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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

Correcting Vision Problems Using Lenses

Light and Geometric Optics

refractive errors hyperopia far sightedness
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
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
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.
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