In this study,1 Lee and colleagues applied big-data analytics to data from the IRIS Registry to evaluate associations between smoking and intraocular pressure (IOP). They extracted data regarding IOP, smoking status, demographics, and clinical covariates for >12 million patients with encounters in 2017. Mean IOP was compared among current, past, and never smokers. The strength of the associations were evaluated in multivariate models adjusting for age, gender, glaucoma, macular degeneration, diabetic retinopathy, cataract, cataract surgery, and glaucoma procedures. Mean IOP was highest among current smokers (15.84 mmHg), followed by never smokers (15.47 mmHg) and past smokers (15.45 mmHg, p<2.2x10-16). IOP was higher in individuals diagnosed with glaucoma than those without glaucoma diagnoses for each smoking category. When controlling for other factors, the IOP difference between current and never smokers exceeded 1 mmHg for young patients with glaucoma (20-39 years).
This study provides further evidence for an association between smoking and increased IOP, supporting prior population-based studies such as the Blue Mountains Eye Study.2 However, due to limitations in the dataset, several areas were unexplored. First, the study did not evaluate different racial/ethnic groups. This is most relevant for patients of African descent, who are at higher risk of developing glaucoma,3 experience more rapid progression, 4 and appear to have greater absorption of nicotine compared to smokers of European descent even with similar levels of cigarette consumption.5 Second, the lack of granularity regarding smoking information (beyond current vs. past vs. never) precluded analyses of dose-response relationships, which would be helpful for patient counseling.
This study provides further evidence for an association between smoking and increased IOP
Overall, this study demonstrates an effective leveraging of existing clinical data to shed light on this important question. Although levels of cigarette smoking have decreased in the U.S. (where the IRIS registry data were derived),6 smoking rates remain high globally, particularly in low- and middle-income countries.7 Future studies may also benefit from examining e-cigarette use, given that vaping has become a growing epidemic among adolescents and young adults,8 with long-term health sequelae as yet unexplored.