Usually, if you see blood in your eye it's because a tiny blood vessel on the eye has broken open, causing a portion or all of the white of your eye (sclera) to appear bright red.
This painless blood in the eye is called a subconjunctival hemorrhage; and though they look scary, subconjunctival hemorrhages are common and harmless and can be caused by something as simple as a sneeze or cough.
But there's a second type of bleeding in the front of the eye that's much more serious — it's called a hyphema, and it requires immediate attention by your eye doctor.
What Is A Hyphema?
A hyphema is bleeding or a broken blood vessel inside the eye that causes blood to collect in the anterior chamber of the eye — the space between the cornea and the iris that's normally filled with a clear liquid called the aqueous humor.
The severity of a hyphema is graded by how much blood accumulates in the eye:
Grade 0 (microhyphema): No visible pooling of blood, but red blood cells can be seen within the anterior chamber upon microscopic examination.
Grade 1: Pooling of blood in less than the lower third of the anterior chamber.
Grade 2: Blood filling one third to one half of the anterior chamber.
Grade 3: Blood filling one half to less than all of the anterior chamber.
Grade 4: Total filling of the anterior chamber with blood. If the blood is bright red, this is called a total hyphema. If it is dark red-black blood, it's sometimes called an "8-ball hyphema."
In general, the higher the grade of hyphema, the greater risk of vision loss and long-term damage to the eye. The dark red or black color of an 8-ball hyphema (the most dangerous type) is associated with decreased circulation of aqueous humor and decreased oxygen in the anterior chamber of the eye.
What Are Other Symptoms Of Hyphema?
In addition to the blood in the eye, the following symptoms usually are associated with hyphema:
Eye pain, sensitivity to light and headache are especially likely to occur if a hyphema is causing increased intraocular pressure (IOP).
