal studies	18 healthy dogs	Daily oral CBD for 36 weeks	Tear production and eye pressure were followed; CBD was found in 91% of tear samples from treated dogs ^[16]
Animal studies summarized in a review, 2025 In animal studies	Rats and monkeys	WIN 55,212-2, a lab-made cannabinoid	Eye pressure 47% lower in rats with induced glaucoma; fluid production 18% lower in monkeys (two different measures) ^[1]
Lab research, 2020 Lab	Laboratory models	How the CB1 receptor controls eye pressure	CB1 appears to push eye pressure in two opposing directions, which may explain mixed results ^[17]

Read top to bottom, the table tells a consistent story. In people, the effect on eye pressure is real but short, the one recent trial measured blood flow rather than pressure, and the large studies of cannabis users show no protection against glaucoma. The most striking numbers come from mice, rats and monkeys, and those have not been repeated in people.

Talk to a licensed doctor about glaucoma

How Big Are the Effects? What Large Studies Found

Two large studies give the clearest picture of cannabis and eye disease in real populations. They answer different questions, so the chart keeps them in separate groups.

Is cannabis use linked with glaucoma or other eye disease?

Each dot is the study’s best estimate; the line is the likely range (95% CI) reported by each study ^[5]^[10]. A hollow dot whose line crosses “No difference” means no clear link.

● estimate · ━ likely range · │ no difference No difference

Genetic study: does cannabis use raise the risk of open-angle glaucoma? ^[5]

Lifetime cannabis use

1.04× (0.88-1.23) no clear difference

Cannabis use disorder

0.97× (0.92-1.03) no clear difference

Patient records: eye conditions in people who use cannabis vs people who don’t ^[10]

Uveitis (inflammation inside the eye)

1.46× (1.07-1.99) more often

Scleritis (inflammation of the eye wall)

2.60× (1.39-4.85) more often

Cataracts, ages 18-45

1.92× (1.20-3.07) more often

No link with glaucoma was found; eye inflammation and early cataracts showed up more often in the records of people who use cannabis, an association, not proof that cannabis caused them.

Show as a table

Effect estimates shown in the chart ^[5]^[10]
Outcome	Comparison	OR	95% CI	p	Source
Open-angle glaucoma, lifetime cannabis use	Genetic tendency to use vs not	1.04	0.88-1.23	–	^[5]
Open-angle glaucoma, cannabis use disorder	Genetic tendency vs none	0.97	0.92-1.03	–	^[5]
Uveitis	Cannabis use vs no use	1.46	1.07-1.99	0.016	^[10]
Scleritis	Cannabis use vs no use	2.60	1.39-4.85	0.002	^[10]
Cataracts, ages 18-45	Cannabis use vs no use	1.92	1.20-3.07	0.005	^[10]

These numbers cannot be added together or carried over to other products. One measured eye pressure in healthy people after smoking, the other measured blood flow, not pressure, in people with glaucoma after a single prescription capsule. Neither tells you what a dispensary edible, tincture or vape would do, or what would happen after months of use.

Why the effect is short, and what might explain it

Mechanisms of Action: How Might Cannabis Affect Glaucoma?

When a cannabinoid docks on receptors in the eye, two things seem to happen: the ciliary body makes less fluid, and more fluid drains out through the meshwork ^[1]^[8]. Less fluid in and more fluid out means lower pressure. Cannabinoids also act on blood vessel tone and on nerve cell signals, which is why researchers are interested in blood flow to the optic nerve as well as pressure ^[1].

The catch is timing. Natural and plant cannabinoids are broken down quickly, so the pressure drop fades within hours, and holding it would mean dosing again and again through the day and night ^[1]^[18]. THC can also lower blood pressure throughout the body, and lower blood pressure can mean less blood reaching the optic nerve, which works against the goal. And people may not respond alike: variation in a gene called GAS7 may change how much eye pressure responds to cannabis ^[12].

THC or CBD: Which One Matters for Glaucoma?

Tested in people, short effect

THC

The compound behind most of the human eye pressure findings. It works through CB1 receptors, and its effect lasts hours, not a day ^[1]. It is also the part of cannabis that affects mood, thinking, heart rate and blood pressure.

