As anime shows, the light which comes by applying a concave lens from a triangle can be turned a little outside.　By this, the light included in a crystalline lens is refracted at a little loose angle, and connects an image to the retina which exists in the distance.
A long distance thing can be vividly seen like stigmatism.

角膜から網膜までの距離が長い場合:In the case the distance from cornea (black part of the eye) to retina is long.

Light has the character which is refracted to the thicker lens.
Since a concave lens is thick on the outside, light is refracted outward.