# Acute respiratory and ocular effects of electronic cigarettes: A pre–post experimental study in healthy users

## TL;DR

This study shows that using electronic cigarettes can cause short-term changes in lung function and eye health, even in healthy users.

## Contribution

The study experimentally demonstrates acute respiratory and ocular effects of e-cigarette use in healthy individuals.

## Key findings

- Acute e-cigarette use significantly reduced FeNO levels, indicating airway inflammation.
- Pulmonary resistance increased in dual users after e-cigarette exposure.
- Ocular assessments showed reduced tear secretion and retinal hemodynamic changes.

## Abstract

The use of electronic cigarettes (ECs) has increased alarmingly among young people, often perceived as a safer alternative to conventional tobacco. Studies demonstrating that these are not harmless products are essential to raise awareness of their potential health risks.

A pre–post exposure experimental study was conducted between March and June 2024 at Virgen de la Victoria University Hospital, Málaga, Spain, in 40 healthy regular EC users aged ≥18 years. Respiratory parameters (FeNO, spirometry, oscillometry) and ophthalmological assessments (Schirmer test, Optical Coherence Tomography, and Pentacam) were evaluated before and after acute EC exposure (40–60 inhalations).

Following acute exposure, a statistically significant decrease in FeNO was observed from 21.88 ± 22.01 to 18.05 ± 18.08 ppb (p=0.019), particularly in non-smokers (p=0.003), suggesting an airway inflammatory response. In dual users, a significant increase in pulmonary resistance from 0.21 ± 0.36 to 0.35 ± 0.48 kPa/L∙s (p=0.028) was detected. At the ocular level, the Schirmer test showed reduced tear secretion in 47.5% of participants. Additionally, significant changes were found in macular flow density (p=0.024) and inferior macular choroidal thickness (p=0.015), suggesting a possible retinal hemodynamic alteration.

Acute use of ECs induces measurable changes in both respiratory function and ocular parameters. These findings underscore the need to raise awareness about the potential adverse effects of vaping and highlight the importance of further research into its long-term consequences.