The human eye can change the shape of its crystalline lens, and thus modify the lens strength (a.k.a., lens power) of the eye in order to bring things at different distances from the observer into sharp focus on its retina. If the total effective lens strength (a.k.a., lens power) of a human's eye at a particular moment is 53.0 D, how far from the eye is the object that is currently in focus on the retina