👁️💊 Miopia, hipermetropia y astigmatismo: Cómo ingresa la luz al ojo? — Transcript

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1. 0:00Hello, everyone studying the eyes,
2. 0:02welcome to astomodosis. Subscribe and
3. 0:04activate the bell. In the optical
4. 0:11system of the eye, I have drawn a
5. 0:13diagram of an eye in which we have a
6. 0:15real image that projects two lines that
7. 0:18travel in parallel and fall on the
8. 0:20chord. After falling on the chord,
9. 0:23these rays that travel in parallel
10. 0:26converge, that is, they approach each
11. 0:28other. They pass through the pupil,
12. 0:31which is an opening in the iris, and
13. 0:34reach the crystalline lens, which is a
14. 0:36natural lens that we have to focus on
15. 0:39things. What do we see? The crystalline
16. 0:41lens also serves as a magnifying glass
17. 0:43and makes the images warp a little more
18. 0:45. The place where the upper and lower
19. 0:49lines meet is called the focal point.
20. 0:53And we have a virtual image that is
21. 0:55projected onto the retina. This virtual
22. 0:58image that falls on the retina is
23. 1:00inverted from right to left and from
24. 1:02top to bottom. The real image that
25. 1:05travels in parallel falls on the cornea
26. 1:09, becomes smaller, and then inverts.
27. 1:12When the virtual image falls on the
28. 1:14retina, it is called hemetropia. In
29. 1:17this case, it is a hemetropic eye, that
30. 1:19is, a normal eye. In the case of
31. 1:22hyperopia, it is an eye that is a
32. 1:24little smaller, flatter, where the
33. 1:26cornea is also a little flatter. The
34. 1:28real image projects parallel rays that
35. 1:31fall on the cornea, converge, and this
36. 1:33convergence produces a virtual image
37. 1:35that is projected behind the retina.
38. 1:38How do we make this image that fell
39. 1:40behind the retina move forward? Well,
40. 1:43we place a positive lens in front of
41. 1:45our optical system. In this way, the
42. 1:47positive lens makes the convergence of
43. 1:50the light rays a little earlier, moving
44. 1:54the focal point that should be where
45. 1:57the image is displayed, moving it
46. 1:59forward. Then the image of the apple
47. 2:03converges, becomes smaller much earlier
48. 2:06and therefore is finally projected on
49. 2:08the retina. In the case of a patient
50. 2:11who has myopia, the eye is a little
51. 2:14larger, more elongated, and the rays
52. 2:16that travel in parallel fall on the
53. 2:19cornea and when the image is projected
54. 2:21onto the retina, it does so much
55. 2:23earlier. How can we move this virtual
56. 2:26image back so that it can fall on the
57. 2:29retina? Well, we place a negative lens.
58. 2:32The function of the negative lens is
59. 2:34that the rays that are traveling in
60. 2:36parallel separate, that is, there is
61. 2:38divergence. When they fall on the
62. 2:41cornea, they begin to converge and
63. 2:43converge a little further apart than
64. 2:46before. In this way, the focal point
65. 2:49that was located there can move a
66. 2:52little further back. So, the image
67. 2:56travels, becomes a little larger when
68. 2:59it passes through the negative lens and
69. 3:02then it shrinks, inverts and is then
70. 3:05projected onto the retina. There are
71. 3:09patients who have astigmatism, in which
72. 3:12the optical system is different.
73. 3:15Usually in astigmatism it is a problem
74. 3:17in the curvature of the cornea in which
75. 3:19it is not homogeneous. As you know,
76. 3:22rays traveling parallel to the cornea
77. 3:24can be projected onto different areas
78. 3:26of the eye when they hit the cornea.
79. 3:30They can be projected in front of the
80. 3:33retina as two unequal images. They can
81. 3:37also be projected behind the retina as
82. 3:40two unequal images. They can be
83. 3:43projected onto the retina and another
84. 3:46image in front of it. They can also be
85. 3:50projected onto the retina and another
86. 3:52image behind it. In slightly more
87. 3:55complex cases, they can be projected
88. 3:58both behind and in front of the retina.
89. 4:00To correct asigment, we need
90. 4:02cylinder-type lenses, and explaining
91. 4:05them could be the subject of another
92. 4:07video if we reach 100 likes. Thank you
93. 4:10very much and don't forget to share
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