In the Dunedin longitudinal cohort, persistent cannabis use from age 18 to 45 showed no significant harmful effects on eye health after adjusting for tobacco and socioeconomic status, with one measure suggesting possible neuroprotection.
Ophthalmologists, cannabis researchers, aging health specialists
All apparent ocular harms from cannabis were explained by tobacco smoking and socioeconomic status
What the researchers found
Initial associations between cannabis and poorer visual acuity and wider retinal vessels were explained by tobacco and SES; one finding persisted: thicker inferior ganglion cell-inner plexiform layer, suggesting possible neuroprotection.
Why it matters
This is the first longitudinal study to examine whether decades of cannabis use affects eye health, finding that apparent harms were actually from tobacco co-use.
The numbers in context
887 participants; associations with visual acuity and retinal vessels no longer significant after adjusting for tobacco and SES; thicker inferior GC-IPL remained significant.
How the study worked
Dunedin Study longitudinal cohort (N=1,037); cannabis use self-reported at every assessment from age 18 to 45; comprehensive ocular health at age 45 including visual acuity, retinal imaging, and OCT; n=887 with complete data.
What this study cannot tell us
Self-reported cannabis use; single ocular assessment at age 45; confounding possible; neuroprotection finding requires replication.
How to read the evidence
Premier longitudinal birth cohort with decades of exposure data, though single-timepoint ocular assessment is a limitation.
When this study was published
Published 2025, ocular data from 2017-2019
The bigger picture
The finding that apparent ocular harms were explained by tobacco co-use is important for isolating cannabis-specific health effects.
Questions still open
- Will the neuroprotective signal persist as this cohort ages? Is the GC-IPL finding driven by CBD, THC, or other cannabinoids? Could cannabis protect against glaucoma-related nerve damage?
Common questions
Does long-term cannabis use damage your eyes?
Could cannabis protect the eyes?
Read the original research
Persistent Cannabis Use and Ocular Health in Midlife.
American journal of preventive medicine, 69(4), 107955
Citation
Cheyne, Kirsten; Niederer, Rachael L; Ambler, Antony; Barrett-Young, Ashleigh; Guiney, Hayley; Poulton, Richie; Ramrakha, Sandhya; Wong, Tien Yin; Wilson, Graham A. (2025). Persistent Cannabis Use and Ocular Health in Midlife.. American journal of preventive medicine, 69(4), 107955. https://doi.org/10.1016/j.amepre.2025.107955