If you’ve ever visited an eye specialist, you’ve probably been told that the cornea is the outermost layer of the eye. It is transparent and dome shaped, and contains five layers. There are many amazing facts about this part of your eye and how it is structured, some of which you may be completely unaware.
What Eye Specialists Know About the Structure & Function of the Cornea
Although the cornea seems to lack substance because it is clear and transparent, your eye specialist would tell you that, realistically, it’s a highly organized group of proteins and cells. However, in order to refract light appropriately, the cornea must remain transparent. In other words, it must be free of any opaque or cloudy areas if you want to see images properly at all times. You may be surprised to know that your corneal tissue is arranged in five distinct layers, and each one has a specific function.
The epithelium is the outermost region of your cornea and makes up approximately ten percent of the tissue’s thickness. The primary functions of the epithelium layer include blocking the passage of foreign material, such as water, dust, or any objects that do not belong on the surface of your eye. Located directly below the bottom epithelium membrane is a clear layer of tissue that is usually referred to by an eye specialist as Bowman’s layer. This part of your cornea is primarily made up of strong protein fibers, most of which have a collagen base.
Under the Bowman’s layer is the stroma, and this comprises approximately 90 percent of the entire cornea. About 74 percent of this layer is water, while 16 percent of the layer is collagen. The latter is what gives your cornea its strength, form and elasticity.
The Descemet’s membrane is located underneath the stroma, and is a strong, yet thin, sheet of tissue that primarily functions as a protective barrier against injury and infection. Similar to the stroma, the Descemet’s membrane is comprised of collagen fibers, but they contain a type of fiber that is different from those seen in the stroma. The Descemet’s membrane quickly regenerates itself following an injury. The endothelium is your cornea’s very thin, innermost cornea and plays an important role in keeping the cornea clean.
Because the cornea is as smooth and clear as glass, but durable and strong, it contributes to total eye function in several ways: it focuses and controls the entry of light, and shields your eyes from dust, germs, and water. Below are five intriguing facts you may hear from an eye specialist about the fascinating cornea:
1. Cornea Contains No Blood Vessels
The cornea is the only area of the human eye that does not have a blood supply. Unlike most body tissues, eye specialists can verify that the cornea contains no blood vessels. To refract light properly, the cornea must remain transparent, and therefore the presence of even a tiny blood vessel can inhibit this process.
Most parts of the eye must be nourished and protected from infection by a fresh supply of blood. However, the cornea obtains nourishment from a fluid called aqueous humor instead. It is also nourished by your natural tears. Aqueous humor is a substance that coagulates in the chamber behind the eye, as well as in its anterior portion. If you are an overall healthy person, you always have an appropriate amount of this fluid surrounding your cornea.
2. Cornea Injuries Heal at a Rapid Pace
Although not all parts of the human eye heal quickly, an eye specialist can confirm that the cornea has remarkable healing powers. Of course, as with any eye injury, proper care must be sought to ensure the best possible recovery. However, in most cases your cornea will repair itself in less than 48 hours following a scratch or other minor injury. It also copes amazingly well with abrasions or minor irritations.
If the cornea, which is by nature highly sensitive, sustains a small scratch, healthy cells immediately slide over the injured patch before your vision is affected or an infection occurs. Nevertheless, if a deep cut or scratch occurs, the cornea may be damaged to the point where vision is affected, but in most cases it is amazingly resilient and will repair itself at a fast pace. Connect with a cornea specialist.
3. The Ability to Bend Light Rays
Unless you were told by an eye specialist, you are probably unaware of the fact that the cornea bulges out at a slightly different angle than the rest of the surface of your eyeball. This bulge cannot be seen with the naked eye, and therefore you likely see a smooth, uniform appearance when you examine your eyes in a mirror.
However, the radius of curvature for the cornea is 6.5mm and 7.5mm for the internal and external surfaces, respectively. This oddity concerning its shape is actually what gives the cornea its refractive power, which is measured in something called dioptres. Eye specialists find that healthy eyes usually measure at least 45 dioptres of strength.
4. Focusing Power
Although most people think of the retina and the eye muscles when focusing is discussed, in reality it is your cornea that contributes approximately 70% of the total focusing power of your eyes. To see clearly, rays of light must be focused and redirected from the cornea and the lens of the eye to its retina in a very precise manner. For this reason, if the cornea was unable to do its job, you would only have approximately 30% of your vision.
The cornea also filters out damaging ultraviolet wavelengths from the sun. Without this protection, the retina and the lens would be severely injured from UV radiation. Of course, you should always take caution not to look directly at the sun and to wear appropriate sunglasses when outdoors. However, this natural filter is always at work and plays a major role in preventing eye damage from UV radiation.
5. Shark Corneas and Eye Transplants
Shark corneas are used in eye transplants. For reasons not yet known to eye specialists, shark corneas are very similar in structure and substance to the human cornea. However, unless you have had a cornea transplant, you will likely never discover this interesting piece of information unless an eye specialist tells you.
The eye is a complicated and intriguing part of the human body. Therefore, those who value their vision should make every effort to care for their eyes. If you suspect you may have this problem, visit an eye specialist as soon as possible. Schedule an appointment online today!
