...Name: Thao Vo Title: The Optics of the Eye Section 202 Monday 4:30pm – 7:15pm Course Name: Physics 246 Lab Partner’s Name: Jennifer Darlington, Hyon Hodge Date: 11/12/2012 Instructor: Dr Vermuru Word Count: 1650 Aim: The aim of this experiment is to examine a scaled up model of the human eye to understand the image formed in the eye, the optics of accommodation, nearsightedness, and farsightedness. Introduction: The basic structure of the human eye consists of cornea, natural crystalline lens and retina, as shown in Figure 1, in which the lens of the eye does little of the bending of the light rays, most of the refraction is done at the front surface of the cornea and retina plays the role of the film in a camera. Figure 1: Diagram of a human eye Accommodation is the focusing adjustment in which the muscles in the eye change the shape of the crystalline lens to change its focal length. Figure 2: Accommodation by a normal eye a) Lens relaxed, focused at infinity b) Lens thickened, focused on a nearby object Nearsightedness refers to an eye that can focus only on nearby objects. Because the far point is not infinity but some shorter distance, distant objects are not seen clearly. This defect is usually caused by an eyeball that is too long and images of distance objects are focused in front of the retina. In order to correct this defect, a diverging lens should be used as it causes parallel rays to diverge which allowing the rays to be focused at the...
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...About LASIK About LASIK surgery: LASIK is laser vision-correction in the blink of an eye . The ultimate solution to replacing contact lenses and spectacles. What is LASIK? LASIK stands for ‘Laser In-Situ Keratomileusis’ which means ‘ to shape the cornea within its layers with the use of the Excimer laser’. Hi-tech solution combining advanced computer technology with laser precision: LASIK is a skilled procedure that combines the state-of-the-art computer technology with advanced laser precision. While the earlier laser procedure viz PRK treated the surface of the cornea, LASIK treats the inner tissue of the cornea and restructures it in a manner which grains down myopia (minus power) and hypermetropia (plus power). LASIK Knowledge Centre: LASIK procedure -step-by-step: * First, the eye surgeon uses an instrument known as a microkeratome to make a thin flap of the outer layer of the cornea. * Then he folds back the flap, which remains attached on one side. * Next, he uses the cool laser light from the Excimer laser to ’ablate'‘ i.e. remove the pre-determined amount of tissue to reshape the cornea with great accuracy and corrects the individual's refractive error. * The cornea is made flatter to treat near-sightedness, and steeper to treat far-sightedness and/or more spherical to correct astigmatism. * Finally, after the laser is administered, he lays back the corneal flap in its original position, where it bonds itself instantly. * Due to...
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...“Optics and the Eye”. 1. Distinguish between somatic and special senses. 2. Explain the importance of vision in our lives. 3. Explain the importance of smell and taste in our lives. 4. With the aid of a diagram, describe the olfactory receptor cells, an olfactory glomerulus, the olfactory pathway 5. List the regions of the brain that receive information on odors transmitted through this pathway. 6. Describe the physiology of olfaction. See notes, B. Physiology of Olfaction 7. Describe the anatomy of taste receptors and the taste pathway. 8. Describe the physiology of taste. 9. Describe what you know about the genetics of taste. 10. Explain the relationship between smell, taste and flavor. 11. Draw a diagram of a sagittal section of the eye, name the parts, and summarize the function of each part. 12. Describe the accessory structures associated with the eye (eyelids, extraocular muscles etc.). 13. Draw a simple outline diagram of the neural retina, showing the arrangement of the five neural cells found in it. What are their names? 14. To your diagram, add the cells of the non-neural retina. 15. Name the glial cell found in the retina. 16. Draw a rod and a cone, showing outer segment, inner segment, mitochondria, nucleus and synapse. 17. Explain how the cornea and lens function to focus an image of the external scene on the retina. 18. Explain why everything looks blurred if you open your eyes under water, and...
