Contact lens wearers should be very careful what they put in their eyes while wearing lenses. The general rule is to not use any drops, even dry eye ones, that come in a bottle while you have your lenses on. The reason for this is preservatives. These chemicals added to the drops in the bottle to keep them “fresh” may be harmful to your lenses. The safest bet is to use drops that come in single dose units, because these contain no preservatives at all.