CBD Eye drops
CBD-infused eye drops are considered favorable in treating neuropathic ocular pain or diabetic retinopathy (eye complications due to diabetes).
But, What are the merits and demerits of CBD eye drops over prescription eye drops?
We are familiar with CBD products in the form of oils, pastes, crystals, creams, balms, patches, edibles, and more. And users are left with a wide variety of choices to deliver these formulations through different administration routes such as oral, sublingual, topical, rectal, nasal, etc.
In this lineup, the ocular route delivers desired cannabinoids through the eyes.
Although scientific references signify that smoking cannabis with a high THC potent lowers intraocular pressure of glaucoma, developing eye drops with cannabis compounds has been a challenge because of its lipophilic nature.
Comparatively, prescription eye drops also have some challenges about targeting the drug to the back of the eye and providing relief for pain and inflammation for eye conditions. For example, in glaucoma, the second leading cause of blindness in the United States, studies report that topical treatments with pharmaceutical eye drops come with adverse effects.
In such a case, do cannabinoids infused eye drops meet these expectations? What novelties are adopted in drug delivery to improve efficacy and relief in affected populations?
Therefore, consider this post as a brief introduction to simplify our understanding of CBD eye drops, let us review the role of cannabinoids in ocular applications.
What Are CBD Eye drops?
Eye drops infused with cannabis extracted cannabidiol (CBD) and dissolved in mineral oil are CBD eye drops. Although it seems simple, research points out the complexities of this type of CBD formulation due to its lipid profile.
The 2019 study 1 contends that cannabidiol is a lipophilic molecule, so its topical delivery to the back of the eye is challenging.
An ophthalmic formula must penetrate the watery tear layer and pass through the cornea to reach the eye. Since cannabis solutions may not dissolve in water, it is difficult for natural and synthetic cannabinoids to be effective topical eye application.
But, contradicting the above reference, a 2017 study 2 points out that lipophilic drugs are absorbed well through the cornea, whereas both lipophilic and hydrophilic compounds are well able to penetrate through the conjunctiva and sclera.
Cannabinoids and Glaucoma
Glaucoma Research Foundation (GRF) defines glaucoma as a complex disease where the optic nerve is damaged and leads to permanent vision loss.
Most importantly, this condition displays itself by a rise in intraocular pressure (IOP). IOP depends on the balance between the amount of fluid produced and drained, thereby maintaining the appropriate eye pressure. And this is an active continuous process responsible for the health of the eye.
- Initial studies in 1971, observed that smoking marijuana displayed a considerable decrease in intraocular pressure in a large percentage of participants in a clinical study.
- A 2017 study 3 compiles from several other studies that cannabinoids can potentially lower IOP through multiple mechanisms besides the currently available anti-glaucoma medications. One of the key inferences of this study is that THC showed beneficial effects in treating glaucoma and neuroprotective actions to treat ocular diseases.
- Bearing in mind that cannabinoids are not water-soluble, researchers from the University of British Columbia have derived an eye drop using nanoparticle technology.
- The study has produced nanoparticles loaded with CBGA to penetrate the cornea. This new formula forms a lens in the eye once administered and then slowly begins to release cannabinoids.
When the drop is administered into the eye, it stays in a liquid state, until it balances with the temperature of the ocular surface. Then transforms to a gel state, taking the form of a lens. This lens slowly releases the CBGA taking eight hours to dissolve in the eye.
- Two conclusions from the 2016 study 4 is noteworthy here:
- Exogenous cannabinoids, THC, and CBD together contain properties capable of bringing structural and functional changes in the retina.
- The study favors the use of synthetic cannabinoids in therapeutic applications for curing and preventing retinal diseases.
- Similarly, 2019 animal model study 1 on analog derivatives of CBD proved that CBD analogs displayed higher penetration into ocular tissues.
Does CBD lower eye pressure?
According to The American Academy of Ophthalmology (AAO) studies proposes that CBD does not lower IOP but increases it.
Additionally, reference from two studies is mention-worthy here.
1.The 2018 study 5 tested and compared the results of IOP on rats after independently administering eye drops containing THC and CBD.
The following observations were reported.
Results of THC
- When eye drops containing THC were applied, IOP declined by 30% within eight hours.
