A problem with any part of the eye can suddenly cause blurred vision.
Slowly progressive blurred vision is usually caused by long-term medical conditions. Sudden blurring is most often caused by a single event.
Some instances of sudden blurred vision are medical emergencies that must be treated as soon as possible to prevent permanent damage and vision loss.
Contact an eye doctor near you who can evaluate the cause of your blurred vision.
SEE RELATED: What Is an Eye Stroke?
Find an eye doctor near you
When is blurred vision a medical emergency?
There are two types of strokes: ischemic and hemorrhagic. When a blood clot blocks an artery transporting blood to the brain, an ischemic stroke occurs. When a blood vessel in the brain ruptures, the result is a hemorrhagic stroke, which is less common.
Strokes can cause a sudden, severe headache and blurred vision in one or both eyes.
Other symptoms often associated with strokes include sudden:
- Difficulty speaking and understanding speech
- Numbness or weakness of the arm, face, or leg, especially on one side of the body
- Trouble walking, dizziness, and loss of balance or coordination
Strokes may have life-threatening and permanently debilitating consequences if they are not treated quickly. If a person suspects they or someone close to them is having a stroke, they should call for an ambulance right away.
2. Traumatic brain injury
Traumatic brain injury (TBI) is a type of head injury that causes damage to the brain. There are different types of brain injuries, including concussions and skull fractures.
A jolt, hit, blow, bump, or penetrating objects cause most TBIs.
The symptoms of a TBI vary depending on the part of the brain that was injured and the extent of the damage. While some TBI symptoms occur right away, others may take days or weeks to appear.
Symptoms of TBI can range from mild to severe, depending on the extent of the damage.
Symptoms may include:
- Blurred vision
- Lack of coordination
- Loss of consciousness
- Mood changes, such as irritability
- Ringing in the ears
People with a mild TBI should temporarily limit doing certain activities that can stress their brain or increase the risk of reinjury, such as playing sports or computer work. Always follow your physician’s advice.
Severe TBI can be life-threatening without treatment. The treatment for TBI depends on the extent, location, and severity of the injury.
3. Carbon monoxide poisoning
Carbon monoxide is a colorless, tasteless and odorless gas present in the fumes that burning fuel creates.
Carbon monoxide binds to hemoglobin, the red protein in blood that transports oxygen throughout the body, as people breathe it in. Hemoglobin is unable to transport oxygen to organs and tissues when it’s bound to carbon monoxide.
A headache and vision problems, such as blurred vision, are common signs of carbon monoxide poisoning.
Since carbon monoxide deprives the brain and body of oxygen, it causes a number of symptoms.
Additional symptoms of carbon monoxide poisoning include:
- Chest pains
- Fatigue and weakness
- Flu-like symptoms
- Loss of consciousness
- Upset stomach and vomiting
People with mild to moderate carbon monoxide poisoning should get themselves away from the poisonous gas and seek medical treatment immediately.
4. Angle-closure glaucoma
Angle-closure glaucoma is where fluid in the front part of the eye is suddenly blocked from draining out of the eye, causing eye pressure to rise quickly.
Symptoms include headache and severe pain in or above the eyes, along with:
- Changes in your vision, including blurred vision
- Redness and pain in the eyes
If you have any of these symptoms seek help right away.
Angle-closure glaucoma is a medical emergency that requires treatment to decrease the eye pressure and the inflammation inside the eye.
Many things can cause your vision to suddenly become blurred. When treatment is delayed, some can result in vision loss.
Other medical emergencies are also caused by retinal diseases, retinal detachments and corneal burns.
5. Sudden Onset of Anisocoria (Different Pupil Sizes)
Anisocoria is a condition in which one pupil is bigger than the other. The pupil is the black hole in the center of the iris, the colored part of the eye, that widens and constricts in response to light intensity.
Some people are born with unequal pupil sizes, and if no other symptoms are present and both pupils react to changes in light, there is usually nothing to be concerned about.
However, if one pupil dilates suddenly, you may suddenly experience double or blurred vision or pain in or around the eyes. This it could signal a more serious condition that requires immediate medical attention, such as a brain tumor, aneurysm or nerve disease.
LEARN MORE: Guide to Eye Conditions
Schedule an appointment with an eye doctor near you about any sudden unexplained changes in your vision.
If you notice any sudden changes to your vision, seek medical attention immediately.
What is Acanthamoeba? »