9. Intext Questions I

1. What is meant by power of accommodation of the eye?

 

When we try to see the distant objects, the irisretinaciliary muscles of our eyes are relaxedcontract in order to make the eye lens thickerthinner. Thus, reducingincreasing the focal length of the eye, due to which distant objects are clearly visible to the eyes.

 

When we try to see the nearby objects, the irisretinaciliary muscles of the eye relaxedcontract in order to make the eye lens thickerthinner. Thus, increasingreducing the focal length of the eye lens, as a result, the nearby objects become visible to the eyes.

 

The ability of the lens of the eye to maintains its focal lengthadjust its focal length to clearly focus rays coming from distant as well from a near objects on the ciliary musclesirisretina, is known as the power of accommodation of the eye.

 

2. A person with a myopic eye cannot see objects beyond \(1.2\ m\) distinctly. What should be the type of corrective lens used to restore proper vision?

 

If a person can see nearby objects clearly but have a problem in seeing objects beyond \(1.2\) \(m\). This type of condition occurs when the image of an object beyond \(1.2\ m\) is formed behind the retinain front of the retina and not at the retina, this condition of the eye is called myopia or near-sightednesslong-sightedness.

 

This defect of vision can be corrected using a concave lensconvex lens. The concave lens of correct optical power will bring the image of a nearby object back to the retina.