14. Name two types of colour vision tests 2 marks The two types of colour tests are Ishihara colour test plates and Farnsworth Lantern dichotomous test and Farnsworth-Munsell 100 hue colour test. 15. What are the referral protocols and procedures for Optical Dispensers? 3 marks Optical dispensers do not refer in the medical sense‚ however there will be times where be times when a n optical dispenser will see an individual with an eye injury or eye condition. The dispenser is not permitted
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treated with surgery. Visual loss occurs because opacification of the lens obstructs light from passing and being focused on to the retina at the back of the eye. Signs and symptoms vary depending on the type of
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The Human Eye and the Colourful World Q 1. What is meant by power of accommodation of the eye? Ans. The ability of the eye lens to adjust its focal length‚ so as to clearly focus rays coming from distant as well a near objects on the retina‚ is called the power of accommodation of the eye. Q2. A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the type of the corrective lens used to restore proper vision? Ans. A person with a myopic eye should
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Laser and its medical applications Presented by S. vignesh J. sabastian The Advent of the "Laser Scalpel" Early experimenters with medical lasers pointed out that there are surgical operations that are difficult to perform with the conventional scalpel and that a laser beam might be used instead. Initial trials showed that a finely focused beam from a carbon dioxide gas laser could cut through human tissue easily and neatly. The surgeon could direct the beam from any angle by using a mirror mounted
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VI- CONCLUSION The eye is the organ of vision. It has a complex structure consisting of a transparent lens that focuses light on the retina. The retina is covered with two basic types of light-sensitive cells-rods and cones. The cone cells are sensitive to color and are located in the part of the retina called the fovea‚ where the light is focused by the lens. The rod cells are not sensitive to color‚ but have greater sensitivity to light than the cone cells. These cells are located around the
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less than two pounds. He was also going through retinal detachment. This is where the retina pull away from critical tissue in the back of the eye. This is significant because within the retina there are receptors that absorb light which send visuals to the brain. When the eyes lose the retina the ability to see is lost as well. My brother went under an experimental surgery with a slim chance to reattach his retina. The surgery was not successful‚ as a result Andy is blind and my parents would later
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PART A It is hypothesised the strongest method for curing eye defect is Gas permeable contact lenses (GP lenses). These lenses are able to maintain their shape instead of adapting to the shape of the cornea due to its firm oxygen permeable material. The lenses can provide improved vision‚ deposit resistance and are inexpensive as they are long lasting. PART B Myopia and Hyperopia are both conditions caused by refractive errors in the eye and possess an array of symptoms PART C Vision is able to
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is a personal display device under development at the University of Washington ’s Human Interface Technology Laboratory in Seattle‚ Washington USA. The VRD scans light directly onto the viewer ’s retina. The viewer perceives a wide field of view image. Because the VRD scans light directly on the retina‚ the VRD is not a screen based technology. The VRD was invented at the University of Washington in the Human Interface Technology Lab (HIT) in 1991. The development began in November 1993. The aim
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through the conjuctiva‚ cornea‚ aqueous humour‚ lens and vitreous humour in that order. All these structures refract the light such that it falls on the retina. This is called focussing. Maximum focussing is done by the cornea and the lens. The light then falls on the retina. This light is received by the photoreceptors - rods and cones‚ on the retina. The absorbed light activates the pigments present in the rods and cones. The pigments are present on the membranes of the vesicles. Thus‚ the light is
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he aqueous humor‚ from the aqueous humor to the lens and from the lens to the vitreous humor. Light spreading out from one point on an object can therefore be focused on a particular point on the retina. Syllabus | Exams | Websites | Resources | Exam techniques | Teachers Biology Home > Biology > Options > Communication > Communication: 3. Refraction of light in the eye 9.5 Option – Communication: 3. Refraction of light in the eye Syllabus reference (October 2002 version) 3. The clarity
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