I’m taking about the bright dots which appear that seem to zip around in your sight for five seconds or so, usually after one of the above…..?
In: Biology
I get this only immediately after lifting something heavy or gratuitous physical exertion. There’s a lot of people saying its because its from a sudden drop in blood pressure but that doesn’t directly answer the ‘why the stars’ part.
Here is a more complete answer!
Both of [these situations] are basically artificial phenomena in a sense that in one case – the standing up too quickly – this is an entoptic phenomenon, which means “something going on inside the eyeball”. The retina, as you’ll know as an ophthalmologist, has one of the highest metabolic rates of any tissue in the body. The brain and central nervous system tissue burn off about 20% of the energy that you consume in any given moment in time and yet they contribute only a small fraction [about 2%] of body mass. So the retina is very metabolically hungry. And if you stand up too quickly you can have what’s called a “postural drop” in blood pressure. When you stand up, and before your heart compensates, the return of blood drops slightly which causes the perfusion pressure to drop briefly. That causes a momentary reduction in perfusion of your retina. That slightly reduces the supply of oxygen and sugar to the retina from the blood, which causes the retina to start to fire off abnormal signals, which we experience as “sparkly” light signals; the brain is fooled into thinking you’re seeing light when it’s not there.
Latest Answers