Causes of Blood Clots in the Eye

Lesson Transcript
Instructor: Misty Baker

Dr. Baker has a doctorate in podiatric medicine and practiced medicine in both the hospital and private practice atmosphere.

In this lesson we will explore what a blood clot in the eye consists of as well as examining some of the most common causes. We will also briefly look at when to seek treatment upon the discovery of a blood clot in the eye.

Blood Clots in the Eye

On Monday morning, Mary awoke to the sound of her alarm. As she got out of bed, she thought about all of the tasks she needed to accomplish this week. While she had a very heavy workload, more importantly she was focused on her upcoming wedding. Yes, this was Mary's last full week at work before she got to say her 'I do's.' She couldn't wait. Mary hopped out of bed and went to the bathroom sink to brush her teeth. Yikes! Mary squealed.

As Mary gazed into the bathroom mirror, she noticed that her right eye looked bloodshot. Upon further inspection, Mary noticed a big red dot right in the middle of the white area of her eye. Oh no… this can't be! Mary thought.

She immediately picked up her phone and called her friend Sally, a nurse. Sally explained that what Mary was experiencing was a common condition known as subconjunctival hemorrhage, or a blood clot in the eye. Sally said that, while there were numerous causes, most of the time it was not due to a serious problem.

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  • 0:04 Blood Clots in the Eye
  • 0:58 Eye Anatomy
  • 1:29 Causes of Clots
  • 3:00 Duration of Blood Clots
  • 3:30 Lesson Summary
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Eye Anatomy

The conjunctiva is the white portion of the eye covered by a thin film. Beneath the conjunctiva we find a multitude of little blood vessels. Should one of these blood vessels rupture, or break, blood will begin to escape. Our bodies' natural response to this event is to coagulate the blood in order to minimize the amount of blood loss. This means that our bodies send signals to the area to thicken the blood or form clots within the blood vessels to control the bleeding. When this clotting of blood occurs within the eye, we see the appearance of a red spot or patch visible on the white portion of the eye.

Causes of Clots

While the source of a blood clot within an eye cannot always be isolated, some of the more common potential causes include the following:

Eye trauma is the most common cause of a subconjunctival hemorrhage. Eye trauma can be categorized as either obvious or not-so-obvious. For example, let's say Mary attended a picnic on Sunday afternoon where some nearby children were playing baseball. If one of the children accidentally threw the ball and it hit Mary in the eye, we'd know the obvious cause of eye trauma: blunt force trauma by a baseball. However, the tiny vessels that are located beneath the conjunctiva are so delicate that sometimes everyday motions can cause the vessels to rupture. An example of one of these more natural causes could include rubbing the eyes.

Sometimes we perform both voluntary and involuntary actions that cause excessive eye strain and a brief spike in blood pressure. Some of these actions include constipation, coughing, laughing, lifting, and sneezing, all of which are causes of blood clots within the eye.

Additionally, if you're on one of the many prescription or non-prescription medications to thin your blood, like aspirin (acetylsalicylic acid) and Warfarin (one brand name is Coumadin), you may develop a blood clot in the eye. These medications work to thin your blood to prevent blood clots, but actually can make bruising and bleeding worse due to the inability to clot.

Other times, blood clots in the eye are a complication from certain eye procedures such as LASIK and cataract surgery. Rarely, other diseases such as a blood clotting disorder or a vitamin K deficiency can stimulate the formation of blood clots within the eye.

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