Convert from gnat's eye to parasang

Unit Definition (gnat's eye)
The gnat's eye is an idiomatic "unit" of distance; it's common to hear that something is "as small as a gnat's eye". In fact, the eyes of typical gnats tend to have diameters similar in size to a hair's breadth: roughly 100-150 micrometers (0.10-0.15 millimeters).

Unit Definition (parasang)
The parasang (Persian - farsang) is an ancient Persian unit of itinerant distance corresponding to approximately 3.5 miles (5.6 kilometers)., or the distance that can be traversed on foot in an hour.