A burst blood vessel in the eye, known medically as a subconjunctival hemorrhage, happens when a tiny vessel in the clear membrane covering the white of your eye breaks and leaks blood into the space beneath it. It looks alarming, sometimes turning a large patch of the white of your eye bright red, but it’s almost always harmless and painless. Most cases heal on their own within about two weeks.
Why These Blood Vessels Are So Fragile
The conjunctiva is a thin, transparent tissue that sits over the sclera (the white part of your eye). It contains many extremely small, delicate blood vessels. Because these vessels are so fine and sit close to the surface, even a modest spike in pressure or minor friction can cause one to rupture. When it does, the blood has nowhere to drain quickly. It pools between the conjunctiva and the sclera, spreading out into the vivid red patch you see in the mirror.
Everyday Physical Triggers
The most common cause is a sudden increase in pressure inside your veins. Any action where you bear down, hold your breath, or strain against a closed airway pushes venous pressure higher throughout your body, including in the tiny vessels of your eye. This pressure spike is often enough to pop one.
Specific triggers include:
- Coughing or sneezing, especially a hard or prolonged fit
- Vomiting
- Straining during a bowel movement
- Heavy lifting or intense physical exertion
- Rubbing your eye
- A bump or poke to the eye, even a minor one
- Labor and childbirth
- Playing wind or brass instruments
Sometimes you wake up with a red eye and have no idea what caused it. That’s normal. Many people never identify a specific trigger, and the hemorrhage is still nothing to worry about.
Health Conditions That Raise Your Risk
High blood pressure is one of the strongest risk factors. A large population study in Taiwan found that people with hypertension were about 36% more likely to experience a spontaneous burst vessel in the eye compared to those with normal blood pressure. The constant elevated pressure in the vascular system makes those fragile conjunctival vessels more prone to breaking.
Bleeding disorders also matter. Conditions that reduce your platelet count or impair clotting, such as purpura and thrombocytopenia, carried a similarly elevated risk in the same study, roughly 34% higher odds. Interestingly, diabetes appeared to increase risk at first glance, but once researchers accounted for age and other conditions, the link disappeared. So if you have diabetes and get a burst vessel, it’s more likely related to blood pressure or another factor than to blood sugar itself.
Medications That May Play a Role
Blood thinners and antiplatelet medications like aspirin and warfarin can make bleeding easier to trigger and slower to resolve. If you’re taking one of these medications and notice a burst vessel, the blood patch may appear larger or take a bit longer to clear. That said, the hemorrhage is still superficial and resolves on its own. If you’re on a blood thinner, don’t stop taking it because of a red eye. The risks of stopping anticoagulant therapy far outweigh the cosmetic nuisance of a subconjunctival hemorrhage.
How It Heals
Your body reabsorbs the trapped blood gradually. Most burst vessels clear up completely within two weeks, though larger ones can take a bit longer. The color shifts as it heals, much like a bruise on your skin. The bright red fades and may turn yellowish before disappearing entirely. You don’t need drops, patches, or any treatment. Artificial tears can help if the eye feels slightly scratchy, but the hemorrhage itself doesn’t need intervention.
When a Red Eye Needs Attention
A straightforward burst vessel doesn’t hurt and doesn’t affect your vision. Those two features are the most important things to pay attention to. If you have pain in the eye, blurry or distorted vision, or the red spot appeared after significant trauma to the face or eye, you could be dealing with something more serious.
One condition worth distinguishing is a hyphema, where blood collects inside the front chamber of the eye rather than on the surface. A hyphema causes pain, can blur your vision, and sometimes triggers nausea from increased pressure inside the eye. It typically results from a direct blow and requires prompt medical evaluation. A subconjunctival hemorrhage, by contrast, sits on the outside of the eye, causes no pain, and doesn’t change your sight at all.
If your eye suffered blunt or penetrating trauma and the hemorrhage is large, the red patch can sometimes mask a more serious injury to the eyeball itself. In that scenario, getting checked is important even if you feel fine. Recurrent burst vessels, meaning they keep happening without an obvious trigger, are also worth mentioning to a doctor, since they can occasionally point to undiagnosed high blood pressure or a clotting problem.