- The effect of THC was sex-dependent. Female rats showed no effect in IOP at the end of eight hours, but they showed a moderate drop in IOP at the end of four hours.
- Male rats retained the effects of THC for 8 hours, whereas female rats for 4 hours.
Results of CBD
- IOP considerably increased in male and female mice at the 1st and 4th hour after administering CBD eye drops.
Results of THC & CBD
- Combined administration of THC and CBD showed no reduction in IOP in male rats.
2. A 2006 randomized study 6 examined six glaucoma patients for IOP levels after sublingual administration of THC and CBD. Here too, similar results as the above study are reported. They are:
- IOP substantially reduced in two hours after sublingual administration of 5mg THC and was well tolerated by patients.
- Sublingual administration of 20 mg CBD did not decline IOP.
- A higher dose of 40mg CBD displayed a short time elevation of IOP at 4 hours.
Are CBD Eye Drops Safe?
From the above discussions, we can perceive that research so far shows mixed results on the effect of CBD eye drops. Also, research in this area is complicated, expensive, and time-consuming. Therefore, it is hardly possible to arrive at any conclusion if CBD as eye drops are safe to use.
Furthermore, a 2019 study 7 points out that while the use of CBD for several diseases is growing, it lacks sufficient scientific evidence to prove its efficacy.
In general, although CBD has a good safety profile, some adverse effects of CBD intake may be CBD-induced drug-drug interactions, diarrhea, fatigue, vomiting, hypersomnia or excess sleepiness, and abnormalities in the liver.
CBD drops and eye dryness
There are quite a few aspects to take into consideration before addressing CBD and eye dryness.
- Firstly, determining the cause of eye dryness is essential. Is the condition the result of consumption of CBD, THC, or both?
- Dry eye syndrome is typical in glaucoma. 40-50% of glaucoma patients experience eye dryness.
- Immune system disorders such as Sjogren’s syndrome are associated with dry eyes and dry mouth symptoms. The most common causes being rheumatoid arthritis and lupus.
- Xerostomia or dry mouth also referred to as cottonmouth, is an adverse side effect for people using marijuana.
- Prolonged use of glaucoma eye drops, prescription medication such as antihistamines and antidepressants.
Can you use CBD oil as eye drops?
There is little to no reference about the use of CBD in its oil formulation for topical eye applications. The above reference from several studies that we have discussed has highlighted the implications of the use of CBD on eye pressure. But there is no specific mention of CBD oil.
Moreover, concerning the lipophilic nature of CBD oil and its compatibility with the eyes, there is a need for more qualitative evidence.
A textual reference 8 discusses that a non-randomized study in healthy volunteers compared with glaucoma patients showed temporary reductions in IOP with oral, topical eye drops, and intravenous administration of cannabinoids. And, it also points out that systematic reviews concluded that the trial was unclear.
Again, in the above reference, none of the trials have mentioned the use of CBD oil as eye drops.
CBD Eye drops for macular degeneration
Another potential application of cannabinoids in ocular health is Macular Degeneration. (MD) Yet another leading cause for vision loss in the USA.
‘Macula’ is the central region of the retina, which controls our sharp focus. All of our activities, reading, recognizing, image capturing, involves macular functioning. Deterioration in this region results in macular degeneration leading to loss of central vision.
According to a 2008 study 9 abundant growth of vascular endothelial growth factor (VEGF) proteins is the major cause of abnormal blood vessel growth in the retina.
Reference from anecdotal evidence from a patient suffering from MD reports that after administering CBD oil sublingually, the severity of MD went down. The patient observed improvements in her condition from Intermediate MD to an early stage of MD.
The Ocular Endocannabinoid system
Briefly summarising key points from the 2016 study 4 :
- The retina is an extension of the Central Nervous System (CNS)
- The study identifies the presence of cannabinoid systems in ocular tissues.
- The receptors, ligands, and enzymes that constitute the endocannabinoid system are expressed in the retina.
Additionally, a recent study 10 confirms that the endocannabinoid system (ECS) plays a crucial role in regulating inflammation, tissue repair, and pain perception in the conjunctiva and the cornea in humans.
