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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.
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Symptoms
The three 3 F’s are the most common symptoms of a retinal detachment:
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Flashes: Flashing lights that are usually seen in peripheral (side) vision.
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Floaters: Hundreds of dark spots that persist in the center of vision.
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Field cut: Curtain or shadow that usually starts in peripheral vision that may move to involve the center of vision.
Causes
Retinal detachments can be broadly divided into three categories depending on the cause of the detachment:
Rhegmatogenous retinal detachments: Rhegmatogenous means “arising from a rupture,” so these detachments are due to a break in the retina that allows fluid to collect underneath the retina. A retinal tear can develop when the vitreous (the gel-like substance that fills the back cavity of the eye) separates from the retina as part of the normal aging process.
The risk factors associated with this type of retinal detachment:
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Lattice degeneration – thinning of the retina.
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High myopia (nearsighted) - can result in thinning of the retina.
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History of a previous retinal break or detachment in the other eye.
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Trauma.
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Family history of retinal detachment.
Tractional retinal detachments: These are caused by scar tissue that grows on the surface of the retina and contraction of the scar tissue pulls the retina off the back of the eye. The most common cause of scar tissue formation is due to uncontrolled diabetes.
Exudative retinal detachments: These types of detachments form when fluid accumulates underneath the retina. This is due to inflammation inside the eye that results in leaking blood vessels. The visual changes can vary depending on your head position because the fluid will shift as you move your head. There is no associated retinal hole or break in this type detachment. Of the three types of retinal detachments, exudative is the least common.
Diagnostic tests
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A dilated eye exam is needed to examine the retina and the periphery. This may entail a scleral depression exam where gentle pressure is applied to the eye to examine the peripheral retina.
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A scan of the retina (optical coherence tomography) may be performed to detect any subtle fluid that may accumulate under the retina.
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If there is significant blood or a clear view of the retina is not possible then an ultrasound of the eye may be performed.
Treatment
The goal of treatment is to re-attach the retina to the eye wall and treat the retinal tears or holes.
In general, there are four treatment options:
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Laser: A small retinal detachment can be walled off with a barrier laser to prevent further spread of the fluid and the retinal detachment.
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Pneumatic Retinopexy: This is an office-based procedure that requires injecting a gas bubble inside the eye. After this procedure, you need to position your head in a certain direction for the gas bubble to reposition the retina back along the inside wall of the eye. A freezing or laser procedure is performed around the retinal break. This procedure has about 70% to 80% success rate but not everyone is a good candidate for a pneumatic retinopexy.
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Scleral buckle: This is a surgery that needs to be performed in the operating room. This procedure involves placing a silicone band around the outside of the eye to bring the eye wall closer to the retina. The retinal tear is then treated with a freezing procedure. Vitrectomy: In this surgery, the vitreous inside the eye is removed and the fluid underneath the retina is drained. The retinal tear is then treated with either a laser or freezing procedure. At the completion of the surgery, a gas bubble fills the eye to hold the retina in place. The gas bubble will slowly dissipate over several weeks. Sometimes a scleral buckle is combined with a vitrectomy surgery.
Prognosis
Final vision after retinal detachment repair is usually dependent on whether the macula (central part of the retina that you use for fine vision) is involved. If the macula is detached, then there is usually some decrease in final vision after reattachment. Therefore, a good predictor is initial presenting vision. We recommend that patients with symptoms of retinal detachments (flashes, floaters, or field cuts) have a dilated eye exam. The sooner the diagnosis is made, the better the treatment outcome.
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.
