Eye and the endocannabinoid system
Eye fluid and retina.
Eye fluid and retina. Where the cannabinoid receptors CB1 and CB2 sit in this region, what they do there, and what is actually known about CBD; at three levels for Everyone, Students and Experts, with sources.
Nerves and sensesCB1 low · CB2 very low (Human Protein Atlas)Last updated:
What's on this page?
Interactive 3D · real anatomy and real data
Where in your body are the cannabinoid receptors?
About 1.4 MB to download.
Regions
How to read it Choose a region, or tap a glowing point on the map.
- Solid light is the CB1 receptor, a ring is CB2. Each region has its own color; the color only tells regions apart.
- The strength of the light is the receptor gene level measured in human tissue (Human Protein Atlas). That is why the liver’s point is dim: a healthy liver has few receptors.
- With the layer selector above you can also see other receptors, the enzymes that make and break down endocannabinoids, and the liver enzymes that break down CBD and THC.
- Every piece of information shows its source and the type of evidence (human, animal, cell). You can change the reading level above.
- Drag to rotate. Use the + and − buttons to zoom; on a computer, Ctrl or ⌘ with the scroll wheel, on a phone, two fingers.
Retina: RNA level of the receptor gene in human tissue (tissue consensus data). For the eye, HPA measures only the retina; the ciliary body at the front of the eye is not in this data. Human Protein AtlasHuman tissue
| Receptor | Gene | RNA (nTPM) | Level |
|---|---|---|---|
| CB1 | CNR1 | 1.1 | low |
| CB2 | CNR2 | 0.1 | very low |
What does it do there?
Pressure inside the eye depends on the balance between how much fluid is made to fill the front part of the eye and how much drains out. In human eyes examined after death, the CB1 receptor was prominent in the ciliary body, which makes this fluid, and in the trabecular meshwork, where the fluid drains out; the body's own cannabinoids were also measured in the same tissues. Civan and Macknight 2004ReviewStraiker 1999aHuman tissuePorcella 2000Human tissueStamer 2001Human tissueAnimalChen 2005Human tissue
CB1 was also found in the human retina: in the two synaptic layers where the visual signal passes from cell to cell, and in the outer segments of the light-sensing cells. In all six species studied, from monkeys to fish, the receptor was in the same two layers; cannabinoids reduced calcium currents in bipolar cells in animal retinas. According to a review, how this translates into vision is unknown. Straiker 1999aHuman tissueStraiker 1999bAnimalYazulla 2008Review
Student level: terms and cell types
Intraocular pressure reflects the balance between aqueous humor inflow and outflow; aqueous humor is secreted by the ciliary epithelium. In postmortem human eyes, strong CB1 staining was seen in the ciliary epithelium and in the corneal epithelium and endothelium, and strong-to-moderate staining in the trabecular meshwork and Schlemm's canal. On RT-PCR, CB1 mRNA was found most in the ciliary body, then in the iris and retina; CB2 mRNA could not be detected. In human and bovine tissue, CB1 was shown in the nonpigmented epithelium of the ciliary processes and in trabecular meshwork cells; anandamide, 2-AG and palmitoylethanolamide were measured in human ocular tissues. Civan and Macknight 2004ReviewStraiker 1999aHuman tissuePorcella 2000Human tissueStamer 2001Human tissueAnimalChen 2005Human tissue
In the human retina, the inner and outer plexiform layers, the inner nuclear layer and the ganglion cell layer stained moderately, and photoreceptor outer segments stained strongly. In rhesus monkeys, mice, rats, chicks, goldfish and tiger salamanders, CB1 was in both plexiform layers; in the outer plexiform layer, it was in cone pedicles and rod spherules. Cannabinoid agonists markedly reduced L-type calcium channel currents in bipolar cells. According to a review, there is consensus that cannabinoids reduce transmitter release from cones and bipolar cells; how this relates to light–dark adaptation or visual perception is unknown. Straiker 1999aHuman tissueStraiker 1999bAnimalYazulla 2008Review
Expert level: method notes and numbers
