Eye redness is most often due to swollen or dilated blood vessels. This makes the surface of the eye look red or bloodshot. "Pink eye" is a term commonly used to describe red eye and refers to both viral and bacterial infections of the conjunctiva (conjunctivitis).
Pink eye caused by a virus may involve clear discharge or some amount of pus and mucous discharge.
Pink eye caused by bacteria is more common in children than adults and may involve a more continuous and thicker discharge of pus and mucus.
Other reasons for red eye include: eye dryness, too much sun exposure, dust or other particles in the eye, allergies, infection, injury.
Sometimes, a bright red spot, called a subconjunctival hemorrhage, will appear on the white of the eye. This often happens after straining or coughing, which causes a broken blood vessel on the surface of the eye. Most often, there is no pain and your vision is normal. It is almost never a serious problem. Because the blood leaks into the conjunctiva, which is clear, you cannot wipe or rinse the blood away. Like a bruise, the red spot will go away within a week or two.
Try to rest your eyes if redness is due to fatigue or eye strain. No other treatment is needed.
If you have eye pain or a vision problem, call your eye doctor right away. Your optometrist will perform an eye exam, and ask questions about your medical history. In most cases, red, bloodshot eyes will clear up on their own. If you are experiencing bloodshot eyes due to allergies or environmental irritants, you can try using oral antihistamines or over-the-counter eye drops before seeking further medical attention. This solution often clears up red eyes quickly. Your doctor will be able to prescribe medicated eye drops, oral antihistamines, and pain relievers if necessary.