The three main layers of the eye include: a) the cornea b) the uveal tract, and c) the retina.
The cornea is the outermost layer of the eye and is made up of five layers of tissue itself. The cornea is clear, which allows light to enter through the pupil to shine on the retina. The cornea also helps protect the eye from things like dirt and bacteria.
The uvual tract is the middle layer of the eye and contains the iris, choroid, and ciliary body. The iris is the coloured part of the eye and is made of muscles. These muscles contract and release to allow the proper amount of light through the pupul. The choroid contains blood vessels and is the main supply of blood to the eye. The ciliary body is where the clear liquid that coats the eye is formed.
The retina is the layer at the back of the eye. This is where the photorecepters (rods and cones) are located. Light is reflected onto the retina through the pupil. The optic nerve is attached to the back of the retina, and this is how our brain gets the information from our eyes.
The eye comprises of three layers namely; the outer layer, the middle layer and the inner layer.
The outer layer is made up of the sclera and the cornea. The sclera is the outermost transparent layer of the eye that maintains the shape of the eye as well as protects the inner parts of the eye form harm by foreign particles and bacteria. By virtue of it being transparent, it allows for the entry of light into the eye that ultimately allows sight. The cornea has a curved structure that enables the focus of light waves.
The middle layer is also referred to as uvea or vascular tunic because it contains blood vessels that transmit blood throughout the eye. This layer is made up of the choroid, ciliary body and retina. The choroid has a brown pigment that facilitates the absorption of light where as the ciliary body is responsible for controlling the shape of the lens. The iris, which is the colored part of the eye, regulates the amount of light entering the eye by increasing or decreasing depending on the light intensity.
The inner layer is also known as the retina or the sensory tunic. The purpose of this layer is to receive the light from an object and convert it into electrical impulses that are then transmitted via the optic nerve to the brain. It consists of photorecetors (rods and cons), macula lutea, fovea centralis and optic disc.