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.
The retina forms the circular shape at the back of the eye surrounded by a layer called the choroid and then another layer called the sclera. Within the retina is the macula the size of a pinpoint, vitreous body and blood vessels. The area of the retina called the fovea contains the greatest concentration of cones. Other colours are seen as combinations of these primary colours. Conjunctiva This is the lining on the inside of your eyelid and the outside of the front of your eye except for the special skin of the cornea.
You can see some tiny blood vessels on the conjunctiva over your eye. If your eyes get sore, these blood vessels get bigger and your eye looks red.
Cornea This is the see-through skin that covers the front of your eye. It is clear like glass and it has no blood vessels in it. Fovea A small indentation at the centre of the macula and is described as the area with the greatest concentration of cone cells, the messages encoded at the centre of the fovea will be interpreted by the brain in the form of a visual image. Iris The iris controls the amount of light that enters the eye.
The iris is the coloured part of your eye. It forms a coloured muscular diaphragm across the front of your lens. Lens The lens focuses light onto the retina. It changes shape to make sure that the 'picture' on the retina is as clear as possible. Macula The yellow spot on the retina at the back of the eye, which surrounds the fovea, the area with the greatest concentration of cone cells, and is therefore the area of greatest acuity of vision.
When the eye is directed at an object, the part of the image that is focused on the fovea is the image most accurately registered by the brain.
Optic Disk Is the visible portion of the optic nerve also found on the retina of the eye. The optic disk identifies the start of the optic nerve where messages from cone and rod cells leave the eye via nerve fibres to the optic centre of the brain.
This area is also known as the 'blind spot'. Optic nerve This nerve is a continuation of the retina, leaving the eye at the optic disk, and it transfers all the visual information it gets to the brain, via millions of nerve fibres branching from the rods and cones. It's a bit like the cable that carries all the TV pictures from your aerial to your TV so that you can see the programs. Pupil This is the hole in the coloured iris. It lets light into your eye.
It gets very small in bright light, and bigger in dull light. Retina The retina works much in the same way as film in a camera. It is a light sensitive layer that lines the interior of your eye. It is made up of light sensitive cells known as rods and cones. The human eye contains about million rods, which are necessary for seeing in dim light. Cones on the other hand function best in bright light - there are between 6 and 7 million in the eye - they are essential for receiving a sharp accurate image; cones can also distinguish colours.
They turn the picture they receive into an electrical message for the brain, which in turn translates that image to you. Rod Cells One of the two types of light-sensitive cells in the retina. The iris is the colorful part of your eye that gives it its blue, green, hazel, brown or dark appearance. The iris is actually made up of muscles that expand and contract to control the pupil and adjust its size.
So when you see your pupil getting bigger or smaller, it is really the iris that is controlling the pupil opening in response to the intensity of light entering the eye. The light passes through the pupil to the lens behind it. The lens adjusts its shape to bend and focus the light a second time, to ensure that you have a clear image of what you are looking at.
At this point, the light has been bent twice— as it moved from the cornea through the lens, and then from the lens to the retina. If you suspect you have blurry vision or an eye condition, contact an eye doctor near you, who can diagnose and treat the condition. The light then passes from the lens to the back of the eye which is filled with a clear, gelatinous substance called the vitreous until it reaches the retina , the light-sensitive layer at the back of the eye.
The light is then focused throughout the retina which contains nerves called photoreceptors. The photoreceptors are made up of rods and cones, and are responsible for transforming the light rays into electrical impulses. While the light is focused throughout the retina, most of the light entering the eye is focused onto the focal point on the retina, known as the macula.
The nerves of the retina collect all of the electrical impulses, which then travel through the optic nerve at the very back of the eye up to the occipital lobe in the back of the brain. At this point, The light then passes from the lens to the back of the eye which is filled with a clear, gelatinous substance called the vitreous until it reaches the retina , the light-sensitive layer at the back of the eye.
The light that enters the eye is required to go through a specific process in order to focus properly on the retina. If the connections between the eye and brain are not well developed, the visual information that is sent to the brain will not be interpreted properly, and the image will be difficult to see. The process of seeing is dependent on the perfection of the eye and all of its components, including:. If any of these components do not function properly, or are irregularly shaped, vision problems can occur— most commonly, blurry vision will develop.
When this happens, corrective lenses in the form of eyeglasses or contact lenses are prescribed to help the light focus accurately onto the retina and enable clear vision.
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