That bright red patch on the white of your eye is almost certainly a subconjunctival hemorrhage, a tiny blood vessel that burst under the clear membrane covering your eye. It looks alarming, but it’s one of the most common and harmless eye issues. Most cases heal on their own within about two weeks without any treatment.
What a Subconjunctival Hemorrhage Looks Like
The hallmark is a well-defined, bright red patch on the white part of your eye. It’s flat, not raised, and the borders are sharp rather than blurry or diffuse. Your vision stays completely normal, your pupil reacts to light the way it should, and there’s little to no pain. You might not have noticed it at all if you hadn’t looked in the mirror.
Over the next several days the red patch often shifts color, turning from bright red to orange, yellow, or brownish as the blood gets reabsorbed, similar to a bruise fading on your skin. In some people the spot actually spreads slightly before it starts to clear, which can be unsettling but is still normal.
Why It Happened Overnight
A sudden spike in pressure inside the tiny blood vessels of your eye is the usual trigger. This pressure spike can come from something you barely remember doing. Sneezing, coughing, straining on the toilet, vomiting, heavy lifting, vigorous exercise, or even intense sexual activity can all force enough venous pressure into the eye’s capillaries to rupture one. These are all forms of what’s called a Valsalva maneuver: you bear down against a closed airway, blood backs up in the venous system, and a fragile capillary in the eye gives way.
Rubbing your eyes in your sleep is another common culprit. Some people do this aggressively without ever waking up. If you use a CPAP machine for sleep apnea, air leaking from a poorly fitting mask can dry out and irritate your eyes overnight, leading to redness or making you rub your eyes more. An improper fit, too-high pressure settings, or a mask that’s overdue for replacement all increase the chance of leaks.
Certain medications and health conditions raise your risk. Blood thinners (including daily aspirin) make blood vessels more prone to leaking. High blood pressure puts chronic stress on small vessels throughout the body, including the eye. Diabetes can affect blood vessel integrity as well. If you’re on blood thinners and notice these red spots repeatedly, that’s worth mentioning to your doctor.
How Long It Takes to Clear
Most subconjunctival hemorrhages resolve within two weeks. Larger spots can take closer to three. There’s no way to speed up the process. Your body reabsorbs the trapped blood at its own pace, just as it does with a bruise anywhere else.
If the spot bothers you with mild itchiness or a gritty sensation, over-the-counter artificial tears can help with comfort. Avoid “redness relief” eye drops (vasoconstrictors), which work by shrinking blood vessels on the surface of the eye. They won’t do anything useful for blood that’s already pooled under the membrane, and they can cause rebound redness with repeated use.
Conditions That Look Similar but Aren’t
A couple of other conditions can cause redness in one eye, and they’re worth knowing about so you can tell the difference.
Episcleritis is inflammation of a thin layer of tissue between the white of the eye and the outer membrane. It produces a confined red patch that can look a lot like a hemorrhage at first glance. The key difference: episcleritis usually involves mildly dilated blood vessels you can see individually, slight swelling over the red area, tenderness when you press gently on the spot, and mild watering. Vision stays normal. It’s not dangerous, but it may need anti-inflammatory drops to resolve.
Uveitis is inflammation inside the eye itself, and it’s a more serious concern. Symptoms tend to come on suddenly and worsen quickly. You’ll typically notice eye pain, sensitivity to light, blurred vision, dark floating spots, or a general decline in how well you can see. Uveitis can affect one or both eyes and, left untreated, can lead to permanent vision loss through complications like retinal swelling, glaucoma, cataracts, or optic nerve damage. This is not a wait-and-see situation.
Signs That Need Prompt Attention
A painless red patch with perfectly normal vision is almost never an emergency. But certain symptoms alongside eye redness signal something more serious. Seek care promptly if you experience any of the following:
- Loss of vision or gray/black areas in your visual field
- Severe eye pain
- Intense sensitivity to light
- Floating spots, webs, or flashes in your vision
- Inability to open or close the eye
- Nausea, vomiting, or severe headache accompanying the redness
These can indicate conditions ranging from uveitis to acute glaucoma to retinal detachment, all of which need same-day evaluation.
If you keep getting subconjunctival hemorrhages, especially without an obvious trigger like a hard sneeze or heavy workout, it’s worth having your blood pressure checked and reviewing any medications you take. Recurring episodes occasionally point to an underlying clotting issue or uncontrolled hypertension that’s putting your small blood vessels under more stress than they can handle.