A broken blood vessel in the eye is almost always a subconjunctival hemorrhage, a harmless burst of a tiny capillary in the clear tissue covering the white of your eye. It looks alarming (a bright red patch that seems to appear out of nowhere) but rarely causes pain or affects your vision. The blood leaks into the space between this clear membrane, called the conjunctiva, and the white of the eye, where it sits until your body gradually reabsorbs it.
How the Vessel Actually Breaks
The conjunctiva is packed with fragile, hair-thin blood vessels. When pressure inside those vessels spikes, even briefly, one can rupture. The most common trigger is anything that forces you to bear down or strain, which raises pressure in the veins of your head and face. Doctors call this a Valsalva maneuver: you’re pushing hard against a closed airway, and the pressure wave travels up through your venous system and into the small capillaries around your eyes.
That’s why seemingly ordinary actions are the usual culprits:
- Coughing or sneezing hard, especially during a cold or allergy flare
- Vomiting
- Straining during a bowel movement
- Heavy lifting or intense physical exertion
- Rubbing your eyes
- A bump or poke to the eye, even a minor one
Less obvious triggers include labor and delivery, playing wind instruments, and vigorous sexual activity. In many cases, people never identify the exact moment it happened. You wake up, look in the mirror, and there it is.
High Blood Pressure and Other Health Conditions
If broken blood vessels in your eye keep coming back, an underlying health condition may be weakening the vessels or raising your blood pressure. A study in the British Journal of Ophthalmology found that 46% of people who came in with a spontaneous subconjunctival hemorrhage had high blood pressure, compared to 23% in a control group. That’s a striking difference, and it suggests your eye can sometimes act as an early warning sign for cardiovascular problems you didn’t know about.
Diabetes is another major factor. Persistently elevated blood sugar damages the walls of small blood vessels throughout the body, including in the eye. Over time, damaged vessels can leak, close off, or prompt the growth of fragile new vessels that are even more prone to bleeding. This process, known as diabetic retinopathy, primarily affects the retina at the back of the eye, but the underlying vascular fragility extends to vessels across the eye’s surface as well.
Blood Thinners and Medications
Medications that reduce your blood’s ability to clot make it easier for a small vessel break to produce a visible hemorrhage, and harder for it to stop. Aspirin, ibuprofen, and prescription anticoagulants all increase the risk. Data analyzed by the American Academy of Ophthalmology covering reports from 1968 to 2015 found a strong link between both older and newer blood thinners and intraocular bleeding events. If you take a blood thinner and notice frequent red patches in your eye, it’s worth mentioning to your prescribing doctor, though you should never stop these medications on your own.
How It Differs From Serious Eye Bleeding
A subconjunctival hemorrhage sits on the surface of your eye. It’s painless and doesn’t interfere with your sight. A hyphema, by contrast, is bleeding inside the eye itself, specifically into the fluid-filled chamber behind your cornea. With a hyphema, you can sometimes see blood pooling in front of your iris (the colored part of your eye), and it typically causes pain and blurred vision. Both can result from trauma, and they can even happen simultaneously after an eye injury, but the two conditions are very different in severity. A hyphema needs prompt medical attention; a standard broken blood vessel on the surface does not.
The key warning signs that something more serious is going on: eye pain, changes in your vision, bleeding that covers a large area of the eye, or hemorrhages that keep recurring without an obvious trigger.
What Healing Looks Like
Most broken blood vessels heal completely within two weeks without any treatment. Larger patches of blood can take a bit longer. As your body reabsorbs the blood, the bright red spot will shift through colors much like a bruise, fading to orange, yellow, or yellowish-green before disappearing entirely. If your eye feels scratchy or irritated during this time, artificial tears can help with comfort, but no medication speeds up the process.
If you notice these hemorrhages happening repeatedly, an eye doctor may want to check your blood pressure, run bloodwork to look at clotting function, or investigate other underlying causes. A single episode, though, is almost never a sign of anything dangerous. It’s one of those conditions that looks far worse than it is.