This is an anesthetic drop used to numb the eye during an eye exam or prior to surgery. Tetracaine works similar to the novacaine that a dentist uses, but can be applied as a simple eye drop. This drop (or a similar drop called proparacaine) is commonly used to anesthetize the cornea prior to checking eye pressure with applanation tonometry. This drop is also used immediately prior to cataract surgery and minor surgical procedures. Tetracaine stings a little going in and will make the eye feel strange for a few minutes. The numbing effect lasts about 10-20 minutes before it begins to wear off. It is important that you not rub your eye while it is numb … you may be scratching your cornea and cause damage to yourself without realizing it. This drop is never prescribed for home use as repeated applications can actually be toxic to the ocular surface and will keep wounds and corneal abrasions from healing properly.