Of the five senses, sight is the sense assigned to the perception of visual stimuli .
What is sight?
Sight is the sense that allows you to discriminate forms, reliefs, distance and colors of everything that is observed. The mechanism that allows the vision of our surroundings is very complex. In humans, vision is performed by both eyes simultaneously. This is binocular vision , which allows you to perceive the three – dimensional shapes of objects – stereoscopic vision . The visual stimuli perceived thanks to the eyes pass through each of the transparent components that form the eye – that is, the cornea, aqueous humor, the crystalline and the vitreous . Subsequently, they reach the retina and are interpreted by the brain.
The retina has about 6 million cones and 120 million rods – these are retinal receptors , also known as photoreceptors – highly specialized cells that transform light stimuli into nerve impulses. The cones react in the presence of high brightness levels , while the rods respond to low brightness levels . A complex system formed by optic nerves, optic chiasma, optic tracts and geniculate bodies (the optic pathways) then sends these impulses to the visual cortex, an area of the brain responsible for decoding them.
The vision is an active process : once the image of what we are observing is imprinted on the retina, the visual process is able to discriminate different information depending on the requests processed by the brain . This mechanism makes it possible to focus on specific details of an object (such as shape, color or distance) with respect to other details.
The defects of vision are various : clear vision up close, and blurred and indistinct from afar ( nearsightedness ), blurred vision and indistinct from close range, and clear up close ( hyperopia ). Then there are astigmatism , or the perception of deformed images and the deformation is greater the higher the degree of astigmatism, a disturbance due to the physiological reduction of the ability to focus on things that are at close range, which usually occurs not before the age of 45 ( presbyopia ), and a condition characterized by a reduction in visual acuity whose causes are not yet fully known, amblyopia .
What is the view for?
Sight is the sense that provides for the perception of visual stimuli allowing to discriminate forms, reliefs, distance and colors of what is observed.