Does CBD Promote Eye Health?
- There is conflicting evidence on CBD’s effects on eye conditions. A 2018 study has found that CBD might be helpful in the treatment of corneal neuropathic pain and inflammation(1).
- Another study in the World Journal of Diabetes revealed that CBD might have therapeutic effects on diabetic neuropathy(2).
- However, studies have shown that CBD might worsen eye pressure in glaucoma patients(3). In one study, the administration of 40mg of CBD increased the test subjects’ eye pressure significantly(4).
- Due to inconclusive evidence of CBD’s effects on eye health, individuals with eye conditions should take caution when deciding to use CBD. Individuals are strongly encouraged to consult with their ophthalmologists before using CBD as an eye treatment.
Why People Are Turning to CBD for Eye Conditions
CBD has been found to have several therapeutic benefits, including anti-inflammatory and neuroprotective properties. For this reason, people are turning to CBD for treating several ailments, including eye conditions(5).
However, the American Academy of Ophthalmology (AAO) says that CBD should be used cautiously as its administration may worsen some eye conditions, such as glaucoma(6).
How CBD Oil Works to Alleviate Eye Conditions
Cannabinoids are compounds that help the endocannabinoid system (ECS) regulate body functions, such as pain reception, mood, appetite, and memory(7).
These cannabinoids bind with the cannabinoid receptors to assist the ECS with these essential functions. These are the cannabinoid receptor 1 (CB1 receptor) and the cannabinoid receptor 2 (CB2 receptor).
The most extensively researched cannabinoids are CBD and THC. Unlike CBD, THC has psychoactive properties that may get users high.
CBD and Corneal Neuropathic Pain
A study done in 2018 and published in the journal Cannabis and Cannabinoid Research has found that topically applied cannabinoids might help reduce corneal pain and inflammation resulting from an injury of the eye surface(8).
The primary cannabinoids that were studied were CBD and tetrahydrocannabinol (THC).
According to the study, surgery, trauma, neurological diseases, and infections might damage the cornea’s nerve endings and develop into corneal neuropathic pain (CNP).
CNP is characterized by debilitating pain, dryness, burning and stinging sensations, and inflammation in the eyes.
CBD and Diabetic Neuropathy
According to research published in the World Journal of Diabetes, CBD might be used as a “personalized medicine” by those with diabetic neuropathy.
The study highlighted CBD’s anti-inflammatory and antioxidant properties, which might help alleviate some symptoms of diabetic neuropathy(9).
The authors also suggested that further clinical trials be done to examine CBD as a novel therapy for eye complications associated with diabetes.
A study published in the journal Molecular Vision has found that CBD protected the retinal neurons in the rat test subjects with diabetes(10).
Diabetic neuropathy may eventually lead to vision loss.
CBD and Glaucoma
Glaucoma refers to a group of eye conditions that damage the optic nerve because of abnormally high pressure in the eye(11).
Studies on CBD’s effects on glaucoma are conflicted, however.
Some studies have discovered that the use of cannabinoids might have promising effects on glaucoma.
In a study led by ophthalmologist Dr. Ileana Tomida, it was found that cannabinoids might help treat glaucoma(12).
Cannabinoids have also been observed to reduce intraocular pressure (IOP) and have neuroprotective effects.
IOP is pressure in the human eye, which may vary depending on the cornea’s thickness(13).
A 2016 study reported that targeting the ECS might have therapeutic benefits on the eye, such as retinal protection and contribution to the restoration of normal vision(14).
Another study reported that CBD combined with THC had been approved for treating inflammation, spasticity (muscle tightening), and pain in humans with multiple sclerosis.
The researchers suggested that CBD combined with THC should be tested to treat degenerative eye diseases, like glaucoma(15).
The study highlighted the role of endocannabinoids in retinal neurodegeneration and neuroprotection.
To treat glaucoma, eye experts focus on lowering IOP. However, lead author Alex Straiker and his co-researchers noted that CBD worsened eye pressure(16). Their findings were published in the journal Investigative Ophthalmology and Visual Science.
