Question

In the myopia eye defect, the light rays from the iris
A. Do not enter the eye at all
B. Come to a focus at the back of the retina
C. Come to a focus in front of the retina
D. Come to a focus in between retina and iris

Answer 1

Hint: The iris is a small, annular arrangement in the eye that controls the depth and size of the pupil, and hence the amount of light touching the retina in humans and most mammals and birds. The iris determines the color of the eyes. The pupil is the aperture of the eye, while the iris is the diaphragm.

Complete answer:
Nearsightedness (myopia) is a general vision disorder in which you can see things close to you distinctly but not those further away. It happens because the structure of your eye allows light rays to bend (refract) wrongly, projecting images in front of your retina rather than on it. Nearsightedness can occur gradually or suddenly, and it often worsens during puberty and adolescence. Nearsightedness is a trait that runs through households.

To be able to see distant points, light must be refracted less. Nearsightedness occurs when light from distant sources is refracted more than is needed. The condition is most frequent in children and is commonly caused by a bulging cornea or an elongated eyeball. As the cornea bulges beyond its normal curvature, it appears to refract light rather than average. Photos of remote points appear to develop in front of the eye as a result of this. If the eyeball is elongated horizontally, the pupil is positioned farther apart from the cornea-lens system. Photos of remote objects form in front of the retina as a result. Just because the location of the formation of the image is in front of the retina, the options A, B, D are incorrect.

Hence the correct answer is option C.

Note: The treatment for nearsightedness is to fit the eye with a diverging mirror. Since the essence of the nearsightedness issue is that light is concentrated in front of the retina, a diverging lens will diverge light before it enters the eye. The cornea and lens would then converge on this light to form an impression on the retina.