Blepharitis is an inflammation that affects the margins of the eyelids causing them to become red, irritated and itchy. It is a common eye condition caused by either bacteria or a skin disorder, such as rosacea.

Blepharitis is usually not contagious and does not cause any permanent damage to eyesight; however, blepharitis is uncomfortable and tends to recur.

Blepharitis is classified into three types based on where symptoms develop; anterior blepharitis, posterior blepharitis and mixed blepharitis. Anterior blepharitis affects the outside rim of the eyelid where eyelashes attach. Posterior blepharitis affects the inner edge of the eyelid that is in contact with the eyeball, while mixed blepharitis, the most common type, occurs on both the inner and the outer margins of the eyelid.

Although the exact cause of blepharitis is not known in most cases, it has been associated with a reaction to bacteria that live naturally on the skin of the eyelid such as staphylococcus. Other possible causes are skin conditions that may lead to blepharitis, such as seborrhoeic dermatitis and rosacea.

The risk of getting blepharitis is increased in people who have oily skin, dandruff, or dry eyes. Blepharitis is more common in young children and those over 50 years of age, but it can affect people of all ages.

The pathophysiology of blepharitis is not very well understood. It often involves colonization of bacteria on the eyelids, which leads to direct microbial infection or an allergic response to microbial antigens.

Blepharitis usually causes a burning sensation in the eyes, tearing excessively, itching, red and swollen eyelids, dry eyes or scarring of the eyelid margins which leads to abnormal growth of eyelashes.

For most people, blepharitis causes only minor symptoms, but the condition can lead to more severe complications in very rare cases; complications include dry eye syndrome that usually leads to severe inflammation, chalazion, also known Meibomian cyst, and inflammation of other eye tissue, particularly the cornea and conjunctiva.

Doctors will first establish a diagnosis of blepharitis by taking a history of signs and symptoms and determine the type of blepharitis based on the appearance of the eyelid margins. Then, a careful examination of the eye will be conducted through a special magnifying instrument to evaluate lid structure, skin texture and eyelash appearance. Lid margins, Meibomian gland openings and the quantity and quality of tears will also be checked to look for abnormalities or evidence of other conditions.

Blepharitis is usually a chronic condition, which means once it develops it can come back later. However, a routine eyelid-hygiene habit can go a long way in controlling the symptoms and preventing future episodes. Eyelid-hygiene habits aim to remove excess oil, crusts, bacteria, dust and grime that may have accumulated by using a warm compress and massaging and cleaning the eyelids.

More severe cases of blepharitis may require the use of antibiotics and steroids to help fight the infection and control the inflammation. When blepharitis is caused by skin diseases, treating the other disease usually helps in getting rid of blepharitis.

Blepharitis is not always preventable and prevention steps are directed toward preventing complications, and avoiding recurrent infections. These steps include keeping the eyelids clean, removing eye and facial makeup before going to bed and controlling dandruff to reduce inflammation.

Blepharitis will not cause permanent damage to eyesight if the symptoms are treated promptly and appropriately with continued adherence to lid-hygiene habits; therefore, the prognosis of blepharitis is usually positive.

Although blepharitis is one of the most common problems affecting the eye, the true prevalence and incidence within defined populations is unknown.

Blepharitis is a common eye condition characterized by inflammation of the edges of the eyelids in which they become red, irritated and swollen. Blepharitis is usually chronic in that it can reappear in later episodes separated by periods without symptoms. Although blepharitis is usually caused by bacteria, it is not contagious.

Blepharitis is classified mainly into three types based on the location of the inflammation:

• Anterior blepharitis occurs at the external eyelid where the eyelashes attach.
• Posterior blepharitis affects the inner rims of the eyelid in contact with the eyeball.
• Mixed blepharitis affects both the internal and external edges. It is the most common type.

The exact cause of blepharitis is unknown in most cases, but it has been linked to a reaction to the bacteria that live naturally on eyelid skin, and to related skin conditions.

Possible causes of anterior blepharitis include:

• Staphylococcal infection: Staphylococcal bacteria are harmless bacteria that often colonize the base of the eyelash. These bacteria sometimes overgrow for unknown reasons and lead to inflammation of the eyelids.
• Seborrhoeic dermatitis or dandruff: A skin condition where the eyelid is colonized by yeast such as malassezia causing the skin to become oily or flaky and the Meibomian glands to block, leading to inflammation.
• Ocular rosacea: Rosacea is a long-term, inflammatory skin condition that mainly causes flushing, facial redness and spots.
• Eyelash mites or lice: Parasites, such as lice and Demodex mite, that infect eyelashes can lead to blepharitis.
• Contact allergy: Blepharitis may result from allergies to substances that come into direct contact with the eyelid. Substances include eye medications, contact lens solutions or eye makeup.

