Eye Injury · Patient & Clinician Series
A red line behind
the cornea is blood
inside the eye.
A hyphema is bleeding into the front chamber of the eye, usually after a blow from a ball, a fist or a projectile, sometimes with no injury at all. Small ones often clear in days. The risks are a second bleed, a pressure spike and the hidden damage the injury may have caused. Here is how it is graded, who is most at risk, and how it is treated.
by chamber fill
for a rebleed
elevation advised
Section 01 — What It Is
Blood in the chamber
that should be
crystal clear.
The anterior chamber is the small space between the cornea at the front and the iris behind it. It is filled with aqueous humour, a clear fluid that is made continuously and drains out through the trabecular meshwork in the angle where the iris meets the cornea. When a blood vessel in the iris or the ciliary body tears, blood enters that space. That is a hyphema.
Red cells are heavier than aqueous, so with the head upright they sink and form a layer at the bottom of the chamber with a flat, horizontal top — often visible without any instrument as a red crescent below the pupil. Very small bleeds leave red cells floating in the fluid without a layer; clinicians call this a microhyphema and see it only at the slit lamp.
A hyphema is blood in the front chamber of the eye, most often from blunt trauma that stretches and tears vessels at the root of the iris. It is graded by how much of the chamber it fills, from floating cells only to a total hyphema. Most small hyphemas clear within about a week with rest, head elevation, a protective shield and drops. The dangers are a rebleed in the first days, a rise in eye pressure as red cells clog the drain, staining of the cornea with blood pigment, and injuries the blow may have caused elsewhere in the eye. People with sickle cell disease or trait need especially careful pressure control. Any blood in the coloured part of the eye needs a same-day eye examination.
Section 02 — Interactive
Add blood to the chamber,
and watch the grade change.
Move the slider to change how much of the anterior chamber is filled with blood. Red cells drift down and settle into a layer, and the readout shows the grade a clinician would assign. Drag the model to rotate it.
| Grade | What the clinician sees | What it means |
|---|---|---|
| Microhyphema (0) | Red cells circulating in the aqueous, no layer | Mildest form, but still needs pressure checks and follow-up |
| Grade 1 | Layered blood filling less than one third of the chamber | The most common presentation; usually clears with conservative care |
| Grade 2 | One third to one half | Higher chance of pressure rise; closer monitoring |
| Grade 3 | More than half, but not total | Pressure problems and corneal staining become more likely |
| Grade 4 | Total hyphema; a dark clotted form is called an “eight-ball” hyphema | Highest risk of pressure damage and staining; surgery more often needed |
Section 03 — The Real Risks
The first bleed
is rarely the danger.
What follows can be.
Blood in the chamber is visible and alarming, but the outcome is shaped mostly by what happens over the next days and by what else the injury damaged.
Rebleeding rates reported in the literature vary widely, from a few percent to roughly a third of patients in older series, depending on the population, the size of the first bleed and the treatment used. That spread is itself informative: the people at greatest risk of a rebleed are those with larger initial hyphemas, high pressure at presentation, and blood disorders or blood-thinning medication.
Section 04 — Sickle Cell
One blood test
that changes
the whole plan.
In sickle cell disease and in sickle cell trait, red cells in the anterior chamber can sickle in the low-oxygen, relatively acidic aqueous. Sickled cells are stiff, pass through the drainage meshwork poorly, and pressure can rise even with a small hyphema.
The optic nerve and retinal circulation in these patients also appear less tolerant of raised pressure, so clinicians treat at lower pressure levels and recommend surgery sooner. Some common pressure-lowering medicines are used with caution or avoided: carbonic anhydrase inhibitors such as acetazolamide can increase acidity and sickling, and hyperosmotic agents can raise blood viscosity. For that reason, eye clinics frequently ask about sickle status, or test for it, in patients of African, Mediterranean, Middle Eastern or South Asian ancestry who present with a hyphema.
Section 05 — Treatment
Most hyphemas are
managed by rest,
drops and watching.
The goals are to stop a rebleed, keep the pressure safe, control inflammation and find any other damage. Most patients are managed as outpatients; children, people who cannot be relied on to rest, and those with sickle cell disease or high pressure are sometimes admitted.
| Measure | Why |
|---|---|
| Rigid eye shield | Protects the eye from further pressure or rubbing, especially during sleep |
| Head elevated 30–45° | Lets blood settle low, away from the pupil, so vision clears sooner and the back of the eye can be examined |
| Reduced activity | Strenuous activity and bending may increase the risk of rebleeding in the first week |
| Avoid aspirin and NSAIDs | They impair platelet function; paracetamol is generally preferred for pain |
| Steroid and dilating drops | Reduce inflammation and ease pain from iris spasm; a dilated, still pupil may also limit stress on the injured vessels |
| Pressure-lowering drops | Used when pressure is raised; drug choice is adjusted in children and sickle cell patients |
Antifibrinolytic drugs. Aminocaproic acid and tranexamic acid slow clot breakdown and have been studied to prevent rebleeding. A Cochrane systematic review of medical treatments for traumatic hyphema found that antifibrinolytics may reduce rebleeding, but with no clear effect on final visual acuity and with side effects to weigh, so they are not used routinely everywhere.
