The internal structures of the eye consist of three layers of tissue arranged concentrically: The sclera and cornea make up the exterior layers. The uvea is the vascular layer in the middle, subdivided into the iris, ciliary body, and choroid. The retina constitutes the innermost layer and is made up of nervous tissue.
Much of the eyeball is filled with a transparent gel-like material, called the vitreous humour, that helps to maintain the spheroidal shape. Immediately beneath the sclera is an underlying vascular layer, called the uvea, that supplies nutrients to many parts of the eye.
The episclera is a thin, loose, collagenous connective tissue. The stroma is a thick layer of dense, collagenous connective tissue made of interlacing type I collagen fibers alternating with networks of elastic fibers. The suprachoroid lamina is a thin connective tissue layer containing fibroblasts and melanocytes.
Retina: a light sensitive layer that lines the interior of the eye. It is composed of light sensitive cells known as rods and cones. The human eye contains about 125 million rods, which are necessary for seeing in dim light. Cones, on the other hand, function best in bright light.
Aging – The eyes mainly consist of water and protein. As we grow older, some of the protein may form chunks and cloud a certain area of the eye's lens.
Your eyes are organs that allow you to see. Many parts of your eye work together to bring objects into focus and send visual information to your brain. Several conditions and injures can cause changes in eyesight. Some conditions can lead to permanent vision loss.
The internal structures of the eye consist of three layers of tissue arranged concentrically: The sclera and cornea make up the exterior layers. The uvea is the vascular layer in the middle, subdivided into the iris, ciliary body, and choroid. The retina constitutes the innermost layer and is made up of nervous tissue.
Each eye has six muscles attached to the sclera — the white part of the eye. These muscles, five of which are shown above, allow you to move the eye and track an object without turning your head. The eye muscles also allow you to shift your field of gaze left, right, up, down and diagonally.
The vitreous is the gel-like fluid that fills your eye. It's full of tiny fibers that attach to your retina (the light-sensitive layer of tissue at the back of the eye).
The results indicate that our kind of eye—the type common across vertebrates—took shape in less than 100 million years, evolving from a simple light sensor for circadian (daily) and seasonal rhythms around 600 million years ago to an optically and neurologically sophisticated organ by 500 million years ago.
Listen to pronunciation. (SKLAYR-uh) The white layer of the eye that covers most of the outside of the eyeball. Enlarge.
Crystallin is a water-soluble structural protein, found in the lens and the cornea of the eye accounting for the transparency of the structure.
In the majority of vertebrate species the sclera contains cartilage and in some cases also bone, which give an extra degree of support to the eyeball (Caprette et al., 2004; Franz-Odendaal and Vickaryous, 2006). Commonly this is a hyaline cartilage layer forming a cuplike structure within the sclera.
Our eyes are also incredibly durable. In fact, they're one of the fastest healing body parts. With adequate care, a corneal scratch can heal in a period of as little as two days. However, our eyes are not invincible.
Eye discharge consists of mucus, oil, skin cells, and other debris that builds up in the corner of the eyes as you sleep. It is secreted by the conjunctiva and meibum, an oily substance produced by the meibomian glands. This substance also helps in keeping your eyes moist between blinks.
During steady state, the central cornea is sterile and swabs routinely yield no viable bacteria. In fact, even in cases of infection-caused corneal ulcers, cultures routinely yield nothing.
According to the American Academy of Ophthalmology, waking up with some sticky or crustiness around the eyes is normal. This discharge is the result of not blinking during the night and various debris and mucus depositing at the corners of the eyes.
Dirt and debris near the eyes: When the eyes have accumulated debris around them, such as when a person sleeps without cleaning off mascara, they can become irritated. The eyes will produce extra mucus that can then get trapped in the eyes and on the eyelashes.
Most of the time, eye boogers are a normal part of waking up. They mean that your body is doing its job. But some conditions cause extra discharge, mucus, or irritation.
The eye sits in a protective bony socket called the orbit. Six extraocular muscles in the orbit are attached to the eye. These muscles move the eye up and down, side to side, and rotate the eye.
The muscles that move your eyes are the fastest and strongest muscles in your body, relative to their function. They're 100 times more powerful than necessary. After the brain, your eyes are the second most complex organ in your body.
Saccades or saccadic eye movements are very fast jumps from one eye position to another. The velocity of saccades can be as large as 1000 deg/sec.
The human eye is a sensory organ, part of the sensory nervous system, that reacts to visible light and allows humans to use visual information for various purposes including seeing things, keeping balance, and maintaining circadian rhythm. The eye can be considered as a living optical device.
When light hits the retina (a light-sensitive layer of tissue at the back of the eye), special cells called photoreceptors turn the light into electrical signals. These electrical signals travel from the retina through the optic nerve to the brain. Then the brain turns the signals into the images you see.