Getting started: Work in group and answer the questions Task (Group and 2): Use the key words to label the parts of the eye Key words: Lens; Cornea; Iris; Pupil; Sclera; Retina; Optic Nerve; Ciliary Muscle; Suspensory Ligament Getting started: Work in group and answer the questions Task (Group and 4): Key words: Lens, Cornea, Iris, Pupil, Sclera, Retina, Optic Nerve, Ciliary Muscle, Suspensory Ligament Warmer: Work in group and answer the questions Task (Group and 6): : Key words: relax; contract; go slack; pull tight; allowed to become ‘fatter’; pull ‘thinner’, bent more, not bent as mush Getting started: Work in group and answer the questions Task (Group and 2): Use the key words to label Use the key words parts the of eye tothe label the of parts the eye Getting started: Work in group and answer the questions Task (Group and 4): Warmer: Work in group and answer the questions Task (Group and 6): :  The human eyes are amazing optical instruments, it helps us to see the beautiful, colourful world around us The eye may gradually lose its power of accommodation The person cannot see the objects distinctly and comfortably The vision becomes blurred Vision problems have many causes, including defective lenses, eye injury, disease, stresses, heredity, and aging Revision Myopia Hyperopia Definition Near/Far point Causes Treatment 45 Myopia Definition Can see near ojbect, near/far point cannot see far object clearly < 25 cm/ < ∞ Causes *Decrease in focal length of eye lens * Elongation of eyeball Treatment Using a concave (deverging) lens Hyperopia Can see far ojbect, cannot see near object clearly > 25 cm/ = ∞ •Great focal length of the eyelens •Short eyeball Using a convex (converging) lens 46 Question : Someone says: “When I looked, my eyes must regulate What is the defect of my eyes? A Normal eye B Myopia C Hypermetropia D Presbyopia MENU QUESTION 4: A person whose eyes 've been near sighted from he was young, when he is old his eyes are in presbyopia How can he treat his vision problems? Sometimes, a person may suffer from both myopia and hypermetropia Such people often require bi-focal lenses In the bi-focal lens, the upper portion of the bifocal lens is a concave lens, used for distant vision The lower part of the bi-focal lens is a convex lens, used for reading purposes DEVELOPMENT Eyes are the windows to the body, If your body is healthy, your eyes will be too Take care and protect your eyes [...]... length of eye lens 2. Elongation of eyeball => Parallel light rays from distant objects are focused in front of the retina c Treatment I Myopia  Myopia can be treated with glasses, contact lenses or refractive surgery By using a concave (diverging) lens A concave lens of suitable power or focal length is able to bring the image of the object back on the retina Some repair and maintenance facilities: 25 ... Wearing contact lenses 26 wearing contact lenses 27 28 29 30 II Hypermetropia (Far-sightedness) 31 II Hypermetropia II Hypermetropia a Definiton: This is also called hyperopia, or farsightedness, is a common vision problem People with hyperopia can see far objects very well, but have problem with seeing near objects In hyperopic eye: farther than- 25 cm far point : at ∞ b Causes: This defect arises because... arises because 1 the focal length of the eyelens is too great 2 the eyeball becomes too short => the image is formed behind the retina c Treatment This defect can be treated by using a convex (converging) lens of suitable focal length When the object is nearer to our eyes than the near point , the eye does maximum accommodation Convex lens supply the focussing power of forming the image on the retina... students of the gifted schools have amblyopia  This rate is 3-4 times higher than the other schools 11 I Myopia (Near-sightedness): a Definiton: This is also called short sightedness This is the most common refractive error of the eye, and it has become more prevalent in recent years Myope can see the nearby object clearly but can not see distant object clearly In myopic eye: near point ͌ 25 cm These