Question

Name the defect of vision depicted in this diagram stating the part of the eye responsible for this condition.

Answer 1

Step 1: Identify the defect shown in the diagram:
The diagram depicts light rays from a nearby object converging behind the retina, not on it.
This condition is known as Hypermetropia (farsightedness).

Step 2: Understand what hypermetropia means:
- Individuals with hypermetropia can see distant objects clearly.
- However, they struggle to view nearby objects as the image is focused behind the retina.

Step 3: State the part of the eye responsible:
The primary causes of this defect are:
1. Weak lens: The lens lacks sufficient thickness or convexity to adequately converge incoming light rays.
2. Short eyeball: The eyeball's length from front to back is less than normal, resulting in image formation behind the retina.

Step 4: Conclusion:
The visual defect illustrated is Hypermetropia. The contributing factors are a lens that is too weak or an eyeball that is too short, causing light rays from nearby objects to focus behind the retina.

Answer 2

Step 1: Understand Hypermetropia:
Hypermetropia, also known as farsightedness, is a visual defect where distant objects are seen clearly, but nearby objects appear blurred.

Step 2: Cause 1 – Eyeball Length:
- Some individuals have an eyeball that is shorter than average in length.
- This causes light rays from nearby objects to converge behind the retina rather than directly on it.
- The result is a blurred image of close-up objects.

Step 3: Cause 2 – Lens Strength:
- In other cases, the eye lens lacks sufficient power (is not convex enough).
- This prevents it from effectively focusing light rays from near objects.
- Consequently, the image forms behind the retina, leading to difficulty in clear vision of nearby objects.

Step 4: Summary of Causes:
The primary causes of hypermetropia are:
1. Short Eyeball: Light focuses behind the retina.
2. Weak Lens: The lens fails to adequately converge light rays for focus on the retina.

Answer 3

The vision defect is hypermetropia (farsightedness), where distant objects are clear but nearby objects are blurry.
This occurs because the eyeball is too short or the eye lens lacks sufficient converging power, causing light from nearby objects to focus behind the retina.
A convex lens (converging lens) corrects hypermetropia.
The convex lens converges incoming light rays before they reach the eye, effectively shortening the focal length so the image forms on the retina.
This enables clear vision of nearby objects.
In conclusion, a convex lens corrects hypermetropia by converging light rays to focus on the retina, thus facilitating clear vision of near objects.