Most eye conditions are treated with the topical use of eye drops. It is therefore very important to be able to use eye drops effectively. The effective treatment of your eyes depend on the correct use of eye drops, and wastage leads to an unnecessary financial loss, especially so in chronic conditions where the drops are repeated monthly.
If the lower eyelid is pulled away slightly, you can see a shallow gutter, called the inferior fornix. Any eye drop instilled will fil the inferior fornix and be absorbed slowly into the eye. Most manufacturers will calibrate the dropper bottle to provide a drop of sufficient volume to fill the inferior fornix. Instilling a second drop will just wash out the first drop and will not in any way add to the effectiveness of the treatment. When you use more than one drop that has to be instilled the same time of day, it is therefore very important to wait at least five minutes between the installations.
Some people prefer to hold their heads back and drop a single drop onto the eye, but this can be very intimidating. The sight of a drop approaching the eye can lead to reactive blinking and the drop falling on the eyelids. A drop can be instilled in the inferior fornix at any position on the lower eyelid, whichever is easiest for you. It does not matter whether you instill the drop in the middle of the lower lid, on the outside or on the inside closest to the nose. Pulling the eyelid away slightly with one hand will make it easier to instill the drop. It will also help to perform this in front of the mirror. You can hold your head upright; it is not necessary to hold your head back. If you suspend a drop out of the dropper bottle and bring it close to the lower eyelid, it will be pulled into the lower fornix. One hand can be used to pull the lower eyelid slightly away from the eyeball, and with the other hand the drop can be squeezed out of the dropper bottle and brought closer to the lower eyelid. Doing this in front of the mirror will be a great help. The lower lid can also be pinched between the thumb and forefinger creating a small triangular dam that the drop will fit in.
It is sometimes difficult to be sure whether the drop was successfully instilled. If a large drop enters the eye only a small volume will fit in the lower fornix and the rest will flow out of the eye. This is no indication that you missed the inferior fornix. Most drops does not need to be stored in the fridge, but a cold drop will be easily felt as it enters the eye. If a drop is successfully instilled, a part will be absorbed into the eye, but a small amount will be washed through small canals communicating with the nose at the inside edge of the eye. These can sometimes be tasted as a bitter taste at the back of the mouth. This is a good sign that you were successful.