What is a scotoma?

A scotoma is a blind spot in your vision. It can be temporary or permanent, and it may stay in the same place or move around in your vision. The spot may be in the center, or it may be around the edges of your vision. Rather than a dark spot in your vision, you may have a spot of flickering light near the center of your vision that may drift around the eye, or create arcs of light. A temporary blind spot may the first sign of a migraine headache.

What is the cause?

A fixed, permanent, blind spot can be due to a problem in the:

• Brain, such as a stroke or tumor
• Optic nerve, such as glaucoma, or multiple sclerosis
• Retina, such as an injury or scar

A temporary blind spot is usually due to problems in the brain, such as migraine or seizure, but can also be related to low blood flow to the brain.

A slowly growing blind spot can be due to a retinal detachment, which may require surgery.

What are the symptoms?

Symptoms may include:

• A spot in your vision that can be dark, very light, blurred, or flickering
• Trouble seeing certain colors
• The need for bright light in order to see clearly

How is it diagnosed?

Your eye care provider will ask about your symptoms and medical history and do exams and tests such as:

• An exam using a microscope with a light attached, called a slit lamp, to look closely at the front and back of your eye
• An exam using drops to enlarge, or dilate, your pupils and a light to look into the back of your eyes
• A visual field test, which uses spots of light to measure your central vision and how well you see things on all sides

How is it treated?

Treatment depends on the cause. A scotoma that happens before a migraine headache is temporary and usually goes away within an hour.

If the scotoma is on the outer edges of your vision, it usually does not cause severe vision problems. If you have a scotoma in your central vision, it cannot be corrected or treated with glasses, contact lenses, or surgery. Your provider will recommend that you use aids to support your decreased vision. Tools that can be used to help include:

• Large-number phone keypads and watch faces
• Filters to reduce glare on computer screens
• “Talking” clocks or scales
• Audio books, magazines, or newspapers or machines that “read” printed material aloud in a computer voice
• Using large type printed books or enlarging the type size in an eReader (electronic devices such as iPads, Nooks, or Kindle)
• Personal computer hardware such as lighted keyboards, large type, and software that magnifies screens and converts text to speech for both computers and mobile phones
• Closed CCTV systems that use video cameras and large TV screens to enlarge reading material, medicine bottles, or pictures
• Magnifying eyeglasses, hand-held magnifiers, or stand magnifiers to enlarge your reading material or other objects