Question

A human eye is a convex lens. In normal eyesight, the image of an object in front of our eyes is formed exactly on the retina and is inverted. In farsighted and nearsighted eyesight, where is the image formed? Which lens can be use as a corrective measure in each case? You may use online or other resources to help you answer this question. Be sure to record your research sources in the References section near the end of this document.

Answer 1

The farsighted eyesight is the result of the visual image being focused behind the retina rather than directly on it. ,which can result in blurred vision. This occurs when the eyeball is too short.

The nearsighted eyesight is the result of visual image being focused in front of the retina, rather than directly on it ,which results in blurred vision. This occurs when the eyeball becomes too long .

Convex lenses are used in eyeglasses for correcting farsightedness, where the distance between the eye's lens and retina is too short, as a result of which the focal point lies behind the retina. Eyeglasses with convex lenses increase refraction, and accordingly reduce the focal length.

Concave lenses are used in eyeglasses that correct nearsightedness. Because the distance between the eye's lens and retina in nearsighted people is longer than it should be, such people are unable to make out distant objects clearly.

Step-by-step explanation:

Answer 2

In farsighted eyesight (Hypermetropia )

A person with hypermetropia can see distant objects clearly but cannot see nearby objects distinctly.The light rays from a close by object are focused at a point behind the retina

In nearsighted eyesight (Myopia )

A person with myopia can see nearby objects clearly but cannot see distant objects distinctly.the image of a distant object is formed in front of the retina

corrective measure in each case

1. In farsighted eyesight

This defect can be corrected by using a convex lens of appropriate power

2. In nearsighted eyesight

A concave lens of suitable power will bring the image back on to the retina and thus the defect is corrected.