Some eye drops should be avoided while wearing contact lenses. There aren't many safety data available, but be careful not to overlook additives that clearly require attention.

Benzalkonium chloride
Since eye drops are prone to putrefaction and contamination of chemicals, preservatives and preservatives are basically added except for single-use type eye drops. "Benzalkonium" is one of them, and it is often used as a preservative for eye drops because it has an excellent antiseptic effect and has little adverse effect on the human body under normal use.
However, since this "benzalkonium" has the property of adsorbing to water-containing soft contact lenses, if you instill it while wearing the lens, the contact time between "benzalkonium" and the cornea will become longer, causing keratitis. there is). Therefore, in the case of eye drops containing "benzalkonium", it is recommended to remove the contact lenses once before applying the eye drops, and then wait about 10 minutes after instilling the eye drops).
If this is not possible or is a hassle, you should choose eye drops that do not contain "benzalkonium".

In addition, it is said that adsorption of "benzalkonium" is unlikely to occur with hard-type contact lenses, so there is no problem with eye drops while wearing them. However, it has been reported that long-term use of eye drops containing "benzalkonium" tends to cause conjunctival hyperemia), so eye symptoms have already appeared to some extent due to hay fever and dry eyes. If you are a person or if you continue to use eye drops for a while, it is safer to choose a product that does not contain "benzalkonium" if possible.

As long as it does not contain "benzalkonium", it is not always possible to use it while wearing any contact lenses. This is because not all of the effects of each ingredient and additive contained in eye drops on the properties of various contact lenses have been clarified.
For example, "boric acid" may be added to eye drops as a substitute for "benzalkonium", but this "boric acid" modifies "polyvinyl alcohol", which is the material of some colored contact lenses. It is reported to let you. Therefore, if you are using special lenses such as colored contact lenses, it is safer to avoid instillation while wearing them as much as possible, or to consult with an ophthalmologist individually.