Eye Redness, Red Eye

Red eyes are caused by enlarged, dilated blood vessels leading to the appearance of redness on the surface of the eye. Bloodshot eyes appear red because the vessels in the surface of the white portion of the eye (sclera) become enlarged and irritated. This may result from extremely dry air, sun exposure, dust, foreign body, an allergic reaction, infection, trauma, or other conditions:

• Allergic rhinitis is characterized by nasal congestion; frequent sneezing; itchy eyes, nose, and throat.
• Anaphylaxis is characterized by itching and hives; swelling of the eyes, lips and tongue; weakness or faintness; tightening in the chest or throat; wheezing; shortness of breath; profuse sweating; palpitations; sudden, intense distress; feelings of impending doom; stomach cramps; nausea, vomiting, or diarrhea; bluish tinge (cyanosis) to the skin, lips, and nail beds due to oxygen deficiency.
• Conjunctivitis is characterized by itching and redness in the affected eye; discharge from the eye, clear or pus-filled; excessive tearing; aversion to bright light; possibly, swollen eyelids.
Corneal ulcers and infections is characterized by severe eye pain; blurred vision; increased tear production; aversion to light.
• Crohn's disease is characterized by episodes by abdominal pain or cramps in lower abdomen; nausea; diarrhea; loss of weight and appetite; fatigue; anal fissures; joint pains; inflammation of the eyes.
• Glaucoma is characterized by no symptoms at the early stages; in later stages, the symptoms of closed-angle glaucoma include: appearance of halos and rainbows around lights; dilated pupil in the affected eye; severe headache and eye pain; possibly nausea and vomiting. Open-angle glaucoma symptoms include: blurred vision and a gradual loss of peripheral vision.
• Cluster headache is characterized by persistent pain in or around one eye; redness and tearing of one eye; nasal congestion on the sme side of the face as the affected eye.
• Hyphema is characterized by visible bleeding within the front portion of the eye in and around the iris; impaired vision.
• Sarcoidosis often goes with no symptoms; swollen lymph nodes in the neck or armpits; muscle aches; fever; shortness of breath; possibly, purple rash on the face; reddish or brownish skin spots on the forearms, face, or legs; numbness; joint pain or stiffness; a painful and red eye; blurred vision; loss of appetite and weight;
• Scleritis and episcleritis is characterized by dull eye pain; redness in the white of the eye; possibly, blurred vision; aversion to light; excessive tearing.
• Toxic shock syndrome is characterized by lethargy; conjunctivitis; confusion; sudden high fever accompanied by nausea, watery diarrhea, sore throat, and headache. Red rash on the palm and soles of the feet, which, after week or two, begins to peel.
• Uveitis and iritis is characterized by moderate or severe eye pain; aversion to light; redness in the eye; excessive tearing; blurred vision; spots in the field of vision.
• Whooping cough is characterized by initial mild cough, sneezing, nasal congestion, and irritated eyes. Within approximately 2 weeks, cough becomes severe and persistent, and is accompanied by characteristic high-pitched "whooping" sound during inhalation; loss of appetite; listlessness; vomiting or choking spells. Most common among young children.