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...the age of 40.1,2 There are more than 22 million Americans that are affected by cataracts.1 Cataracts are a clouding of lens in the eyes that can eventually cause vision loss.2 Cataracts can happen in either or both eyes. The eye’s lenses works just like a camera lens.1 The purpose of the lens is to focus light onto the retina to create clear vision, and to adjusts the eye’s focus.1 The lens consists of water and proteins.1 The proteins in the lens are arranged in a certain way that allows light to pass through the lens and to let the lens keep clear.1 When people start to age, the proteins in the lens start to clump up and start to cloud certain areas of the lens.1 This causes vision loss. There are different factors that can cause cataracts. The factors are diabetes, ultraviolet radiation, hypertension, obesity, smoking, previous eye surgery, family history, high myopia, significant alcohol consumption, and previous eye injury.1...
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...Opacity of the lens that distorts the image projected on to the retina and which can progress to blindness. Types of cataracts include: * * Senile * Congenital * Traumatic * Secondary Anatomy and Physiology: * Cornea - It is the outermost lens of the eye, controlling and focusing incoming light. It shields the rest of the eye from dust, germs and other harmful foreign matter. * Sclera - The visible white part of the eye.The sclera is a protective layer that maintains the global shape of the eye and offers resistance to internal and external forces. * Iris - The part of the eye which is colored. The iris is a diaphragm that regulates the expansion and contraction of the pupil to allow in the required amount of light. * Choroid – contains blood vessels and supplies nutrients to the retina. * Ciliary Body - Connects the choroids with the iris and secretes aqueous humor that helps the eye its shape. * Retina - The retina is the link between the brain and the light entering the eye. The retina is a complex structure able to convert the impacting light into nerve impulses that are then sent to the brain along the optic nerve. * Rods are photoreceptors responsible for peripheral vision and function at reduced levels of illumination. * Cones function at bright levels of illumination and are responsible for color vision and central vision. * Vitreous body – transmits light and gives shape to the posterior eye. * Vitreous...
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...I. Introduction The human eye is one of the most important things to a person and thus has many forms and protection. Do you know that there is also physics in your eyes. The human eye is a complex anatomical device that remarkably demonstrates the architectural wonders of the human body. Like a camera, the eye is able to refract light and produce a focused image that can stimulate neural responses and enable the ability to see. The human eye is an adjustable lens system consisting out of two focussing elements and a light receptor sysytem. In this term paper, we will focus on the physics of sight. We will use our understanding of refraction and image formation to understand the means by which the human eye produces images of distant and nearby objects. Additionally, we will investigate some of the common vision problems that plague humans and the customary solutions to those problems. Each part of the eye plays a distinct part in enabling humans to see. In the body of my term paper, we will know the important parts of our eye. And how they are related with each other. We will also know the relation of the human eye with the camera. II. Body There are imporant parts of the eye, if they will be damaged, your eyesight will not function. The eye is essentially an opaque eyeball filled with a water-like fluid. These are the parts that can be located in our eyes: the cornea, the iris and pupil, the lens, the retina, the fovea centralis, and the optic nerve. In...
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...HISTORY OF THE CORRECTIVE LENS And how they correct vision 11/16/2012 We generally take for granted one of the world’s most important inventions – spectacles. Imagine what life would be like not being able to see images clearly or sharply. The early history of image magnification is shrouded with mystery. In ancient times, someone noticed that convex-shaped glass magnified images. Around the year 1000 A.D. crude technology began to develop reading stones which were nothing more than simple magnifiers. English Franciscan Friar Roger Bacon discovered that letters could be seen better and larger when viewed through less than half a sphere of glass. Bacon's experiments confirmed the principle of the converging lens. Bacon recognized that this could assist weak eyes or the vision of aged persons. Early recorded evidence demonstrates that glasses first appeared in Pisa, Italy about the year 1286. Each crude lens or crystal was surrounded by a frame and given a handle. They were worn on the face like glasses you see today but held in front of the eyes while reading. Essentially someone took two existing mounted stones and connected them with a rivet. Benjamin Franklin in the 1780's developed the bifocal. Later he wrote, "I therefore had formerly two pairs of spectacles, which I shifted occasionally, as in traveling I sometimes read, and often wanted to regard the prospects. Finding this change troublesome, and not always sufficiently ready...
