Common causes of a whiteout
If you have recurrent whiteouts, counting their duration in real time can help get you the correct diagnosis. Note any specific details the whiteouts appear to have in common. Do they happen right after you stand up from a chair, for example? Most often, whiteouts occur when a person is ready to pass out because of a sudden drop in blood pressure. About 1 in 3 people will faint at some point in their lives.
“Fainting can be benign when it’s related to a sudden stress,” says Sarah Thornton, a neuro-ophthalmologist at Wills Eye Hospital in Philadelphia. “Standing up too fast, overexerting, becoming dehydrated or taking certain medications can also lead to hypotension — low blood pressure — and potentially, a whiteout.”
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A less common risk: “Whiteouts can occur with changes in G force,” says Geist, for instance, in a car accident or on a roller coaster. A whiteout caused by physical stress or exertion will clear within just a few minutes.
A link to more serious conditions?
Although fainting is usually benign, always tell your doctor if you’ve fainted — occasionally, whiteouts and fainting are tied to something serious.
“An underlying heart condition, such as aortic stenosis, could cause fainting symptoms, including whiteout,” says Dean M. Cestari, a neuro-ophthalmologist at Mass General Brigham Mass Eye and Ear in Boston and associate professor of ophthalmology at Harvard Medical School. Other such conditions can include arrhythmias, heart failure and atrial fibrillation.
Whiteouts can also have neurological implications. “Transient visual obscurations, also known as TVOs, last seconds,” says Cestari. “They can appear as flashes of white light and cause a loss of vision. TVOs are caused by swelling of the optic nerve and can happen when you change position, say, standing up quickly.”
TVOs are a symptom of papilledema, a rare swelling of the optic disk swelling caused by increased intracranial pressure (ICP). ICP can be caused by brain tumors or hemorrhages.
A retinal detachment is another possibility. “If you have any kind of new-onset vision loss in which you see flashes of light, which you could think is a whiteout, plus floaters, go to an eye doctor to rule out that condition,” says Cestari. “Or if they happen suddenly, go to the ER.”
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But whiteouts typically are not associated with strokes or transient ischemic attacks (TIAs), says Eric R. Eggenberger, an ophthalmologist and neurologist at the Mayo Clinic in Jacksonville, Fla.
“In general, stroke-type events cause a painless sudden onset, and a pure blackout or loss of vision, often involving the upper or lower half of the visual field in only one eye,” Eggenberger says. “In contrast, whiteouts typically involve both eyes and begin in a 360-degree peripheral pattern with a slower progressive constriction toward the center of your vision.”
Take notes on timing and duration of whiteouts
To help your doctor determine the exact cause of a whiteout, try to determine whether only one eye is affected. It might not be immediately apparent.
“Closing one eye is actually what you should do if you have sudden vision loss — close the eye you think is affected. You can cover your eye, but it’s best to close it, so you don’t spread out your fingers and obscure anything,” Cestari says. “Then see what you see out of the other eye. If everything looks normal, you lost vision in the eye you’ve closed, and you can tell your doctor you lost vision in that single eye. If everything looks weird, you’ve lost vision in your right eye, too. Knowing this information can help your doctor determine a cause.”
Again, make note of how long the whiteout lasted as precisely as possible.
It’s always worth consulting an optometrist or ophthalmologist or your primary care physician after experiencing a whiteout. “Discuss the episode, along with any other symptoms you may have experienced, to help determine the underlying cause and to identify the appropriate treatment, if necessary,” Geist adds.