Question

Write a note on eye defects and their correction.

Answer 1

Eye defects:

1. Human eyes slowly lose their accommodating power and can not see clearly and comfortably in these situations.
2. There are three types of eye abnormalities-

1. Myopia (near-sightedness)
2. Far-sightedness or hypermetropia, and
3. Presbyopia.

i. Myopia

1. It is also referred to as short-sightedness or near-sightedness.
2. Here, light rays do not focus on the surface of the retina, but they focus just in front of it. When perceived, it results in images being blurry.
3. In such a scene, distant objects appear out of sight, but close objects are still visible.

Correcting myopia.

1. It is not an eye disorder, but an eye defect that can be corrected.
2. Sight-saving courses, exercises, under-correction, cycloplegic treatment, contact lenses, pinhole glasses, and several other treatments have been also introduced.

ii. Hyperopia

1. Far-sightedness is referred to as hyperopia. It is a refractive error that displays distant objects, but nearby objects appear blurred.
2. For focusing on images, the human eye relies on two parts: the cornea, which is the clear front surface of the eye, and the crystalline lens, a clear structure inside the eye that changes shape to focus on images.
3. These focusing components have a smooth curvature in an eye without refractive error and bend the incoming light to create a strong central image on the retina.
4. The light would not correctly bend or refract light if the cornea is not smoothly curved.

Method of correcting hyperopia

1. The problem is related to an eyeball that is shortened in this situation.
2. With the eyeball shortening, the retina comes closer to the cornea and lens than normal.
3. The result is the creation of an image outside the retina of surrounding objects.
4. The same converging lens is required for adults to rectify this problem.

iii. Presbyopia

1. For a person with presbyopia, closed objects appear blurred.
2. As part of the normal aging phase of the retina, presbyopia occurs.
3. Over time, the ciliary muscles lose their ideal working condition and do not operate effectively.
4. Over time, the crystalline lens loses its flexibility, which affects focusing power and it occurs between the ages of 40-60.

Method of correcting Presbyopia

1. It can be treated with the help of simple eyeglasses with convex lenses.
2. Contact lenses can also be used.
3. Although they are more convenient, cases of both myopia and presbyopia also occur, so bi-focal lenses can also be used in such a situation.