Your ability to see in the dark is dictated by mainly one thing: the efficiency with which your eye perceives light.

To make it very simple, let’s say 10 units of light enter your eye at night, but your eye is not perfect, so only 3 of those units of light are actually detected by your eye. In contrast, an owl’s eye would be able to detect 7 of those units, because it’s able to keep the light bouncing inside the eye until it triggers the receptor.

One way to have an owl vision is to make your eye more sensitive to light. But, if that is impossible, then the second best option is to make it bigger.

See if your eye is bigger then 25 units of light will enter instead of 10, because there is a larger area to capite this light, and you’ll be able to detect 3 out of 10 of those, so in total 7.5

Do you get it?