A Closer Look at Scotoma (Blind Spot in Vision)

What is a Scotoma (Blind Spot in Vision)?

A scotoma is a blind spot in your field of vision. This condition may be temporary or permanent.

Everyone has a pinhead-sized blind spot that occurs where the optic nerve enters the retina. Most people don’t notice these blind spots because our brains fill in the missing information.

On the other hand, a scotoma is an abnormal blind spot. This visual field defect might indicate an underlying health condition. There are different kinds of scotomas, and each affects your field of vision differently.

What Does Scotoma Look Like?

Scotoma can stay within the same area or shift in your visual field. Depending on the type, a scotoma might look like:

• A dark, blurry, or fuzzy spot
• A spot that flickers between light and dark
• An arc of light
• A floater

The scotoma type, as well as its duration, will depend on the underlying cause. A temporary blind spot could mean the onset of a migraine headache. Or, a more serious health issue may be contributing to vision loss.

If you notice a blind spot, call your eye doctor and schedule an appointment immediately.

Symptoms of a Scotoma

Symptoms can vary depending on the type of scotoma and its underlying cause.

Symptoms that can occur with a scotoma include:

• Vision loss (temporary or permanent)
• A blind or blurry spot (it may be one or multiple)
• Possible headache 
• Floaters or dots 
• Trouble reading or seeing specific colors or details

What Causes a Scotoma?

Many conditions and factors can cause a scotoma to develop, including:

Migraines

A temporary scintillating scotoma might appear during the aura phase of a migraine attack. They can also occur during an ocular migraine. This type involves visual disturbances without the accompanying headache of a classic migraine.

Certain Medications

Some drugs (e.g., digoxin) used for chronic heart failure or antiarrhythmic agents could contribute to ocular symptoms. The vision change could happen because of direct toxicity to photoreceptors. If you develop a scotoma, discontinuing the drug can reverse this eye condition. 

Sclerotherapy

Sclerotherapy is a medical procedure that treats varicose and spider veins. It involves injecting the vein to force scarring and redirect blood through other healthier veins. This can cause a scotoma. 

Macular Degeneration

Age-related macular degeneration (AMD or ARMD) can cause a blind spot in your central vision. AMD affects the macula, which helps with visual acuity. You can suffer from blurred vision and scotomas when it begins to deteriorate. 

Diabetic Retinopathy

People with diabetes are at an increased risk for eye problems. Diabetic retinopathy occurs when high blood sugar levels damage the back of the eye (retina). Without treatment, diabetic retinopathy can cause low vision, a central scotoma, or even blindness. 

Optic Neuropathy & Toxic Optic Neuropathy

Optic neuropathy happens when blood flow to the optic decreases or is interrupted, leading to sudden vision loss. The optic nerve can be interrupted by:

• Inflammation or swelling
• Infections
• Trauma
• Dietary deficiencies

On the other hand, toxic optic neuropathy occurs when a toxin like alcohol or drugs damages the optic nerve. Both conditions can lead to central or cecocentral scotoma. 

Optic Atrophy

Optic atrophy is the death of retinal ganglion cells that make up the optic nerve. This condition can lead to poorer visual acuity and color vision.

Optic neuritis (swelling of the optic nerve) can cause optic atrophy. About 55% of people with Multiple Sclerosis (MS) experience optic neuritis.

Brain Injury

A brain injury like an occipital cortex lesion rarely causes a scotoma. These injuries can be caused by various things such as:

• Vehicular accidents
• Physical harm or abuse
• Sports-related accidents

Glaucoma

Glaucoma is an eye disease that can damage the optic nerve due to fluid build-up in the front part of the eye. It can cause vision disturbances, including scotoma.

Other Health Conditions

Health conditions that are linked to scotomas include:

• MS
• Stroke
• Seizures
• Food allergies
• Hypertension
• Preeclampsia (high blood pressure during pregnancy)

Can a Scotoma be a Sign of Something Serious?

Yes, a scotoma can indicate an underlying health condition that requires treatment. Scotomas are more likely to develop in people who have certain health conditions. Many of these conditions are serious, including:

• Stroke
• Cardiovascular disease
• MS

It’s important to consult your doctor if you develop a scotoma. They can rule out severe health problems and give you a proper diagnosis.

When to See Your Doctor

You should see your doctor if you suddenly experience a blind spot or other visual disturbances. Seek emergency medical care if any of the following signs or symptoms accompany the scotoma:

• Confusion or disorientation
• Dizziness or nausea
• Muscle weakness
• Sudden intense headache
• Numbness in your limbs or face
• Slurred speech or difficulty speaking

A scotoma that follows a head or eye injury also warrants emergency medical care.

Types of Scotomas

Various different types of scotomas make blind spots in certain areas of your eye. Each type affects your eyesight differently.