Animal studies only

CBD

CBD does not switch on the CB1 receptor and can even dampen it ^[1]. It has been given to healthy horses and dogs ^[15]^[16], but not tested for glaucoma in people. A THC result does not carry over to CBD, and a CBD result does not carry over to THC.

Small trial in people

Dronabinol (prescription THC)

A lab-made THC sold by prescription. In a crossover trial in 23 people with glaucoma, a single dose increased blood flow to the optic nerve head compared with placebo ^[9]. Long-term use was not tested.

In animal studies

Lab compounds (WIN 55,212-2, MAGL blockers)

Experimental molecules that act on the same system. In animal studies, a MAGL blocker kept eye pressure lower for 12 hours in mice ^[1]. None is an approved medicine.

Nerve protection and blood flow Hypothesis

Glaucoma is ultimately about nerve cells dying, so researchers also ask whether cannabinoids could protect them directly, apart from pressure. In mice bred to develop glaucoma, cannabinoid eye drops helped preserve nerve function over the long term ^[14]. In people, the closest evidence is the small dronabinol trial that measured more blood flow to the optic nerve after one dose ^[9]. Whether that protects vision over years is not known.

What changes with smoking, vaping, edibles and drops

Does the Form Matter? Smoking, Vaping, Edibles, Tinctures and Eye Drops

Cannabis is not the same as smoking. The eye pressure research tested a handful of specific routes: smoked THC, THC under the tongue, dronabinol capsules and experimental eye drops. Each form enters the body differently, avoids some problems and keeps others.

Which form are you asking about?

The dispensary label names the form: flower, vape cartridge, edible, tincture, cream. Prescription cannabinoids come from a pharmacy, not a dispensary.

Smoking

Tested for eye pressure?: In healthy volunteers, an older study: pressure was 25% lower after smoked THC ^[8].
How it enters the body: Joints, pipes and bongs: smoke goes into the lungs and THC reaches the blood within minutes.
What it avoids: The long delay of edibles, so effects are easier to notice early.
What still applies: Smoke reddens and dries the eyes and reaches the lungs; THC can lower blood pressure, change how you feel and impair driving.

Vaping and dabs

Tested for eye pressure?: No.
How it enters the body: Dry-herb vaporizers, oil cartridges and dabbed concentrates: a hot aerosol goes into the lungs.
What it avoids: Burning plant material and its smoke.
What still applies: The aerosol still passes the same airways and can dry and redden the eyes; concentrates can carry a lot of THC, with the same blood pressure, mood and driving concerns.

Edibles and capsules

Tested for eye pressure?: No, for dispensary edibles. Prescription dronabinol capsules were studied separately; see that tile.
How it enters the body: Gummies, chocolates, drinks and capsules are digested and pass through the liver before reaching the blood, so they start later and last longer.
What it avoids: Smoke and vapor on the eyes, airways and lungs.
What still applies: Slow onset tempts people to take more; THC still affects blood pressure, mood and driving; the liver route matters for interactions with other medicines.

Under the tongue

Tested for eye pressure?: Yes, with a short effect: about four hours in human studies ^[1].
How it enters the body: Tinctures, oils and sprays held under the tongue or in the cheek are absorbed through the lining of the mouth.
What it avoids: Smoke and vapor; part of the dose skips the first pass through the liver.
What still applies: The effect on pressure fades within hours; THC still affects blood pressure, mood and driving; some of the dose is swallowed.

Creams and patches

Tested for eye pressure?: No.
How it enters the body: Creams and balms act mostly in the skin; transdermal patches are built to deliver cannabinoids into the blood.
What it avoids: Smoke and vapor; creams avoid most whole-body effects.
What still applies: A patch with THC brings the same blood pressure, mood and driving concerns; skin products are not meant for use near the eyes.

Eye drops

Tested for eye pressure?: There are no approved cannabis eye drops; experimental versions irritated the eye ^[18].
How it enters the body: Through the surface of the eye. Only about 3-5% of any eye drop’s dose reaches the inside of the eye ^[19], and cannabinoids are oily and hard to dissolve in drops.
What it avoids: In theory, most whole-body effects, which is why researchers keep working on them.
What still applies: Never put a dispensary product or homemade oil in your eyes: it can irritate or injure the eye surface ^[7].