The researchers administered CBD and THC to rodents topically. For eight hours, THC lowered the rodents’ IOP significantly. CBD was also observed to interfere with THC’s IOP-lowering properties.
Another study revealed that glaucoma patients who received THC sublingually (under the tongue) reported lower IOP(17).
The administration of 20mg of CBD did not lower the patients’ IOP. However, when the test subjects were given 40mg of CBD, IOP increased significantly.
The American Academy of Ophthalmology (AAO), meanwhile, discourages THC use for glaucoma treatment.
THC has exhibited its detrimental effects on an individual’s mood, mental clarity, and ability to perform daily activities(18).
AAO also says that to treat glaucoma, patients should use marijuana or THC every three to four hours daily. However, this approach may not be sustainable and cost-efficient.
The Pros and Cons of CBD Oil for the Eyes
- Studies revealed that CBD might help in the treatment of eye conditions, like corneal neuropathic pain and diabetic neuropathy.
- For specific eye conditions, such as diabetic neuropathy, CBD may have a more favorable safety profile(19). Eye injections, on the other hand, can cause eye irritation, bleeding inside the eye, watery, dry, and itchy eyes, and the feeling of having something inside the eye (floaters)(20).
- The World Health Organization has no reported case of CBD dependence in humans(21). Hence, those with eye conditions should not worry about developing a dependence on the substance.
- There is growing evidence of CBD’s detrimental effects on glaucoma.
- CBD use may result in side effects, like changes in weight or appetite, tiredness, and diarrhea(22).
- The United States Food and Drug Administration (US FDA) has approved CBD use for the treatment of epilepsy only. However, it has not approved the use of CBD in treating eye conditions.
- The FDA does not regulate the CBD market. Therefore, mislabeled CBD products being sold online have become prevalent(23).
How CBD Oil Compares to Alternative Treatments for Eye Conditions
One of the alternative medicines that can be used for diabetic neuropathy treatment is acetyl-L-carnitine.
Acetyl-L-carnitine is a nutrient in the body that may help ease nerve pain in some individuals(24). It may also be taken as a supplement.
Acupuncture may be useful in treating diabetic neuropathy and even corneal neuropathic pain because it helps relieve pain.
According to a 2018 study, those with corneal neuropathic pain have reported pain relief for several days after one acupuncture session(25).
Vitamin C has been shown to reduce IOP in individuals with glaucoma. However, massive doses are required for it to be effective(26).
The Glaucoma Research Foundation also says that vitamin C administration may be impractical and dangerous as it can result in other complications, like dehydration and diarrhea.
Like acetyl-L-carnitine, CBD is suggested to have analgesic properties. Aside from its suggested pain-relieving properties, CBD has also been found to have neuroprotective and anti-psychotic effects(27).
CBD may be used in conjunction with acupuncture. Unfortunately, as mentioned in previous studies cited, CBD, may worsen intraocular pressure in individuals with glaucoma(28).
How to Choose the Right CBD for the Eyes
When choosing CBD products, consumers have three options. These include full-spectrum CBD oil, broad-spectrum, and isolates.
Among the three, full-spectrum CBD is believed to be the most effective because it uses all the ingredients of the cannabis plant.
These ingredients, namely THC, terpenes, flavonoids, fatty acids, and essential oils, synergize to generate the maximum therapeutic benefits of the Cannabis sativa plant. This synergistic process is known as the entourage effect.
Full-spectrum CBD may be useful for those who have corneal neuropathic pain and diabetic neuropathy. However, it is not recommended for glaucoma.
As mentioned in the studies cited previously, THC may reduce intraocular pressure in the eye. At the same time, CBD interferes with this therapeutic effect of THC.
Full-spectrum CBD may have THC, but only in trace amounts, as required by federal laws. As such, it may be ineffective in glaucoma treatment.
Individuals with other eye conditions who want to use CBD without THC may purchase broad-spectrum CBD products. They contain all the ingredients of a full-spectrum product but without THC.
Those who prefer to use pure isolated cannabidiol are recommended to purchase CBD isolates.
Before purchasing CBD, buyers should remember the following:
- They should make sure their state allows the use of CBD products.
