Eye drops can deliver medications directly to the conjunctiva, the clear tissue that covers the white of the eye (sclera) and the inner eyelid, along with other parts of the eye. Because many eye allergies involve allergic conjunctivitis (inflammation of the conjunctiva), eye drops can be effective at relieving eye-related symptoms such as itchiness, burning and stinging.

A variety of medications can be administered in the form of eye drops for the treatment of allergies or nonallergic eye disorders such as pink eye (infectious conjunctivitis) or glaucoma (a disorder that involves optic nerve damage).

Eye drops may also be used during eye examinations to dilate (enlarge) the pupils of the eye or administer an anesthetic (painkiller). Dilating the eye allows the ophthalmologist (medical and surgical eye doctor) to view the inner eye while the anesthetic makes the examination more comfortable for the patient.

Eye drops can be used to deliver a wide range of medications. Some are available over-the-counter, while others require a prescription. The frequency of use and directions for use will depend on the type of medication being administered, and the severity of the condition for which they are administered.

Eye drops are frequently prescribed to treat allergies. Allergens that become airborne can easily affect the eye, which has many blood vessels and mast cells. When an allergen irritates the eyes, the mast cells release histamine and other chemicals. This causes swelling of the blood vessels and other symptoms, such as watery buildup and itchiness. Allergy medications in eye drop form may be used to prevent symptoms or to treat them once they have begun.

Over-the-counter eye drops typically provide short-term relief for allergy symptoms, while prescription eye drops provide both short-term and long-term relief. Because eye drops do not relieve nasal allergy symptoms, they may be used in conjunction with oral allergy medications.  

Eye drops are effective only when used properly. It is important to ensure that the medication not only reaches the eye, but that it is fully absorbed so that the eye receives the maximum benefit of the drug. Those who use eye drops should follow these steps:

1. Wash hands, and dry them with a clean towel.
   
   
2. Pull lower eyelid from the eye, by placing index finger on the skin below the lid and gently pulling down.
   
   
3. Place drop into the pouch between the lower eyelid and eye. The tip of the bottle or tube should not touch the eye, eyelid or surrounding areas to avoid contamination.
   
   
4. Let go of eyelid and close eye.

If more than one drop is required, wait five minutes between drops. The cap should be immediately replaced on the eye drops after each use.

It is not always easy to tell if eye drops have been instilled properly. If possible, patients should have someone watch to make sure the drops land in the eye. Another option is to store medicine in the refrigerator so the drop will feel cold when it hits the eye. The cold drops also help to refresh eyes affected by allergies.

The ingredients in some eye drop solutions can be absorbed into soft contact lenses. Therefore, patients who wear contact lenses may be advised to remove the lenses before inserting eye drops and to wait 10 minutes or more before reinserting their lenses.