Vision is the capability of seeing, this is also known as sight. The main basic components of vision are that of the eye itself, the optic nerve, and the visual center in the brain which is connected to the eye via the optic nerve. The eye functions like a camera, when light rays enter it through the adjustable iris, they are then focused by the lens onto the retina, which is a thin light sensitive layer that corresponds to the ‘film’ of the ‘camera’. Thus the retina converts the light rays into several nerve impulses, which are furthermore relayed to the visual center and from here the brain interprets them as images. The retina is made up of millions of tiny nerve cells that contain many specialized chemicals that are sensitive to light. Like the lens of a camera, the lens of the eye reverses images as it focuses them. Vision is one of the five senses, along with touch, hearing, taste and smell. Sight is the sense responsible for the perception of visual stimuli.
What is vision?
Vision (sight) is the sense that allows us to identify shapes, reliefs, distance and color of what is currently being observed. Binocular vision (i.e. that of one being performed in both eyes simultaneously) allows for the three-dimensional perception of objects (stereoscopic vision).
The mechanism that allows the vision of what surrounds us is a very complex function. To ensure that the visual stimuli that affect the eyes are correctly interpreted by the brain it is necessary that before the stimuli arrive at the retina luminous, they pass through the different transparent components that form the eye, those are; the cornea, aqueous waters, lens and vitreous.
Highly specialized cells, known as photoreceptors or retinal receptors, which are present on the retina (about 6 million cones and 120 million rods) convert light stimuli into nerve impulses (cones respond to high light levels, while rods respond to lower levels of bright intensity). These nerve impulses are then transmitted by the optic tract (a complex system made up of the optic nerves, optic chiasm, optic tracts and geniculate bodies) in a specific area of the brain, the visual cortex, deputed to their decoding.
Vision is the act of 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 request processed by the brain. It is this mechanism that makes it possible to focus on the specific details of an object (such as its shape, color or distance) with respect to other details.
Vision defects are myopia (vision is clear up close and fuzzy and indistinct from a distance), hyperopia (vision is blurred and indistinct from close range and crisp up close), astigmatism (distorted images are perceived and the deformation is greater the higher the degree of astigmatism), presbyopia (a disorder due to reduced physiological capacity to focus on the things that are within close range, which occurs usually after the age of 45), and amblyopia (a condition characterized by reduced visual acuity whose causes are not yet full known).
What function does vision serve?
Vision or sight is the sense that governs the perception of visual stimuli allowing us to identify shapes, reliefs, distance and color of what is currently being observed in the space around us.