As an optometrist, I see many patients who have red eyes and expect a quick fix eye drop to be prescribed. “I don’t like the way my eyes look! Can’t I just use V----- to take the red out?”
The truth of the matter is, a red eye is often indicative of a more serious underlying ocular condition; using OTC red eye relief drops won't solve the condition and it may even exacerbate symptoms. That’s why I always do not recommend them...they never address the underlying issue and only mask it.
Overuse and abuse of these “get the red out” drops is very common.
The active ingredient in these formulations are either Naphazoline or Tetrahydrozoline hydrochloride which are vasoconstrictors, and therefore they constrict the eye's superficial blood vessels. With the blood vessels constricted, it gives the appearance of “whiter, healthier” eyes.
If the eye is irritated, the blood vessels often dilate in response. This increase in blood flow is the body’s way of trying to help repair whatever irritation is affecting the surface of the eye. Clamping down on those vessels by using a vasoconstrictor counteracts the body’s efforts to repair the problem.
The vasoconstrictor will only work for a few hours and the redness will always come back because the underlying issue is still there. The vessels often dilate to an even larger degree than before, and because it looks worse, everyone’s natural response is to add more drops. This is called the "rebound effect" and leads to overuse of the eye drops.
Prolonged use can cause blood vessels to be dilated for an extended period of time.
Wearing contacts in conjunction to using these drops is even worse. If you use these drops while wearing contacts, the contact will absorb the drug and keep it on your eye surface longer, thus increasing the vasoconstriction. Another reason red eye relief drops are not advised for contact lens wearers is because decreased blood flow to the surface of the eye will further lower the levels of oxygen available to the eye. Decreased oxygen to the cornea is one of the biggest reasons for contact lens-related problems and infections.
Treating the underlying condition causing a red eye is never a quick fix and will always take time; I know it’s not what patients want to hear. My philosophy has always been figuring out what's causing the redness, treating it properly, and taking care of it permanently rather than temporarily.