The eyes are the most complex sensory organ in our body. Allergies are a common disorder that affects the eyes. You may have eye allergies if your eyes itch, appear red, are tearing up or you feel burning. Eye allergies often affect the conjunctiva, the clear thin, membrane that covers the inside of your eyelids and the white part of your eye (sclera).
An eye allergy occurs when something you are allergic to comes into contact with your eyes. Any substance that causes an allergy is called an allergen.
The most common allergens are pollen, dust mites and animal dander. The conjunctiva contains mast cells that release chemical mediators such as histamine in response to allergens. When airborne allergens contact the conjunctiva of the eyes, they bind to the IgE antibodies on the surface of mast cells which release mediators that are responsible for causing an allergic reaction. This in turn causes blood vessels in the eyes to swell, and the eyes to become red, inflamed and very itchy.
Allergic conjunctivitis is one of the most common allergic eye diseases.
- Allergic conjunctivitis is inflammation of the conjunctiva.
- Symptoms include watery, itchy, red, swollen eyes, and dark circles under the eyes (allergic shiners).
- Allergic conjunctivitis can occur alone, but often accompanies nasal allergy symptoms.
- Seasonal allergic conjunctivitis occurs only at certain times of the year, usually in spring.
- Perennial allergic conjunctivitis occurs throughout the year and is caused mostly by exposure to dust mites, animal dander, or other allergens present in the home or workplace environment.
- Your allergist diagnoses eye allergies from your complaints (symptoms), eye examination and discussing your medical history, including any family history of allergy.
- A skin test may be helpful to identify the substances that you are most allergic to.
- Your eyes are examined using a special microscope called a slit lamp to check for swollen blood vessels on the surface of the eye which is indicative of an allergic reaction.
- In most severe cases, gentle scraping of the conjunctiva is performed to check for eosinophils (specific type of white blood cells that are commonly associated with allergies).
- The key to treating eye allergies is to evaluate and control the allergens.
- Some people may have temporary relief from cold compresses on the eyes, however, medications such as oral anti-histamines and eye drops may be necessary to treat the symptoms.
- Topical antihistamines, decongestants, mast-cell stabilizers, and the use of oral steroids may help control the itching.
- Immunotherapy or allergy shots may be an option for relieving eye allergies if your symptoms are not controlled by avoiding allergens, using eye drops or medications.
Watery eye or epiphora is generally seen in young babies and older people. In this condition, tears accumulate in the eyes due to a blockage in one or both tear ducts. As a result, excessive tears trickle down the face instead of draining from the tear ducts.
The delicate balance between tear production and loss is maintained by the lacrimal system present in the eye. However, sometimes this balance is disrupted and the eye becomes prone to irritants that include:
- Allergic inflammations
- Dirt or a piece of grit
- Inwardly growing eye lashes
The eyes secrete excess tears as a protective mechanism to steer away these irritants.
A normal eye is kept moist by a definite amount of tears. Extra tears, if any, pass on to the tear duct and nose. The tear duct may be blocked due to narrowing of its upper part over time. In such cases, the excess tears trickle down the cheeks.
Treatment of epiphora (watery eyes) includes the following:
Dacryocystorhinostomy (External and Transcanalicular Laser): Dacryocystorhinostomy is a procedure to treat watery and sticky eyes caused by narrowing or blockage of the tear drainage tubes. Depending on your condition, dacryocystorhinostomy may be performed externally (through the skin) or endoscopically using a transcanalicular laser.
- External Dacryocystorhinostomy: During this procedure, a nick is made on the side of your nose to access the tear sac. A small piece of bone is removed from between the tear sac and the nose to access the inside of the nose.
- Transcanalicular Laser: Transcanalicular laser dacryocystorhinostomy is a minimally invasive endoscopic procedure to treat epiphora. During this procedure, a fibre optic light probe is inserted through the nasal cavity to the lacrimal sac (tear sac).
Probing & Syringing +/- Intubation: Probing and syringing are performed to open up blocked tear ducts. It can be performed under local or general anesthesia as an outpatient procedure. During this procedure a thin flexible probe (wire) is inserted down the tear duct to clear any blockage.
Lacrimal Stents: Lacrimal stenting can be performed as an outpatient procedure under moderate sedation. Lacrimal stents are thin tubes that are implanted in patients with narrowed but not completely blocked tear ducts. They help keep the tear duct open and help prevent further scarring.
Urticaria affecting deeper layers of the skin is referred to as angioedema. Angioedema usually involves the skin around the eyes, cheeks or lips. However, it can also involve the hands, feet, genitals and the mucosa of the throat and bowel in severe cases. Angioedema and urticaria can occur disjointedly or at the same time.
The symptoms of angioedema include:
- Swelling of the skin
- Pain and local rise of temperature of the affected region
- Discrete welts
- In severe cases, patients may experience difficulty in breathing or swallowing due to swelling of the inner lining of the throat and air tubes
- Patients may also experience distortion of vision secondary to swelling of the conjunctiva
Types of angioedema
The four major types of angioedema include:
- Allergic angioedema- caused due to allergic reactions, such as reaction to ingestion of peanuts
- Idiopathic angioedema- the underlying cause is not known; certain factors such as stress or infection may be involved
- Drug-induced angioedema- caused secondary to a reaction to some medications
- Hereditary angioedema- caused due to faulty genes inherited from their parents. This form of angioedema is not associated with urticaria.
Angioedema may be caused due to the allergic reaction resulting in the release of histamine and other chemicals into the bloodstream. In a majority of the cases the cause of angioedema is not known. The following are the common causes of angioedema:
- Allergies to food, medication, cosmetic, soaps, detergents and pet dander
- Insect stings and bites
- Emotional and physical stress
- Exposure to physical agents such as sunlight, heat, cold and pressure
- Infections and certain diseases such as lupus, lymphoma and leukemia
The diagnosis of angioedema involves the physical examination of the skin. The doctor will inquire about exposure to any irritating substance. In a few cases, blood tests may also be conducted. Physical examination may also reveal abnormal breath sounds such as stridor.
Mild angioedema may not require any treatment. In moderate to severe cases medications may be required to relieve the symptoms. Cold compresses can help relieve pain. The other approaches used for the management of angioedema are listed below:
- In case of allergic angioedema eliminate the exposure to the allergen which can include food, medication, contact allergen etc.
- For drug induced angioedema, the offending medication can be substituted by an alternative medication.
- Antihistamines provide symptomatic relief
- A prophylactic approach is recommended in hereditary angioedema as it does not respond well to the commonly used medications.
- Adrenaline and steroid shot may be used in severe cases
- In the case of severe breathing difficulty, the patient may be intubated.
In cases of severe angioedema that does not respond to treatment contact your physician immediately.