Ocular Symptoms and Conditions: The Red Eye
There are numerous conditions which can cause eye redness, and nearly any condition causing symptoms of discomfort will also lead to eye redness. Redness usually specifically refers to the "white of the eye." Redness here can be due to engorged blood vessels on the surface of the eye, or due to hemorrhage on the surface. The location and pattern of redness may be important to making a diagnosis, as may be any associated symptoms and findings.
This page discusses a few causes of eye redness which are not discussed elsewhere. There are also links to other Symptom and Diagnosis pages based on other symptoms in addition to the redness.
Conditions Discussed on this Page:
- Conjunctivitis (Pink eye)
- Subconjunctival hemorrhage
- Medication (eye drop) toxicity
- Other conditions causing eye redness found on other pages
Conjunctivitis, or "pink eye", is an infection of the membrane that covers the sclera, or the "white of the eye". This lining is the conjunctiva, and it also lines the inside of the eyelids. The infection is typically either caused by a virus or by bacteria.
Viral conjunctivitis is common in adults, and is extremely contagious (even with indirect contact). Sometimes it may occur with the common cold. The eyes become injected and itch. There may be a watery or mucoid discharge, and the lids may swell. Both eyes are usually affected. Treatment is to reduce symptoms, since antibiotics are ineffective and antiviral medication is not available for this condition. It usually runs its course in about 2 weeks. Care must be taken to wash the hands after touching the eyes and disposing of tissues used to wipe the eyes to help prevent spread to other people.
Bacterial conjunctivitis is more common in children. While also contagious, it requires more direct contact for spread than a viral infection. Eye redness, lid swelling, and a heavy pus-like discharge are common. Treatment with antibiotic eye drops, ointments, and sometimes even pills by mouth are necessary for treatment. Cultures may be taken to determine the bacteria involved and to select appropriate antibiotics.
A subconjunctival hemorrhage usually appears as a sudden, spontaneous, bright red patch on the surface of the eye. This occurs when a small blood vessel breaks in the lining over the eye (the conjunctiva). It is usually otherwise painless, and the vision is not affected. The redness can be quite dramatic. This can occur spontaneously, or after direct trauma, sneezing or coughing, or straining. It often happens overnight while sleeping. High blood pressure is another possible cause. The redness usually disappears over a one week period. While blood thinners do no typically cause this condition, it may make it appear worse. There are rare cases of clotting disorders that can also lead to this condition. In some cases the hemorrhage can stretch the conjunctiva which can cause pain. In these cases, the conjunctiva might be swollen or raised, and could lead to patches of dryness on the cornea due to a disturbance in the tear flow that lubricates the eye.
Episcleritis is an inflammation of the episclera, which is a fibrous layer between the white wall of the eye (the sclera) and the lining of the eye (the conjunctiva). With this condition, there is a patch of injected blood vessels on the surface of the eye (only a part of the eye is red). It may be associated with mild irritation, or sometimes iritis. The condition may resolve without treatment, but it also can recur, and may affect both eyes. It sometimes is associated with gout.
Medication (eye drop) toxicity
Many prescription and non-prescription eye drops can create ocular irritation or allergy, especially if used for a long period of time. Over-the-counter eye drops such as artificial tears, allergy eye drops, and contact lens solutions all contain preservatives unless the bottle specifically states "preservative free". These preservatives can commonly cause eye irritation and redness, if the user is sensitive to that preservative.
Prescription antibiotic eye drops can be effective at treating infection, but they can also be quite irritating to the eye and may cause prolonged irritation and redness. This may lead to confusion as to whether or not the infection has really been treated. Steroid eye drops usually are not particularly irritating. A few prescription allergy eye drops are known to cause some eye redness and burning on installation.
Vasoconstricting or decongestant eye drops ("get the red out" drops) simply blanch out blood vessels on the eye surface, concealing redness. If these eye drops are used frequently to mask redness, there may be a rebound redness when the drops are discontinued. This may lead to more usage of the eye drop to conceal the worsening redness.
A pterygium is a non-cancerous growth of the conjunctiva onto the cornea. It may start as a "pingueculum", which is a small lump of tissue located on either side of the cornea on the sclera. A pterygium has a "head", which may progressively cover the cornea, and a "body" which extends toward the corner of the eye (usually the inside corner). Often the "body" of a pterygium may appear red, with noticeable blood vessels.
A pterygium which progressively moves toward the pupil may need to be surgically removed in order to prevent the vision from being affected. Redness and irritation from a pterygium can be managed with artificial tears, and with other prescription eye drops.
Pterygia seem to occur more frequently in people who spent much time outside, and is especially common in the southern latitudes. If they need to be removed, there is a possibility of recurrence.
Other Conditions causing ocular redness found on other pages:
A link to each condition is listed along with other hallmark features of the condition.
- Allergic problems - usually with itching and irritation.
- Blepharitis - itching, burning, eyelid irritation.
- Cellulitis (infection) of eyelid skin - eyelid swelling, tenderness.
- Contact lens related problems - may have pain, scratchy sensation.
- Corneal abrasion - pain, tearing, sensation that something is in eye.
- Dry eye - irritation, scratchy sensation, sometimes tearing.
- Ectropion (out-turning) of eyelid - scratchy sensation, pain, tearing.
- Entropion (in-turning) of eyelid - scratchy sensation, pain, tearing and discharge.
- Eyestrain - associated with prolonged visual work, especially reading or computer use
- Glaucoma (acute) - pain, blurred vision.
- Iritis - pain, sensitivity to light, blurred vision.
- Phlyctenulosis - sensation that something is in eye, burning, itching.
- Scleritis - pain, blurred vision.
- Thyroid related eye disease - scratchy sensation, double or blurred vision, protruding eyes.
- Trichiasis (in-turning of eyelashes) - scratchy sensation, pain, tearing.
- Ocular cicatricial pemphigoid - an autoimmune disorder that leads to conjunctival scarring with in-turning of the eyelids and lashes.
- Endophthalmitis - intraocular infection usually after eye surgery with severe ocular redness, loss of vision and severe rapidly increasing pain.