Defects of Vision and Their Correction

Q.

Distinguish between hypermetropia and presbyopia.

Q.

When do we consider a person to be myopic or hypermetropic? Explain using diagrams how the defects associated with myopic and hypermetropic eye can be corrected?

Q.

What is myopia. State the two causes of myopia? With the help of labelled ray diagram show

(i) Eye defect

(ii) Correction of myopia

Q.

Differentiate between Near vision and Distant vision (Shape of the eye lens)

Q. Which of the following defects of vision can be corrected using a concave lens?

1. Hypermetropia
2. Myopia
3. Both a and b
4. None of the above

Q.

Give main difference in eye defects myopia and hypermetropia(causes of defect)

Q.

A certain person has minimum distance of distinct vision of 150cm. He wishes to read at a distance of 25cm. What focal length glass should he use? What is the nature of eye defect? [3 MARKS]

Q.

What is the near point or far point of normal eye?

Q.

Which eye defect is corrected by wearing spectacles of the convex lens?

Q.

Name the following:

The kind of lens required to correct Myopia.

Q.

What is the function of iris and muscles connected to the lens in the human eye?

Q.

What is meant by the persistence of vision? How is this phenomenon employed in industry?

Q. Hypermetropia may arise due to _____:
a. Shrinking of the eyeball.
b. Elongation of eyeball.
c. Long focal length of the eye.
d. Excessive curvature of the eye lens.

1. b and c
2. a and c
3. a and d
4. b and d

Q. The defect hypermetropia of an eye can be corrected by using spectacles containing ....................... lens.

Q. Myopia may arise due to ____ .

1. a and b
2. b and c
3. c and d
4. a and d

Q. What is the mechanism of dark and light adaptation in eye?

Q. What is myopia? How can it be corrected?

Q. What is myopia? Explain two possible reasons of myopia. How can it be corrected? Explain with suitable diagram.

Q. Match the following eye defects with their remedial lenses.

1. Concave lenses
2. Cylindrical lens
3. Convex lenses
4. Bifocal lenses

Q.

Relaxation of the ciliary muscles causes the focal length of eye lens to:

1. remains constant

2. increases

3. decreases

4. may increase or decrease

Q. What is hypermetropia? What are the possible reasons of hypermetropia? How is hypermetropia corrected? Explain with figures.

Q.

What is the major function of aqueous humour?

1. It reflects light.

2. It prevents dispersion of light.

3. It is present to maintain the pressure inside.

4. It filters the light that is going in to form the image.

Q. A person can not see the distant objects clearly (though he can see the nearby object clearly). He is suffering from the defect of vision called:

1. cataract
2. presbyopia
3. hypermetropia
4. myopia

Q. Match the columns:

i. convex lens	a. presbyopia
ii. concave lens	b. cataract
iii. Artificial lens	c. myopia
iv. focal lens	d. hypermetropia

1. i-d, ii-c, iii-b, iv-a
2. i-c, ii-d, iii-a, iv-b
3. i-a, ii-b-iii-d, iv-c
4. i-b, ii-c, iii-a, iv-d

Q. In a Std. X class, out of $40$ students, $10$ students use spectacles, $2$ students have positive power and $8$ students have negative power of lenses in their spectacles.
Answer the following questions :
(i) What does the negative power indicate?
(ii) What does the positive power indicate?
(iii) Generally which type of spectacles do most of the students use?
(iv) What defect of eyesight do most of the students suffer from?
(v) Give two possible reasons for the above defect.

Q.

Give the biological /technical terms for the following:

The lens of eye losing flexibility in a kind of long-sightedness in middle aged people.

Q. (i) What is myopia? state the two cause of myopia. With the help of labelled ray diagrams show
(a) the eye defect myopia
(b) correction of myopia using a lens.
(ii) Why is the normal eye unable to focus on an object placed within $10cm$ from the eye?

Q.

Q. A student is unable to see clearly the words written on the black board placed at a distance of approximately $3$ m from him. Name the defect of vision the boy is suffering from. State the possible causes of this defect and explain the method of correcting it.

Q.

What is myopia. State the two causes of myopia. With the help of labelled ray diagram show

(i) Eye defect

(ii) Correction of myopia