Surgery. A washout of the anterior chamber is considered when pressure stays high despite medical treatment, when corneal blood staining begins, when a large or total hyphema fails to clear, or when the clot is blocking the pupil. Classic criteria from the 1970s and later reviews describe sustained pressures of roughly 50 mmHg for around five days, or about 35 mmHg for about a week, as thresholds for intervention in otherwise healthy eyes — with much lower thresholds in sickle cell patients, often around 24 mmHg sustained for more than a day. In practice, the decision is individual.
Section 06 — Spontaneous & Post-Surgical
When there was
no injury.
A hyphema without trauma is a clue, not a diagnosis. The cause has to be found because it is often a disease elsewhere in the eye or the body.
In adults, abnormal new vessels on the iris from diabetic retinopathy or a central retinal vein occlusion are a leading cause, and these eyes are also at risk of neovascular glaucoma. Blood thinners and clotting disorders make bleeding more likely from small vessels. After cataract surgery, a small hyphema in the first days is usually from the wound or the iris and clears on its own. A recurrent hyphema months or years after surgery can come from an intraocular lens rubbing against the iris or ciliary body — part of the uveitis–glaucoma–hyphema (UGH) syndrome. It is classically linked to anterior chamber lenses and to lenses placed in the ciliary sulcus that are not designed for that position, and it may need the lens repositioned or exchanged.
Section 07 — After It Clears
The blood goes.
The follow-up
should not.
Once the chamber is clear, the eye is examined fully: the drainage angle with a gonioscopy lens and the retina with the pupil dilated. Both are often impossible to see properly while blood is present.
The most important late finding is angle recession, a tear between layers of the ciliary body caused by the same force that produced the bleed. It is common after traumatic hyphema and is associated with a raised risk of glaucoma in the injured eye, sometimes developing many years later and often without symptoms. Long-term, periodic pressure checks are the usual advice, and the other eye is examined too as a baseline. Protective eyewear for racquet sports, paintball, airsoft and some workplaces prevents a large share of these injuries in the first place.
Section 08 — FAQ
Frequently asked questions
about hyphema.
A hyphema is blood collecting in the anterior chamber, the fluid-filled space between the cornea and the iris. Because red cells are heavier than the aqueous fluid, the blood usually settles at the bottom of the chamber and forms a visible red layer with a flat top when the person is upright.
Yes. Any visible blood inside the coloured part of the eye after an injury, or appearing without an obvious cause, should be examined by an eye doctor the same day. The injury that caused it can also damage the retina, the drainage angle or the eye wall, and the blood itself can raise eye pressure.
A subconjunctival haemorrhage is a flat red patch on the white of the eye, under its clear surface membrane. It looks dramatic but is usually harmless and does not affect vision. A hyphema is blood inside the eye, in front of the iris and pupil. It often blurs vision and needs an eye examination.
Small hyphemas commonly clear within about a week as the drainage system removes the red cells. Larger or clotted hyphemas take longer, and the timeline depends on the size, whether there is a rebleed, and the eye pressure.
A rebleed is a second bleed from the injured vessel, most often in the first few days as the original clot retracts and loosens. Rebleeds tend to be larger than the first bleed and are linked to higher eye pressure and worse outcomes, which is why rest and close follow-up are emphasised in the first week.
In people with sickle cell disease or sickle cell trait, red cells can sickle in the low-oxygen environment of the anterior chamber, become stiff and clog the drainage meshwork. Eye pressure can rise more easily, and the optic nerve can be damaged at pressures that would be tolerated in other people. Some pressure-lowering drugs are used with caution or avoided, so doctors often ask about or test for sickle status in at-risk patients.
Paracetamol (acetaminophen) is usually the preferred option. Aspirin and many anti-inflammatory painkillers affect platelet function and are generally avoided because of the risk of rebleeding. Always check with the treating eye doctor before taking any medicine, and do not stop a prescribed blood thinner without talking to the doctor who prescribed it.
Many hyphemas clear without lasting damage. The injury behind it can, however, leave problems such as angle recession, which can raise the risk of glaucoma years later. That is why people who have had a traumatic hyphema are usually advised to have periodic pressure checks long after the blood has gone.
References & Evidence Base
Peer-reviewed
citations.
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