The light reflected by objects crosses the cornea, pupil, lens and reaches the retina, where specialized cells encode the image and the optic nerve takes the stimulus to the brain.
The pupil works like the diaphragm of a camera, it controls the entry of light according to the environment. In bright places, the iris contracts, closing the pupil, thus reducing light entry and focusing on the center of the retina. In dark environments, the iris dilates and allows more light to enter through the pupil, stimulating more the periphery of the retina, where the cells responsible for night vision are found. The variation of the pupil opening, from 2 to 8 mm, is equivalent to magnifying up to 30 times the entry of light into the eye.
When light arrives at the retina, it stimulates specialized cells, the photoreceptors, to convert the light impulse into an electrical stimulus. There are 2 types; the cones, specialized in color vision and details, located especially in the central region and the rods, specialized in night vision, which are located in the periphery of the retina. The electrical stimulus decoded by retinal cells is conducted to the brain, which interprets the information.
* Diseases related to overexposure to UV rays, such as macular degeneration, cataracts, and pterygium, can be prevented by wearing glasses with UV protection, maintaining eye health.
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