I am blind, but marijuana gives me access to some visual information, as described in my paper. using an eye tracker, I will be conducting some experiments to determine whether the affects on my vision have to do with an increase in the fidelity of the retinal image, increased proprioception/control of my eye muscles, or a combination of the two. I have anecdotal evidence that different strains affect my vision differently. Sometimes, I am more aware of using eye movements to interact with my environment, and sometimes I am more aware of having an intuitive knowledge that I am seeing an object that I am unable to localize. Roughly, these effects break down into what pathway vs. where pathway effects. I don't have empirical evidence that these effects are strain-dependent; maybe they are dosage dependent, or dependent on the type of stimuli I am looking at. But I wanted to make sure there wasn't any sort of established findings about different strains affecting the dorsal vs. the ventral streams before proceeding with my experiments. Thanks!
There are over 85 different phytocannabinoids in cannabis and different strains have varying levels of each constituent. Indeed, GW Pharmaceuticals have bread a strain with the exact levels of THC and CBD that they require for their Sativex preparation. Given the almost ubiquitous nature of the endogenous cannabinoid system I think it follows that differing the active constituents (by varying the strain) will have wide ranging effects.
Hi Tasha,
This sounds fascinating. I've just downloaded your paper- I won't have a chance to read it for the next few days but a quick scan has me intrigued.
Regards,
Paul.
Dear Tasha,
I have researched the effects of THC and CBD on night vision, which THC improves, presumably at the retinal level. Please see attached article. I would be happy to follow-up with you on additional corroboratory studies.
Cheers,
Ethan Russo, MD
Dear Tasha,
I am an addiction medicine specialist and have worked with a number of patients who have used varying strains of cannabis and synthetic cannabinoids. While I do not have data specific to each strain, I can tell you from patient reports that each strain does produce differential effects on vision (some causing blurring while other seem to improve visual acuity). I have also conducted reviews of cannabinoid pharmaceuticals and cannabis for medical use for the State of Wisconsin as part of the State Council on Alcohol and Other Drug Abuse (SCAODA). As Ian has already mentioned, each of the strains of cannabis has a completely different phytocannabinoid profile which will affect how the plant interacts with the endocannabinoid system. In addition, the effects of the majority of the phytocannabinoids in cannabis are not well described. It is important to realize, however, that there is very good data that the THC:CBD ratios and phytocannabinoid content in cannabis also demonstrate significant variability even WITHIN THE SAME STRAIN depending on growing conditions, lighting, etc. of the grow. As a result, the effects may even vary within the same strain depending on the growing conditions at the time. I can send you the citations for these studies if it would help. Many of these studies regarding intra-species variability were performed in Southeast Asia and Europe. I believe GW Pharmaceuticals performed some of the studies in preparation for developing their cannabinoid program which is why their plants are grown under very consistent conditions.
Sincerely,
David Galbis-Reig, MD
There are today 134 different cannabinoids (which are sometimes today called phytocannabinoids. At different strains are usually the main cannabinoids in different ratios and some minor cannabinoids. Never all of them just in one strain. So the influence on vision will be complex question as I am sure that not only cannabinoids and not only cannabinoids and terpenes but also the other content compound can influence our body.
Dear Tasha, regarding above I want add two another aspects for your question. First of all, endocannabinoid system functions are very sensitive for the dosage of the phytocannabinoids mixture, what may provide to bidirectional effects itself (e.g. THC low dose may produce anxiolitic effect vs high dose may produce anxiogenic effect in the same body-mind). Second, the route of application can be extremely important for the psychopharmacological effects (e.g. smoking, eating, vaporizing the same amount of the same cannabis herb may induce different effects). Most probably, depend on the route and dosage, the complex mixture of bioactive ingredients of herba cannabis (which contains not only phytocannabinoids but also few-hundreds other compounds) may activate various receptor complexes (e.g. CB/TRPV/PPAR etc) and receptor mosaics (e.g. CB1-D2-A2A) what further may provide to higher/lower activation of different cortical and subcortical networks.
