The problem with the available red eye–reducing eye drops is that they contain a decongestant as the active ingredient for vasoconstriction. Naphazoline, tetrahydrozoline, and phenylephrine have relatively short durations of action and require frequent dosing, 1 to 2 drops up to four times daily.
Soparkar and colleagues reported in 1997 that misuse of these OTC eye drops can lead to chronic conjunctivitis. His study of 137 eyes demonstrated that, over the course of a median 3-year use cycle, OTC decongestant eye drops can produce both acute and chronic conjunctivitis, which can take several weeks to resolve. It is also well-known to eye care professionals that chronic use of these whitening agents can have a rebound effect, causing vasodilation and actually making the redness worse for the user. Some experience rebound effects, others experience tachyphylaxis, a rapid decrease in response to a drug after use….
Read full article by Dr. Leslie O’Dell at eyetubeOD