Abstract
Purpose :
Wildfires release large quantities of particulate matter (PM) into ambient air. These particles could deposit on contact lenses and induce symptoms of ocular discomfort for lens wearers. This study used simulated wildfire smoke to examine PM deposition on soft contact lenses.
Methods :
A wildfire was simulated by burning vegetation to generate airborne PM (FireLab, University of Tasmania). PM2.5 concentration was monitored with DustTrak II. Worn and unworn contact lenses (Verofilcon A, Stenfilcon A, Nesofilcon A, Comfilcon A) were exposed to smoke from simulated wildfire for 5 - 10 minutes.
Worn (n=10) and unworn (n=2) lenses were fixed with 2.5% glutaraldehyde and dehydrated by critical point drying. A further 2 worn and 2 unworn lenses were air dried in a dessicator for 8 days. No lenses were rinsed post exposure.
Lens surfaces were examined with scanning electron microscopy (Hitachi TM4000 Plus). Up to 5 digital images (20x – 5000x ) per lens were obtained. Images were qualitatively assessed for density, size, and shape of PM deposition. Comparisons were made between worn and unworn lenses exposed to smoke, and to a single worn lens, fixed as described above and not exposed to smoke (control lens).
Results :
The mean PM2.5 concentration during the exposure period was 3,200 µg/m3 (range= 200 – 18, 400 µg/m3). PM of variable size (2µm – 100µm) and shape were deposited on the front surfaces of all worn and unworn lenses exposed to simulated wildfire. Greater numbers of larger PM were observed on unworn lenses compared to worn lenses (Figure 1). Qualitatively, more PM was observed to be deposited on lenses exposed to wildfire smoke compared to the unexposed control lens. No clear differences were observed in PM density between worn and unworn lenses.
Conclusions :
Wildfire smoke particles in ambient air can deposit on soft contact lens surfaces. This should be considered by practitioners when recommending lens wear or managing symptomatic patients when air quality is poor
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.