A sudden red patch in the eye – should you worry?

Sometimes people look in the mirror and suddenly notice a bright red patch on the white part of the eye.

It can appear overnight or be discovered completely by accident.

Understandably, this can be alarming. Many people worry that something serious has happened to the eye.

In most cases, however, the cause is something called a subconjunctival hemorrhage.

What is a subconjunctival hemorrhage?

The white part of the eye is covered by a thin transparent membrane called the conjunctiva.

Under this membrane there are many tiny blood vessels.

Sometimes one of these small vessels can break, allowing a small amount of blood to spread under the conjunctiva. Because the membrane is transparent, the blood becomes clearly visible.

This creates the characteristic bright red patch on the eye.

Although it may look dramatic, the bleeding itself is usually harmless.

Why does it happen?

In many cases, there is no clear cause.

A subconjunctival hemorrhage can occur after:

• coughing or sneezing
• heavy lifting or physical strain
• rubbing the eye
• minor trauma

It can also appear in people who take blood-thinning medications or who have high blood pressure.

Sometimes it simply happens spontaneously.

Does it affect vision?

One of the reassuring features of a subconjunctival hemorrhage is that it usually does not affect vision.

Most people do not feel pain.

Aside from the visible red patch, the eye often feels completely normal.

How long does it take to disappear?

The blood gradually breaks down and is absorbed by the body.

This process usually takes one to two weeks.

During this time the color may change from bright red to darker red or yellowish before it disappears completely — similar to how a bruise heals on the skin.

No specific treatment is usually required.

Artificial tears can sometimes help if the eye feels slightly irritated.

When should you see an eye doctor?

Although subconjunctival hemorrhages are usually harmless, it is reasonable to seek medical advice if:

• the bleeding occurs repeatedly
• there is eye pain
• vision is affected
• the bleeding follows significant eye trauma

An eye examination can confirm the diagnosis and rule out other causes.

A condition that often looks worse than it is

Because the eye is so visible, even small changes can appear alarming.

Fortunately, a subconjunctival hemorrhage is one of the few eye conditions that often looks dramatic but is usually harmless.

Still, if there is any uncertainty, an eye examination is always the safest way to be sure.