Subjective Type

A student sitting at the back of the classroom cannot read clearly the letters written on the blackboard. What advice will a doctor give to her? Draw ray diagram for the correction of this defect.

Solution

If distant objects appear to be blurred or not clearly visible then the student has near-sighted, or myopia. In this case a concave lens is used to correct the problem.
Myopia is also known as near-sightedness. A person with myopia can see nearby objects clearly but cannot see distant objects distinctly. A person with this defect has the far point nearer than infinity. Such a person may see clearly upto a distance of a few metres. In a myopic eye, the image of a distant object is formed in front of the retina and not at the retina itself. This defect may arise due to (i) excessive curvature of the eye lens, or (ii) elongation of the eyeball. This defect can be corrected by using a concave lens of suitable power. A concave lens of suitable power will bring the image back on to the retina and thus the defect is corrected.

SIMILAR QUESTIONS

Optics

Does short-sightedness (myopia) or long-sightedness (hypermetropia) imply necessarily that the eye has partially lost its ability of accommodation? If not, what might cause these defects of vision?

Optics

A defective eye cannot see close objects clearly because their image is formed:

Optics

Identify the wrong description of the given figures.

Optics

For the myopic eye, the defect is cured by

Optics

Match the list I with the List II for the combination shown Presbiopia Sphero-cylindrical lens Hypermetropia Convex lens of proper power may be used close to the eye Astigmatism Concave lens of suitable focal length Myopia Bifocal lens of suitable focal length

Optics

To remove myopia ( short sightedness ) a lens of power $$0.66\ D$$ is required. The distant point of the eye is approximately

Optics

A person is suffering from 'presbyopia' ( myopia and hyper metropia both defects ) should use

Optics

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?

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