There is evidence for cannabinoid receptors in the retina, eg. A. Porcella, C. Maxia, G.L. Gessa, L. Pani The human eye expresses high levels of CB1 cannabinoid receptor mRNA and protein European Journal of Neuroscience, 12 (2000), 1123–1127

There is anecdotal evidence of cannabis improving vision see the letter to Nature: M.E. West Cannabis and night vision Nature, 351 (1991), 703–704

And evidence of improved dark adaptometry in another study with three subjects: E.B. Russoa, , , A. Merzoukib, c, J.Molero Mesab, K.A. Freyd, P.J. Bache Cannabis improves night vision: a case study of dark adaptometry and scotopic sensitivity in kif smokers of the Rif mountains of northern Morocco Journal of Ethnopharmacology 93, 2004, 99–104

There is also a body of literature documenting , still in  anecdotal ways, how smoking cannabis helps reduce nystagmus (wiggly eyes).  With Lebers amaurosis, nystagmus is common.  A slight improvement in vision is thus possible due to the reduction in nystagmus.

See for instance:  Pardeep et al (2008) Reduction of congenital nystagmus in a patient after smoking cannabis.  Strabismus. 2008 Jan-Mar;16(1):29-32.

 F Schon (1999 )Suppression of pendular nystagmus by smoking cannabis in a patient with multiple sclerosis.  Neurology vol. 53 no. 9 2209-2209 

I've read a lot of the literature, but right now am looking to turn my discovery (that marijuana improves vision in people with LCA) into something practical (a drug that improves vision without the psychoactive affects).

Before even thinking to look at the possibility of a new drug derived from cannabis, you'll need to demonstrate out of any doubt that Marijuana itself improves vision in LCA patients.  Such a study, if it passes REB, would need to be against a placebo formula (not necessarily easy to formulate but naive subjects, contrary to long standing users,  may probably be fooled by other smokes (french tobacco, for instance), in a randomized, blinded study using standardized, widely used clinical tests investigating visual acuity, contrast and movement perception... etc...   This is the first step.  You have to demonstrate that what YOU are experiencing, can be first documented by scientific methodology and second, that it can be reproduced on others.

Agreed. However, I have no idea how to do that, which is why I want to collaborate with other researchers. In addition, a complicating factor is that I think that the affects of cannabis on my vision were cumulative; it took two years after I started using in order for me to experience effects. I think that may be why I have not been able to find other blind people who have experienced what I have experienced. I also have a strong motivation to learn about sight, which is atypical of people who are congenitally blind. There must be another way of approaching this problem that I am overlooking; it would just be so frustrating if I manage to make this discovery about marijuana improving my vision, only to get stuck because i'm not able to document it in other people.

There are some negative aspects to cannabinoid-1 receptor signalling in the cardiovascular system during diabetes, and also in the diabetic retina:

El-Remessy AB, Rajesh M, Mukhopadhyay P, et al. (2011) Cannabinoid 1 receptor activation contributes to vascular inflammation and cell death in a mouse model of diabetic retinopathy and a human retinal cell line. Diabetologia 54(6): 1567-1578

Tasha's paper a number of interesting observations about the effects of cannabis on visual function in an individual with severe congenital impairment of visual function at the level of the photoreceptor cilia (LCA 5). From her experience she generates essentially two hypotheses:

1. Cannabis potentiates visual function at the level of the retinal circuitry, e.g. by enhancing inner retinal summation of surviving photoreceptor responses

2. Cannabis potentiates visual function at the level of the visual association cortex, e.g. by reactivating "critical period" circuitry in the mirror neuron system, allowing the brain to map visual input onto perceptual constructs derived from other somatosensory modalities

I think the first step in pursuing hypothesis 1 would be to perform electrophysiologic testing (e.g. pattern ERG, full-field ERG, visual evoked potentials) on yourself at baseline and then again following self-administration of cannabis. A less objective approach would be kinetic perimetry (e.g. Goldmann visual field). If you could demonstrate an objective electrophysiologic or perimetric correlate of your enhanced visual experience, it could serve as a more compelling biomarker for a clinical trial.

The second hypothesis is probably more interesting and -- as you point out in the paper -- might have broader implications for the treatment of amblyopia and the visual rehabilitation of bilaterally blind individuals undergoing treatment with emerging technologies to restore retinal function (gene therapy, stem cell transplants, and retinal prostheses). Perhaps Dr. Ashtari would be willing to collaborate with you in monitoring your visual development by fMRI, in order to determine whether cortical integration is substantially altered. She has reported on the cortical responses in patients undergoing gene therapy for LCA2.

Article The human visual cortex responds to gene therapy-mediated re...

Dear Tasha,

We are just submitting a paper in which we explore the function of CB1R in the retina (in frog tadpole, but the retina is really similar among all vertebrates), and found a novel mechanism by which endocannabinoids improve vision at low light contrast.

Please contact me directly at [email protected] if you wanna chat more about that.

Best.