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Young 'dual use' smokers face more severe ocular symptoms

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Recent data from a study published in JAMA Ophthalmology investigated the frequency and severity of ocular symptoms present in adolescents who smoke cigarettes and electronic cigarettes (e-cigarettes).

Give me some background.

The rise of e-cigarette use among adolescents in the United States (the most common tobacco product since 2014), study assessing the use of both e-cigarettes and cigarettes have noted the following findings:

  • Lower general health
  • Increased sleep latency
  • Higher vascular disorder risk

On the ocular side, research has shown tobacco’s effect on the eye is associated with ocular damage and increased risk of ocular disease, including:

  • Uveitis
  • Thyroid-associated ophthalmopathy
  • Age-related macular degeneration (AMD)
  • Glaucoma
  • Cataract

So why the need for further research?

According to the study’s investigators, literature regarding both the short- and long-term ocular effects of e-cigarette use is severely limited. In fact, according to the authors, “no study has examined the severity and frequency of ocular symptoms among adolescents and young adults who use e-cigarettes, cigarettes, or both.”

Gotcha. Now talk about the study.

Investigators conducted an observational cross-sectional survey of e-cigarette use among a total of 4,351 adolescent and young adult participants (ages 13 to 24 years; mean age of 19.1 years) via an experience management software (Qualtrics).

Participants were selected online using strategies such as website intercept, gaming sites, customer loyalty portals, and social media; the sample was balanced based on gender, race, and ethnicity (per recent U.S. census data).

Go on …

The proportion of users to non-users was balanced 50.2% to 49.8%, respectively, based on their reported tobacco use in the last 30 days, 7 days, and, if applicable, the type of tobacco.

Participants were then equally stratified into three age groups:

  • Adolescents (ages 13-17 years)
    • 33.7%
  • Young adults (ages 18 to 20 years)
    • 41.6%
  • Young adults (ages 21 to 24 years)
    • 24.7%

How were they categorized?

All participants were classified based on their tobacco use: e-cigarette users, cigarette users, and dual users. Each classification included a subset series of pairs:

  1. Users vs never users
  2. Past 30-day users vs past 30-day nonusers
  3. Past 7-day users vs past 7-day nonusers

And what were they asked?

A few general vision questions, including their current eyesight rating with glasses or contact lenses (if used) and the amount of time they spent worrying about their eyesight.

For contact lens wearers, they were asked about when they put their lenses on and their frequency of use.

Further, they were asked to indicate the frequency and severity of any of the following ocular symptoms:

  • Ocular discomfort
  • Pain/aching
  • Burning/stinging
  • Itching
  • Redness
  • Dryness/gritty sensation
  • Glare/sensitivity to light
  • Blurry vision
  • Tired/eye strain
  • Headaches

Now the breakdown of users.

Of the 4,351 total participants—63.8% female and 43% White (non-Hispanic)—50.2% (2,183) reported using e-cigarettes and 36.5% smoked cigarettes at least once in their life.

Of the 2,183 e-cigarette users, 55.9% also smoked cigarettes (dual users).

And among all participants, 54.8% used other combustible substances:

  • 46.2% smoked cannabis
  • 40.8% used blunts
  • 25.7% used cigars, little cigars, or cigarillos

To note, participants reported using these substances at least once in their life.

And their vision and ocular symptoms?

Of the dual users, between 1.1% and 3.9% reported severe to very severe ocular symptoms; of that number, between 0.9% and 4.3% reported daily symptoms.

To note, this percentage was higher among dual users than e-cigarette or cigarette-only users.

How did the dual users compare?

Past 7-day dual users were more likely (than all other participants) to have more severe and frequent ophthalmic discomfort, pain aching, burning/stinging, itching, redness, dryness, light sensitivity, tiredness, and headaches.

Similarly, past 30-day dual users also experienced more severe dryness, ophthalmic pain, light sensitivity, blurry vision, and headaches compared to all other participants.


Dual users who less frequently used both cigarettes and e-cigarettes (past 30-day users) were consistently more likely to develop ocular symptoms vs non-users.

Additionally, dual users and cigarette-only users were more likely to report poorer eyesight, respectively:

  • (AOR, 0.64; 95% CI, 0.46-0.90; P = .01)
  • (AOR, 0.51; 95% CI, 0.34-0.76; P = .001)

Of note, e-cigarette-only users reported worrying more about their eyesight (despite no association observed for any outcome).

Any limitations?

Given the U.S.-based population sample, this data can not be generalized to adolescents outside the country. Further, the following were noted:

  • Determination of causal or temporal association between ocular symptoms and use
  • Potential confounders could lead to increased ocular symptoms (such as screen time, face mask use)
  • Potential self-reported bias

See here for the complete list.

Author input?

The study authors concluded that dual use was associated with a higher severity and frequency of ocular symptoms among the 13 to 24 age group in the United States.

However, they advise that, “Further longitudinal studies are necessary to validate our findings. These findings provide additional reasons to screen, counsel, and treat all tobacco users to prevent and reduce ocular symptoms.”

They recommend healthcare practitioners (including eyecare practitioners) to ask patients about nicotinic product use and, if applicable, counsel and treat patients to prevent and reduce potential ophthalmological issues.

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