Allergic Conjunctivitis

Conjunctivitis is commonly known as ‘red eye’ or ‘pink eye’. There can be several causes and types of conjunctivitis. One of the common and preventable types is allergic conjunctivitis. Knowing the causes, prevention and treatment of conjunctivitis can ensure good healthy eyes.

Allergic conjunctivitis is an inflammation in the conjunctiva which is the thin transparent membrane that covers the white of the eye and the inner surfaces of the eyelids.

As the name implies, this inflammation is caused due to allergy which is essentially hypersensitivity of the body to a particular stimulus. The stimuli can be any trivial substance present in the internal or external environment. Usually these are air borne.

The commonest triggers are pollen, grass, weeds, and molds. These may cause seasonal symptoms. Smoke, fumes, dust, dust mites can trigger an attack of allergy. If you have a pet, the secretions, saliva or fur of the pet may cause allergy. Skin or eye cosmetics and perfumes can act as a stimulus.

Allergy is mediated by a biogenic chemical entity called ‘histamine’ which is synthesized and stored in special type of cells called ‘mast cells’ and is released upon contact with a potential trigger of allergy. Histamine causes the small blood vessels to dilate and also causes itching.

The dilation of the blood vessels increases blood flow, and causes redness. These vessels become leaky to cause accumulation of tissue fluids and hence swelling and heaviness in the eyes.

A few symptoms of conjunctivitis is mentioned below:

During an episode of allergic conjunctivitis, the contact with a trigger causes release of histamine, and hence the consequent swelling, redness, itching, and watering in eyes.

These may resolve when exposure to the stimulus is over and can recur upon a second and subsequent contact with the same or different stimulus. Allergy can be due to one or many stimuli. Allergy may run in your family.

Allergic conjunctivitis may be a part of a generalized allergy process like hay fever which is characterized by allergic symptoms in nose, called allergic rhinitis.

You may have other concurrent allergic manifestations like allergy in the windpipes, called allergic asthma, or allergy anywhere in skin.

Allergic conjunctivitis manifests as swollen red watery eyes that may itch. There may be a foreign body sensation and the distress may increase on exposure to light.

Allergic conjunctivitis causes distress, pain and heaviness in the eyes. There are no deleterious effects on eyesight.

Once the contact with the trigger is over, the inflammation subsides and the eyes get healthy again till a second contact with the same or another stimulus precipitates it.

Allergic conjunctivitis treatment includes eye drops and sometimes oral medications, i.e. pills or syrups. Of these, eye drops are commonly used. Since histamine is the main cause of all the symptoms in allergic conjunctivitis, allergic conjunctivitis benefits from eye drops containing antihistamines. This treatment is also called as the pink eye treatment.

These will reduce the swelling and congestion in the eyes. Also, eye drops containing mast cell stabilizers can help to prevent the release of histamine from mast cells. For symptom relief from pain, swelling and redness, a drop with anti-inflammatory agents may help.

An eye drop preparation may contain one or more of these medications. Since, these agents are short acting, the eye drops may need to be used multiple times in a day depending upon severity of symptoms. In severe cases an oral therapy may be required.

Your doctor may advise you for any of these and prescribe you the same. You can also use artificial tears. These irrigate the eyes and wash off the irritants. These also soothe, moisten and give relief to the irritated eyes.

Adverse effects are possible with any of these eye drops or oral medications. The commonest adverse effect can be a stinging sensation or a feeling of burning in the eyes. Usually these are self-limiting and subside over a short span of time. If severe, stop the medication and seek medical help.

Steroid eye drops can cause glaucoma (increase in eye pressure), cataract (opacity in lens) or make eyes more susceptible to infections. Oral antihistamines may causes sedation, dizziness and reduced concentration.

If you have red eye, take good care of your eyes. Avoid exposure to the substances you are allergic to. Wear sunglasses when you go out. Wash your eyes with plenty of cold water many times in a day. Do not rub your eyes vigorously. You may use a soothing cool eye compress.

The best way to prevent another episode of conjunctivitis is to avoid exposure to the stimulus that causes the symptoms.

  • If you are allergic to dust, do not go out when there is a dusty storm.
  • If you are allergic to pollen, avoid going out in seasons when pollens are high.
  • Follow the weather forecasts to help you plan your day.
  • Keep your environment clean and preferably air conditioned.
  • Clean your air conditioning units too.
  • Control moisture and humidity to prevent growth of molds.
  • Swab the floor with a wet rag.
  • Avoid dusting or sweeping.
  • Clean all air ducts of the house.
  • Avoid using carpets; instead select wood flooring or tiles.
  • Use dehumidifiers at home, preferably in basements that have more likelihood of humidity.
  • If you are allergic to some cosmetics or perfumes, avoid using them.
  • If you have a pet, keep it clean and avoid any contact with the possible secretions and fur.
  • Keep the pet out of the bedroom and wash your hands immediately after you handle the pet.

Avoid wearing your contact lenses when you have inflamed eyes. Contact lenses can cause irritation and can worsen the symptoms. Prefer using glasses.

If you have used contact lenses anytime when you have used contact lenses anytime you had symptoms, clean them well before you use them again.