###Rationale: Ans. is 'b' i.e., Error of refraction Retinoscopyo Retinoscopy, also called skiascopy or shadow test, is an objective method of finding out the error of refraction by the method of neutralization.o Retinoscopy is based on the fact that when a light is reflected from a mirror into the eye, the direction in which the light will travel across the pupil will depend upon the refractive state of the eye.o With the help of a retinoscope, light is thrown onto the patient's eye and through a hole in the retinoscope's mirror the examiner observes of red reflex in the pupillary area of the patient,o Then the retinoscope is moved in horizontal the vertical meridia keeping a wratch on red reflex, which also moves when the retinoscope is moved.o Depending upon the movement of the red reflex when a plane mirror retinoscope is used at a distance of 1 meter, the results are interpreted as : -No movement of red reflex - Myopia of 1D.Red reflex moves along with retinoscope - it indicates any of the following : - (i) Normal eye (Emmetropia), or (ii) Hypermetropia, or myopia less than ID.Red reflex moves against to the retinoscope -> Myopia more than ID.

###Answer: OPTION B IS CORRECT.
###Question: Retinoscopy is done for -
###Options:
A. Field of vision
B. Error of refraction
C. Curvature of retina
D. None