Prescription cannabinoids

Tested for eye pressure?: Dronabinol: blood flow to the optic nerve, in a small trial ^[9].
How it enters the body: Dronabinol and nabilone are capsules or liquids taken by mouth, prescribed by a doctor and filled at a pharmacy, not bought with a medical card.
What it avoids: The variable strength of dispensary products: the dose is standardized.
What still applies: They are FDA-approved for other conditions, not glaucoma ^[20], and carry the same THC concerns: blood pressure, mood and driving.

What else researchers have looked at besides pressure

Cannabis for Symptom Management in Ocular Conditions

Beyond eye pressure, researchers have looked at blood flow, nerve protection, tears and the effects people notice in their own eyes. Some findings point to therapeutic potential worth studying; others are side effects. None has been shown to treat an eye condition.

What studies looked at beyond eye pressure
Symptom or eye issue	What studies looked at	Who was studied
Optic nerve blood flow	One dose of dronabinol raised blood flow to the optic nerve head by 10.8% compared with placebo ^[9]	People
Nerve cell protection	Cannabinoid eye drops helped preserve nerve function in mice bred to develop glaucoma ^[14]	In animal studies
Tear production	Tears and eye pressure followed during 36 weeks of daily oral CBD in healthy dogs ^[16]	In animal studies
Glare and halos, night driving	Among people who smoked cannabis, 68% reported worse glare and halos and 74% a reduced ability to drive at night ^[19]	People
Dry and red eyes	Dry eyes reported by 8.7% of medical cannabis users; red eyes in 94% of THC-positive drivers ^[19]	People
Eye inflammation	Uveitis and scleritis recorded more often in people who use cannabis; see the chart above ^[10]	People

If you live with more than one condition, see all qualifying conditions for medical cannabis.

Two of these rows matter for anyone with glaucoma who drives. Glare, halos and poorer contrast at night are already common with glaucoma, and smoked cannabis can add to them. If you drive after dark, raise this with your eye doctor before anything else.

How many eye patients already use cannabis

Cannabis Use in Eye Clinic Patients: Prevalence and Perception

If you are curious about cannabis, you are in good company. A survey at an eye clinic, where most patients were being treated for glaucoma, asked about it directly.

How to tell your eye doctor without feeling judged

What to say: Keep it factual: “I use cannabis, this form, about this often, and my last use was on this day.” Eye doctors ask because it changes how they read your numbers, not to judge you.
When to say it: Before the pressure check, ideally when you are asked about medicines. Telling the technician at the start of the visit works too.
What to ask: “Could this affect my readings? Should I avoid it before visits? Does it interact with my drops or my blood pressure medicines?”

Bring this to your eye appointment

Your type of glaucoma and your last pressure readings
All your eye drops and how often you use each one
Pills for blood pressure or the heart
Whether you use cannabis, which form, and when you last used it before this visit
Any fainting or dizziness when you stand up
Whether you drive, especially at night

Talk it over with a licensed doctor

Dosage, Administration, and Potential Side Effects

Your dose and form are set by your doctor. What follows is only what researchers used in their studies, so you can see the conditions behind each result, not a dose to try.

Table 2. What the studies used
Study	Form	Amount used in the study	What happened
Healthy volunteers, described in a 2023 review	Smoked THC	18 mg THC ^[8]	Eye pressure 25% lower ^[8]
Study described in a 2023 review	Oral dronabinol	7.5 mg ^[8]	Faster blood passage through the retina’s vessels ^[8]
Crossover trial, 23 people with glaucoma, 2026	Oral dronabinol	10 mg, single dose ^[9]	Optic nerve blood flow +10.8% vs placebo ^[9]
Human studies described in a 2025 review	THC under the tongue	Not stated in the review summary	Eye pressure lower for about 4 hours ^[1]

Side effects seen in studies

Changes in perception and mood, from euphoria to anxiety, confusion and sleepiness, are typical effects of THC ^[7].
Red eyes and fewer tears; older smoking studies saw red eyes in many volunteers and perception changes in nearly all of them.
A faster heartbeat and a drop in blood pressure ^[7]. For glaucoma this matters twice: lower blood pressure may mean less blood reaching the optic nerve.
Dizziness, especially on standing, and slower reactions, which affect driving and the risk of falls.

