Scotoma

What is a scotoma?

Scotoma (pronounced skuh-tow-muh) is the medical term for a visual field abnormality, or a blind spot. Most of these blind spots happen in one eye, but they can happen in both eyes.

The retina is a layer at the back of your eye that converts light into electrical signals. The optic nerve sends these signals to your brain.

A scotoma may be a spot on the retina where the nerves don’t work and don’t send signals to your brain. There’s an abnormality in your field of vision: you temporarily or permanently can’t see as well or can’t see at all in a certain location.

A scotoma can happen with conditions that affect your optic nerve or certain areas in the brain.

The word “scotoma” is the Greek word for darkness. The term “visual field” refers to the entire area that you see.

Are there types of scotomas?

Yes, there are several different types of scotomas. (Some people use the word “scotomata” for more than one scotoma.) The types may reflect where the blind spot occurs, like a central scotoma, and some may refer to a color that you see, like a xanthic scotoma.

There are also positive and negative scotomas. With a positive scotoma, you’ll see something, like a spot of a particular color. With a negative scotoma, you don’t know that you have a blind spot. Your healthcare provider will find a negative scotoma during testing. Terms can also refer to being in one eye (unilateral or monocular) or in two (bilateral or binocular).

Some types of scotomas include:

• Central: In this type of scotoma, the blind spot is in the middle of your vision. Some people see it as a dark spot straight ahead. Other people can kind of see straight ahead, but there’s an area where it’s not clear.
• Scintillating: This type of scotoma often appears to be jagged or wavy. It can go from light to dark and back again. It’s a disruption of electrical signals. This kind of scotoma often happens if you have a migraine with aura. Scintillating scotomas often don’t last long.
• Paracentral: Healthcare professionals call the blind spot a paracentral scotoma if it’s within 10 degrees of fixation. In other words, it’s a spot slightly off to the side of where you’re looking. You may have more than one paracentral scotoma.
• Junctional: This type of scotoma happens because of damage to the place where the optic nerve and the optic chiasm come together. The optic chiasm is the part of the brain, near the base, where the optic nerve enters the brain.

How common are scotomas?

Everyone has a scotoma at the point where the optic nerve goes through the retina. Usually, it’s not noticeable because your brain fills in the empty spot.

What are the symptoms of a scotoma?

Signs and symptoms of a scotoma may include:

• A spot where your vision is blocked or disturbed.
• Having difficulty seeing certain colors.
• Needing bright light to be able to see well.
• Eye floaters and flashes.

What causes a scotoma?

Many conditions can cause a scotoma. These include issues with your retina, brain and/or optic nerve. Causes include:

• Cancer.
• Multiple sclerosis (MS).
• Injuries to the retina, including retinal burns.
• Glaucoma.
• Stroke.
• Age-related macular degeneration.
• Diabetes.
• Medication side effects.

Common causes of central scotomas

Central scotoma causes include:

• Macular degeneration.
• Strokes.
• Tumors.
• Scars from eye injuries.
• Traumatic brain injury.

Common causes of junctional scotomas

Junctional scotoma causes include:

• Tumors of the pituitary gland.
• Other types of cancers, such as craniopharyngioma.
• Aneurysms, or bulges, in your arteries.
• Infections, like syphilis and tuberculosis.
• Demyelinating conditions like multiple sclerosis.

Common causes of paracentral scotomas

Paracentral scotoma causes include:

• Glaucoma (which can cause an arcuate, or arc-shaped, paracentral scotoma).
• Diabetes-related retinopathy.
• Retinal tears and retinal detachments.

Common causes of scintillating scotomas

Scintillating scotoma causes include:

• Migraine headaches, including migraine with aura with and without pain.
• High blood pressure (hypertension).
• Changes in hormone levels.
• Coagulation disorders (problems with the way your blood clots).
• Retinitis pigmentosa, a group of retinal diseases that cause vision loss.
• Cancer-associated retinopathy.

What tests will be done to diagnose a scotoma?

Your healthcare provider will ask you questions about your medical history and symptoms. They might also use the following tests:

• Eye exam: The exam is painless and includes ways to test your vision and eye health.
• Visual field testing: The test measures how far your eye sees in any direction without moving and how sensitive your vision is in different parts of the visual field.
• Optical coherence technology: This is a noninvasive imaging method to create a picture of the back of your eye.

If your provider suspects a certain disease is causing your scotoma, they may recommend other types of testing. These tests could include laboratory tests on your blood or imaging tests to find tumors.

How is a scotoma treated?

Treating the scotoma involves treating the condition that’s causing it. This is especially true of conditions like glaucoma, macular degeneration, stroke and cancer.

Some scotomas don’t need treatment. For instance, you may be able to relieve some symptoms of scintillating scotomas by lying down to rest or drinking water.

If you have migraines and scintillating scotomas, your provider may suggest medications that range from over-the-counter (OTC) pain relievers to triptans to anti-seizure medications.

How can I prevent a scotoma?

At this time, there’s no way to prevent a scotoma from happening in certain situations. In other cases, such as migraines, you may be able to prevent a scotoma with certain medications that prevent migraines.

If you do have conditions that may be associated with scotomas, it’s best to get regular eye examinations and to try to maintain good health. For instance, aiming for steady blood sugar levels if you have diabetes or managing your blood pressure if you have hypertension may help to ward off eye problems in general.

What can I expect if I have a scotoma?

The outlook for a scotoma depends on what’s causing it. Some of these blind spots are temporary. If they are, they’ll go away once your migraine is over or your blood pressure becomes stable.

Other times, a disorder causes the scotoma. In these cases, the scotoma might not disappear and might even become larger.

Having a scotoma, especially a central scotoma, can interfere with your ability to read or to drive. You may want to discuss low vision aids with your provider. These include things like proper lighting, magnifiers for reading or equipment that can read to you.

When should I see my healthcare provider if I have a scotoma?

You should contact your healthcare provider about any changes or worsening symptoms with your vision.

Call 911 or go to the nearest emergency room if you experience these scotoma symptoms:

• A severe headache that starts up suddenly.
• Problems speaking.
• Numbness in your limbs or face.
• Nausea.
• Seeing flashes of light and floaters, along with a shadow or dark spot. These can be signs of retinal detachment. A retinal tear or detachment is often painless, but is a medical emergency.

A note from Cleveland Clinic

You may not know the term “scotoma” as well as you know the term “blind spot,” but they mean the same thing. A scotoma may refer to something that you see that isn’t there, or it could refer to something you don’t see that you should. Some scotomas aren’t noticeable to the people who have them. As with all conditions, it’s important to discuss any changes in your eyesight with your healthcare provider. If you have a condition that creates significant problems with your vision, talk to your provider about things that may help you, like support groups or tools to help with low vision.