Structure and Functionality of Eye Submitted by Satish
Structure and Functionality of Eye Submitted by: : Satish Kumar G.
1 Definitions and Keywords 2 3 4 5 Sclera: : The sclera is commonly known as "the white of the eye. " It is the tough, opaque tissue that serves as the eye's protective outer coat. Choroid: : The choroid lies between the retina and sclera. Cornea: : The cornea is the transparent, domeshaped window covering the front of the eye(at the front of the eye, the sclera is then called cornea). Iris: : The colored part of the eye is called the iris. It controls light levels inside the eye.
1 2 Definitions and Keywords 3 4 5 Pupil: : The round opening in the center of the iris is called the pupil. Lens: : The crystalline lens is located just behind the iris. Its purpose is to focus light onto the retina. Zonules: : The lens is encased in a capsular-like bag and suspended within the eye by tiny "guy wires" called zonules. Optic Nerve: : The optic nerve transmits electrical impulse from retina to the brain.
1 Definitions and Keywords 2 3 4 5 Conjunctiva: : The conjunctiva is the thin, transparent tissue that covers the outer surface of the eye. It begins at the outer edge of the cornea, covering the visible part of the sclera, and lining the inside of the eyelids. It helps keep the eye moist. Retina: : The retina is a multi-layered sensory tissue that lines the back of the eye. It contains millions of photoreceptors that capture light rays and convert them into electrical impulses. These impulses travel along the optic nerve to the brain where they are turned into images.
1 Definitions and Keywords 2 3 4 5 Macula: : The macula is located roughly in the center of the retina, temporal to the optic nerve. It is a small and highly sensitive part of the retina responsible for detailed central vision. The fovea is the very center of the macula. The macula allows us to appreciate detail and perform tasks that require central vision such as reading. Rods and Cones: : Rods and cones are special cells that process light. The human retina contains about 125 million rod cells and 6 million cone cells, two types of photoreceptors named for their shapes. Rods help us see black and white and shades of grey. Cones help us see color.
1 Definitions and Keywords 2 3 Brain: : The brain is where the electrical signals sent from our eyes are processed into vision. Orbital Muscles: : Six muscles are in charge of eye movement. Four of these move the eye up, down, left and right. The other two control the twisting motion of the eye when we tilt our head. 4 There are six muscles which control the movement of the eye. Details given in concept details part II. 5
1 2 3 4 5 • Source: : http: //www. lighthouse. org/medical/how-the-eye-works/
1 This animation has two parts. 2 3 4 5 Part I is about the structure of eye. This part gives the detials of different structures(parts) of eye and more about them. Part II is about the functionality of eye. This part explains how the parts of eye function and how the images are formed. And also about eye movements.
details : : Part I 1 Concept * images are given only for understanding. 2 Step Number Details of the step 1 Text to be displayed Action/motion in the step The human eye is one of the most complex human organs in the body. The eye aids in almost every activity that people participate in. Displays the Human eye model. It automatically rotates itself. (so the user can see the outer structure of eye) 2 This step gives the user to select a part of eye to learn more about the part. This step links to next 11 steps. Several structures compose the human eye. You can click on the names of each of these structures to learn more about them. In this step The model of cross section of eye comes. So user can select a structure to learn more about that. 3 4 5 Image/Diagram*
1 2 3 4 5 Step Number Details of the step Image/Diagram* Text to be displayed 3 -14 These steps give the user more information about the structure of the components of human eye. Each step gives details about a structure(part). When user See the section clicks on a Definitions and structure(part) Keywords. of eye. Then the user can see the zoom of that part as a pop up. (A new model) Action/motion in the step A new model pops up from the model of step 2(in the same window only). Now the user can see both the models(cross secton and of that structre) And the text contains more about that particular structure. When user chooses another structure. The previous poped up model will be colsed automatically and new pop up comes.