Posterior blepharitis results from a malfunction of the Meibomian glands that produce oil in the inner eyelid; the secretions from this gland thicken and block the gland causing inflammation. Additionally, two skin disorders can cause this form of blepharitis, rosacea, and seborrheic dermatitis.

Mixed blepharitis results from both anterior and posterior blepharitis.

Blepharitis most commonly occurs in people who have oily skin, dandruff, or dry eyes. It affects people of all ages, but is more common in early childhood and adults over 50 years of age.

The pathophysiology of blepharitis has not been fully understood. The disease often involves a colonization of bacteria of the eyelids that causes an infection of the lids or an allergic reaction to their antigens. Seborrheic dermatitis, Meibomian gland dysfunction and contact with waste products can increase colonization of bacteria on the lid margin.

The signs and symptoms of blepharitis vary according to the severity of the inflammation, but are usually uncomfortable. Symptoms include:

• Red and swollen eyelid margins
• Itchy eyelids
• Watery or dry eyes
• Burning sensation and feeling the presence of a foreign body in the eye, especially when waking from sleep
• Sensitivity to light
• Abnormal growth of eyelashes as a result of scarring of eyelid margins
• Crusty and flaky eyelids, which may cause matting of the eyelashes
• Scales clinging to the lashes
• Foamy tear formation
• Discomfort when wearing contact lenses

Both eyes are usually affected, but symptoms tend to be more pronounced in one eye. The symptoms tend to be worse in the morning.

Tests and procedures used to diagnose blepharitis include:

• Patient history: This helps the doctor determine the symptoms and any general health conditions that may be contributing to eye problem.
• External examination: Blepharitis can be diagnosed by an examination of the eye that investigates lid structure, skin texture and eyelash appearance by using a special magnifying instrument.
• Lid margin evaluation: The doctor will evaluate lid margins, the base of eyelashes and Meibomian gland openings using bright light and magnification; this helps determine the type of blepharitis.
• Tear evaluation: Evaluating the quantity and quality of tears can help the doctor detect any abnormalities that may point to blepharitis.

• Skin swab: Doctors may use a swab to collect a sample of the oil or crust accumulated on the eyelid. This swab is then analyzed for bacteria, fungi or evidence of an allergy.

Self-care measures may be the only treatment necessary for most cases of blepharitis. Three main eyelid-hygiene measure can be performed to keep eyelids clean:

• Applying a warm compress to dislodge crusts and make the oil produced by Meibomian glands runnier.
• Massaging the eyelids gently to clear oil buildup in the glands.
• Cleaning the eyelids to remove any excess oil and any crusts, bacteria, dust or grime that might have accumulated.

Additional treatment for severe cases of blepharitis may involve using antibiotics and steroids to fight the infection and control the inflammation, respectively.  These medications can be applied directly to the eye in form of eye drops, creams and ointments, or taken orally as tablets.

Other medications that affect the immune system, such as topical cyclosporine inhibitors, have been shown to offer relief for some symptoms of blepharitis.

Blepharitis caused by other skin conditions is controlled by treating the underlying cause. Seborrheic dermatitis is usually treated with antifungal agents and rosacea with oral tetracycline.

Blepharitis can lead to many different problems, although serious complications are rare. Complications of blepharitis include:

• Sty: Sties are bacterial infections that cause pus to build up at the base of the eyelashes. They are usually observed as a painful swelling on the surface of the eyelid.
• Dry eye syndrome: This occurs when tears are not in adequate supply, either due to evaporating quickly or to eyes not producing enough. This condition usually leads to inflammation, and it is a common complication of blepharitis.
• Conjunctivitis: A bacterial infection that causes inflammation of the conjunctiva may arise from blepharitis. The conjunctiva is the transparent membrane that covers the white part of the eye and the inner surfaces of the eyelids. Conjunctivitis is usually mild and does not affect the vision.
• Chalazion: Also known as a Meibomian cyst, this can develop when Meibomian glands become inflamed as a result of blepharitis. A chalazion tends to be prominent on the inside of the eyelid, not the outside like sties.

• Keratitis: Keratitis refers to damage to the cornea by a sore or ulcer that causes constant irritation due to inflamed eyelids or misdirected eyelashes. Insufficient tearing could increase the risk to develop the corneal infection.

Blepharitis is not always preventable, and prevention steps are more directed toward avoiding complications, and preventing recurrent episodes. These steps include keeping eyelids clean, removing eye and facial makeup before going to bed and controlling dandruff.

Blepharitis is usually a chronic disease that cannot be fully cured, however; the prognosis is usually good and the disease will not cause permanent damage to eyesight with appropriate treatment and continued adherence to lid-hygiene procedures.

Although blepharitis is one of the most common ocular disorders, there is no enough epidemiological information on its incidence and prevalence in the world.

Results of a US survey published in The Ocular Surface said that ophthalmologists report that 37% of their patients had blepharitis, while blepharitis was seen 47% of patients visiting optometrists.