Safety for your eyes, driving and blood pressure · How doctors approach medical cannabis dosing

Safety: Eyes, Driving, Blood Pressure and Medications

Safety looks different depending on what you use. It helps to split it into three layers: what comes with smoke and vapor, what comes with any product containing THC, and what comes with sharing devices.

Smoke and vapor

Red eyes were seen in 94% of drivers who tested positive for THC, dry eyes were reported by 8.7% of medical users, and contrast sensitivity fell by about 30% with both eyes and 50% with one eye after smoking ^[19].

Any form with THC

Mood and thinking change, the heart beats faster and blood pressure can drop, whatever the form. Driving is impaired, and glare and halos at night can get worse; see eye symptoms.

Shared devices

Passing a joint, pipe or vape between people passes germs too. If your eyes are irritated or you have just had eye surgery, avoid sharing anything that touches the mouth or face.

Driving and sleepiness

Glaucoma can already narrow your side vision and make night driving harder. THC slows reactions, affects judgment and can make you sleepy, and it is illegal to drive impaired by cannabis in every state, with or without a medical card ^[21]. If cannabis is part of your plan, agree with your doctor on how long to wait before driving.

Long-term data

There are no studies of people with glaucoma using cannabis for years. The longest study in the research here followed healthy dogs on CBD for 36 weeks ^[16]. What long-term use does to eye pressure control, the optic nerve or the rest of the body in glaucoma is unknown.

Medicines that don’t mix

What Science Doesn’t Know Yet

The gaps here are not small print. They are the reason cannabis is not a glaucoma treatment today, and they are worth knowing before you talk to a doctor.

Time

What studies tested
Single doses, followed for hours.

What they did not test
24-hour pressure control kept up for years.
People

What studies tested
Groups of about 18 to 23 people.

What they did not test
Large, long-term trials in people with glaucoma.
Delivery

What studies tested
THC by mouth, by smoking and under the tongue.

What they did not test
An approved cannabinoid eye drop: none exists ^[1].
Nerve protection

What studies tested
Mice bred to develop glaucoma ^[14].

What they did not test
Whether it protects vision in people.
CBD

What studies tested
Healthy horses and dogs ^[15]^[16].

What they did not test
People with glaucoma.

Most of what is known comes from animal and laboratory models, and the body’s own cannabinoids act only briefly ^[1].
The large population studies could not say how much cannabis people used, in which form or for how long, so they cannot show cause and effect ^[5]^[10].
People may be reluctant to report cannabis use, so surveys may undercount it ^[13].

So where does that leave you?

The Verdict: Where Cannabis Fits in Glaucoma Care

Cannabis is not a replacement for glaucoma treatment. For some patients, it may be something to discuss alongside it, especially when another condition such as chronic pain or anxiety is part of the picture.

Eye pressure. THC lowers it in people, but only for hours; it cannot replace drops that work around the clock ^[1].
Large studies. No link between cannabis use and glaucoma risk ^[5]; a signal of more eye inflammation in people who use it ^[10].
Any form. Blood pressure, driving and mood effects come with THC however it is taken.
Decide with your eye doctor. The right plan depends on your type of glaucoma, your target pressure and your other medicines.

Don’t stop or skip your glaucoma drops without your eye doctor.

Discuss cannabis with a licensed doctor

Can You Get a Medical Marijuana Card for Glaucoma?

It depends on your state. Each state writes its own list of qualifying conditions, and glaucoma has a long history on those lists because of the early eye pressure research. In other states, a licensed doctor can recommend cannabis based on a related condition or on their medical judgment.

Glaucoma named on the state list

Your diagnosis itself qualifies. The doctor confirms it from your records and checks that cannabis is reasonable alongside your current treatment.

Through your doctor’s judgment or a related condition

Where glaucoma is not listed, chronic pain, anxiety, insomnia or the doctor’s own judgment may be the route, depending on what your state allows.

What to bring: your glaucoma diagnosis, recent notes from your eye doctor, and a list of every eye drop and medicine you take. These help the doctor confirm the condition and spot interactions. How the medical card evaluation works.

