The composition of the liquid contained in an electronic cigarette is far from harmless.

“[T]hese devices have been found to contain carcinogenic chemicals, air pollutants, and heavy metals,” outline the researchers behind the study in the International Journal of Ophthalmology.

“The purpose of this article is to shed light on the known effects of vaping on the ocular setting,” the study authors continue.

To conduct the research, experts collected their information from more than 1 million people between 2016 and 2018. Participants were asked to answer questions about their visual impairments and frequency of e-cigarette use.

What were their findings? Two chemical components were identified as being able to disrupt the tear film stability that protects the part of the eye in contact with the outside.

Additionally, the lipid layer, which protects tears from evaporation, may be damaged by vaping flavours. Researchers also noted that nicotine can interfere with retinal light-adapted vision.

Finally, the study concluded that “vape-related explosions, though unpredictable, may also result in decreased visual acuity along with long-term ocular trauma.”