Eye Defects and Myopia Correction
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Questions and Answers

What is myopia and how can it be corrected?

Myopia, or near-sightedness, is a condition where distant objects appear blurry while nearby objects can be seen clearly. It can be corrected using a concave lens of suitable power to refocus images onto the retina.

Explain hypermetropia and its correction method.

Hypermetropia, or far-sightedness, is a condition where distant objects are seen more clearly than close ones, as images form behind the retina. It is corrected using a convex lens to bring the focal point forward onto the retina.

Define presbyopia and its relation to age.

Presbyopia is the gradual loss of the eye's ability to focus on nearby objects due to aging, caused by the hardening of the lens. It commonly affects people over the age of 40.

What are the main causes of myopia?

<p>The main causes of myopia are excessive curvature of the eye lens and elongation of the eyeball. Both conditions result in images being focused in front of the retina.</p> Signup and view all the answers

Why do humans benefit from having two eyes?

<p>Having two eyes provides a wider field of view of about 180°, enhances the ability to detect faint objects, and improves depth perception through stereopsis. This allows for better spatial awareness and a three-dimensional understanding of the environment.</p> Signup and view all the answers

How does a concave lens correct myopia?

<p>A concave lens corrects myopia by diverging light rays, allowing them to spread out before entering the eye, which shifts the focus of distant images back onto the retina. This brings clarity to distant vision.</p> Signup and view all the answers

What is the far point in a myopic eye?

<p>In a myopic eye, the far point is the maximum distance at which objects can be seen clearly, and it is closer than infinity. This means the eye cannot clearly focus on distant objects.</p> Signup and view all the answers

Discuss the role of accommodation in vision.

<p>Accommodation is the eye's ability to adjust its focus from distant to near objects through changes in the lens shape. A loss of accommodation can lead to refractive defects like myopia or presbyopia, resulting in blurred vision for certain distances.</p> Signup and view all the answers

Study Notes

Eye Defects

  • Eyes can lose accommodation power, causing blurred vision
  • Three main refractive defects: myopia, hypermetropia, presbyopia
  • Myopia (near-sightedness): Person can see nearby objects clearly but distant objects are blurry
  • Far point is closer than infinity
  • Image of distant object forms in front of the retina
  • Myopia may result from excessive lens curvature or elongated eyeball
  • Corrected with a concave lens

Myopia Correction

  • Concave lens moves image back onto retina
  • Correcting myopia using a concave lens is shown in figure 11.2(c)

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Description

This quiz explores eye defects with a focus on myopia, including its causes and the corrective measures taken using concave lenses. Learn about the different refractive errors and how they affect vision. Test your understanding of accommodation power and visual clarity.

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