Heavy marijuana use was not associated with worse self-reported eyesight quality | Research

The takeaway

In a nationally representative sample, heavy marijuana smokers did not report worse eyesight quality than light or non-users, though sex, race, and education influenced self-reports among heavy users.

Read this if you've wondered whether long-term marijuana use affects your eyesight.

No significant difference in eyesight quality between heavy users and non-users

What the researchers found

Comparing 1,304 heavy marijuana users to 1,304 matched light or non-users from the National Longitudinal Survey of Youths, there was no statistically significant difference in self-reported quality of eyesight.

Within the heavy marijuana group, some demographic patterns emerged: males and high school graduates had decreased odds of reporting poor eyesight, while Black respondents had increased odds of reporting poor eyesight. However, the overall finding was a null result for the marijuana-eyesight association.

Why it matters

Despite known effects of cannabis on intraocular pressure and some aspects of visual processing, this large nationally representative study found no association between heavy use and self-perceived eyesight quality. This contributes to understanding the real-world functional impact of chronic cannabis use on vision.

The numbers in context

No statistically significant difference in self-reported eyesight quality between 1,304 heavy marijuana users and 1,304 light/non-users. Sample drawn from 12,686 participants in NLSY79 (1979-2010).

How the study worked

Cross-sectional analysis of the National Longitudinal Survey of Youths (NLSY79), a nationally representative sample of 12,686 people surveyed from 1979 to 2010. Researchers compared self-reported eyesight quality between 1,304 heavy marijuana users and 1,304 light/non-users using t-tests, multivariate logistic regression, and weighted analysis.

What this study cannot tell us

Eyesight quality was self-reported, not clinically measured. Self-report may not detect subtle visual changes. The study could not assess specific visual functions like contrast sensitivity or color perception. Matching was based on use frequency, not duration or potency. The survey spanned decades during which cannabis potency increased significantly.

How to read the evidence

Cross-sectional analysis of a large nationally representative survey. Reasonable sample size but limited by self-reported outcome measures.

When this study was published

Published in 2017. Research on cannabis and visual function has continued with more sophisticated clinical measures.

The bigger picture

Cannabis is known to temporarily affect visual processing (night vision, contrast sensitivity, intraocular pressure), but whether chronic heavy use leads to lasting changes in perceived eyesight quality had not been examined at this scale. The null finding suggests that whatever acute visual effects cannabis produces may not translate into long-term perceived impairment.

Questions still open

Would clinical vision testing reveal differences that self-report misses? Does cannabis affect specific aspects of vision (like contrast sensitivity or night vision) without altering overall self-perceived quality? Do the demographic differences in self-reported eyesight among heavy users reflect actual visual differences or reporting patterns?

Common questions

Does cannabis affect your eyes at all?

Cannabis is known to reduce intraocular pressure (the basis for its historical use in glaucoma research), cause red eyes from vasodilation, and temporarily affect some visual processing. This study found that heavy long-term use did not associate with self-perceived changes in overall eyesight quality.

Why did demographic factors matter within the heavy user group?

The study found that among heavy users, being male or a high school graduate was associated with better self-reported eyesight, while being Black was associated with worse reports. These likely reflect broader health disparities and access to eye care rather than differential effects of cannabis.

Read the original research

Marijuana Use and Self-reported Quality of Eyesight.

Optometry and vision science : official publication of the American Academy of Optometry, 94(5), 630-633

View on PubMed ↗Publisher’s paper ↗

Citation

Akano, Obinna F. (2017). Marijuana Use and Self-reported Quality of Eyesight.. Optometry and vision science : official publication of the American Academy of Optometry, 94(5), 630-633. https://doi.org/10.1097/OPX.0000000000001069