The human eye is an organ that captures light and sends signals to the brain along the optic nerve. Perhaps one of the most complex organs in the body, the eye is made up of several parts, with each individual part contributing to your ability to see.
The cornea is a transparent domed structure in the front of the eye. It gives the eye two-thirds of its power of focus or refraction. One third is produced by the inner lens.
Like a camera lens, the cornea helps focus light that enters the eye onto the retina.
The cornea is also full of nerves that alert us to irritations that could damage our vision and eye health. And the cornea is prone to injury. Common injuries to the cornea include "scratching" the surface of the cornea, known as abrasions. Minor corneal abrasions usually heal on their own, but deeper injuries can cause pain and sometimes scarring of the cornea.
A corneal scar can cause corneal clouding , which can affect your vision. If you scratch your eye a lot, be sure to see an optometrist. An ophthalmologist can examine the cornea with a slit lamp biomicroscope.
Another common corneal ailment includes contact lens complications, especially corneal ulcers. An ulcer is a wound on the surface of the cornea caused by bacteria, often caused by poor contact lens hygiene; Sometimes the virus can cause corneal ulcers, such as the herpes virus (the one that causes cold sores on the lips), which 90% of people have on their bodies.
The pupil is the opening or opening that is in the center of the iris of the eye. The pupil controls the amount of light that enters the eye. The size of the pupil is controlled by the dilator and sphincter muscles of the iris.
The function of the pupil is very similar to opening a camera, which lets in more light for greater exposure. At night, our pupils dilate to let in more light and improve vision.
In humans, the pupil is round. Some animals have pupils with vertical slits and others horizontal. The pupils appear black because the light that enters the eye is absorbed mainly by the tissues within the eye.
The iris is the colored part of the eye that controls the amount of light that enters the eye. This is the most visible part of the eye. The iris is located in front of the lens and separates the anterior chamber of the eyeball (everything that is in front of the human lens) from the posterior chamber (everything that is behind the human lens).
The iris is part of the uveal tract, the middle layer of the wall of the eye. The uveal tract includes the ciliary body, the structure of the eye that secretes a clear fluid called aqueous humor.
The color of the iris depends on the amount of melanin pigment in the iris. A person with brown eyes has the same melanin pigment color as a person with blue eyes. However, the blue eye pigment is much less.
The lens is a transparent structure in the eye suspended just behind the iris that focuses light rays on the retina. The small muscles attached to the lens can change its shape, allowing the eye to focus on near or far objects.
Over time, the lens loses some elasticity. This causes the eye to lose some of its ability to focus on nearby objects. This condition is known as presbyopia and generally causes reading problems around the age of 40.
A cataract is a clouding of the lens that often occurs with aging. Fortunately, cataracts grow slowly and may not affect your vision for several years.
By the age of 65, more than 90% of people have cataracts. Cataract treatment includes surgical removal of the cloudy lens and its replacement with an implantable intraocular lens.
Aqueous moisture is a clear, watery liquid located behind the cornea in the anterior chamber. Helps carry nutrients to the tissues of the eye.
It forms behind the lens and flows to the front of the eye to maintain pressure within the eye. Problems with watery fluid can lead to eye pressure problems, such as glaucoma .
The vitreous humor, adjacent to the retina, makes up most of the eye. It is a jelly-like substance that fills the inside of the eye.
The vitreous humor, which is made up mostly of water, shapes the eye. It is made up of water, collagen, and protein and contains cells that help keep it clean.
With age, the vitreous becomes less hard. This fluid change is what makes us see floating objects, especially when looking up at empty walls or the sky. This change sometimes brings them closer to the retina.
If the pulling force becomes strong enough, the vitreous can detach from the retina. This is called a posterior vitreous detachment, as it usually occurs at the back of the eye. If this occurs suddenly and is accompanied by many flare-ups, it may indicate that you have caused a retinal tear, and it is important to assess it immediately.
The retina , located inside the eye, is the light-sensitive area at the back of the eye on which the lens focuses the image, making vision possible. The retina is made up of 10 very thin layers. Within these layers are rods and cones that are used to define color.
The retina is very fragile. Retinal detachment occurs when the retina detaches from other structures in the eye. This usually occurs during contact sports or as a result of injury. Retinal detachment is a serious injury that requires the immediate attention of an ophthalmologist.
The whites of the eye are more commonly known as the "white of the eye." Although we can only see the visible part of the sclera, it actually surrounds the entire eye.
The sclera is a fibrous sac that contains the internal mechanisms that provide vision. It also keeps the eye round.
Scleritis is an inflammation of the sclera. For some people, this can cause severe eye pain, redness, and loss of vision. It can also be associated with trauma or infection – more than half of scleritis cases are associated with an underlying systemic disease.