These are drops that are meant to make your eyes “whiter”. The most popular here is Eye gene. It’s important to remember that these drops simply make your blood vessels thinner, therefore making your eyes less red. They do not address what caused the redness in the first place. Prolonged use of these drops results in the opposite effect, that is, they end up making your eyes more red over time. 

Redness can be caused by a lot of different conditions such as eye strain, allergies, dryness or infections. If your eyes are constantly red for no apparent reason, get them examined to find out the cause.