- They should purchase only high-quality CBD products. These products are derived from organic hemp and are non-GMO.
- Look up the CBD brand and its products, especially when it is an online store. Checking online reviews may help.
- Choose CBD products that have been extracted using the CO2 extraction method. The US FDA in pharmaceutical manufacturing acknowledges the safety of this CBD extraction process(29).
- Review the product’s certificate of analysis. This report comes from third-party laboratories certifying the product’s potency and claims.
- Before buying CBD products,individuals should consult with their ophthalmologists first.
CBD Dosage for Eye Conditions
For eye conditions other than glaucoma, CBD dosage should contain small amounts initially. If no adverse effects are experienced, the dosage may be increased gradually.
Currently, there is no standard CBD dosage because the FDA has not approved CBD use in the treatment of several ailments.
How to Take CBD for Eye Conditions
Those with eye conditions may apply CBD directly through eye drops.
However, creating CBD eye drops is challenging to several manufacturers because CBD oil does not mix well with water. Check if the manufacturer is credible before purchasing CBD eye drops.
For ocular pain management, CBD may be taken through vaping. The effects of CBD may be instantaneously observed when one takes it through a vape pen.
However, it may be hard to determine the accurate amount of CBD with every draw. CBD treatment through vaping may also cause lung problems(30).
CBD tinctures may also be used by those experiencing eye problems. These may be applied sublingually (under the tongue) for added efficacy.
Topical formats, such as balms, lotions, and salves, are also available. However, they may not be as useful as they cannot be directly applied to the eyes.
Other formats, such as gummies, capsules, and pills are available. However, their efficacy is not as instantaneous as the other formats, like CBD vape pens.
CBD eye serums are also available. These phytonutrient-rich eye products may be useful in diminishing eye bags.
There are mixed reviews when it comes to the use of CBD for eye conditions. Experts do not recommend CBD as a treatment option for glaucoma.
High doses of CBD have been found to increase intraocular pressure in those with glaucoma.
However, studies have shown that CBD may help with other eye conditions, such as corneal neuropathic pain and diabetic neuropathy. These conditions are related to chronic pain, which CBD is known to help alleviate.
Despite the suggested health benefits of CBD, people should use the substance with caution.
Before using CBD for any eye condition, individuals are advised to consult with their eye doctor first.
- Thapa, D., Cairns, E. A., Szczesniak, A. M., Toguri, J. T., Caldwell, M. D., & Kelly, M. (2018). The Cannabinoids Δ8THC, CBD, and HU-308 Act via Distinct Receptors to Reduce Corneal Pain and Inflammation. Cannabis and cannabinoid research, 3(1), 11–20. https://doi.org/10.1089/can.2017.0041
- Liou G. I. (2010). Diabetic retinopathy: Role of inflammation and potential therapies for anti-inflammation. World journal of diabetes, 1(1), 12–18. https://doi.org/10.4239/wjd.v1.i1.12
- Miller, Sally, et al. “Δ9-Tetrahydrocannabinol and Cannabidiol Differentially Regulate Intraocular Pressure.” Investigative ophthalmology & visual science vol. 59,15 (2018): 5904-5911. doi:10.1167/iovs.18-24838
- Tomida, Ileana, et al. “Effect of sublingual application of cannabinoids on intraocular pressure: a pilot study.” Journal of glaucoma vol. 15,5 (2006): 349-53. doi:10.1097/01.ijg.0000212260.04488.60
- Caceres, V. (2019, April). Patients interested in whether CBD has a role in eye health. Retrieved from https://www.eyeworld.org/patients-interested-whether-cbd-has-role-eye-health
- Shelton, B. (2019, February 05). CBD Oil May Worsen Glaucoma (A. Iwach MD, Ed.). Retrieved from https://www.aao.org/eye-health/news/cbd-oil-may-worsen-glaucoma
- Manzanares, J., Julian, M., & Carrascosa, A. (2006). Role of the cannabinoid system in pain control and therapeutic implications for the management of acute and chronic pain episodes. Current Neuropharmacology, 4(3), 239–257. https://doi.org/10.2174/157015906778019527
- Thapa, D. op. Cit.