Retina: RNA level of the receptor gene in human tissue (tissue consensus data). For the eye, HPA measures only the retina; the ciliary body at the front of the eye is not in this data. Human Protein AtlasHuman tissue
Method note
Straiker 1999a: postmortem human eyes, subtype-specific affinity-purified polyclonal antibody (number of eyes not given in the abstract). Porcella 2000: on RT-PCR, CB1 mRNA relative to β2-microglobulin was 210% in the ciliary body, 62.7% in the iris and 25.8% in the retina. Stamer 2001: CP-55,940 increased [35S]GTPγS binding by 51% in ciliary process epithelium and by 69% in trabecular meshwork cells (blocked by SR-141716A); anandamide was 3.08 in human trabecular meshwork, 49.42 in the ciliary process and 4.48 pmol/g in the retina. McIntosh 2007: in a human trabecular meshwork cell line, CB1 coupled to Gq/11 and Gi/o depending on the agonist. Straiker 1999aHuman tissuePorcella 2000Human tissueStamer 2001Human tissueAnimalMcIntosh 2007Cell / lab
Straiker 1999b: immunolabeling in six species; by GC/MS, 3 nmol of 2-AG per gram of tissue in the retina (anandamide not detected; in the human retina, however, Stamer 2001 measured anandamide); current recordings in bipolar cells. Yazulla 2008: review; the "unknown" statement dates from 2008. Straiker 1999bAnimalStamer 2001Human tissueAnimalYazulla 2008Review
What is known about CBD?
No effect found Insufficient evidence
In the guide: Glaucoma and CBD
Research has not found that CBD lowers the pressure inside the eye; there is only one small study on this. It does not replace your glaucoma treatment. If you are considering CBD, you can tell your eye doctor, so that the pressure inside your eye can be monitored.
Which receptor and enzyme genes are read in this region?
Values in this region for the genes in the map's layer selector: besides CB1 and CB2, the other targets of cannabinoids, the enzymes that make and break down endocannabinoids, and the liver enzymes that break down CBD and THC.
| Gene | What does it do? | Here | Tissue where it is read the most |
|---|---|---|---|
| Receptors | |||
| CB1 CNR1 | Cannabinoid receptor | 1.1 | cerebral cortex (18.6) |
| CB2 CNR2 | Cannabinoid receptor | 0.1 | spleen (8.4) |
| TRPV1 | Heat and chili pepper sensor · ion channel | 12.0 | liver (21.8) |
| GPR55 | Long an "orphan" receptor · in the cell membrane | 0.0 | testis (4.4) |
| PPARγ PPARG | Gene switch · in the cell nucleus | 0.6 | adipose tissue (153.2) |
| 5-HT1A HTR1A | Serotonin receptor · in the cell membrane | 0.0 | hippocampal formation (6.1) |
| TRPV2 | Relative of TRPV1 · ion channel | 0.9 | lung (29.5) |
| Endocannabinoid enzymes | |||
| NAPE-PLD NAPEPLD | Makes anandamide | 4.5 | kidney (13.9) |
| FAAH | Breaks down anandamide | 5.1 | testis (46.0) |
| DAGLα DAGLA | Makes 2-AG | 0.5 | cerebral cortex (12.3) |
| DAGLβ DAGLB | Makes 2-AG | 3.1 | adrenal gland (15.2) |
| MGL MGLL | Breaks down 2-AG | 4.8 | adipose tissue (161.3) |
| ABHD6 | Breaks down 2-AG | 8.6 | liver (60.7) |
| ABHD12 | Breaks down 2-AG | 28.2 | epididymis (125.2) |
| Enzymes that break down CBD and THC | |||
| CYP3A4 | Breaks down CBD and THC | 0.3 | liver (3,367.1) |
| CYP2C19 | Breaks down CBD | 0.0 | liver (178.0) |
| CYP2C9 | Breaks down THC | 0.0 | liver (1,607.6) |
RNA level shows how much the gene is read in this tissue; it does not directly show the amount of protein or how active an enzyme is. Human Protein Atlas (layers)Human tissue
Identifiers and citation
- Eye
- Eye · MeSH D005123 · UBERON 0000970 · Wikidata Q430024
- Receptors
- CB1 (CNR1, UniProt P21554) · CB2 (CNR2, UniProt P34972)
How to cite: cbd.school editorial team. Eye and the endocannabinoid system. Endocannabinoid system 3D map, cbd.school. Last updated October 24, 2026. https://cbd.school/learn/endocannabinoid-system-map/goz/
The body model is derived from BodyParts3D (DBCLS, CC BY 4.0) and Z-Anatomy (CC BY-SA 4.0); receptor levels from Human Protein Atlas v25 (CC BY 4.0). The map, text and downloaded images are CC BY-SA 4.0. An independent expert review has not been done yet. All licenses
Other pages of the map
Overview: what the endocannabinoid system is, the feedback brake at the synapse, CBD's targets, lesson mode, data and licenses.
