The Human Eye

The iris is a part of the eye that is responsible for the size and shape of the pupil which allows light to reach the retina and is often known or seen as the eye color. The word itself is from the Greek word 'rainbow' as they hold many colors themselves.

The retina converts the light into an electric impulse in which the optic nerve carries these impulses to the brain. Eye color on the other hand is created by the type of pigment in the iris which is caused by multiple inheritance of the parents genes for eye color.

The human eye can note up to ten million colors including differentiation and personal depth.

Irritation

We all have had that stinging itch countless of times and its nothing more than a natural problem experienced in all age groups. The symptoms can vary and there isn't a certain definition as to why they occur. It's nothing more than a small or severe defense mechanism for when bacteria or other substances enter our eyes.

The eye isn't a perfect circle. Instead, it takes on oval or donut like shape which is more likely known as a two-piece unit. The cornea, the smaller unit, is linked to the sclera, the larger unit.

It has three coats that surround the transparent structure. The outside holds the cornea and sclera; the middle has the iris, ciliary body, and choroid; and the inside treasures the retina.

Movement

Everyday, we wander from one place to the next and our eyes intake every bit of information from every twist and turn. The brain itself is too slow to process these images all at once and takes up to a few degrees per second to understand what passes by the retina. It is compensated by moving the eyes with the motion of the head as well.

Movements of the eye are a necessity for visual perception. Having two eyes complicates some cases of the brain which must accurately point and control them in the right direction. Failure to do this may cause double vision.

The movement of muscles are caused by skeletal motions. This isn't the same cause of moving the eyes which makes it an exceptional difference.

Conditions

There are many eye conditions that can be caused simply due to age which, as we progress, can cause the degeneration of our vision in both eyes itself. Here's just some conditions that people can get:

• Amblyopia, otherwise known as a lazy eye, is a problem developed during childhood where one eye sees much more clearly than the other.
• Astigmatism is an inability to focus in on light properly which makes vision blurry or fuzzy. It results in either contacts or glasses.
• A black eye is a swelling and change in pigment around the eye when injured from a heavy blow upon the face.
• Blepharitis is a swelling of the eyelids (sensitive eyes) that cause itching and a rather uncomfortable feeling.
• Cataracts are the clouding of the eye lens and makes it hard for the passage of light to properly settle through.
• Chalazions are often mistaken as styes as they are bumps along the eyelashes or lids. They are merely just oil glands that are blocked and thus resulting in a small swelling. It isn't caused from infection.
• Conjunctivitis, rather known as pink eye, is usually caused by a bacterial infection, virus, or allergy. It's nothing more than an inflammation on the clear layer part of your eye.
• Corneal abrasion's are scratches upon the clear part of the front eye and often result in pain and discomfort.
• Diabetic retinopathy can cause the loss of vision when blood vessels disintegrate due to high amounts of blood sugar damaging the vessels.
• Diplopia or double vision must require immediate attention and can be caused for and by various reasons.
• Dry eyes have two causes. Either the tears are of poor quality or they aren't being produced enough. It can be caused by lupus or Sjögren's syndrome.
• Glaucoma is the pressure within the eye that slowly reduces vision. It can cause the loss of peripheral vision and may not be caught for years undetected at a time.
• Hyphema is naturally caused by a trauma in which the bleeding of the eye behind the cornea occurs.
• Keratitis begins when a germ enters the corneal abrasion and is an infection of the cornea itself.
• Optic neuritis is a painful vision loss of one eye that occurs from an overacting immune system.
• Retinal detachment is when the retina loosens itself from the back of the eye and are commonly caused by trauma or diabetes.
• Retinitis is an inflammation of the retina that can be a long term medical condition from a viral infection.

Blindness

It can be caused from neurological or physiological problems lacking peripheral vision. Complete blindness is the loss of light perception and is a severe visual impairment.

Common causes include:

• Cataracts
• Glaucoma
• Age relation
• Corneal opacity
• Diabetic retinopathy
• Childhood blindness
• Trachoma

On the other hand, color blindness is a deficiency in which a person has difficulty perceiving a set amount of color patterns and is a sex linked condition that follows the X chromosome. It may also effect the eye through chemical or physical damage of the optical nerve.