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Correcting Vision Problems Using Lenses. Light and Geometric Optics. Refractive Errors – Hyperopia (Far- Sightedness). those who are farsighted have difficulty focusing on distant objects and are even blurrier up close;
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Correcting Vision Problems Using Lenses Light and Geometric Optics
Refractive Errors – Hyperopia(Far- Sightedness) • those who are farsighted have difficulty focusing on distant objects and are even blurrier up close; • caused by an eyeball that is too short, and a cornea that is too flat • light rays from nearby object diverge more strongly than the ones from faraway objects; • the light rays focus at a point behind the retina; • can be corrected using convex lenses
Refractive Errors - Myopia (Nearsightedness) • - individuals can see objects that are close clearly, but cannot see far away; • happens when light rays focus in front of the retina; • caused by an eyeball that is too long, and a cornea with too much curvature (i.e., too much focusing power); • corrected by concave lenses; • - diverging lenses cause the light from distant objects to diverge as they approach the eye.
Refractive Errors - Astigmatism • occurs along with nearsightedness or farsightedness; • due to a cornea that has an irregular shape • light entering the eye from different directions is focused different amounts; • or example, light entering vertically may be focused more than light entering horizontally; • light is focused the same amount in each axis blurred vision; • letters appear slanted or have tails, and the affected eye sees double; • astigmatism is treated similarly to nearsightedness and farsightedness, but with different amounts of treatment on each axis.