Associated symptoms are itching and watery discharge with allergies and foreign body
sensation/irritation/scratchiness with dry eyes. Other conditions leading to eye redness are ultraviolet sun damage to the conjunctiva in people from tropical climates. These lesions are called pterygia and pingueculae and, though bothersome and sometimes unsightly, are not malignant or dangerous. They may, however, cause visual changes
if they overgrow the cornea. Additional, more serious causes of eye redness include infections such as viral conjunctivitis but these are self limited and associated with ropy, yellow discharge; uveitis
of the uvea, the inner eye coat: iris, ciliary body and choroid) which can cause eye redness with pain, vision loss and photohobia (aversion to light) and may be chronic and should be evaluated; and episcleritis/scleritis (inflammation of the white part of the eye: the sclera and its outer coat) to which young women are particularly prone and which may be related to autoimmune conditions such as lupus and rheumatoid arthritis
. Orbital inflammatory syndrome and glaucoma
are additional causes which should be evaluated. More serious and dangerous conditions include those conditions that may cause reduced venous blood return from the eyes such as cavernous sinus thrombosis
and carotid cavernous fistula
, but these are pretty rare and associated with limited eye movement, double vision, pain and proptosis (eyes jutting out of sockets). In short, if you have chronic eye redness, you probably don’t have much to worry about, but you should have it checked out sooner rather than later.