In short, we can generalize that the ECS has a significant role in the ocular immune response. In the same lines the 2016 study 11 proposes the need for additional studies focussing on the therapeutic potential of ECS modulating drugs in ocular diseases.
Can You Put CBD Oil In Your Eye?
After first putting CBD in my ear and having an amazing near-instant experience, I started wondering whether or not it was ok to put CBD directly in the eyeball – like a common eye drop.
This wasn’t the first time I had this thought about putting CBD in, on, or around the eyes.
When I first had to speculate of potentially “maybe” thinking about giving this a try, was when I was last at Disney Land with my parents, my spouse, my little brother, and my sister’s son.
We took a noon-ish flight from Twin Falls Idaho and landed later that night at later John Wayne Orange County Airport.
Upon waking up the next day, my sister’s little one had reddish goopy pink eyes, with weird goop starting to form around the eyelid.
At this time, he was already taking an oral dose of CBD to help support autism, muscular dystrophy, and mainly to help him stay calm when loud noises made him plug his ear REAL tight.
After looking at his eye, I wondered, could CBD help restore normal eye function?
I mentioned this to my mom and she didn’t want to experiment on the little one, so she took him to a walk-in clinic and got some eye drops that went on to fix the situation.
After doing a bit of research to answer my questions as to whether or not it was both safe and effective to put CBD oil directly into your eye, I found it to be quite challenging to find a straight answer from a high-quality CBD blog, that also linked to authoritative medical journals.
What I found was some mixed information from only a few researchers doing clinical trials on a very small group of patients. My quick understanding of the available information is some researchers are putting CBD directly in the eye, however, Dr. Clifton mentions that taking CBD on the inside (such as CBD drops, edibles, etc) can help the eye function normally.
The best way to help your eye return back to normal function is to utilize high-quality CBD oil for internal use and “not” externally on or in the eyeball. In the near distant future, this may change and there could be various types of CBD eye drops available and recommended by medical authorities.
Currently, there are only a few CBD eye drops that some people might be using, while experiencing desirable results. However, this is anecdotal speculation and not recommended by anyone in medical authority.
What CBD eye drops are available?
The only eye drop I found, specifically made for the eye, didn’t appear to be of high quality.
Their website was poor quality, low resolution (pixelated) images, grammar issues, not linking to any authoritative research, not discussing any research.
It was quite apparent they were saying things just to say things.
They did admit there’s limited research and they also did say a few things that were COMPLETELY opposite of the medical journals we’ll discuss below.
I even found one random blog website saying THE EXACT OPPOSITE of what all the medical journals are saying (all without linking to any medical journal), but, they did lists the journals in text format – with no links to the journal.
Even though researchers are putting CBD drops in the eye, and although put CBD oil drops in your eye might provide some soothing effects, there’s not enough research available for me to want to put CBD directly inside of my eye, nor would I recommend doing so – just yet.
If I were to consider putting CBD in my eye, I would use a CBD oil that was completely pure and safe, had no random additives, sugar, or flavoring.
What can you use CBD eye drops for?
Professor of Pharmaceutics and Drug Delivery, Soumyajit Majumdar, Ph.D., is finding a specific CBD analog that may help the eye return to normal function, in a few specific areas.
Currently, there’s no officially recommended CBD eye drop that I’ve found.
Is CBD oil good for eye pressure?
According to the medical journal of Investigative Ophthalmology & Visual Science (IOVS), THC was shown to return the normal function of the eye and CBD interfered with THC.
In short, CBD may increase the pressure in your eye and THC might be able to lower it.
More research from the American Academy Of Ophthalmology (AAO) echoed what the IOVS said about CBD not helping return normal pressure to the eye.
In this journal, they ask an interesting question as to why the AAO and the American Glaucoma Society (AGS) recommend and support the use of smoking cannabis?
The AGS publishes on their website their position statements regarding the use of THC based cannabis and eye pressure.
Various methods, besides smoking cannabis, are available to help get the THC into the eye.
A few listed methods are oral, sublingual, and eye drops.
Two more studies (2018 & 2019) are verifying the need for more research into using THC for eye drops.
It appears to be quite clear that CBD oil will not help eye pressure.
One company may be in the process of developing a CBD analog, to be used as an eye drop to help the eye function properly.