In this study, we evaluated contact lenses as drug delivery media and the effect of tear physiological pH on drug release behavior. Anionic or cationic hydroxyethyl methacrylate (HEMA) lenses were polymerized with either vinylpyrrolidone (VP) or N-isopropylacrylamide (NIPAAm). The pH of artificial tears was prepared as between 5.8 and 8.35. One of common treatments, hydroxypropyl methylcellulose (HPMC), to dry eye disease was used as a test drug.