A scotoma is another type of vision change that may occur as part of a migraine aura. A scotoma may look like a band of shimmering light that arcs across half of your field of vision. The shimmering light may flicker, take on a zig-zag pattern, or expand in size.

A scotoma is a blind spot 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.


A scotoma is caused by a problem in your brain, a problem in your eye, or a problem in your optic nerve. The optic nerve is located behind your eye and sends pictures to the brain. The kinds of problems that can cause a scotoma include:

• A stroke

• A tumor

• An injury

• Glaucoma or a problem with your retina

• Multiple sclerosis or other diseases that can affect the optic nerve

• Chemicals such as methyl alcohol or quinine


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


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


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 Reviewed for medical accuracy by faculty at the Wilmer Eye Institute at Johns Hopkins.