Human Eyes and Defects of Vision

Myopia is also known as near-sightedness. A person with this defect has the far point nearer than infinity. Draw a neat ray diagram to depict image correction for a myopic eye using a suitable lens.

What is the far point and near point of the human eye with normal vision? 

Give reasons for the following.
Old people wear spectacles having convex lenses.

A student uses a lens of power $-3.5 \mathrm{D}$. Find the focal length and far point of his eye.

Why the image formed at infinity is often considered most suitable for viewing? Explain

The far point of a myopic eye is _____.

An old age person can read the newspaper by keeping it at $80 \mathrm{cm}$ in front of his eyes. What is the nature and power of lens required to correct the problem?

What is light?

A person cannot see objects nearer than $75 \mathrm{cm}$ from his eyes while a person with normal vision can see objects up to $25 \mathrm{cm}$ from his eyes. Find the nature, the focal length and the power of the correcting lens used for the defective vision. 

Increase in the converging power of eye lens cause hypermetropia.

A short sighted person uses a spectacle of power $-0.4 \mathrm{D}$ to see very distant objects. How far can he see without using spectacle?

The term “accommodation” as applied to the eye, refers to its ability to:

Hypermetropia and myopia are the most common defects of vision affecting humans. Both these defects can be corrected and perfect vision can be restored with the use of suitable lenses of appropriate focal lengths. Hypermetropia can be corrected by using convex lenses while myopia can be corrected by using concave lenses. The power of prescribed lens for both these defects depends on the focal length of the respective corrective lens. The power, $P$ of the lens is given by
$P=\frac{1}{f(in \mathrm{metres})} \mathrm{dioptres}$

A person can see clearly up to $3 \mathrm{m}$. What should be the power of the lens in his spectacles so that he could see clearly up to $12 \mathrm{m}$?

Hypermetropia and myopia are the most common defects of vision affecting humans. Both these defects can be corrected and perfect vision can be restored with the use of suitable lenses of appropriate focal lengths. Hypermetropia can be corrected by using convex lenses while myopia can be corrected by using concave lenses. The power of prescribed lens for both these defects depends on the focal length of the respective corrective lens. The power, $P$ of the lens is given by
$P=\frac{1}{f(in \mathrm{metres})} \mathrm{dioptres}$
Now, consider a situation in which the near point of a defective eye is at a distance of $1.0 \mathrm{m}$. Assuming the near point of a normal eye to be $25 \mathrm{cm}$, answer the following question:

What should be the power of the corrective lens?

Hypermetropia and myopia are the most common defects of vision affecting humans. Both these defects can be corrected and perfect vision can be restored with the use of suitable lenses of appropriate focal lengths. Hypermetropia can be corrected by using convex lenses while myopia can be corrected by using concave lenses. The power of prescribed lens for both these defects depends on the focal length of the respective corrective lens. The power, $P$ of the lens is given by
$P=\frac{1}{f(in \mathrm{metres})} \mathrm{dioptres}$
Now, consider a situation in which the near point of a defective eye is at a distance of $1.0 \mathrm{m}$. Assuming the near point of a normal eye to be $25 \mathrm{cm}$, answer the following question:

What type of lens should be used to correct the vision?

There are artificial and natural sources of light.

Explain about different sources of light.

What is the importance of light in our daily lives?

We see objects due to the presence of light.

Vitreous humour fills the space between lens and retina.