Smoking cigarettes can have immediate and transient effects on tear breakup time (TBUT), lipid layer thickness, pupil size, and amplitude of accommodation (AoA), according to research published in Contact Lens and Anterior Eye.
Researchers conducted a study of 45 habitual smokers (mean age, 22.0±4.4 years, 66.7% men) to assess the effect of smoking cigarettes on tear quality and quantity as well as accommodative functioning. They measured TBUT, AoA, lipid layer thickness, tear meniscus height (TMH), and pupil diameter at baseline after participants observed a 1 hour period of abstinence from smoking. The team also measured TBUT using 3 different methods: fluorescein with slit lamp evaluation, non-invasive TBUT, and video capture via corneal topography. They then instructed patients to smoke a cigarette and repeated all measurements.
Investigators noted significant decreases in AoA (10.5±1.8 to 9.9±1.7 D), pupil diameter (5.6±1.1 to 5.4±1.0 mm), and lipid layer thickness (65.8 to 54.2 nm and 79.1 to 61.8 nm measured via tearscope and keratographer, respectively) immediately after smoking (P ≤.001 for all). TBUT also decreased as measured by fluorescein, non-invasive, and video capture methods (6.7 to 4.7 s, 9.8 to 7.0, and 11.7 to 8.7 s, respectively, P <.001 for all 3 methods). However, the researchers did not note any statistically significant differences with respect to change in TMH (0.4±0.1 to 0.3±0.1 mm, P >.05).
“This study revealed that tobacco smoking could immediately decrease TBUT, alter the tear lipid layer, cause miosis of the pupil and reduce the amplitude of accommodation,” according to the researchers. “A possible reason for short-term effects of smoking may be related to the short life span of nicotine as nicotine rapidly changed into a less toxic and relatively inactive substance which may cause a reversal in any change caused by it.”
Study limitations include a lack of objective measurements for AoA and possible confounding caused by the various smoking habits and nicotine contents of cigarettes smoked by the cohort.
Latif N, Naroo SA. Transient effects of smoking on the eye. Cont Lens Ant Eye. Published online April 6, 2022. doi:10.1016/j.clae.2022.101595