There are many reasons why you may have a red spot or blood spot in your eye. Subconjunctival hemorrhages vary from a small dot to looking like your whole eye is bleeding under the lens. This is caused by a burst blood vessel and is very similar to a bruise. However, the reason why so many people are scared by a bruise in your eye is that it is significantly more visible because it is under the clear and transparent conjunctiva in front part of your sclera. Potential causes include: An eye injury that causes your blood vessels to burst Rubbing your eyes causing a rupture of a blood vessel which leads to a blood spot in your eye Straining from constipation or lifting something heavy can cause burst capillaries A strong sneeze or cough Blood disorders such as sickle cell anemia Frequent usage of blood thinners such as aspirin and interferon While a blood spot in the eye usually means that there is internal bleeding in your eye, also known as subconjunctival hemorrhage, it is generally not something that you should worry about. Though the eye may look frightening, there should be no change in vision, discharge, or pain.