The Collaborative International Dictionary of English v.0.48:

Periscopic \Per`i*scop"ic\, a. [Cf. F. p['e]riscopique.]
   Viewing all around, or on all sides.
   [1913 Webster]

   2. of or relating to a periscope[2].
      [1913 Webster]

   Periscopic spectacles (Opt.), spectacles having
      concavo-convex or convexo-concave lenses with a
      considerable curvature corresponding to that of the eye,
      to increase the distinctness of objects viewed obliquely.
      [1913 Webster]