Blood Clot in the Eye: Is It Serious? Causes, Symptoms & Treatment

"Blood clot in the eye" is an everyday phrase that usually means a subconjunctival hemorrhage — a harmless broken blood vessel just under the clear surface of the eye that causes a bright red patch. Less commonly, the same phrase is used for a genuine internal blockage called retinal vein occlusion, which is more serious. Save Sight Centre can quickly tell the two apart with an eye exam.

It depends entirely on where the bleeding or blockage is. A surface subconjunctival hemorrhage is not dangerous — it doesn't affect vision and clears on its own. A blockage inside the eye, such as retinal vein occlusion, is dangerous and needs prompt treatment, since it can threaten your vision if left unaddressed.

A mild, harmless case shows up as a flat red patch on the white of the eye with no pain and no change in vision. A serious case usually involves blurred or distorted vision, dark spots, new floaters, or sudden vision loss — often without any visible redness at all. If you notice any vision changes alongside redness, get it checked promptly rather than assuming it's mild.

Surface bleeding is commonly triggered by coughing, sneezing, straining, minor trauma, or vigorous eye rubbing, and is more likely with high blood pressure, diabetes, or blood-thinning medication. A serious internal blockage (retinal vein occlusion) is linked to the same risk factors — high blood pressure, diabetes, high cholesterol, and clotting disorders — but involves an actual clot blocking blood flow inside the eye rather than a broken surface vessel.

A surface subconjunctival hemorrhage will not cause blindness — it's cosmetic and resolves on its own. However, an untreated retinal vein occlusion can lead to lasting vision loss, since it affects the light-sensing tissue at the back of the eye. This difference is exactly why distinguishing the two matters.

Your doctor will examine the surface of the eye and, if there's any concern about vision or pain, perform a dilated retinal exam to check the blood vessels at the back of the eye. Additional tests like OCT imaging or fluorescein angiography, along with a blood pressure check, may be used if a serious internal cause is suspected.

A surface subconjunctival hemorrhage usually needs no treatment beyond lubricating drops for comfort, and clears in one to two weeks on its own. A retinal vein occlusion is treated differently — with anti-VEGF injections, steroid implants, or laser therapy, depending on severity — and needs specialist care promptly rather than being left to resolve on its own.

No. Lubricating eye drops only soothe irritation while a surface hemorrhage heals naturally — they don't speed up healing or dissolve anything. For an internal clot like retinal vein occlusion, no eye drop can treat it; it requires proper medical intervention such as injections or laser therapy.

A sudden red patch usually happens because a small surface blood vessel breaks from a brief spike in pressure — a hard cough, sneeze, or strain — so it can appear overnight with no warning and often no clear trigger. High blood pressure can make this more likely, but sometimes it happens with no identifiable cause at all.

Recurring surface hemorrhages are often linked to high blood pressure, diabetes, blood-thinning medications, or an underlying clotting disorder, and should be evaluated by a doctor rather than dismissed as coincidence. Identifying and managing the underlying cause is the best way to reduce how often it happens.

Retinal vein occlusion (RVO) is a blockage of one of the veins that carries blood away from the retina, causing fluid buildup, swelling, and sometimes sudden or gradual vision loss. It's strongly linked to high blood pressure, diabetes, and clotting disorders, and needs prompt specialist evaluation and treatment to protect vision.

Yes. High blood pressure can cause both mild surface bleeding (subconjunctival hemorrhage) and, more seriously, contribute to internal blockages like retinal vein occlusion — which is one more reason to keep blood pressure well controlled.

See a doctor urgently if the redness comes with sudden vision loss or blurring, eye pain, new floaters or dark spots, or if the redness itself doesn't improve within two weeks or keeps recurring. These signs suggest something more than a simple surface hemorrhage and deserve prompt evaluation.