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With the legalization of medical marijuana in 29 states as of April 2017, the question of whether marijuana is a good treatment for glaucoma has resurfaced.

Glaucoma is a common eye disease that affects the optic nerve and results in loss of peripheral vision. The treatment for glaucoma is to lower the pressure - intraocular pressure - inside the eye. This can be accomplished by laser, eye drops, or surgery.

The idea that marijuana can be used to treat glaucoma dates back to the 1970s. Smoking marijuana does lower intraocular pressure but the effect lasts only 3-4 hours. In order for marijuana to be an effective treatment, a person would have to smoke marijuana every 3 hours. Since marijuana also has psychoactive effects, consistently smoking it could prevent a person from performing at maximum mental capacity, and frequent use can cause problems with short-term memory.

Marijuana not only lowers intraocular pressure but also blood pressure and blood flow throughout the body. There is, however, evidence that decreased blood flow to the optic nerve may cause further damage. Therefore, it is possible that the lower intraocular pressure is negated by the decreased blood pressure to the eye.

Other ways of administering the active ingredient of marijuana, tetrahydrocannabinol (THC), include oral and topical administration. These forms avoid the potentially harmful compounds that could damage the lungs from marijuana smoke. However, the oral form would not avoid the systemic effects of marijuana.

There has been a research program that enrolled nine patients to take either oral THC or inhaled marijuana. None of the patients could sustain treatment for more than 9 months due to side effects such as distortion of perception, confusion, anxiety, depression, and severe dizziness. (https://www.ncbi.nlm.nih.gov/pubmed/12545695)

Alternatively, though eye drops may potentially avoid systemic effects, there is no formulation currently available to introduce a sufficient amount of the active ingredient into the eye.

The position by the American Glaucoma Society and American Academy of Ophthalmology is that marijuana is not recommended in any form for treatment of glaucoma at the present time.

Article contributed by Dr. Jane Pan

This blog provides general information and discussion about eye health and related subjects. The words and other content provided in this blog, and in any linked materials, are not intended and should not be construed as medical advice. If the reader or any other person has a medical concern, he or she should consult with an appropriately licensed physician. The content of this blog cannot be reproduced or duplicated without the express written consent of Eye IQ.

The Background

Over the last several years, research has indicated a strong correlation between the presence of Obstructive Sleep Apnea (OSA) and glaucoma. Information from some of these pivotal studies is presented below.

Did you know

• Glaucoma affects over 60 million people worldwide and almost 3 million people in the U.S.
• There are many people who have glaucoma but have not yet had it diagnosed.
• Glaucoma is the second-leading cause of blindness in the U.S. behind macular degeneration.
• If glaucoma is not detected and goes untreated, it will result in peripheral vision loss and eventual, irreversible blindness.

• Sleep apnea is a condition that obstructs breathing during sleep.
• It affects 100 million people around the globe and around 25 million people in the U.S.
• A blocked airway can cause loud snoring, gasping or choking because breathing stops for up to two minutes.
• Poor sleep due to sleep apnea results in morning headaches and chronic daytime sleepiness.

The Studies

In January 2016, a meta-analysis by Liu et. al., reviewed studies that collectively encompassed 2,288,701 individuals over six studies. Review of the data showed that if an individual has OSA there is an increased risk of glaucoma that ranged anywhere from 21% to 450% depending on the study.

Later in 2016, a study by Shinmei et al. measured the intraocular pressure in subjects with OSA while they slept and had episodes of apnea. Somewhat surprisingly they found that when the subjects were demonstrating apnea during sleep, their eye pressures were actually lower during those events than when the events were not happening.

This does not mean there is no correlation between sleep apnea and glaucoma - it just means that an increase in intraocular pressure is not the causal reason for this link. It is much more likely that the correlation is caused by a decrease in the oxygenation level (which happens when you stop breathing) in and around the optic nerve.

In September of 2016, Chaitanya et al. produced an exhaustive review of all the studies done to date regarding a connection between obstructive sleep apnea and glaucoma and came to a similar conclusion. The risk for glaucoma in someone with sleep apnea could be as high as 10 times normal. They also concluded that the mechanism of that increased risk is most likely hypoxia – or oxygen deficiency - to the optic nerve.

The Conclusion

There seems to be a definite correlation of having obstructive sleep apnea and a significantly increased risk of getting glaucoma. That risk could be as high as 10 times the normal rate.

In the end, it would extremely wise if you have been diagnosed with obstructive sleep apnea to have a comprehensive eye exam in order to detect your potential risk for glaucoma.

Article contributed by Dr. Brian Wnorowski, M.D.

This blog provides general information and discussion about eye health and related subjects. The words and other content provided on this blog, and in any linked materials, are not intended and should not be construed as medical advice. If the reader or any other person has a medical concern, he or she should consult with an appropriately licensed physician. The content of this blog cannot be reproduced or duplicated without the express written consent of Eye IQ.