Red eye is the presentation of inflammation, which is the natural reaction of the body tissues to infection, allergic reactions, physical trauma and burns. Characteristics symptoms of inflammation are redness, swelling & pain. Due to intimate relationship between the lid margin and the ocular surface; pathologies affecting the eyelids are common causes of red eye.

Blepharitis

Generalized inflammation of the eyelid margins, with symptomatic redness, itching and discharge. It tends to be very persistent and may cause the eyelashes to fall out or to turn inwards so they irritate the cornea. Although the symptoms are uncomfortable, the condition usually is not serious. Blepharitis is probably the single most common cause of all eye discomfort.

Ectropion & Entropion

Ectropion is eversion (turning out) of the eyelid. It can lead to poor tear drainage and excessive exposure of the cornea due to incomplete lid closure. Infection and damage to the cornea are more likely to occur.

Entropion is inversion (turning out) of the eyelids so that the eyelashes rub against the cornea. This can irritate the cornea and make it more susceptible to infection. Eyelid abnormalities that may encourage the development of other eye infections, such as conjunctivitis and Keratitis. They are not infectious conditions on their own.