Source : Webster's Revised Unabridged Dictionary (1913)

Amaurosis \Am`au*ro"sis\, n. [Gr. ?, fr. ? dark, dim.] (Med.)
   A loss or decay of sight, from loss of power in the optic
   nerve, without any perceptible external change in the eye; --
   called also {gutta serena}, the ``{drop serene}'' of Milton.

Source : WordNet®

amaurosis
     n : partial or total loss of sight without pathology of the eye;
         caused by disease of optic nerve or retina or brain