Does short-sightedness (myopia) or long-sightedness (hypermetropia) imply necessarily that the eye has partially lost its ability of accommodation? If not, what might cause these defects of vision?

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Solution

The ability of the eye lens to adjust its focal length is called accommodation.
No, short-sightedness (myopia) or long-sightedness (hypermetropia) does not imply necessarily that the eye has partially lost its ability of accommodation.
The power of accommodation of the eye usually decreases with aging. For most people, the near point gradually recedes away. They find it difficult to see nearby objects comfortably and distinctly without corrective eyeglasses. This defect is called Presbyopia.

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Similar questions

(a) What is long-sightedness ? State the two causes of long-sightedness (or hypermetropia). With the help of ray diagrams, show :
(i) the eye-defect long-sightedness.
(ii) correction of long-sightedness by using a lens.
(b) An eye has a near point distance of 0.75 m. What short of lens in spectacles would be needed to reduce the near point distance to 0.25 m ? Also calculate the power of lens required. Is this eye long-sighted or short-sighted ?
(c) An eye has a far point of 2 m. What type of lens in spectacles would be needed to increase the far point to infinity ? Also calculate the power of lens required. Is this eye long-sighted or short-sighted ?

Q. Long-sightedness : Hypermetropia

Short-sightedness :

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