Your sense of sight allows you to complete your daily tasks efficiently and safely. This is why keeping your eyes in good condition should always be a priority.
Today, Park Slope Eye, your trusted family eye care clinic, explains the vision process. Your capacity to see stems from complex teamwork between your eyes and brain. The vision process starts when light rays from the objects you see pass through the cornea, the clear, dome-like structure covering your eyes. These light rays will then enter a black opening called the pupil. The size of your pupil is controlled by the iris, the colorful part of your eyes.
Afterward, the light rays are bent toward your lenses. Once the light rays reach the back part of your eyes, the retina will then convert them into nerve impulses, with the assistance of light-sensitive photoreceptors.
The optic nerve will then deliver these signals to your brain, which translates them into the images you see. The retina is the light sensitive membrane that covers the back of the eye.
This membrane consists of millions of nerve cells which gather together behind the eye to form a large nerve called the optic nerve. Image of eye anatomy side view. At the front of the eye is the cornea and anterior chamber underneath it. Below that is the iris, the coloured ring which surrounds the pupil, which is the opening in the centre. The lens is underneath the iris and held in place by the suspensory ligament at the top and the posterior chamber and ciliary body and muscle below the eye.
If light covers the entire receptive field, the cell responds weakly. Vision begins with light passing through the cornea and the lens, which combine to produce a clear image of the visual world on a sheet of photoreceptors called the retina. As in a camera, the image on the retina is reversed: Objects above the center project to the lower part and vice versa. The information from the retina — in the form of electrical signals — is sent via the optic nerve to other parts of the brain, which ultimately process the image and allow us to see.
Thus, the visual process begins by comparing the amount of light striking any small region of the retina with the amount of surrounding light. Visual information from the retina is relayed through the lateral geniculate nucleus of the thalamus to the primary visual cortex — a thin sheet of tissue less than one-tenth of an inch thick , a bit larger than a half-dollar, which is located in the occipital lobe in the back of the brain.
The primary visual cortex is densely packed with cells in many layers, just as the retina is. Rods handle vision in low light. They see only in black and white. Cones handle color vision and detail. People who are colorblind have difficulty distinguishing colors. This affliction is caused by the absence of the types of cone cells that are sensitive to blue, green, or yellow.
The retina produces an inverted image of the object that is sent to the brain by the optic nerve. The brain processes the information and constructs an image of the object. Vision is the term for the process of seeing this object. The two most common vision problems involve seeing objects that are out of focus. Both can be corrected with lenses, either in the form of glasses or contacts. Hyperopia, also known as farsightedness, makes it difficult to see objects that are close to the eye. This vision problem occurs when the image is being focused behind the retina because the eyeball is too short.
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