Question

What is the cause of Presbyopia?

Answer 1

Hint: Presbyopia is a term related to the human eye. Like Myopia, Hypermetropia, it may also be a disease related to the human eye. Presbyopia can be corrected with the use of a convex lens and hence students can think of which condition of the eye is corrected with the help of convex lenses.

Complete step by step solution:
Presbyopia is a normal process associated with aging of human beings. It is the loss of the ability of the human eye to focus on the nearby objects. People over the age of 40 are at a risk to suffer from presbyopia and almost all the people are affected at some point of time, at least to some degree.

Signs and symptoms of Presbyopia:
(i) Difficulty in reading fine print, particularly in low light conditions.
(ii) Eyestrain or headache after reading for doing close-up work.
(iii) Blurred vision at a readable distance.

Causes of Presbyopia:
Presbyopia is caused when the lens of the human eye becomes hard, which mostly takes place with aging. As the lens of the human eye becomes less flexible due to the hardening, the lens cannot change shape as it does so as to focus on a particular nearby image. As a result, these images appear out of focus.

Now, every time one is unable to focus on a nearby object it is not serious each time, but at a certain level it might become serious. One must immediately consult a doctor if they experience sudden loss of vision and also hazy or blurred vision.

However, age is not always the factor for presbyopia. Sometimes, it also can be seen in people having far-sightedness and also suffering from diseases like diabetes, sclerosis or cardiovascular diseases. It may also occur in some people who consume drugs. In such cases, presbyopia can be seen in people younger than the age of 40.

The above diagram shows the image formation in a presbyopia eye and it’s correction with the help of a convex lens.

Presbyopia can be corrected with the use of a convex lens which converges the light rays and helps in the formation of the image at the retina as shown in the second figure rather than a point away from the retina as shown in the first figure.

Note: Students must note that presbyopia is different from hyperopia or farsightedness, which occurs when an irregularly shaped eye prevents light from lining up with the retina. But, presbyopia is an age related condition.