The Collaborative International Dictionary
gutta serena
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.
Wiktionary
gutta serena
n. amaurosis