Glaucoma and your state’s cannabis laws

Beyond whether glaucoma qualifies, your state decides how much you can buy and carry, how medical purchases are taxed, and whether you can grow at home. These rules change, so check them before you apply.

Legal status
Possession limits
Taxes
Home cultivation

See your state’s rules

Check your state and get your card

Medical Card vs. Recreational Purchase: What Changes for Glaucoma Patients

In states where adults can buy cannabis without a card, a medical card can still change what you pay, what you can buy and how your use is documented. The details depend on your state.

Taxes

With a medical card
Many states tax medical purchases less, or skip certain cannabis taxes; depends on your state.

Buying recreationally
The full set of state and local cannabis taxes applies.
Purchase limits

With a medical card
Often higher purchase and possession limits; depends on your state.

Buying recreationally
Lower limits set for adult use.
Age

With a medical card
Some states allow adults from 18 to register as patients.

Buying recreationally
21 and older.
Product access

With a medical card
Medical dispensaries and, in some states, products or strengths reserved for patients.

Buying recreationally
Adult-use stores and their product rules.
A doctor’s plan

With a medical card
A licensed doctor reviews your glaucoma, medicines and risks before recommending anything.

Buying recreationally
No medical review; a budtender is not a doctor.

Legal Protections: Firearms, Employment, Privacy and Driving

Firearms

Cannabis remains illegal under federal law, and the federal firearms purchase form, ATF Form 4473, asks about unlawful use of marijuana even where it is legal in your state ^[22]. Weigh this before you apply if you own or plan to buy firearms.

Work and drug tests

Some states protect registered patients from being fired for off-duty use; others do not, and federal and safety-sensitive jobs follow their own rules. A card does not protect you from being impaired at work.

Privacy

Your evaluation is a medical visit, and your health information is protected under HIPAA ^[23]. In most states, patient registry records are confidential.

Driving

A medical card is never permission to drive impaired. Every state treats driving under the influence of cannabis as an offense ^[21].

Some state programs also let a registered caregiver buy or carry cannabis for a patient who cannot do it alone; whether yours does is set by state law.

State laws and regulations · Medical vs recreational cannabis · Medical card FAQ

Where are you now?

Getting a card for the first time The three steps, and what happens after you click I already have a card or need to renew Your documents and orders are in your account Traveling or moving Rules differ by state; check where you will be Worried about work, firearms or privacy What a card changes, and what it does not

How to Get a Medical Marijuana Card for Glaucoma Online

Your appointment is with a doctor licensed in your state, and everything happens online, so there is nowhere to travel and no waiting room. You talk one on one about your glaucoma, your treatment and your questions, and the doctor decides whether a recommendation fits.

4.6out of 5 on Google

Across 250 reviews from patients in the states where we are licensed. We do not sort them by score and do not hide the low ones.

150,000+patients evaluated – everyone who has been through an appointment with us, in every state where we are licensed
Since 2017doing only this: online evaluations for medical cannabis programs, and nothing else on the side

About 5 minutes

Fill out a short form

Your state, your glaucoma diagnosis and your current medicines. Have your eye doctor’s notes nearby if you can.
About 15 minutes

Meet a licensed doctor

The time is agreed with your doctor. Keep an hour free rather than a single minute, in case the previous appointment runs over.
In as little as 15 minutes after the appointment, depending on your state

Get your recommendation

If the doctor approves, the signed recommendation arrives in your account. State registration, where required, runs on the state’s timeline.

What happens after you click

An email: Confirms your request and explains the next step.
Your appointment: You agree on a time with your doctor; the visit is online.
Your documents: Recommendation and receipts are kept in your account.

Renewing Your Medical Card

Recommendations and state cards expire on a schedule set by your state, so renew before the date on yours. If your glaucoma treatment has changed since your last visit, such as new drops, laser or surgery, tell the doctor at renewal. You can start a renewal from your account, and the medical card FAQ covers the common questions.

Trouble with the site? Write to [email protected].

Get your medical card

How the medical card evaluation works · Our doctors

Frequently Asked Questions About Glaucoma and Cannabis

Does marijuana lower eye pressure?

