Effects of Marijuana Legalization In Colorado And The Eye

Dr. Kisling Common Eye Questions for Your Optometrist, Fort Collins Optometrist, glaucoma, Uncategorized Leave a Comment

 Fort Collins Optometrist Sees Colorado Going Up In Smoke With Legalized Pot

With the recent legalization of marijuana in Colorado and Washington State, more people are asking about the effects of marijuana legalization in colorado and the eye and vision from smoking or orally consuming different forms of marijuana. From an eye doctors perspective I feel there are a few things folks in NOCO need to know before inhaling.

Effects of Marijuana Legalization In Colorado  And  The Eye

  1. Marijuana and it’s primary active ingredient  tetrahydrocannabinol (THC), are scheduled as Class 1 controlled substances according to the DEA (Drug Enforcement Agency). Regulations about Class 1 scheduled drugs are as follows:

    Schedule I Controlled Substances

    Substances in this schedule have no currently accepted medical use in the United States, a lack of accepted safety for use under medical supervision, and a high potential for abuse.

    Some examples of substances listed in Schedule I are: heroin, lysergic acid diethylamide (LSD), marijuana (cannabis), peyote, methaqualone, and 3,4-methylenedioxymethamphetamine (“Ecstasy”).

    These substances may not be legally prescribed under federal law, even if they are legalized under state law.

  2. Only Colorado and Washington have legalized marijuana use, while 18 states either allow for the medical use of marijuana with a state permit card, or have decriminalized the use of marijuana to a civil offense (instead of a criminal offense). All states have qualifications on the use that effects the legal age, the amounts, and the situations under which consumption is allowed. In Colorado for instance, Amendment 64 allows use of marijuana by people 21 or older. People can grow up to three immature and three mature cannabis plants privately in a locked space, legally possess all of the cannabis from plants they grow (as long as they do not transport it to another location), possess up to one ounce of cannabis while traveling, and gift up to one ounce to other citizens twenty-one years of age or older. Since these laws are subject to change you should check before presuming this is still correct!
  3.  Federal law still views the possession and consumption of marijuana as criminal. While the Feds seem to have reduced their activity against individual users, there is no guaranty you will not face Federal charges in a state where marijuana has been legalized or decriminalized.  Colorado governor John Hickenlooper is reportedly trying to work out an agreement with the Attorney General to not prosecute minor amounts of possession. Only time will tell if this will be worked out.
  4. No, No, and No!  No. Things You Can’t do! You can’t smoke pot on or around schools. You can’t use marijuana in your friends apartment or at Starbucks (any privately owned building) if the owner or landlord tells you not to. You can’t smoke pot in no smoking areas. (Yes some people need to be told that). You can’t have smoke or even take marijuana with you to a national park or forest (Ruling out sing alongs in Estes Park of John Denver’s  “Rocky Mountain High”. Take pot in your pocket inside a Federal building or courthouse and you might end up spending much more time there than you planned on. Lighting up at a park, outside on the curb in the evening, or in your back yard is also a No! Vail Resort employees-No for the use, consumption, or presence of marijuana.  No for Copper Mountain Ski Area who has pointed out that they operate on Federal property where the use is still criminal. No for cultivation at home that is not secure and can be accessed or even seen by your neighbors. About the only yes is for recreational trips to Colorado from out of state for a  pot vacation-back to a Rocky Mountain High reunion tour it appears.  After the rash of severe forest fires last year, one can only hope that all of this change won’t result in Colorado going up in smoke!


Driving Under The Influence of Marijuana


Pot Plants Colorado



Colorado is currently debating a new law setting limits on the amount of THC in the bloodstream for driving, similar to what is in place today for alcohol consumption. Currently roadside sobriety tests are used and if they are failed blood tests are ordered. any level of THC in the bloodstream in conjunction with failed roadside testing results in a DUI. The new bill is aiming toward a cutoff level of five nanograms per milliliter of blood. There is very little agreement over the correct amount to indicate safe driving. Testing of people driving simulators under the influence and actual roadside results from serious motor vehicle accidents don’t always agree. Some of the current thinking is that even though people show impairments of skills, they compensate by driving slower and increasing following distance behind other cars. It is not logical, but some studies have found lower doses of pot actually increase drivers safety records slightly above normal. Testing is difficult and may not reflect impairment due to delays in testing blood levels and the rapidity of THC being eliminated from the bloodstream. There is currently not a good, widely available equivalent of breath tests used for alcohol. Setting a 5 nanogram cutoff level will actually liberalize the legal limits for driving. We will see how the votes fall but the results of any new legislation are not so clear.

Standardized Field Sobriety Testing (SFST) has become a widely accepted and standardized program for evaluating whether drivers are under the influence of drugs or alcohol. It is usually has several components, observation of eye movements, the ability to follow directions and walk a straight line,  the ability to balance on one foot, and the impact of dividing attention. In the optometry treatment of certain vision disorders we refer to it as loading a visual task.

