Have you ever been on a roller coaster where you experienced gradual dimming of your vision? This phenomenon actually has a name: the greyout. While many people find this visual experience to cause nausea and severe discomfort, there are a large group of thrillseekers out there just looking for their next greyout experience. Let's breakdown what the greyout really is:
Greyout Symptoms
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| King's Dominion Intimidator |
Greyout Symptoms
- gradual dimming of vision
- color vision changes
- possible peripheral vision loss
- transient -- symptoms only last a few seconds and then return to normal
Causes of Greyout
Greyout is the result of a decrease in blood flow to the brain and eye. When the retinal cells experience hypoxia (oxygen deprivation), they fail to react to light normally, causing a dimming of visual perception. You can experience these symptoms when:
- prior to fainting (or blacking out)
- low blood pressure like in orthostatic hypotension (when you stand up too fast)
- hyperventilation
- positive G force (gravitational force) experienced by pilots or in roller coasters
I won't pretend to be an expert on "positive G force," but the general idea is that tight turns or loops can cause a rush of blood flow to the lower extremities, and away from the eye and brain. Roller coasters across the nation create this experience for some riders, but if too many people complain to the park of nausea, generally the roller coasters are reconstructed to lower the G force. In my area, King's Dominion Intimidator 305 (pictured above!) appears to be a popular greyout culprit.
If you experience Greyout repeatedly and at random, CALL YOUR DOCTOR
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| CENTRAL RETINAL ARTERY OCCLUSION |
Greyout can be normal in the situations listed above, but if you notice transient vision loss at any other time, it could be a condition called "amaurosis fugax." Greyout in this case could signal an impending artery occlusion, so please contact your doctor immediately. With an artery occlusion, transient vision loss typically precedes a complete blockage of the artery that could cause permanent vision damage!
Above: a Central Retinal Artery Occlusion doesn't have a lot of bleeding, just whitened retinal cells that are starved for oxygen. Once the retina loses blood flow to the cells, vision is permanently lost! This person will have very minimal vision left in this eye, forever!
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