Concept details: : Part II 1 • 2 This part explains how the image is formed in side the eye(on retina) and how it sends impulses to brain through optic nerve and also about the eye movement. • When user comes to this part, the animation will be played for image formation part to give him/her an idea about how the light reaches our lens and image formed on retina and how it sends signals to brain and how brain reacts. 3 • Later the user can change distance of the object to see how eye responds depending on object distance. • Next step explians the eye movement and how orbital muscles control the movement of eye. • The user can also play around with these muscles to see the movement of eye. • The text displayed will be the concept of image formation and eye movement. (The theory is given in next subsequent slides). 4 5
1 Part II Contd. . . 2 • Light waves from an object enter the eye first through the cornea. The light then progresses through the pupil. • Fluctuations in incoming light change the size of the pupil. When the light entering the eye is bright enough, the pupil will constrict (get smaller), due to the pupillary light response. • Initially, the light waves are bent or converged first by the cornea, and then further by the crystalline lens, to a nodal point located immediately behind the back surface of the lens. At that point, the image becomes reversed and inverted. • The light continues through the vitreous humor, the clear gel that makes up about 80% of the eye’s volume, and then, ideally, back to a clear focus on the retina, behind the vitreous. The macula provides the best vision of any location in the retina. If the eye is considered to be a type of camera, the retina is equivalent to the film inside of the camera, registering the tiny photons of light interacting with it. 3 4 5
1 Part II Contd. . . • 2 Within the layers of the retina, light impulses are changed into electrical signals. • Then they are sent through the optic nerve, along the visual pathway, to the occipital cortex at the posterior (back) of the brain. Here, the electrical signals are interpreted or “seen” by the brain as a visual image. 3 • Actually, then, we do not “see” with our eyes but, rather, with our brains. Our eyes merely are the beginnings of the visual process. Source: http: //www. howard. k 12. md. us/res/eyes/howeyeswork. html 4 5
1 Part II Contd. . . 2 • 3 • 4 5 Six muscles that are responsible for eye movement. Four of the orbital muscles move the eye up, down, left, and right. The other two control the twisting motion of the eye when the head is tilted. The movement of eye is very confusing to understand only from theory. Source: : wikipedia
1 Part II Contd. . . 2 3 4 5 • Each eye has six extraocular muscles (EOM) that bring about the various eye movements: Lateral rectus(LR) Medial rectus(MR) Inferior rectus(IR) Superior rectus(SR) Inferior oblique(IO) Superior oblique(SO)
Part II Contd. . . 1 • MR: * moves the eye inward, toward the nose (adduction) 2 • LR: * moves the eye outward, away from the nose (abduction) • SR: * primarily moves the eye upward (elevation) 3 * secondarily rotates the top of the eye toward the nose (intorsion) * tertiarily moves the eye inward (adduction) 4 • IR: * primarily moves the eye downward (depression) 5 * secondarily rotates the top of the eye away from the nose (extorsion) * tertiarily moves the eye inward (adduction)
1 Part II Contd. . . 2 • SO: * * primarily rotates the top of the eye toward the nose (intorsion) * secondarily moves the eye downward (depression) * tertiarily moves the eye outward (abduction) 3 • 4 IO: * primarily rotates the top of the eye away from the nose (extorsion) * secondarily moves the eye upward (elevation) * tertiarily moves the eye outward (abduction) 5
Part II Contd. . . 1 Source: : wikipedia 2 3 4 5
1 2 3 4 5 Interactivity and Boundary limits Interactivity option number Details of interactivity 1 2 Image /Diagr am Text to be displayed Boundary limit User can select the light values to see the change in size of pupil. The pupil gets wider in the dark but narrower in light. When narrow, the diameter is 3 to 4 millimeters. In the dark it will be the same at first, but will approach the maximum distance for a wide pupil 5 to 9 mm. We will provide different light conditions. (v ery bright, normal, dark, very dark etc. , ) User can change the distance of object from eye to see the effect of lens. Humans focus by changing the shape of the lens. When viewing a distant object, the lens is flat. When focusing on a close object, the lens becomes almost perfectly round. The human eye can see an almost unlimited distance. But in this animation we can limit it , because we are using this only for understandi ng.
1 2 3 4 5 Interactivity and Boundary limits Interactivity option number Details of interactivity 3 The user can play around with these muscles to find out how the eye movement changes or he can rotate the eye to check how the muscles work. Image /Diagr am Text to be displayed The eye movement is controlled by 6 extraocular muscles. 4 of them move the eye up, down, right and left. Other two control the twisting motion of when head is tilted. Boundary limit
1 Questionnaire 1. How the radius of lens changes when distance of object increases? Answers: a) Increases b) Decreases 2 d) No change 2. What is the part of the eye that lies between sclera and retina? Answers: a) Pupil 3 c) Becomes double b)Macula c)Choroid d)Zonules 3. Which type of photoreceptor is most sensitive to bright light and color? Answers: a) Idospin b) Rodospin c) Cone d) Rod 4. If the amount of light is increased, The pupil? 4 Answers: a) Constricts c)Distorts d) Accommodates 5. Which muscle primarily moves the eye upward? Answers: a) MR 5 b) Dilates b) SR c) SO d) IO
1 2 Links for further reading http: //www. tedmontgomery. com/the_eye/index. html http: //www. lighthouse. org/medical/the-anatomy-of-the-eye/ 3 http: //en. wikipedia. org/wiki/Muscles_of_orbit 4 5
Thank you
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