There are a wide range of eye drops used to treat a range of symptoms. Eye drops can vary from harmless artificial tears used to soothe sore, irritated eyes to more dangerous corticosteroids and anesthetic drops used for serious conditions and medical procedures. The degree and type of danger an eye drop poses depends on the type of eye drop and how the patient uses it.
Artificial tears are the safest and mildest eye drops and rarely cause serious side effects. Some versions, however, do contain a preservative which can irritate the eye with frequent use. Use a version without a preservative in order to avoid side effects.
Red Eye Drops
Over-the-counter eyedrops such as Visine treat redness and itchiness in the eyes along with dryness. Allergies often create redness and these drops are marketed to allergy sufferers, but they don't actually treat allergies. Instead, they shrink the blood vessels in the eyes, causing them to look less red and making the eyes feel less allergic. In moderation, these eye drops work well, but if you overuse them, they can cause a rebound effect. The eyes get acclimated to the drops and, when you stop using them, the eyes become more red than before. In rare cases, these eye drops can cause a sudden, acute form of glaucoma. If your eyes become painful and irritated after taking red eye drops, immediately contact your doctor.
Visine is much more dangerous in your mouth than in your eyes. According to Snopes.com, Tetrahydrozoline (found in Visine and similar eyedrops) can cause a range of serious symptoms including difficulty breathing, blurred vision, nausea, vomiting, seizures and even death. Do not swallow it and keep it away from young children.
Eye drops with coritcosteroids treat glaucoma and certain severe allergies. They are powerful medicines and can have very serious side effects. Corticosteroids supress the immune system, putting your eye at risk of scarring and infection. Over time, they can also lead to glaucoma and cataracts. Only use prescription eye drops under medical supervision and report any side effects to the doctor immediately.
Anesthetic eyedrops act as painkillers in the doctor's office to let the doctor perform medical treatments such as surgery. They are not prescribed for home use and should not be used at home for any reason. If you use them repeatedly, they can cause scarring and damage to the cornea or provoke eye infections.