Hypermetropia and Its Correction

Q. The near point of hypermetropic eye is 75 cm from the eye. What is the power of the lens required to enable him to read clearly a book held at 25 cm from the eye?

1. +3 D
2. -2.5 D
3. +2.66 D
4. -2.66 D

Q.

If the image was formed in front of the retina rather than behind the retina, then the person would need to correct the vision problem by using a:

1. polar lens

2. diverging lens

3. converging lens

4. achromatic lens

Q.

(a) What is long-sightedness ? State the two causes of long-sightedness (or hypermetropia). With the help of ray diagrams, show :
(i) the eye-defect long-sightedness.
(ii) correction of long-sightedness by using a lens.
(b) An eye has a near point distance of 0.75 m. What short of lens in spectacles would be needed to reduce the near point distance to 0.25 m ? Also calculate the power of lens required. Is this eye long-sighted or short-sighted ?
(c) An eye has a far point of 2 m. What type of lens in spectacles would be needed to increase the far point to infinity ? Also calculate the power of lens required. Is this eye long-sighted or short-sighted ?

Q.

What is presbyopia? Which part of the bifocal lens contains the concave and convex lens?

Q. The focal length of a hypermetropic person for closeby objects is ______ that of a healthy eye.

1. less than
2. more than
3. equal to
4. half than

Q.

What Is Macula Lutea?

Q. Which defect of vision can be rectified :
(a) by using a concave lens ?
(b) by using a convex lens ?

Q.

How is presbyopia different from hypermetropia?

Q. After testing the eyes of a child, the optician has prescribed the following lenses for his spectacles :
Left eye : 2.00 D Right eye : + 2.25 D
The child is suffering from the defect of vision called :
(a) short-sightedness (b) long-sightedness
(c) cataract (d) prsbyopia

Q. Where is the near point of a person suffering from hypermetropia (or long-sightedness) ?

Q. Why do we have to bring a small object near the eyes in order to see it clearly?

Q.

The decrease of the focal length of the eye-lens causes ______.

Q. Mike can see clearly only the objects situated in the range of 50 cm to 300 cm. The optometrist prescribed him a lens to increase the maximum distance of vision to infinity. Upon using the prescribed lens, he discovered that the near point of his vision has shifted from 50 cm to a distance ‘d’. What is the value of ‘d’?

Q.

What is the reason for the defect called hypermetropia?

1. The focal length of eye lens is large

2. The eye ball has become too small

3. Both a and c

4. The focal length of eye lens is too short

Q.

The picture given here shows a person wearing 'half-moon' spectacles. What sort of eye-defect do you think he has ? Why are these particular spectacles useful to him ?

Q.

A boy is wearing glasses and says that he cannot see the object kept at a distance without glasses. He is suffering from

1. Presbyopia

2. Myopia

3. Cataract

4. Hypermetropia

Q.

A person with defective eye cannot see closer objects clearly because the image is formed on where?

Q. Name the defect of vision which can be corrected by a converging lens. Show clearly by a ray diagram how the lens corrects the defect.

Q.

Focal length of the conacve lens used for correcting myopia should be

1. $25cm$

2. $<25cm$

3. less than the distance of far point from the eye

4. equal to the distance of far point from the eye

Q. If the eyeball of a person is shorter, then the person is suffering from:

1. Hypermetropia
2. Presbyopia
3. Cataract
4. Myopia

Q.

A person can see an object beyond 1m but not closer than it. The defect of the person is

1. Myopia

2. Hypermetropia

3. No defect

4. Presbyopia

Q. Though a woman can see the distant objects clearly, she cannot see the nearby objects clearly. She is suffering from the defect of vision called ?
(a) long-sight (b) short-sight (c) hind-sight (d) mid-sight

Q. Explain all defects of vision and their corrections.

Q.

The near point of a long-sighted person is 50 cm from the eye.
(a) Can she see clearly an object at :
(i) a distance of 20 cm ? (ii) at infinity ?
(b) To read a book held at a distance of 25 cm, will she need converging or diverging spectacle lenses ?

Q.

Choose the odd one out

Myopia, hypermetropia, xerophthalmia, astigmatism

Q. A young man has to hold a book at arm's length to be able to read it clearly. The defect of vision is :
(a) astigmatism (b) myopia (c) presbyopia (d) hypermetropia

Q.

Colour blind person may have:

1. Defective vision

2. Sometimes normal and sometimes defective vision

3. Normal vision

4. Can not say

Q.

If the near point of a far-sighted eye is $1m$, what is the power of the lens required to correct this defect? (Assuming that the near point of a normal eye is $25cm$)

1. +3D

2. +4D

3. - 3D

4. -4D

Q. In a certain murder investigation, it was important to discover whether the victim was long-sighted or short-sighted. How could a detective decide by examining his spectacles ?

Q. What kind of lens is used to correct hypermetropia?

1. Concave
2. Plano concave
3. Cylindrical
4. Convex