Anatomy of the Eye
The Anatomy of the Eye
The front section of the eye's interior where aqueous humor flows in and out providing nourishment to the eye and surrounding tissues.
The cornea is the transparent structure located in the front of the eye, covering the iris, pupil, and anterior chamber. The cornea is supplied with oxygen and nutrients through tear-fluid and not through blood vessels. That also explains why the cornea is so clear. Overusing contact lenses can lead to oxygen deficiency, ultimately causing blood vessels to appear in the cornea.
The fovea is the most central part of the macula. The visual cells located in the fovea (cones) are packed tightest, resulting in optimal sharpness of vision, perfect for reading or watching TV. Rods are packed just outside the fovea, and are active in low light conditions. The fovea covers about 5 degrees of the vision field.
The iris is the part of the eye that regulates the amount of light that enters the eye. With strong light, the iris sphincter muscles will contract the pupil. In darkness, the iris opens the pupil using the dilator muscles.
The macula or macula lutea ( from Latin macula, spot + lutea, yellow) is an oval-shaped highly pigmented yellow spot near the center of the retina of the human eye. It has a diameter of around 5 mm and is often histologically defined as having two or more layers of ganglion cells. Near its center is the fovea, a small pit that contains the largest concentration of cone cells in the eye and is responsible for central, high resolution vision. The macula also contains the parafovea and perifovea.
The optic nerve sends signals from the eye to the different parts of the brain where the signals are interpreted into images. The optic nerve consists of about 1,000,000 nerve threads.
The pupil is essentially just a hole in the iris. The reason why it's black is because the layer of pigment inside the eye absorbs major parts of the light, thus resulting in a darker shade. However, when pupils appear red in photos it is actually the color of the retina that is reflected.
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical events that ultimately trigger nerve impulses. These are sent to various visual centers of the brain through the fibers of the optic nerve.
The sclera is a membrane of tendon in the eye, also known as the white of the eye. Rugged and robust, the sclera works to protect the inner, more sensitive parts of the eye. On top of the sclera, the episclera is located. The episclera contains blood vessels that nourish the sclera with oxygen and nutrients. These vessels are thus visible on the surface of the white of the eye.