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Showing posts from April, 2020

COMPUTER VISION SYNDROME

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COMPUTER VISION SYNDROME/ OFFICE SYNDROME These days, many of us have jobs that require us to stare at computer screens for hours at a time which can put a real strain on your eyes. We probably use screens for just about everything -- to work, to relax, or just to keep up with daily life. Eye problems caused by computer use are collectively called computer vision syndrome(CVS). It isn’t one specific problem. Instead, it includes a whole range of eye strain and discomfort. Research shows that between 50% and 90% of people who work at a computer screen have at least some symptoms. Working adults aren't the only affected. Kids who stare at tablets or use computers during the day at school can have issues too. How do Computers affect our Eyes? When you work at a computer, your eyes have to focus and refocus all the time. They move back and forth as you read. You may have to look down at papers and then back up to type. Your eyes react to images constantly moving and chan...

REFRACTIVE ERRORS OF THE EYE

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REFRACTIVE ERRORS Refractive error/ refraction error , is a problem with focusing light accurately on the retina.   The most common types of refractive error are near-nearsightedness, farsightedness, astigmatism, and presbyopia. Nearsightedness : When the optics are too powerful for the length of the eyeball one has myopia or nearsightedness. This can arise from a cornea or crystalline lens with too much curvature (refractive myopia) or an eyeball that is too long (axial myopia). Myopia can be corrected with a concave lens, which causes the divergence of light rays before they reach the cornea. Farsightedness : When the optics are too weak for the length of the eyeball, one has hyperopia or farsightedness. This can arise from a cornea or crystalline lens with not enough curvature (refractive hyperopia) or an eyeball that is too short (axial hyperopia). This can be corrected with convex lenses, which cause light rays to converge...

Structure and working of Human eye

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Hello Friends! Welcome to the section dedicated to eye care and vision related topics. Firstly we will see the basic structure of the human eyes and how they work. The anatomy and physiology of the human eye is very complex and to understand in simple terms we can compare its structure and working with a camera: Image focusing: Human and camera lenses both focus an inverted image onto light-sensitive surface. In the case of a camera, it’s focused onto film or a sensor chip. In your eyes, the light-sensitive surface is the retina on the inside of your eyeball. Light adjustment: Both the eye and a camera can adjust quantity of light entering. On a camera, it’s done with the aperture control built into your lens, whilst in your eye, it’s done by having a larger or smaller iris. Your Cornea behaves much like the front lens element of a camera. Together with the lens, which is behind the iris, they are the eye’s focusing elements. The cornea takes widely diverging rays of l...