Some types of Scotomas include:

Scintillating Scotomas

Unlike the other types, a scintillating scotoma doesn’t look like a dark spot. A scintillating scotoma might look like the following:

• Flickering, pulsating, or shimmering light
• A zigzag or wave that alternates between light and dark
• An arc-shaped or jagged line

Medical professionals may refer to scintillating scotomas as teichopsia.

Central Scotomas    

A central scotoma is a blind spot directly in your line of sight. This type causes visual field defects that make daily tasks seem challenging or impossible. People with a central scotoma may look from the side of their eyes to compensate for the defect.

It can cause problems seeing colors and details. Driving and reading regular-sized prints can be difficult.

Dim lighting might cause a slight improvement in central vision. Low-level lighting dilates the pupils. This lets more information about surroundings reach the retina.  

Paracentral Scotomas 

A paracentral or arcuate scotoma causes vision loss within 10 degrees of the focal point. This type of blind spot won’t be directly in the line of sight.

Paracentral scotomas accompanied by peripheral vision loss may cause tunnel vision. You may have one paracentral scotoma or several depending on the underlying cause. 

This type of scotoma often begins as a single area of relative loss that gets larger. It’s typically caused by glaucoma.

Hemianopic Scotomas

A hemianopic scotoma is a type of paracentral scotoma that affects half of the visual field. It is also referred to as a homonymous hemianopsia. Because half of your visual field is affected, it can cause severe reading problems.

A cerebrovascular injury or tumor typically causes hemianopic scotomas. A proper evaluation of the field loss can help find the location of the injury.

Junctional Scotomas

A junctional scotoma occurs when the place where the optic nerve and optic chiasm meet is damaged. An optic chiasm is the part of the brain where the optic never enters the brain.

It typically presents as a central scotoma in one eye and temporal field loss in the other. The vision loss depends on which part of the optic nerve is damaged.

Who is at Risk for Scotomas?

People with certain health conditions are at greater risk for scotomas. You should schedule an annual eye exam to help prevent scotomas if you have:

• Diabetes
• Glaucoma
• High blood pressure
• Cardiovascular disease 
• Stroke
• MS
• History of migraines 
• High levels of stress and anxiety
• Mental health conditions, such as depression

Are Scotomas Preventable?

You may be able to prevent a scotoma if it’s related to certain conditions like migraines or diabetes. You can do this by taking medication and maintaining good health. However, there’s no way to prevent a scotoma from happening in certain situations.

How to Diagnose a Scotoma

Your eye doctor can diagnose a scotoma with a comprehensive eye exam. They may perform various tests, including:

Visual Field Test

During this test, you will look into the opening of a bowl-shaped instrument. Each eye will be examined individually. 

Small lights will flash from various areas inside the bowl. You’ll click a handheld device to indicate that you saw the flashing light. 

Once you finish the test, the instrument prepares visual field maps of your eyes. Your doctor will examine the maps and determine if you have any scotomas.

Because the instrument stores your data, you can repeat the test. This helps your doctor monitor changes in your visual field over time.

Dilated Eye Exam

Your eye doctor may use eye drops to dilate your pupils. This allows them to examine your retina and optic nerve. 

They check for damages that may lead to scotoma, including:

• Retinal damage
• Macula damage
• Damage to the optic nerve

A dilated eye exam and visual field test can help your doctor determine the type and cause of the scotoma. Sometimes, a doctor may refer you to a neurology clinic for a definitive diagnosis. 

How to Treat a Scotoma

Scotoma treatment varies depending on the type and cause. A temporary scotoma that occurs with a migraine usually doesn’t require treatment. 

Other scotomas might be alleviated by treating the underlying health condition causing it. For example, a scotoma due to high blood pressure may improve with treatments that lower your blood pressure.

Common treatments for scotomas include:

• Over-the-counter pain relievers like ibuprofen and acetaminophen
• Antidepressants
• Anti-seizure medications
• Beta-blockers to relax blood vessels

Tools That Can Help Manage Scotoma

Central scotomas are not treatable with corrective lenses or surgery. However, tools and adaptive devices can help with daily activities when living with a scotoma. Examples include:

• Magnifying devices
• Large-print books
• Talking clocks and scales
• Filters to reduce glare on computer screens
• Audiobooks, magazines, and newspapers

It’s critical to seek medical care and report any accompanying symptoms if you suddenly develop a scotoma. These details help your doctor determine the best approach to treatment.

Summary

A scotoma is a temporary or permanent condition that causes a blind spot in your eye. It can cause reading problems, floaters, and vision loss, which may be permanent.

Various health conditions and injuries can cause scotomas. Different types of scotomas may affect your eye in different ways.

Although there is no way to prevent certain types of scotomas, treatment options are available. There are also tools and adaptive devices that can help you manage living with it.