The Acute Effects of Passive Smoke Exposure on the Ocular Surface and Tear Stability of Contact Lens Wearers

Abstract

Purpose:: The adverse effects of smoking on the body are already well established. However, research on the effects of smoking on the ocular surface and tear stability is limited. Our research sought to determine the acute effects of passive cigarette smoke exposure on the ocular surface and tear stability of contact lens wearers.

Methods:: Subjects were divided into two groups. The contact lens group consisted of 2 eyes of 1 hard contact lens wearer and 12 eyes of 6 soft contact lens wearers. (3 males, 3 females, average age 25.3 years). The control group consisted of 20 eyes of 10 non contact lens wearers. (9 males, 1 female, average age 26.7 ±; 6.7 years). All subjects were exposed to 5 minutes of passive smoke in a chamber where the CO concentration was maintained at 25 million ppm. Subjects underwent BUT measurement and staining with Rose Bengal (RB) and fluorescein prior to smoke exposure and again 1 hour following smoke exposure. 10 µl tear samples obtained before and 24 hours after smoke exposure underwent flow cytometry to quantify inflammatory cytokine (INF-γ, TNF-α, IL-10, IL-6, IL-4, IL-2) levels. Informed consent was obtained from all subjects and the experiment was carried out according to the tenets of the Declaration of Helsinki.

Results:: The tear break-up time was significantly reduced and fluorescein and RB staining scores significantly increased in both groups one hour after smoke exposure. IL-6 cytokine levels increased in both groups following smoke exposure, significantly in the control group. At baseline and at one hour following smoke exposure, the BUT value was significantly lower and both staining scores and IL-6 levels were significantly higher in the contact lens group.

Conclusions:: Passive smoke exposure significantly alters the tear film and ocular surface of both contact lens wearers and non-contact lens wearers, even after brief exposure. Measured baseline tear stability and ocular surface parameters were worse in contact lens wearers and continued to decline following smoke exposure.

Keywords: contact lens • flow cytometry • ocular irritancy/toxicity testing