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...Lens Crafter Case Study Dawnmarie E. Gaines Professor: Gary Reinke Business 430- Operations Management January 14, 2016 INTRODUCTION Lens Crafters was founded in 1983 by Dean Butler, a 38-year-old who had previously worked at Procter & Gamble (lens crafter 1983). A knowledgeable marketer, Butler had managed the Ivory liquid, Cheer laundry detergent, and Folger's instant coffee brands for the venerable Cincinnati consumer goods company. Lens Crafters has always been focused on providing better vision health for the customers who visit their stores (Lens Crafter 1983). But not everyone has access to vision care. Since 1988, Lens Crafters has supported One Sight, an independent nonprofit; in helping provide quality eye care and eyewear to underserved communities worldwide (Lens crafter 1988). Lens Crafters continually invests in new technologies to improve care for your eyes, customize your prescription, and help select the right frames for you. Associates at Lens Crafters are trained to provide you with personalized eye health service throughout your experience (Lens Crafter 1983). There love of eyes and higher standard of quality have made Lens Crafters a leader in vision care for over 30 years. Lens Crafter Operations Strategy Strategy is considered as the general view or perspective that the organization follows so as to do its operations and to attain competitive edge in the market (lens crafter history). The strategy takes into consideration the purpose, goals...
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...Vistakon had grown from a specialty manufacturer with $20 million in annual sales to a market leader in the contact lens industry with over $250 million in annual sales. Gary Kunkle had succeeded Walsh in 1993 and the two were meeting in early 1995 to review the performance of 1 Day Acuvue contact lenses in the western regional rollout. The world’s first daily disposable contact lens, 1 Day Acuvue was designed to be worn for one day and then discarded. A national launch decision needed to be made, but based on the test market and the western regional results, there were lingering concerns regarding product positioning, pricing, promotion, advertising and trade support. Vistakon was an autonomous and highly entrepreneurial division in J&J’s renowned decentralized organization, and Gary Kunkle knew the decision was his to make. However, he also knew that J&J expected product excellence and market success. As Kunkle considered his options, he recalled a remark made by Walsh, We need to be careful that we don’t allow our past success to undermine our future growth. Big companies tend to be too cautious. Now that Vistakon has a major existing business to protect, it runs the risk of becoming overly analytical and moving too slowly. The Eye Care Industry Approximately 146 million people in the United States required corrective lenses, with the number of lens wearers increasing slowly with the aging of the overall U.S. population. The need for corrective lenses created...
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...microscopes are effectively just tubes packed with lenses, curved pieces of glass that bend light rays passing through them. The simplest microscope of all is a magnifying glass made from a single convex lens, which typically magnifies by about 5–10 times. Microscopes used in homes, schools, and professional laboratories are actually compound microscopes and use at least two lenses to produce a magnified image. There's a lens above the object (called the objective lens) and another lens near your eye (called the eyepiece or ocular lens). Each of these may, in fact, be made up of a series of different lenses. Most compound microscopes can magnify by 10, 20, 40, or 100 times, though professional ones can magnify by 1000 times or more. For greater magnification than this, scientists generally use electron microscopes. To see a fly's eye in detail, our own eyes would need to be able to process details that are millimeters divided into thousands—millionths of a meter (or microns, as they're usually called). To study a fly's eye really well, we need it to be maybe 10–100 cm (4–40 in) across: the sort of size it would be in a nice big photo. That's the job a microscope does. Using very precisely made glass lenses, it takes the minutely separated light rays coming from something tiny (like a fly's eye) and spreads them apart so they appear to be coming from a much bigger object. The optical or light microscope uses visible light transmitted through, refracted around, or reflected from a specimen...
