Why do you see colors when you close or rub your eyes?
Most of us have experienced it. You rub your closed eyes, or sneeze, and suddenly notice some flickers or sparks of light in your vision. But, by the time you open your eyes, they’re gone. These small lights are usually phosphenes, a visual phenomenon caused by mechanical stimuli resulting in pressure or tension on the eye when the eyelids are closed.
The internal lining of the eye ball is called the retina. The retina’s job is to take visual information entering your eye through the pupil and convert this information into an electrical signal. The electrical signal is then sent to the brain to provide us with the visual image we see of the world. Phosphenes are generated by the retina after there’s some sort of stimulation, even with the eye closed.
Some activities that stimulate the retina in this way include:
- standing up too quickly
- head trauma
- looking at the sky
- moving the eyes quickly
Usually, phosphenes are described as sparks, twinkling lights or pin-prick light shapes that can be brightly colored. Phosphenes will subside quickly, in less than a few seconds, and don’t cause any change to vision.
Migraines and auras
Visual patterns or sudden lights in your vision also can be caused by ocular migraines, or auras. Auras generally last from 20 to 60 minutes and start slowly in one area of the vision. They grow over a course of minutes to cause a scotoma, or blind spot, with your eyes open or closed. Usually auras precede a headache or migraine and have geometric associated shapes and shimmering colors. After auras subside, vision will return to normal.
Retinal tears or detachment and photopsia
Flashes of light, or photopsia, which occur with the eyes open or closed due to a retinal tear or detachment are due to mechanical tugging of the retina. This tugging can cause a tear in the retina, pulling away from the eyeball and causing a detachment. These flashes are seen intermittently after development of a retina tear or detachment and usually don’t subside until it’s repaired. The retina doesn’t sense any pain or discomfort; flashing lights can be one of the first signs that there’s a change in the retina. Retinal tears and detachments are sight threatening and need to be evaluated immediately by an eye doctor.
If you’re concerned about any lights you see in your vision or have new flashes of light, a thorough dilated eye exam is required. Even if you have no change in vision or don’t wear glasses or contact lenses, a yearly dilated eye exam is encouraged to evaluate the health of the retina before any problems develop.
Stephanie Pisano is an optometrist at The Ohio State University Wexner Medical Center.