Consider the following statements regarding 'Cataract': 1. It occurs exclusively in children. 2. It is caused by the eye lens becoming cloudy. 3. It cannot be treated. Which of the statements given above is/are correct?

Correct Option The correct option is (b). Explanation The human eye functions as a natural optical instrument where a crystalline lens focuses light onto the retina. A cataract is a common ocular defect characterized by the opacification (clouding) of this natural lens, leading to vision impairment. Statement-wise Analysis - Statement 1 is Incorrect. Cataracts do not occur exclusively in children. While congenital cataracts (present at birth) do exist, the condition is predominantly associated with aging (senile cataract). It is most common in elderly individuals due to the denaturation of lens proteins over time. - Statement 2 is Correct. The primary physiological change in a cataract is the crystalline lens becoming milky or cloudy. This opacity obstructs or scatters the passage of light, preventing a clear image from forming on the retina, which results in blurred vision or partial blindness. - Statement 3 is Incorrect. Cataracts can be treated effectively. The standard treatment involves a surgical procedure where the opaque natural lens is removed and replaced with an artificial Intraocular Lens (IOL) to restore clear vision. Key Takeaway: A cataract is the clouding of the eye's crystalline lens, primarily caused by aging, and is treatable through surgical replacement of the lens.

Consider the following statements regarding 'Cataract': 1. It… - NCERT Class 8 Science MCQ

NCERT Class 8 Science — Chapter 4: Light

mcqeasy

Consider the following statements regarding 'Cataract':

It occurs exclusively in children.
It is caused by the eye lens becoming cloudy.
It cannot be treated.

Which of the statements given above is/are correct?

NCERT textbook question

From NCERT Science - class 8 · Page 173

Options

A1 only
B2 only
C1 and 3 only
D1, 2 and 3

Did you get this right?

Solution

Correct Option

The correct option is (b).

Explanation

The human eye functions as a natural optical instrument where a crystalline lens focuses light onto the retina. A cataract is a common ocular defect characterized by the opacification (clouding) of this natural lens, leading to vision impairment.

Statement-wise Analysis

Statement 1 is Incorrect. Cataracts do not occur exclusively in children. While congenital cataracts (present at birth) do exist, the condition is predominantly associated with aging (senile cataract). It is most common in elderly individuals due to the denaturation of lens proteins over time.
Statement 2 is Correct. The primary physiological change in a cataract is the crystalline lens becoming milky or cloudy. This opacity obstructs or scatters the passage of light, preventing a clear image from forming on the retina, which results in blurred vision or partial blindness.
Statement 3 is Incorrect. Cataracts can be treated effectively. The standard treatment involves a surgical procedure where the opaque natural lens is removed and replaced with an artificial Intraocular Lens (IOL) to restore clear vision.

Key Takeaway: A cataract is the clouding of the eye's crystalline lens, primarily caused by aging, and is treatable through surgical replacement of the lens.

Your note

More from Chapter 4: Light

With reference to the Periscope, consider the following statements: 1. It works on the principle of multiple reflections. 2. It uses two plane mirrors arranged at right angles to each other. 3. It allows viewing of objects that are not directly in the line of sight. Which of the statements given above are correct?

medium

With reference to image formation by a plane mirror, consider the following statements: 1. The image formed cannot be obtained on a screen. 2. The image appears at a greater distance behind the mirror than the object is in front. 3. The image undergoes lateral inversion. Which of the statements given above are correct?

medium

Consider the following statements about the image formed by a plane mirror: 1. It is inverted vertically. 2. It is of the same size as the object. 3. It appears to be at the same distance behind the mirror as the object is in front. Which of the statements given above is/are correct?

easy

In the context of the reflection of light, what does the term 'angle of incidence' refer to?

easy

With reference to the eye's ability to see, consider the following statements: 1. A normal eye can clearly see distant objects as well as objects nearby. 2. The minimum distance for distinct vision is constant at 50 cm for all ages. 3. In old age, eyesight may become foggy due to the eye lens becoming cloudy. Which of the statements given above is/are correct?

medium

Keep practising Chapter 4: Light

Work through every question from this NCERT chapter.

Browse all NCERT Class 8 Science chapters