Structure and working of Human Eye

The eye is one of the most complex organs in the body. Responsible for taking light signals to the brain, it functions as a natural camera that is an extension of the brain. It has several layers that are similar to the lens of the camera, the film, and the lens cover. Any part of the eye can be involved in the disease process, and may require a sub-specialist. AJEH has specialists in all areas of ophthalmology that deal exclusively with specific diseases of the eye and surrounding areas. Like the glass on a watch, the cornea is the clear protective coating in the front of the eye that allows light to pass through it without distortion. It covers the colored iris. The lens of the eye focuses on the image which is then transmitted through the cornea to the retina. Therefore, it must be clear and regularly shaped to give good vision. These images are then transferred via the optic nerve to the brain where sight is interpreted. A "scratched" cornea, when the surface layer itorn, is extremely painful.

The conjunctiva is the clear covering (like cellophane) of the white part of the eye; the sclera. When it gets irritated or infected it becomes red, which is called conjunctivitis. Conjunctivitis can be allergic or infectious, viral conjunctivitis is often called "pink eye."

Every camera must have a lens to properly focus on the image. The eye has a lens too, which lies directly behind the pupil in a sac-like capsule. The lens, which is about the size of an ‘M&M’ is normally clear and transparent. It focuses images onto the retina which acts as the film that records the picture. The picture is then transmitted by the optic nerve to the brain, where the image is interpreted. It's the brain that does the actual seeing.

The dark center of the iris (the colored part of the eye) is the pupil. The pupil decides how much light is needed for the eye to see properly. It changes sizes to adjust to changes in light..

The retina is the light-sensitive part of the eye. It has one major artery and one major vein which is called the central retinal vein. Sometimes the branches of this vein can be blocked.

The uvea is the middle section of the eye. It has three parts: the iris (the colored part of the eye), the ciliary body and the choroid. Inflammation (or swelling) of any of these parts or their adjacent tissues is called "uveitis."

The macula is a part of the eye that contains special light-sensitive cells which allows us to see fine details clearly. It is located in the retina. The macula is an important part of the eye because even small changes can cause severe vision loss.

The sclera is the ‘white’ part of the eye.