Q. 45 F Numerical4.5( 2 Votes )

Explain with the

Answer :

Explain the eye defects in detail along with the method to correct them.


● Myopia –


A person with myopia can see near by objects clearly but cannot see distant objects distinctly. A person with this defect has the far point nearer than infinity. In a myopic eye , the image of a distant object is formed in front of the retina.


Causes of defect


● Excessive curvature of eye lens


● Elongation of eye-ball


Correction of defect


This defect can be corrected by using concave lens of suitable power. A concave lens of suitable power will bring the image back on the retina.



● Hypermetropia


In hypermetropia person Is able to see distant objects clearly but cannot see nearby objects distinctly. The near point for the person is farther away from the normal near point (25cms).


Cause of defect


● The focal length of eye is too long


● The eye ball has become too small


Correction of defect


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




Presbyopia


The power of accommodation of eye usually decreases with aging. For most of the people, the near point gradually recedes away. They find it difficult to see nearby objects comfortably and distant objects also. This defect can be corrected using Bifocal Lens.


Astigmatism


It takes place due to irregular curvature or spherical shape of the cornea. In this defect, person is not able to differentiate between vertical and horizontal lines at a time. It can be corrected using the cylindrical lens.


● Cataract


With ageing, the transparency and elasticity of lens gradually decrease. The crystalline lens of people of old age becomes milky and cloudy. Due to this reason, it starts reflection and objects seems cloudy. This condition is called Cataract. This can be corrected using minor surgical operation.


Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Light - 2Light - 2Light - 243 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
caricature
view all courses
RELATED QUESTIONS :

What are PresbyopRajasthan Board Science

What is HypermetrRajasthan Board Science

What do you underRajasthan Board Science

Which eye defect Rajasthan Board Science

What is a cataracRajasthan Board Science

In which conditioRajasthan Board Science

In far sightednesRajasthan Board Science

Explain with the Rajasthan Board Science