The Eyeball is the body’s organ that detects light rays entering then sends signals to the brain, where the picture we see is formed, via the optic nerve. Light rays enter through the pupil, the eye’s window to the world, and in perfect circumstances come to rest and focus on the retina. Once the rays land on the retina a signal is sent to the brain; this is when it is decided what image(s) the colors of the light rays are forming. In imperfect circumstances the light rays enter the eye and do not come to one focal point on the retina. Instead, the light rays are coming in from different angles and landing all over the retina’s surface, stopping short of the retina’s surface, or hypothetically falling behind the retina’s surface. In any of these three circumstances corrective eyewear such as (prescription eyeglasses) are required to bring the eye into focus.
The eyeball is made up of many intricate parts and works a lot like a simple camera.
Cornea – the clear covering on the front part of the eye; it covers the pupil, iris, and anterior chamber.
Anterior Chamber (aqueous humor) – space filled with a watery substance, thick in structure, and is between the cornea and the lens.
Iris – is the ring around the eye’s pupil.
Ciliary Muscle – this muscle controls an eye's viewing objects accommodation at different distances. This muscle affects the zonular fibers that suspend the lens during accommodation by causing the lens shape to change to focus light rays.
Zonule of Zinn – also known as the suspensory ligament is a ring of fibrous strands connecting the crystalline lens and the ciliary body together.
Pupil – is a circular clear opening, the eye’s window to the world, and is located in the middle of the iris. The reason the pupil appears to be black is because most of the light coming in through the pupil is absorbed by the eye’s tissues inside.
Crystalline Lens – helps refract light being focused on the retina by changing shape. This action changes the focal distance causing the light rays to come to one focal point on the retina.
Sclera – is a tough protective exterior shell of the eyeball. Its composition is a dense fibrous tissue that covers the majority (four-fifths) of the eyeball and it also provides a place for the muscles responsible for moving the eyeball to attach to.
Conjunctiva – is the sclera’s anterior cover and is transparent, or clear mucous membrane whose purpose is to prevent the eye from drying out.
Choroid – the vascular layer that lies between the sclera and the retina and is about 0.5 mm thick; this is also known as the choroid coat or .
Retina – is made up of millions of tiny light receptors, also known as photoreceptors, which are part of an extreme metabolic active layer of nerves.
Hyaloid Canal – holds and carries the hyaloid artery.
Vitreous Humor – the clear gel substance that fills the space between the eyeball’s retina and the lens. Often it is referred to as the vitreous or the vitreous body.
Fovea – is responsible for sharp central vision that’s necessary for watching television, viewing up close, such as reading, driving, or any other activity where detail is the primary importance of what is being viewed.
Optic Disc – lacks the light sensitive rods and cones causing a break in the visual field known as the blind spot.
– is part of the central nervous system; it transmits vision information from the retina to the brain and is also known as the cranial nerve II.