Electronic cigarettes (e-cigarettes) or vaping devices heat nicotine, flavours and other chemicals to create a vapour the user inhales. Vaping has been marketed as a substitute for tobacco cigarettes to help smokers kick their addiction, but vaping’s harmful effects are still largely unknown.
Nicotine is addictive¹ and is found in the majority of e-cigarettes, potentially making them as addictive as tobacco, leading the US Food and Drug Administration to classify them as "tobacco products". More worryingly, a 2019 study found 64% of e-cigarette users in New Zealand were still smoking tobacco², compounding health risks.
Vapour vs tobacco?
The health implications of vaping are starting to emerge in the literature. A paper published last year in Respiratory Research, revealed the bacterial persistence and inflammatory potential in the lungs caused by e-cigarette vapour is similar to that found in a tobacco smoker³. Lead researcher Dr Deirdre Gilpin said, “Bacteria have long been associated with the development of lung diseases, such as bronchitis and pneumonia, where smoking plays a role. Our study is the first of its kind which aimed to compare the effect of cigarette smoke and e-cigarette vapour on key lung bacteria. E-cigarettes are perceived as being safer and we are really concerned about that.”
Nicotine in tobacco and e-cigarettes is associated with cardiovascular risks and activation of carcinogenic pathways, including proliferation and angiogenesis, and can predispose a person to inflammation, infection and neoplastic disease¹,⁴. Studies have also shown second-hand e-cigarette exposure leads to the same nicotine blood levels as second-hand cigarette smoke inhalation⁴. Plus, like tobacco, e-cigarettes contain high levels of formaldehyde and other carcinogens, such as acetaldehyde⁴, and a 2015 study showed an increase in bacterial virulence and decrease in host defence with e-cigarettes when compared with tobacco⁵.
Tobacco and the eye
We have long understood how smoking tobacco can affect the integrity of the ocular surface and contribute to the development of macular degeneration and cataracts. Chronic smoking has also been linked to squamous metaplasia and loss of goblet cells which makes it a significant risk factor in the development of ocular surface disease⁶,⁷.
Smoking promotes molecular and pathological changes in the body: vascular inflammation, endothelial cell abnormality, oxidative and toxic damage⁸. These changes can lead to the development of macular degeneration and choroidal neovascular membranes. An increased prevalence of age-related cataracts has also been associated with smoking⁹. Several biological mechanisms have been put forward for the likely cause including oxidative damage, chemicals causing lens toxicity and opacity and increased aldehyde levels in smokers’ blood which modifies lens proteins.
Vaping and the eye
The effect of vaping on ocular health is still widely unknown but literature is evolving. Complaints of eye irritation by users and bystanders when exposed to vaping aerosols have been reported but there’s been few peer-reviewed studies. Formaldehyde is a biproduct of combustion in tobacco and e-cigarettes and the American National Cancer Institute warned that when airborne, it can cause a burning sensation and watering of the eyes. Another known eye irritant, propylene glycol is also one of the common base ingredients of vape e-liquid. Exposure to it can cause ocular and respiratory irritation10.
In the first study of its kind, published in September 2019, Malaysian researchers looked at ocular surface data from 21 vapour users and compared it with 21 non-smokers¹¹. They looked at the clinical features of the ocular surface, tear breakup time, fluorescein breakup time, surface staining, tear meniscus and Schirmer test scores to evaluate ocular surface health. Results revealed a significant reduction in non-invasive tear breakup time, fluorescein breakup time and tear meniscus height when compared with non-smokers, while an increase in vaping voltage increased tear film instability, indicating vapour users experience moderate-to-severe symptomatic dry eye when compared to healthy non-smokers.
There has been no specific research into other ocular side effects of e-cigarettes though a 2014 study found that nicotine can affect the eye when ingested¹². In this study, patients who chewed nicotine gum had significantly thinner choroids than non-gum chewers, possibly as a result of reduced ocular blood flow from the vasoconstrictive properties of nicotine. Thus, given the presence of nicotine in most e-cigarettes, it is reasonable to assume comparable side effects. Similarly, an increased prevalence of age-related cataracts may be connected to the toxic chemicals found in e-cigarette vapour in much the same way studies have found with tobacco use.
