Understanding The Eye: Anatomy

Eyes anatomySome have called the human eye the most complex organ in the body. Being such a small organ, while having so many working parts. However, when you think of all of the various functions that the eye has to do in order provide vision, you can understand why some believe it is the most complex organ in the body.

How does the Human work?

The eye works in much the same way a digital camera works.

First the cornea, which is the clear front surface of the eye, functioning much a light a camera lens, Helps to focused light.

Secondly, The Iris, working as a diaphragm of the camera, controls the amount of light that reaches the back of the eye, by automatic adjusting the size of the pupil (aperture). This results in the size of the pupil changing as the amount of light are decreased or increased.

Third, The eye’s crystalline lens is directly behind the pupil and provides further light focus. Through an accommodation, The between helps the eye focus automatically on near objects and approaching objects, similar to an autofocus camera lens.

Lastly, the light focused by the cornea ad crystalline lens, which is limited by the iris and pupil. When light touches the retina, the light-sensitive inner lining of the back o f the eye, the retina acts as an image sensor, converting optical images into electronic signals. The optic nerves the transmit these signals to the visual cortex. In which the brains controls, managing our sense of sight.

Parts of the Eye:

cornea-and-external-disease_page-bannerSclera

The sclera is a membrane of the tendon in the eye, this the white of the eye. This eye is tough, rugged and the sclera works to protect the inner part of the strive parts of the eye such as the choroid and retina. The sclera is 0.03 of an inch in thickness. Except there are four straight eye muscles appeared, where the depth is no ore than 0.1 of an inch.
The straight eye muscles are four of six eye muscles on each eye but all six control the movements of the eye.
One top of the sclera, The episclera is located. The episclera contains blood vessels that provide nourishment the sclera with oxygen and nutrients. These nourish are thus visible on the surface of the white of the eye.
Choroid

The choroid is the layer that thikn creaiting within the sclera. The choroid encompasses a network of the vessel that nourish the retinas with nutrients and oxygen. The maul and the anterior part of the optic nerve are dependent on blood supply from the choroid. Macular generation (specifically the “wet type”) is a condition that occurs when the eye experiences abnormal blood vessle growth. The state growth ins the choroid an go through the Bruch’s Membrane to the retina (know as choroidal neovascularization). SInce the choird has weaker structure, these vesels have a tendency to rupture ofr to breed, thus causing edemas.

Retina

The retina consists of the light-sensitive tissue that is located in the back of the eyeball. The retain absorbs light that ultimately is sent as visual signal to the brain. The retina has tow different types of light receptors, cones, and rods. The cones are color sensitive and located in the center of the retina and mainly absorb stronger light sources. The rods absorb softer light in black and white and are found perpial to the retain is retinal detachment. There are some common symptom are sensation of light flashes in the field of vision or partial to full vision loss that may lead to permanent vision loss if left untreated. If any of these symptoms occur immediate medical care is required.

Viterious Body

The viterous body is a gel-like substance that is clear, filling the eyeball, behind the lens. Aqueous fluid fills the space in fornt of the lens. When you age the vitreous body shrinks in volume. When there is a decrease in the size of the vitreous body, it can be leas to detachment from the retina. This however is not a dangerous condition, however can lead to complications in which the vitreous body drags along the retina, called retinal detachment.

Macula
The macula is an area of the around the fovea. These are tightly packed visual cells inside the macula enables high image rsolution or high visual accuity. Around the macular area, visual cells are not as tightly packed as within the macula itself, however if they are good enoughf ro the peripheral vision to work properly. A common eye disease that affects every age people is age-related macular degeneration (AMD). This is conitoon that is divided into two different categories. Dry or wet. Wet AMD is treatedble with drugs approved by the FDA such as Lcuentis, although the effects are worse than dry AMD often leading to mores seirous cases of vision loss. Dry is an incurable eye disease and unfortunately, is most common form of AMD.

foveaFovea

The fovea is in the central part of the macula. The visual cells located in the fovea (cones) are packed the tightest, that results in the optimal sharpness of vision. perfect of reading or watching TV. Rods are packed just outside the fovea, and are active in low light conditions. The cover covers about 5 degrees of the vision field.