At last, Dutch products - such as Bediol, Bedrocan (...) - the first EU legal medical herba cannabis with various and standarized THC:CBD:CBN proportion may help you answer the question about dosage and strain impact on the vision. They provide very nice spectrum of THC:CBD contents in the various strains of cannabis (indica/sativa hybrid) from high psychoactive specimen to completly non-intoxicant.
David writes;
"I can tell you from patient reports that each strain does produce differential effects on vision (some causing blurring while other seem to improve visual acuity)".
This sort of effect is probably (as Ethan suggests in relation to improved night vision) due to cannabinoids altering perception by acting on receptors in the retina or the visual cortex, but another possible factor is that cannabinoids can affect interocular pressure, (which is why some glaucoma sufferers claim cannabis use relieves their symptoms). Changes in pressure within the eyeball distort it, and might account for self-report of blurriness or increased visual acuity.
Przemyslaw is quite correct to point out the importance of dose in producing variation in effect, and also in highlighting the importance of route of administration.
Vapourised smoke will have different ratios of components compared to smoke produced by combustion. Inhaled smoke or vapour, or oral sprays like Sativex, both allow the psychoactive components to enter the bloodstream directly (via the lining of the lungs in the case of smoking/inhalation, or via sub-lingual and buccal mucus membranes in the case of oral sprays). In comparison, ingestion of edible cannabis products allows first-pass liver metabolism before the substances enter the blood stream. This will substantially alter the ratio of cannabinoids and their metabolites that reach the brain and other organs, and so will change the subjective effect of the dose that is administered. I've attached two papers which give a comprehensive overview of cannabinoid pharmacokinetics.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3570572/
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2689518/
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Paul.
Since more time has passed, I'm starting to think that my claims about different strains affecting the visual system differently might have been spurious. The type of effects I experience seem to have a lot more to do with the accumulation of cannabinoids in my system and the type of ingestion method used than with strains themselves. My latest idea is that there are two separable effects of the marijuana: the impact on my retina and the impact on sensorimotor functioning. The problem is that in order for there to be an effect on the retina, I need to consume large amounts of marijuana over time, and it cannot just be vaped. However, these large amounts can produce vertigo and other unpleasant side effects, and can amplify connections between visual and motor systems so much that any sort of visual feedback becomes overwhelming. I'd love to be able to isolate the retinal effects, because, in an effort to prevent the side effects, I've cut down on my usage so all I'm left with is increased connections between my eyes and the rest of my body (limbs, etc) but very little visual perception.
This is an interesting question. THC and CBD may have differential effects on the eye and visual perception, likewise terpenes may be also influencing visual perception. THC-rich cannabis is associated with improving eye sight or Moroccan fishermen at night, I believe Ethan Russo conducted the study.
I have been looking for information about how terpenes can affect vision and have not found much. Also, there is some evidence that high doses of CBD can INCREASE IOP, which may not be a good thing if you have glaucoma...there isn't a lot of public, peer reviewed data on CBD and IOP.
It definitely seems to be true that some cannabinoids or terpines improve my retinas' sensitivity to light. Even though the effects only last for a short period of time, it would be amazing to identify what chemical is doing this. However, a much more common effect of the marijuana is changes in visuomotor integration. Suddenly my eyes, which I usually can't control and don't really feel because of nystagmus, feel as if they are connected to other body parts, like the arms and legs. I think this is happening as a result of gain field modulation of neurons in the parietal lobe. The reason this is important is because it possibly provides another way to simulate vision that is more effective than other modalities, like sound. Vision is highly directional, so for a totally blind person who doesn't have a concept of that, imagining push pull sensations between my eyes and other body parts, which then causes the perception of circles and horizontal and vertical lines, allows me to construct a 3d spatial representation of the world. I think others could learn to do this, but I feel that virtual reality, or some kind of wearable device, would be much more effective than marijuana.