Vaping is becoming a popular craze, especially among younger people. Vaping products have been found to transiently reduce blood flow and oxygen use in the body, and the eye has a great demand for both. It may take decades to categorically determine if it is a safer long-term option than tobacco, but e-cigarette use is rapidly increasing and preliminary research shows close similarities between the two.
We should continue to counsel patients on their lifestyle choices and how these may affect their health with time. E-cigarettes may be used as an alternative to tobacco to help with smoking cessation but should be stopped as soon as possible to mitigate long-term health issues, including eye disease.
- Mishra A, Chaturvedi P, Datta S, Sinukumar S, Joshi P, Garg A. Harmful effects of nicotine. Indian J Med Paediatr Oncol. 2015;36(1):24‐31
- Oakly A, & Martin G. (2019). Dual use of electronic cigarettes and tobacco in New Zealand from a nationally representative sample. Australian and New Zealand Journal of Public Health
- Gilpin DF, McGown K, Gallagher K et al. Electronic cigarette vapour increases virulence and inflammatory potential of respiratory pathogens. Respir Res 20, 267 (2019)
- Crotty Alexander LE, Vyas A, Schraufnagel DE, Malhotra A. Electronic cigarettes: the new face of nicotine delivery and addiction. J Thorac Dis. 2015;7(8):E248–E251
- Crotty Alexander LE, Hwang JH, Lyes M, et al. E-Cigarette Vapor Decreases Antimicrobial Function of Macrophages, Neutrophils and Airway Epithelial Cells. American Thoracic Society Journals, 2015
- Agrawal N, Jharawal MK, Paharia N, Bansal K. Effect of Smoking on Ocular Surface and Tear Film: A Clinico Pathological Study. Madridge J Ophthalmol. 2018; 3(1): 39-42
- Uchino, Y. et al. Impact of Cigarette Smoking on Tear Function and Correlation between Conjunctival Goblet Cells and Tear MUC5AC Concentration in Office Workers. Sci. Rep. 6, 27699 (2016)
- Velilla S, García-Medina JJ, García-Layana A, et al. Smoking and age-related macular degeneration: review and update. J Ophthalmol. 2013
- Ye J, He J, Wang C, Wu H, Shi X, Zhang H et al. Smoking and Risk of Age-Related Cataract: A Meta-Analysis. Inv Ophth & Vis Sci. June 2012, Vol.53, 3885-3895
- Grana R, Benowitz N, Glantz S. E-Cigarettes. A Scientific Review. Originally published13 May 2014
- Md Isa NA, Koh PY, Doraj P. The tear function in electronic cigarette smokers. Optom Vis Sci. 2019 Sep;96(9):678-685
- Zengin M, Cinar E, Kucukerdonmez C. The effect of nicotine on choroidal thickness. Br J Ophthamol.l 2014;98:233–237
Louise Wood is a therapeutically qualified optometrist working at City Eye Specialists in Auckland, New Zealand.
Vaping legalities in NZ
The Ministry of Health (MoH) ruled the sale of nicotine-containing vaping devices was legal in New Zealand in May 2018. Following criticism, the Smokefree Environments and Regulated Products (Vaping) Amendment Bill was put to Parliament on 24 February 2020 to:
- Ban the sale of vaping products to under-18-year-olds
- Stop vaping or smokeless tobacco use in smokefree areas
- Prohibit advertising of vaping products
- Restrict the sale of flavoured vaping products and e-cigarettes to R-18 specialty stores, and limit general retailers’ sales to three flavours
- Introduce a product safety system, enabling the MoH to recall, suspend and issue warnings about vaping products
"The Bill aims to strike the right balance between making sure vaping is available for smokers who want to use it as a quit tool for cigarettes while ensuring vaping products are not marketed or sold to children and young people," said associate health minister Jenny Salesa.
But many are concerned restrictions don’t go far enough, including some who profit from the industry. “Currently, it appears that anyone will still be able to make a purchase from an overseas website and have the product shipped to their door, which may bypass age restrictions and quality controls,” said Paul Williamson from Shosha, the country’s largest retailer of e-cigarettes.
The government has set a long-term goal of making New Zealand essentially smokefree by 2025. Submissions on the Bill closed at the end of April with the Health Select Committee expected to report back this month.