Cannabis Lowered Eye Pressure but Was Linked to Earlier Glaucoma Diagnosis | Research

The takeaway

In a large UK cohort, cannabis users who used 100+ times developed glaucoma about 10 years younger than non-users, despite cannabis being associated with lower eye pressure.

People using cannabis for eye conditions, ophthalmology researchers

~10 years earlier glaucoma diagnosis in heavy users

What the researchers found

Heavy cannabis users (100+ times) were diagnosed with glaucoma approximately 10 years earlier than never-users. Cannabis use modestly lowered intraocular pressure but did not increase overall glaucoma risk. The earlier age of diagnosis was independent of IOP effects and cigarette smoking.

Why it matters

Cannabis has long been discussed as a potential glaucoma treatment because it lowers eye pressure. This study complicates that narrative by showing that despite lower IOP, frequent cannabis users developed glaucoma earlier.

The numbers in context

~10 years younger glaucoma diagnosis in 100+ time users; cannabis effect on glaucoma incidence not significant (P=0.662); IOP significantly lower in 11-100 time users

How the study worked

Retrospective analysis of UK Biobank data examining relationships between cannabis use frequency, intraocular pressure, and glaucoma diagnosis age, controlling for cigarette smoking and age.

What this study cannot tell us

Self-reported cannabis use. UK Biobank participants may not represent the general population. Cannot establish causation from observational data.

How to read the evidence

Large population cohort (UK Biobank) with robust statistical controls, but observational design limits causal conclusions.

When this study was published

Published in 2022

The bigger picture

The finding that cannabis lowers eye pressure yet is associated with earlier glaucoma challenges the assumption that IOP reduction alone is protective. Other mechanisms of glaucoma damage may be at play.

Questions still open

Through what mechanism might cannabis accelerate glaucoma development while simultaneously lowering IOP? Could cannabis smoke contain compounds that damage the optic nerve through pathways unrelated to eye pressure?

Common questions

Does cannabis help with glaucoma?

This study found a paradox: cannabis lowered eye pressure (which should help) but was associated with earlier glaucoma development. The authors concluded that cannabis-based glaucoma treatments are "of questionable value."

How much younger were cannabis users when diagnosed with glaucoma?

Users who consumed cannabis 100+ times were diagnosed with glaucoma approximately 10 years earlier than those who never used cannabis, and this was independent of eye pressure effects.

Read the original research

Cannabis smoking and glaucoma in the UK Biobank cohort.

Journal francais d'ophtalmologie, 45(4), 423-429

View on PubMed ↗Publisher’s paper ↗

Citation

Lehrer, S; Rheinstein, P H. (2022). Cannabis smoking and glaucoma in the UK Biobank cohort.. Journal francais d'ophtalmologie, 45(4), 423-429. https://doi.org/10.1016/j.jfo.2021.12.012