Eye redness

[Little_Girl]

Eye redness refers to a red appearance of the normally white part of the eye. The eye looks red or bloodshot because blood vessels on the surface of the eye widen (dilate), bringing extra blood into the eye. Pinkeye typically refers to eye redness caused by a specific viral infection.
Blood vessels can dilate as a result of

Infection
Allergy
Inflammation caused by something other than an infection
Elevated pressure inside the eye, typically caused by sudden, closed-angle glaucoma, in which fluid pressure increases in the front chamber of the eye

Several parts of the eye may be affected, most commonly the conjunctiva (the thin membrane that lines the eyelid and covers the front of the eye), but also the iris (the colored part of the eye), the sclera (the tough white fiber layer covering the eye), and the episclera (the connective tissue layer between the sclera and the conjunctiva).
Rarely is eye redness the only eye symptom. People may have tearing, itching, the feeling that a foreign object is in the eye (foreign body sensation), sensitivity to light, pain, or even changes in vision. Sometimes people have symptoms that affect other areas of the body, such as a runny nose or cough, or nausea and vomiting.