File:EB1911 Vision - Forms of eye - normal, short and far-sighted.jpg
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Summary
| Description |
English: In the normal eye, any number of parallel rays, coming from a great distance, are focused on the retina. Such an eye is termed emmetropic (A in the figure). Another form of eye (B) may be such that parallel rays are brought to a focus in front of the retina. This form of eye is myopic or short-sighted, inasmuch as, for distinct vision, the object must be brought near the eye, so as to catch the divergent rays, which are then focused on the retina. A third form is seen in C, where the focal point, for ordinary distances, is behind the retina, and consequently the object must be held far off, so as to allow only the less divergent or parallel rays to reach the eye. This kind of eye is called hypermetropic, or far-sighted. |
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| Date | published 1911 | |||
| Source | “Vision,” Encyclopædia Britannica (11th ed.), v. 28, 1911, p. 134, fig. 11. | |||
| Author | Unknown artist | |||
| Permission (Reusing this file) |
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File history
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 23:08, 4 September 2021 | | 539 × 749 (111 KB) | Bob Burkhardt | {{Information |description = {{en|1=In the normal eye, any number of parallel rays, coming from a great distance, are focused on the retina. Such an eye is termed ''emmetropic'' (A in the figure). Another form of eye (B) may be such that parallel rays are brought to a focus ''in front of'' the retina. This form of eye is myopic or short-sighted, inasmuch as, for distinct vision, the object must be brought near the eye, so as to catch the divergent rays, which are then focused on the retina. A... |
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