- Liou G. I. op. Cit.
- El-Remessy, A. B., Khalifa, Y., Ola, S., Ibrahim, A. S., & Liou, G. I. (2010). Cannabidiol protects retinal neurons by preserving glutamine synthetase activity in diabetes. Molecular vision, 16, 1487–1495. (Retraction published Mol Vis. 2014;20:1226)
- Mayo Clinic Staff. (2018, November 14). Glaucoma. Retrieved from https://www.mayoclinic.org/diseases-conditions/glaucoma/symptoms-causes/syc-20372839
- Tomida, I et al. “Cannabinoids and glaucoma.” The British journal of ophthalmology vol. 88,5 (2004): 708-13. doi:10.1136/bjo.2003.032250
- Fountain, T. R., MD. (2012, September 4). What is eye pressure? Retrieved from https://www.aao.org/eye-health/ask-ophthalmologist-q/eye-pressure-glaucoma
- Bouskila, Joseph, et al. “Cannabinoid Receptors CB1 and CB2 Modulate the Electroretinographic Waves in Vervet Monkeys.” Neural Plasticity, Hindawi, 16 Mar. 2016, www.hindawi.com/journals/np/2016/1253245/.
- Rapino, C., Tortolani, D., Scipioni, L., & Maccarrone, M. (2018). Neuroprotection by (endo)Cannabinoids in Glaucoma and Retinal Neurodegenerative Diseases. Current Neuropharmacology, 16(7), 959–970. https://doi.org/10.2174/1570159X15666170724104305
- Miller, S. op. cit.
- Tomida, I. (2006) op. cit.
- Turbert, D. and Gudgel, D. (26 June 2019). “Does Marijuana Help Treat Glaucoma or Other Eye Conditions?” American Academy of Ophthalmology. Retrieved from www.aao.org/eye-health/tips-prevention/medical-marijuana-glaucoma-treament?gclid=EAIaIQobChMImp-l9dzX6QIVRJ3VCh3o3gsHEAMYASAAEgJwWPD_BwE.
- Iffland, Kerstin, and Franjo Grotenhermen. “An Update on Safety and Side Effects of Cannabidiol: A Review of Clinical Data and Relevant Animal Studies.” Cannabis and cannabinoid research vol. 2,1 139-154. 1 Jun. 2017, doi:10.1089/can.2016.0034
Diabetic Neuropathy Treatment. (2018, October 30). Retrieved from https://www.nhs.uk/conditions/diabetic-retinopathy/treatment/
- “CANNABIDIOL (CBD) Critical Review Report.” World Health Organization, 2018.Parkinson’s Foundation. op. cit.
- Iffland, K. op. cit.
- Freedman, Daniel A, and Anup D Patel. “Inadequate Regulation Contributes to Mislabeled Online Cannabidiol Products.” Pediatric neurology briefs vol. 32 3. 18 Jun. 2018, doi:10.15844/pedneurbriefs-32-3
- Mayo Clinic Staff. (2020, March 03). Diabetic neuropathy. Retrieved from https://www.mayoclinic.org/diseases-conditions/diabetic-neuropathy/diagnosis-treatment/drc-20371587
- Dieckmann, G., Goyal, S., & Hamrah, P. (2017). Neuropathic Corneal Pain: Approaches for Management. Ophthalmology, 124(11S), S34–S47. https://doi.org/10.1016/j.ophtha.2017.08.004
- Update on Alternative Glaucoma Medications. (n.d.). Retrieved from https://www.glaucoma.org/treatment/update-on-alternative-glaucoma-medications.php
- Russo E. B. (2008). Cannabinoids in the management of difficult to treat pain. Therapeutics and clinical risk management, 4(1), 245–259. https://doi.org/10.2147/tcrm.s1928
- Turbert, D. op. cit.
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- Outbreak of Lung Injury Associated with the Use of E-Cigarette, or Vaping, Products. (2020, February 25). Retrieved July 13, 2020, from https://www.cdc.gov/tobacco/basic_information/e-cigarettes/severe-lung-disease.html