Sources
Show 10 references
- Human Protein Atlas v25: tissue RNA consensus data (rna_tissue_consensus.tsv, HPA and GTEx, nTPM) and brain region data (rna_brain_region_hpa.tsv, nTPM), CNR1 (ENSG00000118432) and CNR2 (ENSG00000188822); v25.proteinatlas.org, file date November 6, 2025, downloaded October 24, 2026. Uhlén M et al. Tissue-based map of the human proteome. Science. 2015;347(6220):1260419. License CC BY 4.0. PMID 25613900 · doi:10.1126/science.1260419 Human tissue
- Civan MM, Macknight AD. The ins and outs of aqueous humour secretion. Exp Eye Res. 2004;78(3):625-31. PMID 15106942 · doi:10.1016/j.exer.2003.09.021 Review
- Straiker AJ, Maguire G, Mackie K et al. Localization of cannabinoid CB1 receptors in the human anterior eye and retina. Invest Ophthalmol Vis Sci. 1999;40(10):2442-8. PMID 10476817 Human tissue
- Porcella A, Maxia C, Gessa GL et al. The human eye expresses high levels of CB1 cannabinoid receptor mRNA and protein. Eur J Neurosci. 2000;12(3):1123-7. PMID 10762343 · doi:10.1046/j.1460-9568.2000.01027.x Human tissue
- Stamer WD, Golightly SF, Hosohata Y et al. Cannabinoid CB(1) receptor expression, activation and detection of endogenous ligand in trabecular meshwork and ciliary process tissues. Eur J Pharmacol. 2001;431(3):277-86. PMID 11730719 · doi:10.1016/s0014-2999(01)01438-8 Human tissueAnimal
- Chen J, Matias I, Dinh T et al. Finding of endocannabinoids in human eye tissues: implications for glaucoma. Biochem Biophys Res Commun. 2005;330(4):1062-7. PMID 15823551 · doi:10.1016/j.bbrc.2005.03.095 Human tissue
- Straiker A, Stella N, Piomelli D et al. Cannabinoid CB1 receptors and ligands in vertebrate retina: localization and function of an endogenous signaling system. Proc Natl Acad Sci U S A. 1999;96(25):14565-70. PMID 10588745 · doi:10.1073/pnas.96.25.14565 Animal
- Yazulla S. Endocannabinoids in the retina: from marijuana to neuroprotection. Prog Retin Eye Res. 2008;27(5):501-26. PMID 18725316 · doi:10.1016/j.preteyeres.2008.07.002 Review
- McIntosh BT, Hudson B, Yegorova S et al. Agonist-dependent cannabinoid receptor signalling in human trabecular meshwork cells. Br J Pharmacol. 2007;152(7):1111-20. PMID 17922024 · doi:10.1038/sj.bjp.0707495 Cell / lab
- Human Protein Atlas v25: tissue RNA consensus data (rna_tissue_consensus.tsv, HPA and GTEx, nTPM), the 17 genes in the map's layer selector: CNR1, CNR2, TRPV1, GPR55, PPARG, HTR1A, TRPV2, NAPEPLD, FAAH, DAGLA, DAGLB, MGLL, ABHD6, ABHD12, CYP3A4, CYP2C19, CYP2C9; v25.proteinatlas.org/download/tsv/rna_tissue_consensus.tsv.zip, downloaded October 24, 2026. Uhlén M et al. Tissue-based map of the human proteome. Science. 2015;347(6220):1260419. License CC BY 4.0. PMID 25613900 · doi:10.1126/science.1260419 Human tissue