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Teens and young adults who puff on both cigarettes and e-cigarettes are more likely to experience severe and frequent ocular symptoms, with past 7-day users reporting more symptoms than all other participants in an observational cross-sectional study.

These past 7-day dual users reported more severe ocular symptoms, including itching, redness, dryness, glare, blurriness, headaches, and more frequent pain compared with all other participants, including 30-day users, ever users, and never users, reported Albert Y. Wu, MD, PhD, of Stanford University School of Medicine in Palo Alto, California, and colleagues in .

"In ophthalmology clinics, I've increasingly noticed patients, particularly adolescents and young adults, presenting with eye-related symptoms such as dryness, irritation, and even vision disturbances," co-author Anne X. Nguyen, MD, an ophthalmology resident at the University of Toronto, told 麻豆传媒.

"These symptoms often didn't correlate with typical risk factors like systemic diseases, aging, contact lens wear, and medications," she said. "However, many of these patients did have a history of using e-cigarettes and cigarettes. This observation sparked my curiosity about the possible link between smoking or vaping and ocular symptoms."

According to a 2021 survey, 22% of people in the U.S. ages 12 and older smoked within the last month. Traditional cigarettes remain the most popular, used by an estimated 15.6% of the population. Vape devices -- also known as e-cigarettes -- were used by just 4.7%, but they're especially common among younger people. In a 2022 survey, 21% of high-school seniors said they'd vaped within the past 30 days versus just 4% who reported smoking cigarettes.

How might smoking affect eye health? "Based on previous studies, smoking is believed to cause ocular symptoms primarily through oxidative stress and inflammation," Nguyen said. "These processes can damage the tear film lipid layer, leading to symptoms like dry eyes and poor vision. E-cigarettes have also been found to reduce tear film quality. Some solvents in e-cigarettes, like propylene glycol, may further contribute to eye issues by generating free radicals that harm the tear film."

Still, she added, there's been scant research on the effects of e-cigarettes on the eyes, "and not all studies agree on the level of impact, particularly for mild exposure."

In an , Jennifer P. Craig, PhD, an ophthalmologist at the University of Auckland in New Zealand, and colleagues wrote that the study "raises awareness of a conceivably concerning lifestyle choice that has grown rapidly in popularity among youth, providing a much-needed initial step toward addressing the current paucity in scientific evidence surrounding the potential effect of e-cigarette use on ocular health."

In an interview with 麻豆传媒, Craig said the new research confirms that it's "critical" that eye doctors ask patients about smoking. But even while ophthalmologists see cases of early macular degeneration and cataracts in heavy smokers, "this is something that clinicians are really not that great at asking about."

While the large size of the study is a plus, the research has limitations, she noted. It doesn't examine whether dual users have more eye symptoms because they smoke more overall, and there's no way to know whether smoking both kinds of cigarettes has a synergistic effect.

Still, she said that the study is "a really good conversation starter."

As for solutions, the study authors and Craig emphasized the importance of quitting smoking. Study co-author Bonnie Halpern-Felsher, PhD, also of Stanford University, told 麻豆传媒 that "we clearly need to help young people not use at all, or quit or cut back if using. We have created the and the to help prevent, reduce, and stop use among youth."

For this study, Wu and colleagues examined the results of a May 2020 online survey with 4,351 respondents ages 13-24 in the U.S. (mean age 19.1, 63.8% female, 43% white). Of these respondents, 2,168 said they'd never smoked, 2,183 had ever smoked, including 1,092 within the past 30 days and 919 within the past week; 55.9% smoked both cigarettes and e-cigarettes.

Among the ever dual users, 1.1% to 3.9% reported severe to very severe ocular symptoms, and 0.9% to 4.3% reported daily symptoms, which was higher than the proportion of symptoms in e-cigarette- or cigarette-only users.

Compared with all other participants, past 7-day dual users were most likely to have more severe ophthalmic discomfort (adjusted OR 2.19, 95% CI 1.30-3.70), pain/aching (aOR 2.06, 95% CI 1.24-3.42), burning/ stinging (aOR 2.08, 95% CI 1.18-3.66), itching (adjusted OR 2.37, 95% CI 1.36-4.13), redness (aOR 2.58, 95% CI 1.50-4.46), dryness/gritty sensation (aOR 2.89, 95% CI 1.64-5.08), glare/light sensitivity (aOR 2.56, 95% CI 1.50-4.35), blurriness (aOR 2.47, 95% CI 1.36-4.50), headaches (aOR 2.31, 95% CI 1.34-4.00), and tired/strain (aOR 2.07, 95% CI 1.11-3.83).

Past 30-day dual users were also more likely to have more severe ophthalmic discomfort (aOR 2.10, 95% CI 1.33-3.32), pain/aching (aOR 1.99, 95% CI 1.27-3.13), burning/stinging (aOR 1.81, 95% CI 1.09-2.99), itching (aOR 1.83, 95% CI 1.11-3.02), redness (aOR 1.98, 95% CI 1.23-3.17), dryness/gritty sensation (aOR 2.65, 95% CI 1.61-4.36), glare/light sensitivity (aOR 2.10, 95% CI 1.32-3.33), blurry vision (aOR 2.19, 95% CI 1.32-3.65), and headaches (aOR 1.78, 95% CI 1.15- 2.78) compared with all other participants.

Smokers who only vaped were not more likely to have more of any of these symptoms compared with all other participants, while cigarette-only smokers were only more likely than other participants to report blurry vision (past 7-day users: aOR 3.66, P=0.001; past 30-day users: aOR 2.34, P=0.02).

Debate continues on the role of vaping devices in harm reduction aimed at reducing the risk of traditional cigarettes. A found that "there is an increasing body of evidence that e-cigarettes may be an effective smoking cessation tool, reducing harm to users of combustible tobacco."

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