One of the most commonly seen problems in an eye doctor’s office is the red eye. Conjunctivitis, a generic term which describes inflammation of the conjunctiva, the clear membrane which covers the eye, is only one of many causes of red eyes. Many other diseases, from benign to vision-threatening, must be considered and will be described in the following discussion.
Like the tissues which line the inside of the nose and mouth, the conjunctivae are mucous membranes. Conjunctiva covers nearly the entire exposed surface of the eye, as well as the inside of the eyelids. This tissue serves a number of functions, including protection of the eye from injury and infection, as well as production of tear components to keep the eyes moist. Inflammation of the conjunctivae, or conjunctivitis, is a very common problem with many possible causes, including infection, allergy, trauma, and immune reactions. Symptoms vary depending upon the type of conjunctivitis present.
Viral conjunctivitis is the most common form. Often called “pink eye,” this disease is caused by a number of different viruses, often the same pathogens which are responsible for respiratory infections such as the common cold. These viruses are often very contagious, and viral conjunctivitis frequently passes between members of shared environments, such as among children in daycare or between members of a family. Infection can be transmitted through the air by a sneeze, or by contact with contaminated objects such as towels, doorknobs, phones, etc. Ocular changes may be preceded by cold-like symptoms. The eyes often become red, watery, and swolen, with a gritty or foreign body senstation. Crusting of the lashes with clear or yellow discharge is often noted, and the eyelids are commonly stuck shut in the morning. Discharge is usually thin and watery, though may become thicker with mucous. Vision may be blurred slightly. The disease usually peaks after a few days to a week and resolves within 7 to 10 days, much like a cold. No specific therapy is available for viral conjunctivitis, and treatment is supportive. Cool compresses and artificial tear drops provide comfort and cleansing for the eyes. Antibiotics, though often prescribed by physicians, will not treat viral illness and are usually unnecessary. Most important is to remember that the disease may be contagious; thorough and frequent washing of hands will help prevent transmission to others. Rarely, a keratitis, or inflammation of the cornea, will develop, usually with more significant pain and blurred vision. This may require treatment with other medications. An examination by an eye doctor can determine if this is necessary.

Bacterial conjunctivitis is much less common than the viral form. Presentation of symptoms may be similar to viral disease, however pus is typically present. Pus is often white, yellow, or green, and less stringy than mucous. It may reaccumulate quickly if washed or wiped away. The eyes are often very red and inflamed, and may be quite uncomfortable. Unlike viral conjunctivitis, this form is responsive to antibiotics, usually prescribed in the form of eye drops. Recovery is usual within one to two weeks.

Not all conjunctivitis is infectious. Seasonal allergies are commonly associated with ocular symptoms.The primary symptom of allergic conjunctivitis is itching, often severe. The eyes typically appear pink and boggy, tear significantly, and may have a discharge of mucous. Other symptoms of allergy, including runny nose and irritated throat, are often present. Oral antihistamines and other systemic allergy medications are often helpful, however greater relief is often achieved with eye drops specially formulated for ocular allergy. Prescription medications are usually superior to over-the-counter products.

Toxic or chemcal conjunctivitis is due to exposure to certain chemicals or irritants. Any chemcial exposure to the eye should be considered an emergency, requiring immediate and throrough irrigation of the offending substance. Assuming no significant chemical burn is present, care is generally supportive. Occasionally, specific medications are necessary.

Conjunctivitis is often associated with blepharitis and dry eye syndrome. These conditions are covered in separate sections of the library, and will not be detailed further here.

Red eyes, as discussed earlier, do not always signify conjunctivitis. Numerous other ocular diseases and conditions cause the eyes to take on this hue. Inflammation of a deeper layer of tissue, the episclera, will often cause a focal area of redness, at times associated with mild discomfort. This episceritis is generally an isolated condition. The condition resolves spontaneously within a few days to a week with treatment usually unnecessary, although mild steroids can speed recovery.

Inflammation of the sclera, the thick white wall of the eye, can also cause localized or diffuse redness and swelling. Scleritis is often very uncomfortable, described as a deep, piercing pain which may wake an individual from sleep. The eye may be very tender to touch. About half of the time scleritis is associated with autoimmune diseases such as rheumatoid arthritis or lupus. This disease can be serious, potentially leading to loss of vision. Treatment involves steroid eye drops, systemic non-steroidal or steroid medications, and rarely other immunosuppressive drugs.

Redness concentrated in a ring around the cornea is often seen with iritis or uveitis. This inflammation of uveal tissue, which includes the iris, the ciliary body, and the choroid, is not uncommon and has many possible causes. Other frequently occuring symptoms include blurred vision, pain, and sensitivity to light. One or both eyes may be affected, and recurrences are common. Treatment is with steroid eye drops, and occasionally systemic medications if severe.

Keratitis, or inflammation of the cornea, will also lead to redness along the corneal margin. There are many causes of keratitis, both infectious and non-infectious, and diagnosis requires careful examination and, at times, special tests. Treatment depends upon the underlying cause.

Acute angle closure glaucoma will cause a red eye with blurred vision, halos around lights, and pain. This condition is discussed in the section on glaucoma.scheme

A very common cause of red eye is subconjunctival hemorrhage. In this condition, a small blood vessel breaks, leading to bleeding within or under the conjunctiva. A bright red, bloody appearing spot, sometimes quite large, is noted on the surface of the eye. A mild ache or irritation may be present. These hemorrhages may occur after coughing, sneezing, vomiting, or straining at stool.
They may be more common in individuals on blood thinning medications. Often, no specific cause can be found. This condition can appear quite frightening, however is nearly always benign, the equavalent of a bruise on the skin. The eye will not be injured and vision will not be affected. The blood will clear over a few days to a few weeks, depending upon the extent of bleeding.

Clearly, there are numerous causes of red eyes, some totally benign and some more serious. A thorough eye examination will allow your doctor make the diagnosis and prescribe appropriate therapy. Contact us to schedule an appointment today.