A new study published in Investigative Ophthalmology & Visual Science has found that traditional cigarette smoke causes significantly more oxidative stress and tissue damage to the human cornea than heated tobacco products (HTPs), offering new insight into the ocular risks of smoking and potential harm reduction alternatives.
Researchers from the University of Catania and collaborators conducted a head-to-head comparison between cigarette smoke and emissions from IQOS, a popular HTP, using human corneal tissue and cell models exposed under clinically relevant air-liquid interface conditions. They analyzed structural damage, oxidative stress markers, inflammatory gene expression, protein oxidation, and wound healing capacity.
Their findings indicate that exposure to cigarette smoke severely compromised corneal epithelial integrity, triggered high levels of reactive oxygen species (ROS), and elevated inflammatory markers such as IL-6, IL-1β, and PTGS2. Cigarette smoke also impaired the cells’ ability to close wounds – critical for corneal healing – while HTP exposure did not significantly affect tissue structure or healing ability.
Proteomic analysis revealed different patterns of protein oxidation. Cigarette smoke oxidized key structural proteins like collagens, which are vital for corneal stability, while HTPs primarily affected intracellular cytoskeletal proteins. Although both products induced oxidative stress, the conventional cigarette had a more detrimental impact on protein networks and cellular function.
The findings underscore the unique sensitivity of the ocular surface to environmental toxins and highlight smoking as a modifiable risk factor for corneal diseases. While HTPs are not without biological effects, the study suggests they may pose a lower risk of ocular damage compared to traditional cigarettes. However, the study authors point out – as I’m sure most doctors do to their patients – that “quitting smoking remains the most reliable strategy to avoid smoke-related complications.”