Roadside sobriety test can be altered by marijuana consumption.  Several years ago I observed this when a young male was driving erratically down the road.  He was obviously grossly impaired in his motor skills while being given a quick roadside test. Part of this testing is the horizontal gaze nystagmus test (HGN). The effect of marijuana on eye movements is still clouded in confusion. Saccadic eye movements are the fast jumps we use when moving to new points or when reading. Pursuit movements are the continuous following of a moving object. The eye can use pursuit movements up to 30 degrees per second. At some point above 30 degrees per second the eye can no longer keep up and  it has to resort to saccadic jumping movements to keep on track.  Pursuit eye movements are normally not effected by THC consumption. Saccadic eye movements are impaired by THC, but the effect is probably not usually  discernible by observation. Horizontal gaze nystagmus is a breakdown of pursuit eye movements when looking to the side. With alcohol consumption, pusuits break down and a person under the influence will have to use a saccadic eye movement to follow an object out to a point 45 degrees to the side. On reaching the point, a normal person will have several small saccadic readjustments for 1-2 seconds then the eyes will remain on target. Someone under the influence of alcohol will have this period of readjustments last twice as long or more, as the eyes drift inward and lose fixation then jump back to gain fixation repeatedly. HGN that occurs under gazes to the side that are below 45 degrees and lasts longer at 45 degrees is significant for alcohol intoxication, but not for marijuana. .  Nystagmus is also checked for when the person is looking upward, the so called vertical gaze nystagmus test. This is often viewed as a more telling test for drug and alcohol intoxication. Again, it is reportedly not a good test for the presence of marijuana. Pupil responses are also used at times for roadside sobriety testing, but are not part of the widely used standardized battery.  With marijuana use here is a tendency for pupils to constrict slightly, and possibly to have a more sluggish rate of constriction and dilation reaction to light and darkness. This is not a large effect and not a significant test for detecting marijuana impairment.  Roadside sobriety testing might be able to tell if an individual was impaired enough to warrant further blood analysis, but it lacks in specificity for the presence of  marijuana.

I watched this testing scenario  from twenty feet away while sitting in the patrol car on a ride along with the Larimer County Sheriff’s Department. Impairment was grossly obvious from balance tests.  The driver did produce a medical marijuana card. Medical marijuana cards do not legalize use while driving.  Driving impaired from alcohol, marijuana, other drugs, and even fatigue is not legal and can be very dangerous to innocent people. It can also result in severe criminal charges.


Effects of Marijuana Legalization In Colorado And The Eye

Did John Denver Secretly Have Glaucoma When He Wrote The song Rocky Mountain High?


We know some of the effects of marijuana on the eyes, but not close to everything. Marijuana (smoke and oral food routes of consumption) use cause the heart rate to go up and blood vessels to dilate. It also causes the pressure inside the eye to drop for 2-4 hours (normally a good thing in people with glaucoma). Since there is currently no way to know the dosage of active ingredients being taken by an individual there is no way to predict the actual effect on the eyes. The concentration of active ingredients varies from batch to batch. The amount consumed varies from how much is inhaled each breath in, the number of intake breaths, the time held in the lungs before release; and that’s  just for starters. Drugs are typically measured for how they metabolize with time and we have very little information on this.Even if we tried to control the intake levels, one would have to consume it every 2-4 hours, and with that level of consumption the impairment would not likely result in compliance with a regular schedule and amount of intake, much less allow someone to be able to be productive at any type of job.  While red eyes from dilated blood vessels in the conjunctival tissue and to some extent the deeper white scleral tissue are what we think of as being characteristic of pot smokers, the effects on glaucoma are much more important. As noted above, there can be a reduction of eye pressure  With most types of glaucoma, the eye pressure is elevated and it restricts the blood flow to the vital optic nerve.  It is now thought that the difference between blood pressure and eye pressure keeps the nerve healthy. Marijuana lowers eye pressure and that increases the difference which is good. Unfortunately, while it raises the heart rate this is offset by the dilation of blood vessels that lowers blood pressure. Low blood pressure reduces the spread between eye pressure and blood pressure. This reduction may result in inadequate blood flow to the nerve and a consequent slow death of the nerve cells we use to see.  It is still unclear (and probably will remain that way). We are most concerned about what happens at night with patients who have glaucoma  Typically the eye pressure goes up a little and blood pressure goes down a little, which makes the night hours the critical time period for suffering damage from glaucoma. While marijuana does lower blood pressure,  there has been one small study that found this occurs when sitting and actually the opposite was found to happen when lying down. Blood pressure might go up when lying down and sleeping. If this is occurring it would be a good thing unless the overall blood pressure is too high and poses a health risk form other complications.

As a consequence of being scheduled a class 1 drug, marijuana has has limited research done on how it works and potential side effects.  Research on the carcinogenic activity of the smoke was first shown to cause lung cancer, then thought to be preventive. Some recent research indicated it may be a risk factor for lung cancer. Don’t presume we have an answer one way or the other at this time. Funding for studies typically only goes to drugs with future high potential profits, not to substances that cannot be patented. Don’t expect the true side effects or benefits to be known any time soon.  And absolutely don’t quit using your glaucoma medication because of this new law. Marijuana does not work anywhere close to the current glaucoma medications for treatment we have today.  Since it would need to be taken every 2-4 hours I doubt you would remember to take it anyway! And no, John Denver did not have glaucoma. 


A New Study Finds Driving Impairment

A recent study at the University of Iowa utilizing the most advanced driving simulators in the U.S. found blood levels of THC equivalent to 13.l µg/L induce the same amount of weaving within a lane as blood alcohol levels of .08 (which is the legal limit of alcohol for driving above the age of 21- the legal limit for THC is 5µ/L). Many studies in the past have relied on the dose of THC administered instead of the actual blood levels. Since blood levels are greatly influenced by how the marijuana is inhaled this study is thought to be a much better real world estimate of the effects on driving. Unfortunately there is no good way for a driver to measure their level of impairment as saliva tests have a large amount of variability in their readings. A note of caution, marijuana and alcohol have additive effects so it is possible to be under the legal levels of both and still be impaired. When combining the two, even in moderate consumption,  having a designated driver is the only way to avoid possible charges for driving while impaired.    






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