3 Sensory StructuresAqueous humor - The liquid substance found in the eye chambers. Made mostly of water, the aqueous humor delivers vital nutrients to the eyes, as well as serving the purpose maintaining correct pressure balance in the eye chamber, also forces the eye to maintain shape.Vitreous humor- A clear fluid which fills the eye between the lens and the retina also helps hold eyes shape. Lights get transmitted through the vitreous humor to the retina.Optic disc- A vertically oval spot in the back of the eye, made up of nerve fibers and nerve cells, called ganglion cells that reside within the light sensitive layer of the retina.Cornea- Light enters the eye through the cornea, which protects the eye and bends light to provide focus.
4 Sensory structures cont…. Pupil- The adjustable opening in the center of the eye.Iris- Adjusts light intake by dilating and constricting in response to light intensity and even to inner emotions.Lens- The transparent structure behind the pupil that changes shape to help focus images on the retina.Retina- The light-sensitive inner surface of the eye containing the receptors rods and cones plus layers of neurons that begin the processing of visual information.Fovea- The central focal point in the retina, around which the eyes cone cluster.Sclera- The sclera is commonly known as the white of the eye. It is the tough, opaque tissue that serves as the eye's protective outer coat. Six tiny muscles connect to it around the eye and control the eye's movements.
5 Sensory Structures cont… Choroid- The choroid lies between the retina and sclera. It is composed of layers of blood vessels that nourish the back of the eye. The choroid connects with the ciliary body toward the front of the eye and is attached to edges of the optic nerve at the back of the eye.Optic Nerve- The optic nerve transmits electrical impulses from the retina to the brain. It connects to the back of the eye near the macula. When examining the back of the eye, a portion of the optic nerve called the optic disc can be seen.
7 Sensory PathwayLight enters the eye through the cornea which bends it to provide focus when looking at an object.The light then passes through the pupil. The pupils size and amount of light entering the eye gets regulated by the iris.The iris adjusts the light intake by dilating and constricting based on light intensity and inner emotions.The light gets focused onto a small patch of photoreceptive cells on a part of the eye called the retina as it receives the upside-down image.The single particle of light energy first makes its way through the retina’s outer layer of cells to its buried receptor cells – rods and cones.The light energy striking the rods and cones produce chemical changes that generate signals which activates the bipolar cells that activate the ganglion cells. The long axons of the cells intertwine forming the optic nerve leading into the brain such as the hypothalamus or occipital lobe. When the impulses are sent to the brain, they are constructed there into a perceived, upright image.
8 Eye Disorder: Cataracts Cataracts occur when there is a buildup of protein in the lens that makes it cloudy.Seeing through cloudy lenses is a bit like looking through a frosty or fogged-up window.This prevents light from passing clearly through the lens, causing some loss of vision.
9 Eye Disorder: Glaucoma Glaucoma is not just one eye disease, but a group of eye conditions resulting in optic nerve damage, which may cause loss of vision.It usually happens when the fluid pressure inside the eyes slowly rises, damaging the optic nerve.Glaucoma is one of the leading causes of blindness in the United States.