How Do Ophthalmic Mast Cell Stabilizers Work?

Ophthalmic mast cell stabilizers are medications used to prevent allergic reactions in the eyes by blocking the release of inflammatory substances such as histamines by mast cells. Histamines cause symptoms such as tearing, redness, swelling and itching in allergic eye inflammations.

Mast cells are a type of immune cell, part of the front-line immune system defense against antigens. Mast cells are present in mucous and epithelial tissue that line the surface of all organs. In the eyes, mast cells are abundant in the conjunctiva, the clear mucous membrane that forms a protective layer over the eyes and the inner surfaces of the eyelids.

Mast cells have granules that contain several types of chemicals such as histamines, proteases, leukotrienes and cytokines. On exposure to pathogens such as bacteria, or allergens in the case of allergies, mast cells release these inflammatory chemicals, in a process known as degranulation, and initiate the inflammatory process.

The released inflammatory chemicals directly attack the allergen particles, and in addition, promote further inflammation by:

• Dilating blood vessels in the area
• Activating other types of immune cells such as eosinophils
• Increasing the permeability of blood vessels which allows leakage of inflammatory chemicals, and enables movement of other immune cells to the inflammation site.

Mast cell stabilizers inhibit the mast cell degranulation process and prevent the initiation of inflammation in response to allergens. Mast cell stabilizers can inhibit mast cell response to subsequent exposure to allergens, but cannot generally relieve existing allergy symptoms.

Ophthalmic mast cell stabilizers are used prophylactically, starting ahead of and throughout the risk period for allergies. Ophthalmic mast cell stabilizers are solutions that are topically administered in the eyes to treat the following eye conditions:

• Conjunctivitis: Inflammation of the conjunctiva
• Allergic conjunctivitis: Conjunctivitis resulting from allergies
• Vernal conjunctivitis: Seasonal conjunctivitis caused by an increase in airborne allergens such as pollen, typically in spring and summer
• Vernal keratitis: Seasonal allergic inflammation of the cornea
• Vernal keratoconjunctivitis: Seasonal allergic inflammation of cornea and conjunctiva

Side effects of ophthalmic mast cell stabilizers may include the following:

Ocular side effects:

• Transient local stinging and burning
• Irritation and foreign body sensation
• Dryness around the eyes
• Puffy and watery eyes
• Stye
• Ocular itching (pruritus)
• Blurred vision
• Dry eye
• Redness of eye
• Tearing and discharge
• Dilation of eye blood vessels (hyperemia)
• Crystalline deposits
• Corneal erosion and ulcers
• Corneal abrasion
• Corneal inflammation (keratitis)
• Damage to cornea (keratopathy)
• Eyelid inflammation (blepharitis)
• Scales on eyelids and eyelashes
• Eye pain
• Eye edema
• Ocular warming sensation
• Ocular fatigue
• Swelling of the conjunctiva (chemosis)
• Inflammation of the conjunctiva (conjunctivitis)
• Allergic reaction
• Sticky sensation
• Inflammation of retinal pigment epithelium (epitheliopathy)
• Light sensitivity

Systemic side effects:

• Rash
• Shortness of breath (dyspnea)
• Headache
• Heat sensation
• Dizziness
• Drowsiness
• Sneezing
• Dry nose
• Nasal congestion
• Nausea and stomach discomfort
• Unpleasant taste
• Asthma
• Inflammation of the nasal passage (rhinitis)

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of some ophthalmic mast cell stabilizer drugs include:

• Cromolyn sodium ophthalmic
• Lodoxamide tromethamine ophthalmic (Alomide)
• Nedocromil sodium ophthalmic (Alocril)