온도 조건에 따른 Airflow 반복 노출이 소프트콘택트렌즈의 파라미터에 미치는 영향

Purpose
This study investigated differences in the parameters of soft contact lenses (hereinafter soft lenses) repeatedly exposed and hydrated in warm vs. cold airflow conditions.

Methods
Two hydrogel (FDA groups II and IV), and two silicone hydrogel lenses were placed on a mold simulating corneal environment. The lenses were exposed to warm or cold airflow for two minutes, and then re-hydrated in phosphate buffered saline for 10 minutes. The lens parameters were respectively measured after dehydration and rehydration. This process was repeated 10 times.

Results
The base curves of nesofilcon A and senofilcon A lenses showed significant changes after rehydration, under warm airflow. The base curve of the nesofilcon A lens showed significant change after rehydration, under cold airflow. The total diameter was significantly different after dehydration, except for comfilcon A lens under cold airflow. Significant changes were observed in the central thicknesses of senofilcon A and etafilcon A lenses upon dehydration and rehydration, respectively, under warm airflow; and of senofilcon A upon rehydration between the comparison of each point, under cold airflow.

Conclusions
When soft lenses are repeatedly exposed to airflow at various temperatures, parameter changes may be induced, and not be recovered to the value before airflow exposure. In the case of reusable soft lenses, it suggests that the lens stability may not be sustained even if the lenses are re-hydrated after dehydration by various kinds of airflow.