Yes, for a short time. In human studies, THC under the tongue lowered eye pressure for about four hours ^[1], and smoked THC lowered it by 25% in healthy volunteers ^[8]. Glaucoma needs pressure controlled day and night, so a few hours at a time is not enough to treat it.

Is cannabis safe for glaucoma treatment?

It has not been shown to work as a glaucoma treatment and is not approved for it, and its long-term safety in glaucoma has not been studied. THC can lower blood pressure, speed the heart, cause red and dry eyes and affect thinking and driving ^[7]^[19]. Whether it is reasonable for you, alongside your treatment, is a question for your eye doctor.

Is CBD good for glaucoma?

There is no evidence that it helps glaucoma in people. CBD does not work through the CB1 receptor that THC uses to lower pressure ^[1], and it has only been given to healthy horses and dogs in eye studies ^[15]^[16]. CBD can also change how other medicines are processed ^[19].

Why isn’t cannabis a standard treatment for glaucoma?

Because its effect on pressure is short, it would have to be taken many times a day, THC affects blood pressure, mood and driving, there are no approved cannabis eye drops, and no long-term trials exist ^[1]^[18]. Drops, laser and surgery control pressure for much longer.

What are the main risks of using marijuana for glaucoma?

A false sense of control if it replaces drops; pressure readings that look better than they are; lower blood pressure, which may reduce blood flow to the optic nerve; red and dry eyes and night glare with smoking ^[19]; and impaired driving. See serious risks and contraindications.

Are there benefits of cannabinoids for eye health beyond eye pressure?

Possibly, but not shown in people yet. One small trial found more blood flow to the optic nerve after a dose of dronabinol ^[9], and in animal studies cannabinoid drops helped preserve nerve function ^[14]. Neither has shown that vision is protected in people.

What does genetic research say about cannabis use and glaucoma risk?

A large genetic study found no link between cannabis use, or cannabis use disorder, and the risk of open-angle glaucoma ^[5]. In other words, cannabis does not appear to cause glaucoma, and it does not appear to prevent it either.

Can I tell my eye doctor if I use cannabis?

Yes, and you should. Recent use can lower your pressure reading for a few hours and hide how your treatment is really working ^[13]. Say which form you use, how often and when you last used it. Here is how to bring it up.

Can glaucoma be cured with eye drops?

No. Drops control glaucoma by keeping pressure down, but they do not cure it, and they work only as long as you keep using them ^[2].

Is glaucoma hereditary?

It runs in families. Having a parent, brother or sister with glaucoma raises your risk, so tell your eye doctor and get checked regularly ^[2].

Can I have glaucoma in one eye?

Yes. Glaucoma often starts in one eye or is worse in one eye, especially after an injury or with some secondary forms. The other eye still needs regular checks, because glaucoma frequently affects both over time.

Does glaucoma cause headaches?

The common, slow forms usually do not. A sudden headache with eye pain, blurred vision, halos and nausea can be an acute angle-closure attack and needs emergency care ^[3]. For ordinary headaches, see our page on migraine.

Glaucoma in dogs: can my dog use cannabis?

Only your veterinarian can answer that. Marijuana is listed as toxic to dogs ^[24], and products made for people can poison pets. The one long-term study looked at oral CBD in healthy dogs without glaucoma ^[16], so it says nothing about treating glaucoma in your dog.

Is delta-8 the same as medical cannabis?

No. Delta-8 THC products are sold outside medical programs, have not been evaluated or approved by the FDA, and may be made with chemicals and contain impurities ^[25]. None of the glaucoma research on this page studied delta-8.

How do I choose a dispensary?

Choose one licensed by your state, with products that list THC and CBD content and lab testing. Tell the staff about your glaucoma and medicines, but take dosing questions back to your doctor.

Does my card work in other states?

Sometimes. A few states honor out-of-state medical cards and many do not. Check the rules of the state you are visiting in laws and regulations before you travel, and never cross state lines with cannabis.

What if I lose my card?

Your recommendation is stored in your account, and a replacement state card is requested through your state’s program.

How do I renew?

Start from your account before your recommendation expires, and tell the doctor about any change in your glaucoma treatment since the last visit.

