How can the visual deficiencies known as myopia and hypermetropia be optically explained?

1 year ago
Biology

Myopia is the visual condition in which the images are formed before (in front of) the retina. Hypermetropia is the visual condition in which the point of image formation is beyond (behind) the retina. Actually myopia is due to an increase in the distance between the retina and the crystalline lens, mainly caused by a slight flattening of the eyeball. In hypermetropia the retina is too close to the crystalline lens due to slight shortening of the eyeball.

In myopia the near point and the far point of vision come closer (the refractivity of the crystalline lens that corresponds to the maximum distension capacity of the ciliary muscles is not enough to provide visual accommodation). In hypermetropia the ciliary muscles are not able to contract more to compensate the inadequate position of the retina, i.e., the near point becomes more distant.

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Dipti KC
May 25, 2023
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