The retina performs various key functions – and it also holds the answer to why we sometimes see 'stars' after standing up too quickly or sneezing hard.
So what happens when we see 'stars' – and why? The most frequent cause is a sudden drop in blood pressure. Any sudden movement such as quickly standing up or sneezing heavily sends blood rushing from your head to the rest of your body. Until your blood pressure stabilizes, your brain and eyes are briefly deprived of blood and oxygen. That stops the retina from functioning normally – and it relays that information to the brain. That's why you start to see the tell-tale flashes of light or 'stars.' If the lack of oxygen persists, then your body shifts to the next stage in which the photoreceptor cells in the retina stop sending information to the brain. That's the stage at which everything goes black. Normally your vision is quickly restored because the symptoms disappear as soon as your blood starts flowing normally again.
Our eyes contain many other important components apart from the retina.
Still on the subject of blood flow, the annoying "red eye" effect that you see on photographs shows just how much blood is typically flowing through the retina. The red eye effect is caused by the camera flash lighting up the blood in the retina and making it visible. It happens whenever the flash is reflected straight back from the retina to the camera lens.
Did you know...? The structure of the blood vessels in our eyes can help eye care professionals spot the early signs of certain diseases during an eye examination. More information…
Important: If you frequently see 'stars' or experience any other form of impaired vision, please make sure to have the symptoms checked out by an eye care professional to rule out anything serious. In some cases these symptoms can be caused by a disease or by side-effects of drugs.
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