The human eye is a complex sense organ that not only allows clear vision, but also to perceive depth, size, color, and details of a stationary or moving object. As Figure 1 shows, it is made up of the eyeball and the accessory structures which are the eyelids, extraocular muscles (EOMs) and the lacrimal apparatus. The eyeball is composed of the eyeball wall and the eyeball content that includes the crystalline lens, vitreous body, and the aqueous humor. While the eyeball wall is made of three main layers surrounding the different anatomical structures. An outer layer called the fibrous tunic and is formed of the cornea and the sclera. The middle layer is known as the vascular tunic (Uvea) and consist of the iris, choroid, and ciliary body. While the third layer is known as the nervous tunic and constitutes the retina. (McCaa, 1982) (Duong, 2015) Figure 1: Overview of the Ocular Structures
1.2. Physiology of the Ocular Structures:
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The cornea and the crystalline lens act together to focus the light on the retina and provide vision following a specific procedure as shown in figures 2 and 3. It begins when light enters the eye through the cornea which is the transparent, prolate, front refractive surface of the eye with 43 Dioptric power. After that, the light is refracted to pass through the pupil where its amount is regulated by the constriction or dilation of the sphincter or dilator muscles of the iris, respectively. Then the light will pass through the second refractive surface of the eye which is the crystalline lens with 20 Diopters of power and having a transparent biconvex shape, the light is refracted onto the retina. (Garrity, 2015) (Vail,
In Barre Toelken’s essay “Seeing with a Native Eye: How Many Sheep Will It Hold?”, the ways in which one culture perceives another and the criteria used to make judgements are explored. Toelken states “I think I can say something about how differently we see things, envision things, look at things, how dissimilarly different cultures try to process the world of reality” (10-11). In essence, Toelken is alluding to how different cultures will interpret their experiences and rituals according to their own set of beliefs and practices. This complicates situations in which the experiences or rituals are not comparable across cultural lines; someone will always be missing an aspect or a significant purpose if they do not try to “see it as much as possible with the ‘native eye’” (12). In other words, one must immerse themselves in the culture they are analyzing, while not comparing it to their own cultural experiences. One must consider all the cultural implications of that specific culture when wondering why things are done a certain way. Toelken provides
In the editorial cartoon, Our Eyes Secure Your Safety, is dealing with giving up rights and freedoms. The cartoonist has presented the perspective that rejecting collectivism can be ineffective, which is shown by people walking around surrounded by video surveillance. The author uses irony of large eyes in the sky with big bold letters that states the quote our eyes secure individuals' safety to show the ideas presented on portraying negative notion on the subject of which is surrendering our rights and freedoms for more collective security; he/she also stresses the idea of individualism. The individualist view of a society without high government involvement was furthermore illustrated in the source by the idea of all the eyes, gloominess
The eye is an important sensory organ for vision which houses a sensitive optical apparatus in a relatively isolated tissue compartment. Eye is essentially made of three layers: (1) sclera, (2) uveal tract, and (3) retina with each of these layers performing intricate duties which ensure proper functioning of the eye.
Myopia is a condition in which visual images come into focus in front of the retina of the eye. This condition causes objects at a distance to appear blurry, while objects nearby are seen clearly. If not severe, myopia can be treated with contacts or glasses. Other treatments for myopia include photoreactive keratectomy (PRK), LASIK, and orthokeratology. Degenerative myopia is a quick progression of myopia and leads to complete loss of vision. The treatment for degenerative myopia is a combination of medication and laser surgery.
Dissecting the cow’s eye helped us to see all the different parts of the cow eye and see how they work and where they are in the eye.
The four main components of the eye that are responsible for producing an image are the cornea, lens, ciliary muscles and retina. Incoming light rays first encounter the cornea. The bulging shape of the cornea causes it to refract light similar to a convex lens. Because of the great difference in optical density between the air and the corneal material and because of the shape of the cornea, most of the refraction to incoming light rays takes place here. Light rays then pass through the pupil, and then onto the lens. A small amount of additional refraction takes place here as the light rays are "fine tuned" so that they focus on the retina.
Fluid circulating inside the front portion of the eye is produced by a structure called the ciliary body, which is located behind the iris. This fluid moves through the opening of the pupil, passes into the space between the iris and the cornea, and drains out of the eye through a tissue called the angle. With glaucoma, the passing of fluid through the angle is either reduced or suddenly stops, and amounts of fluid inside the eye increase. This high fluid pressure hurts the nerve fibers and the eye's optic nerve and causes blind spots. It may lead to blindness in some cases.
of the eye, this is what gives form to the eyeball. The vascular tunic has three
An inspection of the modern animal phyla will reveal that eyes are just as diverse as they are complex. Some organisms like the rag worm have pigmented cup eyes while other like he box jellyfish have two lens eyes and two pairs of pigment pit eyes. To account for the diversity in eye structure, we must first examine the eye ‘prototype’, the original structure that was acted upon by evolution. The simplest organ that can be considered an eye is composed of a single photoreceptor cell and a single pigment cell, without any lens or other refractive body (Arendt, 2003). Such organs are know as eyespots, and...
Our eyes are an incredible and incredibly complex organ. We are able to look at and around our surrounding environments and dynamically adjust as needed. The camera can be used as an analogy to the eye and visual system, though it should be noted that there are limitations such as, cameras only capture a single still image (from that perspective, perhaps what we see is more akin to that of a video camera). The table below explains how individual components of the eye can be compared to individual components of the camera and their roles in each system.
The eyes are supposed to be windows into the soul--here I see stubborn resentment, fear, hurt, dull lifelessness and simply the question "Why?"
The third eye can also be considered as an organ “beyond.” It is composed of your brain, including all the other
Have you ever wondered why the sky is blue. Often times I find myself looking up on a clear day, pondering over that question? Why isn’t it green, or red or pink for even that matter. Every day, the human eye blinks more than 23,00 times. The human eye is a complicated organ that performs one of the most important tasks for our body. There are many questions about the eye however. What function do they perform? What happens if we don’t take care of them? How exactly do they work together to help us form images? Exactly how far can they human eye see?
As further protection, the eyelids automatically close when an object suddenly moves close to the eye.Parts Of the EyeThe eye is made of 3 coats, or tunics. The outermost coat consists of the cornea and the sclera. The middle coat contains the main blood supply to the eye and consists of the choroid, the ciliary body, and the Iris. The innermost layer is the retina.Cornea and ScleraThe Sclera, or the white of the eye, is composed of tough fibrous tissue. On the exposed area of the eye the scleral surface is covered with a mucous membrane called the conjunctiva.