High blood pressure can cause red eyes. As the blood pressure goes high, the blood vessels will suffer great pressure from it. Though most of the blood vessels have thick walls and can bear this elevated pressure, the blood vessels in the eyes are thin and they will expand and eventually break under such circumstances, giving rise to hemorrhage in the eyes. And the liquid in the eyes makes the hemorrhage visible, hence the eyes appear red. Apart from high blood pressure, red eyes can be a sign of pink eyes, blepharitis, dry eyes, uveitis, frequent use of eye drops, contact lens wear, eye injury, corneal ulcer or infection, subconjunctival hemorrhage and acute glaucoma. Also, those who suffer osteoporosis, rheumatoid arthritis, erection problems can find themselves red eyes.
