Over half of adolescents surveyed reported that they had used e-cigarettes or cigarettes ever in their lives, with more recent use equating to worse symptom frequency and severity. Photo: Getty Images. Click image to enlarge.

Throughout the last decade, the use of electronic cigarettes (e-cigarettes) has grown exponentially, and their use has been associated with numerous systemic health effects. Nevertheless, little research has been done to investigate the potential effects of this smoking modality on the eye, which recently led a team of doctors to conduct a cross-sectional survey study on the ocular symptoms experienced by users of e-cigarettes and/or cigarettes. They found that adolescents and young adults who used both smoking modalities had a higher likelihood of experiencing severe and frequent ocular symptoms. Additionally, they observed the highest rate of symptoms in those who used both e-cigarettes and cigarettes within the last seven days.

More than 4,300 participants aged 13 to 24 years completed the survey, which asked about the use of e-cigarettes and cigarettes at three time periods: (1) ever, (2) within the past 30 days and (3) in the past seven days. The researchers then performed a multivariable analysis on the responses adjusting for sociodemographic factors, contact lens use and other combustible substance use to evaluate the associations between vision-related outcomes and e-cigarette or tobacco use.

Just above 50% of respondents reported having ever used one or both smoking modalities (2,168 never users and 2,183 ever users), and roughly a quarter reported use in the last 30 days (1,092 participants). Additionally, 919 reported having used e-cigarettes or cigarettes in the past seven days. Among those who had ever used e-cigarettes, 55.9% also used cigarettes (referred to as “dual users” in this study).

After analyzing the survey responses on ocular symptoms, the researchers found that between 1.1% and 3.9% of those who had even been dual users reported severe to very severe ocular symptoms, which were experienced daily by between 0.9% and 4.3%. These proportions were higher than that observed in e-cigarette- or cigarette-only users.

With more recent use came more symptoms; compared with all other participants, those who reported dual use in the past seven days had more severe itching, redness, dryness, glare, blurriness, headaches and more frequent pain, burning and redness. Past 30-day dual users also experienced more severe dryness and more frequent pain than all other participants. Those who were ever dual users had more severe dryness and blurriness and more frequent pain and blurriness than those who never used e-cigarettes or cigarettes.

The researchers made three main conclusions from the data in their paper on the study, published in JAMA Ophthalmology: “(1) Users of both e-cigarettes and cigarettes have a higher likelihood of experiencing more severe and frequent ocular symptoms than users of a single tobacco product; (2) cigarette users experienced more ocular symptoms than e-cigarette users and (3) those who used these products more recently reported more symptoms than others.”¹

While these findings help to fill the research gap on the ocular surface symptoms associated with nicotinic products, the study does have several limitations, which were brought to light by the authors of an invited commentary, also appearing in JAMA Ophthalmology.² For one, they point out that the study failed to adjust for several potentially relevant lifestyle factors, including digital screen use, sleep and alcohol and caffeine consumption. Additionally, they note that the self-reporting of participants’ e-cigarette and cigarette use might introduce recall bias, though they add that this is unavoidable with survey study designs.

“Furthermore, there was a modest gender bias among the recruited cohort, with 63.8% of the respondents being female, despite a number of previous reports in the literature indicating that e-cigarette use is more prevalent among males in the adolescent and younger adult population,” the commentary authors wrote, adding that the influence of this discordance on the study’s outcomes is unclear.

Another concern they present is that the data obtained didn’t quantify the frequency and amount of e-cigarette and conventional cigarette use during the three periods (ever, 30 days and seven days). Because of this, the commentary authors argue that “it cannot be reliably determined whether the higher rates of ocular symptoms among users of both smoking modalities might simply be attributable to a greater overall quantity of nicotine intake or whether an interaction effect may exist between use of both modalities that risks additional adverse ocular effects.” They also note that “exposure to smoke itself can play a role in exacerbating ocular surface symptoms and signs.”

While current evidence supports a positive association between e-cigarette and cigarette use and ocular symptoms, further research will need to address the lingering questions about the nature of the relationship, a conclusion that the authors of the study and commentary both landed on.

Until then, the study authors conclude that based on what we know, they “recommend that healthcare clinicians ask all patients about nicotinic product use and counsel and treat those using these products to help prevent and reduce ophthalmologic issues.”¹