Functioning of the eye
The light that penetrates the interior of the eyeball passes through the cornea, and the lens focuses the image on the retina, where the photoreceptor cells (rods and cones) are excited and transmit the nerve impulse, through the optic nerves , to the brain.
The image that is formed on the retina is an inverted image (upside down) and smaller than reality, although the brain interprets this information and makes us see it in its real position. Remember that the sense organs only transform the different stimuli into nerve impulses, and it is the nervous system that interprets the information received. It is in the visual cortex that the sensation of seeing occurs.
Light intensity regulation
The pupil, by contracting or relaxing some muscles of the iris, is responsible for regulating the amount of light that reaches the retina.
In low light, the iris relaxes and the pupil increases in size to let in as much light as possible.
If there is a lot of light, the iris contracts to prevent too much light from reaching the retina and can damage the photoreceptor cells.
The lens accommodates itself, curving more or less according to the distance to which objects are located so that the image is focused correctly (although inverted) on the retina. Thus, if the object is far away, the ciliary muscle causes the lens to flatten, and if it is close, to bulge.
Interactive activity: Accommodation of the eye.
The stereoscopic vision is the ability to integrate into a single three - dimensional image, emboss the two images we receive from each of our eyes, located one on the other side. Although the eyes are very close together, we see the object from different angles. This information is transmitted to the brain, where the visualized image is processed and created.