When the white part of eyes appears red, it is called a red eye.  It is caused by  dilatation of local blood vessels  due to  inflammation usually from either infection or irritation. Red eye can be a manifestation of local eye pathology or a sign of systemic disease. Red eyes may be accompanied by itching, eyelid swelling, pain, discharge, eye irritation or visual disturbances. It can affect one or both eyes. It is a common condition that is usually not serious. However,  some causes may threaten vision if not treated promptly.

Common Causes

• Conjunctivitis: It is the inflammation of the conjunctiva (thin, transparent covering membrane of the sclera) caused by bacterial or viral infection, or allergen. Symptoms include eye discomfort, foreign body sensation, photophobia, sticky eyelids and purulent discharge.
• Dry eyes syndrome: dryness of the eyes caused by inadequate production of tears.
• Injury related: Subconjunctival hemorrhage ( e. g. after traumatic eye injury such as fractured skull), or  conjunctival or corneal foreign body.
• Episcleritis and scleritis: inflammation under conjunctiva or in the sclera.
• Keratitis and Corneal ulcer:  due to  bacteria, virus (Herpes), trauma (including contact lens), or chemical burns
• Glaucoma: increased intraocular pressure due to excess production or inadequate drainage of aqueous humor. Acute glaucoma is eye emergency and can lead to blindness if not treated immediately.
• Uveitis: Inflammation of the uveal tract (middle layer of eyeball) which includes iris, ciliary body and choroid.
• Infection/inflammation inside the eyes (endophthalmitis).
• Diseases of eyelids like inflammation (blepharitis), eyelids turning out (ectropion) or eyelids turning in ( entropion)
• Systemic disease: Rheumatoid arthritis, Systemic lupus erythematosus, Sjogren syndrome and other autoimmune conditions may cause red eyes.
• Environmental pollution: exposure to dust, vehicle exhaust, chlorine in swimming pool can lead to red eyes.
• Substance use: Excessive alcohol consumption, marijuana use also causes red eyes.

When to visit the Doctor?

Seek prompt medical care if red eye is accompanied by:

• Loss  of vision
• Eye pain
• Trauma related or foreign body in the eye
• History of eye surgery or known eye disease like glaucoma
• Use of contact lens
• Severe headache
• Difficulty opening eyes/ profuse purulent discharge
• Associated discharge from penis or vagina
• Presence of systemic autoimmune disease.
• Newborn

Treatment Options:

History and physical examination can recognize most cases of red eyes. Referral to Eye specialist is needed for more serious or undiagnosed cases. Slit lamp eye examination, gonioscopy, funduscopy, tonometry are some of the specialized eye exam techniques.

• Bacterial conjunctivitis is treated with topical antibiotic eye drop.  There is no specific treatment for viral conjunctivitis which resolves within 7-14 days.
• Allergen and environmental pollution should be avoided.
• Dry eyes can be treated with lubricant eye drops
• Corneal ulcer due to infectious cause is treated with appropriate antimicrobials.
• Glaucoma is  treated with eye drops to reduce pressure inside the eyes. Some require surgery
• Red eyes associated with systemic disease should be managed by Eye specialist in consultation with respective disease specialist.
• Red eyes associated  upper respiratory tract infection resolves once infection resolves.
• Red eyes in pregnancy resolve with hormonal stability after childbirth
• Wear swimming goggles while swimming.
• Red eyes associated with substance dependence is treated with substance detoxification.