Turn to the sky when it has a light color, or look at a white sheet, you will notice that in a matter of seconds you will see small spots as shown in the image above. This curious phenomenon is caused by particles called "floating flies", in English known as "eye floaters".
Inside our eyes, between the external part (lens) and the retina (nervous tissue that deciphers the light in the lower part of the eye), there is a liquid called vitreous humor, which consists of 99% water and 1% other elements , such as acid and collagen. Over the years, the collagen fibers accumulate or join the acid particles, forming small bodies that when passing in front of the retina, project a shadow that causes us to see those spots.
There are other causes for floating flies, but this is the most common. In most cases, they are not a cause for concern and do not require any type of medical or surgical intervention. However, if you suddenly begin to see a lot of these points, it is best to seek an ophthalmologist as soon as possible, as it can be a sign of retinal detachment causing permanent blindness.
It is more common to see spots on sunny days or illuminated surfaces, since in these situations the pupil greatly diminishes its opening, controlling the entry of light, and with this the retina ends up focusing the shadows better.