The vision of the left eye is 400 degrees. What is the naked eye vision?

"How much is my son's eyesight?" Vision is 0.3 ",and then the question may be" How much myopia is that equivalent to? "It's easy to ask people, a big answer. A similar question "How deep is my son's myopia? "100 degrees", the question comes again. "How can the vision of 100 degrees be 0. 1? My sister is nearsighted 125 degrees, and her vision is still 0.3. Can it be measured? " Another sap.

Let's talk about the degree of myopia first. Frontal eye is an eye with no degree, which means that the light from infinite distance passes through the entire optical system of the eyeball and focuses on the retina correctly, so you can see things clearly. Relative ametropia, that is, myopia, hyperopia and astigmatism, are concentrated in the front and back of retina respectively; In addition, astigmatism, that is, confusion, has two focuses, and the two focuses on the vertical axis and the horizontal axis do not converge at the same point.

These focal points that do not fall on the retina will cause blurred vision and need different lenses to correct it. Myopia uses concave lenses to disperse light, so that the focus in front of the retina retreats and focuses on the retina; Hyperopia uses a convex lens to enlarge the focus; Astigmatism is corrected with a cylindrical mirror. The refractive power of these corrective lenses is what we call degrees, so 100 degree myopia means that one eye needs to focus on the retina with 100 degree lenses.

Vision, that's another matter, refers to how clearly a person can see. It is normal for ancient Arabs to see Chumaoxing clearly based on the auxiliary star and cat star next to Ursa major. Modern vision measurement was conducted by Dutch ophthalmologist Snellen in 1862. We know that a circle is divided into 360 degrees and 60 points at a time. His standard vision is a five-point letter that can be distinguished in 20 places, and his vision is 20/20, which is 1.0. If a person can only see this letter at half the standard distance, that is, 10, then the vision is 0.5.

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Vision can be divided into naked eye vision and corrected vision. The so-called naked eye vision is the vision without eye cuffs, and the corrected vision is the vision measured after wearing appropriate eye cuffs. Usually what we mean by vision is based on corrected vision. It may be easier to understand the relationship between vision and degree by analogy with digital cameras. Vision is the pixel of this camera, and 6.5438+million pixels is definitely better than 3 million pixels. Degree is the problem of focal length, that is, how much the focus of the camera has to turn to make the focal length just right. If the focal length is out of alignment, a camera with10 million pixels may be more blurred than a camera with 3 million pixels.

It is also possible that the camera is in focus and the photo quality is still very poor. For example, corneal leukoplakia (lens scratch) may require corneal transplantation to restore vision; Although the elderly with cataract (mildewed in the middle of the lens) have no myopia and hyperopia, their vision may be only 0. 1. Retinopathy (failure of photosensitive element) may have little effect on vision whether wearing eye cover or not, because the photosensitive element is broken, and no matter how much focusing help is limited; Amblyopia (digital arithmetic processor failure), amblyopia children wear the correct degree of eye cuffs, and their vision may be only 0.5; These factors will make the photos ill-imaged, and the corresponding eye conditions will also make the vision worse.

Myopia with the same 100 degree may produce different naked eye vision in different people's eyes, and the difference may be very large, from 0. 1 to 0.6 or even 0.7! 0. 1 vision may be caused by myopia, or it may not be caused by myopia at all, but by other eye diseases. After reading this article, please don't mention the problem that myopia 100 degrees equals zero vision next time.