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...appear blurry. Myopia develops in eyes that focus images in front of the retina instead of on the retina, which results in blurred vision. This occurs when the eyeball becomes too long and prevents incoming light from focusing directly on the retina. It may also be caused by an abnormal shape of the cornea or lens. Myopia can affect both children and adults. Some of the signs and symptoms of myopia include: * Headaches * Eyestrain * Squinting * Difficulty seeing distant objects, such as highway signs Myopia can be corrected with eyeglasses and contact lenses and surgery. 2. Hyperopia/farsightedness: Hyperopia, also known as farsightedness, is a common type of refractive error where distant objects may be seen more clearly than objects that are near. Hyperopia develops in eyes that focus images behind the retina instead of on the retina, which can result in blurred vision. This occurs when the eyeball is too short, which prevents incoming light from focusing directly on the retina. It may also be caused by an abnormal shape of the cornea or lens. Hyperopia can affect both children and adults. The symptoms of hyperopia vary from person to person. But some common signs and symptoms of hyperopia are very similar to Myopia which are: * Headaches * Eyestrain * Squinting * Blurry vision, especially for close objects 3. Astigmatism: Astigmatism is a common type of refractive error. It is a condition in which the eye does not focus light evenly...
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...3D Printed Glass for the Correction of Eye Defects Shyam Vignesh Perumal1 Affiliations: 1 Department of Chemical and Biomedical Engineering, University of South Florida Abstract: We propose to use 3D printing for fabrication of glasses providing image correction for myopia. Since myopia commonly known short-sightedness is a condition characterized by the light focusing in from of retina instead of on its surface, concave lenses are typically used for correction. Unfortunately price of the glasses is high and in developing countries, people cannot afford buying them. We propose to use 3D printing technology for making out glasses for low cost. Additionally 3D printing gives flexibility of the design and allows adding more sophisticated components...
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...Environmental Health Perspectives Vol. 44, pp. 1-8, 1982 The Eye and Visual Nervous System: Anatomy, Physiology and Toxicology by Connie S. McCaa* The eyes are at risk to environmental injury by direct exposure to airborne pollutants, to splash injury from chemicals and to exposure via the circulatory system to numerous drugs and bloodborne toxins. In addition, drugs or toxins can destroy vision by damaging the visual nervous system. This review describes the anatomy and physiology of the eye and visual nervous system and includes a discussion of some of the more common toxins affecting vision in man. Anatomy of the Eyeball The eye consists of a retinal-lined fibrovascular sphere which contains the aqueous humor, the lens and the vitreous body as illustrated in Figure 1. The retina is the essential component of the eye and serves the primary purpose of photoreception. All other structures of the eye are subsidiary and act to focus images on the retina, to regulate the amount of light entering the eye or to provide nutrition, protection or motion. The retina may be considered as an outlying island of the central nervous system, to which it is connected by a tract of nerve fibers, the optic nerve. As in the case of the brain and the spinal cord, the retina is within two coats of tissue which contribute protection and nourishment. On the outside of the sphere, corresponding to the dura mater, a layer composed of dense fibrous tissue serves as a protective envelope, the fibrous...
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...A cataract is a “clouding of the lens in the eye that affects vision.” 1 As I observed in my job shadow with Dr. Zeiter, many patients needing cataract surgery were elderly and this observation is supported by fact. Cataracts occur more often as people get older. A shocking statistic holds that by age 80, over a half of all Americans have a cataract or have had cataract surgery.2 Rarely, cataracts occur at birth, or are developed at a younger age by “ physical, drug, or chemical injury.” 3 How do cataracts affect vision? Normally, light passes through the lens to the retina, which is tissue towards the back of the eye, and that light is basically transformed into nerve signals sent to the brain. There, the image will be clear if the lens...
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...on a poor fit. Perhaps you might realize that you're simply lacing them up too tight. Likewise, similar reasons exist for painful eyewear glasses. Eyewear pain is either caused by its physical fit on your head or by its effect on your vision. Here are three common types of eyewear pain and their causes: Headache, Blurred Vision, or Tired Eyes Headache, blurred vision, or tired eyes are symptoms of eye strain. The facial muscles surrounding the eyes as well as those responsible for eye movement will become fatigued when the eyes fixate on something such as a computer screen for too long. This fatigue is similar to that when standing stationary on your feet for too long. The muscles in...
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