Question

what are the causes of presbyopia, draw labeled diagram of a lens used for the correction of this defect of vision?

Answer 1

Hint: The person who is suffering from presbyopia cannot differentiate between objects that are placed distant apart. The main cause of presbyopia is weakening of ciliary muscles and diminishing flexibility of the eye lens due to old age. We can treat this defect in the same way as hypermetropia by using a convex lens.

Complete answer:
In Presbyopia we want to correct the vision to focus nearby objects. Doctors may provide or treat through refractive surgery, include wearing corrective eyeglasses or contact lenses, Corneal inlay implantation and lens implants for presbyopia. This defect may cause hardening of the lens with age especially after the age of 45, blurred vision, reduced flexibility of eye muscles, and reduced elasticity of eye lens, eyestrain or headache after reading, doing close work like embroidery or sewing, because of this reason eye loses its power of accommodation and the person is not able to see nearby objects clearly. We can treat Presbyopia by using convex lense as shown in the figure. This treatment is similar to the hypermetropia we can clearly understand by the diagram.

Near point of Hypermetropic eye

Presbyopia eye

Correction for Presbyopia eye.

Additional information:
$\bullet$ Presbyopia is nothing but It is one of the defect of vision due to which an old person cannot see the nearby object clearly due to loss of accommodation of the eye
$\bullet$ This Presbyopia can correct the use of both concave and convex lens of suitable power.

Note:
Presbyopia is a special case of hypermetropia we can call it old age hypermetropia because its symptoms occur in old age, due to weakening of ciliary muscles and eyes lens becomes inflexible. So, the eye loses its power of accommodation. Student must practice the diagram to get more marks remember to draw the arrows in the figure.