Science · 6 pages · 12 min
Why farsighted and nearsighted eyes need different lenses
One eye meets the rays in front of the retina, the other would meet them behind it.
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From the opening
Farsighted and nearsighted eyes need different lenses because one brings rays to a meeting point in front of the retina and the other would bring them to a meeting point behind it. A correcting lens shifts that meeting point onto the retina. The opening covers focus landing in front of the retina, focus landing behind the retina, and diverging glass versus converging glass.
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Inside
- Focus landing in front of the retina
- Focus landing behind the retina
- Diverging glass versus converging glass
- Why astigmatism is a separate miss
- Where the idea stops applying
- A distinction worth keeping
Sources
- Myopia and hyperopia as focus relative to the retina
- Converging and diverging lenses measured in diopters