Eye drops can be used to treat many symptoms that affect the eyes, including itchiness, burning, redness, excessive watering, infections and discharge. Such symptoms can be caused by a variety of conditions including chronic dryness, allergies and eye infections.

Eye drops are also used during eye examinations to dilate the pupils, and to treat serious eye disorders such as glaucoma (a disorder that involves optic nerve damage). They can deliver a variety of medications directly to the eye tissues, preventing or relieving symptoms directly where they appear. Many eye-related conditions affect the conjunctiva, the clear tissue that covers the white of the eye and the inner eyelid. The conjunctiva contains many mast cells, which play a prominent role in triggering symptoms of an allergic reaction.

Patients who use eye drops should follow several steps to ensure that the medication gets into the eye and is fully absorbed. As with any drug, eye drops should not be used unless a physician approves their use.

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.

Eye drops can be used to deliver a variety of medications, from “artificial tears” to antibiotics. The major allergy drug categories delivered through eye drops include:

• Antihistamines. Medications that attach to histamine receptors, preventing the chemical histamine from triggering symptoms of an allergic reaction. This helps keep the blood vessels in the eye from swelling. They also relieve eye itchiness and redness. Eyes drops have a quicker onset and cause less drying of the eye than oral antihistamines. Antihistamines are available in both over-the-counter and prescription forms. Examples include:
  
  
• • Azelastine (Optivar)
  • Emedastine (Emadine)
  • Ketotifen (Zaditor)
  • Levocabastine hydrochloride (Livostin)
  • Olopatadine (Patanol)
  • Pheniramine (Opcon-A)
    
    
  
  
  
  
• Decongestants. Shrink blood vessels in the eyes that are swollen because of exposure to an allergen. This decreases eye redness, reduces the production of fluid inside the eye and increases the amount of fluid that drains from the eye, alleviating watery eyes. Decongestants are available in both over-the-counter and prescription forms. They should not be used for more than a few days, as overuse of decongestants can trigger a “rebound effect” that actually makes symptoms worse. Examples of decongestants include:
  
  
• • Naphazoline hydrochloride (Allerest, Vasocon)
    
    
  • Tetrahydrozoline hydrochloride (Eyesine, Murine Plus, Visine)
    
    
• Antihistamine/decongestant combinations. Combine the efforts of antihistamines and decongestants. These are available over-the-counter. Examples include naphazoline/pheniramine (Naphcon-A, Opcon-A, Visine-A).
  
  
• Nonsteroidal anti-inflammatory drugs (NSAIDs). Inhibit the body’s ability to produce chemicals called prostaglandins, which are released during an allergic reaction. Anti-inflammatories reduce eye pain, itching and swelling. They are available by prescription only. Examples include ketorolac (Acular) and nepafenac (Nevanac).
  
  
• Corticosteroids. Decreases inflammation during an allergic reaction by mimicking the behavior of cortisol, a hormone in the body that aids proper body function during stressful situations. They are only available by prescription. Examples include:
  
  
• • Prednisone acetate (EconoPred, Pred Forte)
  • Loteprednol etabonate (Alrex, Lotemax)
  • Fluorometholone (FML)
    
    
• Mast cell stabilizers (MCS) and MCS combination drops. Strengthen the mast cells to prevent them from releasing histamine and other chemicals that contribute to the symptoms of an allergic reaction. Mast cell stabilizers also reduce eye redness and wateriness. They are available in both over-the-counter and prescription form. Examples include:
  
  
• • Olopatadine hydrochloride (Patanol)
  • Ketotifen (Zaditor)
  • Azelastine (Astelin)
  • Pemirolast (Alamast)
  • Emedastine (Emadine)
  • Ketotifen (Zaditor)
  • Cromolyn (Crolom)
  • Lodoxamide (Alomide)
  • Nedocromil (Alocril)
  
  
• Artificial tears/saline solutions/ointments. Lubricate, dilute and wash away offending allergens. These medications also moisten the eyes, which frequently become dry as the result of redness and irritation. They are available in over-the-counter form in many brands, including:
  
  
• • Adsorbotear
  • Liquifilm Tears
  • Refresh
  • Tears Renewed
  • Visi White Petroleum Mineral Oil
    
    
• Antibiotics. Prescription medications used to treat bacterial infections. Those available in eye-drop form include:
  
  
• • Monofloxacin (Vigamox)
  • Gatafloxin (Zymar)
  • Ciprofloxacin (Cipro)
  • Erythromycin (Akne-Mycin, Erycette)
  • Gentamicin (Cidomycin, Genoptic)
  • Ofloxacin (Floxin, Ocuflox)
  • Sulfacetamide (Cetamide, Sulfex)
  • Tobramycin (Tobrex)
    
    
• Antivirals. Prescription medications used to treat viral infections, such as herpes eye infections. Those available in eyedrops include:
  
  
• • Adenine arabinoside (Vira-A)
  • Trifluridine (Viroptic)
  • Idoxuridine (Herplex Liquifilm)
  • Trifluorothymidine
    
    
• Glaucoma medications. Prescription eye drop medications used in the treatment of glaucoma (a disorder that involves optic nerve damage) include:
  
  
• • Betaxolol (Betoptic, Kerlone)
  • Dorzolamide (Trusopt)
  • Latanoprost (Xalatan)
  • Levobunolol (AKBeta, Betagan)
  • Metipranolol (OptiPranolol)
  • Pilocarpine (Carpine, Pilocar)
  • Timolol (Blocadren, Timoptic)
    
    
• Homeopathic medications. These alternative therapies use a very small dose of a substance in the belief that this will desensitize the eye to an allergen or irritant. The medical community considers such medications to be unproven. These medications do not have the approval of the Food and Drug Administration (FDA).

