Test, eyedrop

: There are many types of eyedrops and many types of eyedrop tests. One of the most common eyedrop tests is pupil dilation. This examination enables your eye care professional to see more of your retina, the light-sensitive layer of tissue at the back of your eye. Dilating (widening) the pupil permits the retina to be examined for signs of disease. To do this, drops are placed into the eye to dilate (widen) the pupil. After the examination, your vision may (or may not) remain blurred and bothered by the brightness of the sun for several hours. The pupil, the opening of the iris, may appear to open (dilate) and close (constrict) but it is really the iris that is the prime mover; the pupil is merely the absence of iris. The pupil determines how much light is let into the eye. Dilation is the process of enlargement or expansion. Things don't just open in medicine; they dilate. The word "dilatation" means the same thing as dilation. Both come from the Latin "dilatare" meaning "to enlarge or expand."