<prompt> Presbyopia occurs as a result of the followingShoening of eye ballHardening of lensThinning of the lensLengthening of eye ball  <response>: Presbyopia eyesight of old age is not an error of refraction but a condition of physiological insufficiency of accommodation leading to a progressive fall in near vision. The cause of presbyopia is believed to be due to thickening and loss of flexibility of the lens in the eye. Reference: AK khurana 7th edition 