Eye Exams

Refraction :-

This detects the refractive error of the eye. In simple words it tells you the "number of your glasses". 

This is done using a retinoscope. This may be done with undilated pupils or after putting drops in eyes that dilate the pupil.

If dilating drops have been instilled in your eyes, your near vision will remain blurred for a short time. Do not get worried if you are not able to read the newspaper on that day!

An auto-refractor is a machine that detects the refractive error of the person. These are in wide use today. But a reconfirmation of refractive error by the optometrist is preferable before purchasing the glasses.