Synthetic Cannabinoid Use Linked to Severe Vision Loss and Unusual Eye Damage in Case Report | Research

The takeaway

A 32-year-old man developed progressive vision loss and optic nerve damage with unusual black pigmentation after two years of using bonsai, a synthetic cannabinoid product.

People concerned about synthetic cannabinoid health effects and clinicians seeing patients with unexplained vision loss

First reported case

What the researchers found

The patient presented with severely decreased vision in both eyes. His optic discs were covered with black pigment overlying atrophic nerve tissue, with blood vessels appearing to disappear below the pigmentation. Vision loss began gradually after he started using bonsai (a synthetic cannabinoid) two years prior. No similar case had been previously reported.

Why it matters

Synthetic cannabinoids are poorly understood in terms of their long-term effects on specific organs. This case documents a previously unreported type of eye damage that may represent a unique toxicity of these substances.

The numbers in context

1 patient, age 32; 2 years of bonsai use before presentation; bilateral optic disc atrophy with black pigmentation; used tobacco, alcohol, and cannabis in addition to bonsai

How the study worked

Single case report of a 32-year-old male presenting with decreased vision. Ophthalmological examination included optic disc evaluation. Patient history included tobacco, alcohol, and cannabis use, with vision decline temporally linked to synthetic cannabinoid (bonsai) use onset.

What this study cannot tell us

Single case report cannot establish causation. The patient also used tobacco, alcohol, and cannabis, making it difficult to attribute the optic neuropathy solely to bonsai. No toxicological confirmation of specific synthetic cannabinoid compounds used. The pigmentation pattern is unprecedented and not yet confirmed by other cases.

How to read the evidence

Single case report with temporal association but no confirmed causation; confounded by concurrent substance use

When this study was published

2022 study

The bigger picture

Synthetic cannabinoids continue to cause unexpected and severe health effects that differ from natural cannabis. As new synthetic compounds appear on the market, novel toxicities like this optic neuropathy may become more common, and clinicians need to be aware of them.

Questions still open

Which specific synthetic cannabinoid compounds cause optic nerve toxicity? Is this effect reversible with cessation? Would other synthetic cannabinoid users show subclinical optic nerve changes on screening?

Common questions

Can synthetic cannabinoids cause blindness?

This case report documents severe vision loss associated with synthetic cannabinoid use, but it is a single case and cannot prove the substance caused the damage. The unusual pattern of optic nerve damage had not been reported before.

Is this the same risk as with natural cannabis?

No. This type of optic nerve damage has not been associated with natural cannabis use. Synthetic cannabinoids are chemically different compounds with different and often more severe toxicity profiles.

Read the original research

A Case of Presumed Bonsai-induced Severe Toxic Optic Neuropathy.

Neuro-ophthalmology (Aeolus Press), 46(1), 41-43

View on PubMed ↗Publisher’s paper ↗

Citation

Yasar, Erdogan; Tomac, Hatice Suhan; Gurlevik, Ugur. (2022). A Case of Presumed Bonsai-induced Severe Toxic Optic Neuropathy.. Neuro-ophthalmology (Aeolus Press), 46(1), 41-43. https://doi.org/10.1080/01658107.2021.1903510