Is the appointment done online?

Yes. It is a telemedicine appointment with a doctor licensed in your state, which is how online medical cannabis evaluations are done where state law allows them. You do not need to travel anywhere.

Still have questions? Ask a licensed doctor · Medical card FAQ

More research on cannabis and glaucoma

This page cites a selection of studies. Our research library holds every study we track on cannabis and glaucoma, from laboratory work to clinical trials, and lets you filter them by cannabinoid, study type and year.

studies: 540+
in people: 220+
clinical trials: 40

See the studies on glaucoma

Serious Risks and Contraindications: When to Be Especially Cautious

Drug interactions to discuss first

CBD and other medicinesPharmacokinetic

CBD can block and also speed up the liver enzymes and transporters that process many medicines, so their levels in the blood may rise or fall ^[19]. Bring your full medicine list.

Blood pressure medicinesNot studied together

THC can lower blood pressure on its own ^[7]. Together with blood pressure pills, the drop could be larger; this has not been studied in glaucoma. Bring it on your list.

Glaucoma drops taken with heart medicinesNot studied together

Beta-blocker eye drops are absorbed into the body and can slow the heart ^[3], while THC tends to speed it up ^[7]. How the two combine with heart medicines has not been studied. Bring it on your list.

Sedatives, sleep aids and alcoholNot studied together

The prescribing information for dronabinol warns that its effects add to those of alcohol and sedatives ^[20]. Sleepiness, unsteadiness and falls are the concern. Bring it on your list.

Discuss your medicines with a licensed doctor

Key Takeaways for Patients

Tested. THC lowers eye pressure in people for a few hours ^[1].
Not tested. Long-term pressure control, cannabinoid eye drops, and CBD in people with glaucoma.
Any form. Blood pressure, driving and drug interactions apply whether you smoke, vape, eat or use a tincture.
Decide with your eye doctor. Keep using your drops, and tell your doctor before you add anything.

Our part takes little of your time: the form takes about 5 minutes, and the appointment about 15 minutes. If the doctor approves, the recommendation can arrive in as little as 15 minutes after the appointment, depending on your state.

Dr. Weedy is a medical card evaluation service. We connect you with doctors licensed in your state; we do not sell cannabis.

Get your medical card See if I qualify

Important Disclaimer

This page is an educational summary of published research and does not replace a visit with your eye doctor. Medical cannabis does not cure glaucoma, and no result described here is guaranteed for you. Do not stop or change any prescribed glaucoma treatment without the doctor who prescribed it. If you have sudden eye pain, halos around lights, nausea with eye pain or sudden blurred vision, call 911 now; see the warning signs above.

References

26 sources

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12. Lehrer S, Rheinstein PH Cannabis, Intraocular Pressure, and the Growth Arrest-Specific 7 (GAS7) Gene: A Retrospective Analysis. Cureus · 2022 · cross_sectional DOI: 10.7759/cureus.23919 PMID: 35411287
13. Adamek AJ, Hussein MA, Abdulkarim I, et al. An assessment of the prevalence of cannabis use in eye clinic patients and its implications on glaucoma diagnosis and management. Int Ophthalmol · 2025 · cross_sectional DOI: 10.1007/s10792-025-03846-2 PMID: 41243046
14. Gallo Afflitto G, Chou TH, Korsch ML, et al. Topical WIN 55 212-2 Confers Long-Term Intraocular Pressure-Independent Neuroprotection in the DBA/2J Mouse Model of Glaucoma. Ophthalmol Sci · 2026 · preclinical DOI: 10.1016/j.xops.2025.100918 PMID: 41140902
15. Bazzano M, Laus F, Cerquetella M, et al. Effect of orally administered cannabidiol oil on daily tonometric curve in healthy Italian Saddle horses. PLoS One · 2025 · preclinical DOI: 10.1371/journal.pone.0325191 PMID: 40435047
16. Jost HE, Spitznagel K, Alvarenga IC, et al. Long-term effect of oral cannabidiol administration to healthy adult dogs on tear production, intraocular pressure, and tear concentrations. Vet Ophthalmol · 2024 · rct DOI: 10.1111/vop.13164 PMID: 38032014
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