In addition, there are a number of medications in eye-drop form that may be used by an ophthalmologist (eye doctor) during an eye examination. These include medications to dilate (enlarge) the pupils of the eye or administer an anesthetic (painkiller). Dilating the eye allows the physician to view the inner eye while the anesthetic makes the examination comfortable for the patient.

Eye drops are prescribed to treat symptoms that result from a variety of allergic conditions that affect the eyes, including:

• Allergic conjunctivitis. An allergic reaction that involves an inflammation of the conjunctiva, the clear membrane that covers the white of the eye. This can result in itching, burning, and redness in the eye. Swollen eyelids, watery eyes and eye discharge are also symptoms of allergic conjunctivitis.
  
  

  

• Atopic keratoconjunctivitis. An eye allergy usually associated with atopic dermatitis (eczema caused by allergies). It involves inflammation of the conjunctiva and the cornea, a transparent dome on the surface of the eye. Symptoms include heavy discharge from the eye and scaling and crusting of the eyelid. In severe cases, eyelids thicken and the eyes become very sensitive to light (photophobia).
  
  
• Vernal keratoconjunctivitis. A sight-threatening inflammation of the tarsal conjunctiva (the membrane covering the back of the eyelid). Symptoms include stringy discharge from the eye, intense itchiness and sensitivity to light. The condition is uncommon and disproportionately affects preadolescent boys.
  
  
• Allergic rhinitis. Commonly called hay fever, this condition is an inflammation of the inner lining of the nose that occurs when an allergic individual is exposed to airborne allergens (e.g., pollen, mold, dust mites, animal dander). Allergic rhinitis can trigger symptoms in the eyes such as watery eyes, burning and itching. In some people, the eyes are the only part of the body that manifests symptoms related to allergic rhinitis.
  
  

  

Eye drops can be a great benefit to most who suffer from eye allergies. However, some patients have conditions that should be weighed before a decision is made on treatment. A physician should be informed of the following:

• Past allergic reactions to antihistamines, decongestants, aspirin and other medications.
  
  
• Medicines currently taken by the patient.
  
  
• Pregnancy or intention to become pregnant.
  
  
• Breastfeeding.
  
  
• Contact lens use.
  
  
• Present bacterial infection of the eye, including pink eye (conjunctivitis).
  
  
• Hemophilia or other bleeding disorders. Anti-inflammatories can worsen these conditions.
  
  
• Diabetes. Decongestants can worsen this condition.
  
  
• Heart disease. Using antihistamines with decongestants can aggravate some heart conditions.
  
  
• High blood pressure. Using antihistamines with decongestants can aggravate this condition.
  
  
• Glaucoma (a disorder that involves optic nerve damage). Using antihistamines with decongestants can aggravate this condition.
  
  
• Overactive thyroid. Medications containing naphazoline can worsen this condition.
  
  
• Eye disease or injury. Problems that stem from these conditions may be confused with side effects of the drug ophthalmic naphazoline (a decongestant).
  
  
• Difficulty urinating due to an enlarged prostate. Medications containing antihistamines can aggravate this condition.

Most side effects related to eye drop use are minor. These may include:

• Lengthening or thickening of eye lashes
• Darkening of skin around eye lashes
• Taste of drops in throat
• Dilated pupils
• Tingling sensation in the eye
• Redness around eyes
• Burning, stinging eyes
• Watery eyes
• Eye puffiness
• Eye dryness
• Drowsiness
• Sensation of foreign object in eyes
• Blurry vision
• Headaches
• Achy eyes
• Crusting in eyelids, eyelashes or corner of eyes
• Nose dryness
• Runny or stuffy nose

More serious side effects related to eye drop use may include:

• Respiratory distress
• Heart palpitations (an awareness of a strong, fast, irregular, abnormal or "galloping" heartbeat)

• Eye pain
• Vision changes
• Persistent redness or irritation of the eyes
• Symptoms worsen or last more than 72 hours

Patients should consult their physician before taking any additional prescriptions, over-the-counter medications, nutritional supplements or herbal medications. Drugs that may adversely interact with eye drops include:

• Aspirin
  
  
• Ketoconazole (used to treat skin infections)
  
  
• Itraconazole (used to treat fungal infections of the lungs, blood, and toenails)
  
  
• Erythromycin (antibiotic used to treat bacterial infections)
  
  
• Isoproterenol (used to treat asthma and other respiratory disorders)
  
  
• Monoamine oxidase (MAO) inhibitors (an antidepressant)

Symptoms of eye drop overdose can be similar to the medication’s side effects, but are usually more severe. Most eye drop medications for allergies should be used sparingly and for no longer than a week. Eye drop medications that contain decongestants should not be used for more than three consecutive days. Overuse of decongestants can lead to a rebound effect, with redness and swelling actually increasing instead of decreasing.

Corticosteroids can be used to treat eye allergies, but only with caution and under a physician’s close monitoring. Long-term use can lead to pressure buildup in the eye from glaucoma or the formation of cataracts, a clouding of the eye lens that can impact vision.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians. Patients may wish to ask their doctors the following questions about eye drops:

1. Are eye drops appropriate for me to use?
   
   
2. Will eye drops prevent my allergic reactions from occurring or will I still require oral medication?
   
   
3. What is the proper way to use eye drops? When should I use them?
   
   
4. Is it possible to overuse eye drops?
   
   
5. Do eye drops pose a danger to me?
   
   
6. What side effects may I develop?
   
   
7. What should I do if side effects occur from using eye drops?
   
   
8. Will eye drops interfere with any of my other medications?
   
   
9. What should I do if I miss a scheduled dose of eye drops?
   
   
10. Can I wear contact lenses while using eye drops?