Bloody eye is a form of eye redness. There are many causes of eye redness; some could be symptoms of a serious problem, others are of no consequence. Often, when people have large amounts of blood in their eye, it might be thought that they have a serious problem, but the degree of blood in the eye is not indicative of this.
Subconjunctival Hemorrhage
Coughing or straining is one of the most common causes of eye redness. When that strain leads to a bright splotch of blood on the sclera, this is called a subconjunctival hemorrhage. Subconjunctival hemorrhage can appear a little scary. But if it doesn't hurt, it's nothing to worry about and will go away in a couple of weeks.
Infections and Inflammations
When your eye becomes infected, it can lead to redness and other symptoms like discharge, itching and, occasionally, vision problems. There are a variety of infections that could be responsible, including blepharitis (an inflammation of the eyelash follicles), conjunctivitis (an infection of the membrane that coats the eye), corneal ulcers (a complication of bacterial or viral infection) and uveitis (an inflammation of the uvea, the middle layer of the eye).
Colds and Allergies
If you've ever had hay fever, you undoubtedly understand how your eyes could get red from all the itching. Colds can also lead to blood in the eye, especially coughing.
Acute Glaucoma
Acute Glaucoma is where the pressure in the eye leads to bleeding. This is a very serious condition since most glaucoma is gradual and requires immediate medical attention.
Obstruction
Getting something in your eye, whether it's removed or stays in, can irritate the cornea and cause itching and redness.