a_02_cr_vis_1aOptic Disc

The optic disc is also called the optic nerve head or the blind spot. The optic disc is where the eye attaches to the optic nerves. All the visual cell nerves threads and several blood vessels have their entrance to the eyeball here. There are visual cells in the optic disc causes the appearance of a blind spot in your field of vision

Lens
The lens is where around 20 oof the eye’s 60 diopters obtain dipertic ability. Diopter is a measurement of optic power of a lenses or curved mirror. The diopters are equal to the reciprocal of the focal length measured in meters (that is, 1/meters). The reminder of the eye’s dioptric power is concentrated in the cornea. Lens enable the eye to change the focus according to different distances. This is how we can change focus from looking a bird in the sky to the tv across the living and the newspaper in your hand. The lens is attached to an a mass of many threads called zonula threads. The zone threads The zonula threads are also attached to the ciliary body the rim. This can compare this optic correlation with a bicycle wheel where the lens is the hub, the thread the spokes ,and the ciliary body, the rim.When you want to focus on a nearby object, a muscle in the ciliary body will contract to narrow in. The zonula thread will lossen up allowing the lens to contract in diameter and thicken creating increased its acuity. As people age, the flexibility of the lens will decrease. By the age of 45 the lens will have weakened to the point where reading without corrective glasses or lenses is unattainable. Cataracts are an age-related condition in which affects the lens sooner or later in everyone in some form. The most common symptom will be associated with blurry vision. Cataracts can end in removal or replacement of the lens.
optic nerveOptic Nerve

The optic nerve carries signals from the eye to different parts of the brain, in which signals are interpreted into images. The optic nerves consist of around 1,000,000 nerve threads. The optic nerves from both eyes are reconnected begin the eyes so that everything that is seen in the right field of vision is sent to the left cerable hemisphere and vice Versa.

The Pupil is basically a hole in the iris. The reason why this is black is so the layer of pigment inside the eye absorbs major parts of the light, which creates  a darker shade. In cases when people pupils appear red in photos is the retina that is reflected.

eye irisIris

The iris is the part of the eye that determines the amount of light that enters the eye. The iris sphincter muscles contract and pull with strong light. In darkens the iris opens the pupil using the dilator muscles. When focusing near objects, the pupil decreases in diameter, but will expand when looking at distant objects. A reflex was known as accommodation reflex. A smaller pupil enables better focal depth. A person eye color actually refers to the amount and type of pigment that is in his/her irs. The most common is brown, and the least common is green.

Aqueous Fluid

Aqueous Fluid or aqueous humor) fills he front part of the eye, between the cornea and lens. The fluid creates at the back of the ciliary body, then seeps through the pupil into the anterior chamber and ultimately is drained through the trabecular meshwork. The aqueous fluid primary function is to supply he corne and the lens with nutrients and oxygen. The anterior chamber is the space located between the iri and the cornea. The antitor chamber is the space located between the iris and the corna. If an imbalance occurs between fluid production and outflow, ther increase of aqueous liquid, the pressure in the eye inevitably increases. This is one of the contributing factors hat cause glaucoma.

cornea-and-external-disease_page-bannerThe Cornea

The cornea is a transparent part that is located in front of the eye, which covers the iris, pupil and anterior chamber. Around 40 of the eye’s 60 adapters are present in the cornea. The cornea is supplied with oxygen and nutrients through tear fluid and not through blood vessels. Tis also explains why the conra is s clear. Overusing contact lenses can lad to oxygen deficiency, ultimately causing the blood vessel to appear. If blood vessels grow too close to the center, it can cause partial vision loss. Refractive eye surgery to correct eye disorders such as hyperopia, myopia, astigmatism * Refractive errors usually involve surgically reshaping the cornea using laser technology. * through lasers are not always used. FDA approved procedures are PRK, Epi-LASIK, LASIK

 

The ciliary body contains the ciliary muscle, the muscle that controls the vison accommodation reflex. the cilary body alos produces aqueous fluid (aqueous humor) and is a pint of attachment for the onula threads that holds the lens

The conjunctiva is a mucous membrane that covers the sclera and the indise of the eyelids. Many of the glands that play a part in the production of tear-film are found in the conjunctiva. When the conjunctiva is irritated often due to an allergy of infections, the membrane swells, becomes uneven and causes blood vessels to expand. This is usually referred to as pinkeye.


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