These optics are also of special crystal and fit over the eyes of the wearer. 

They give vision 100 times greater than normal at distances of 1-ft or more, i.e. the wearer can see at 2,000-ft what a person could normally see at 20-ft. 

Wearing only 1 of the cusps will cause the character to become dizzy, and in effect stunned, for 1 round. Thereafter, 1 eye must always be covered to avoid this vertigo.

Note: Mixing eye types is certain to cause immediate insanity for 2-8 (2d4) turns.