Portable Diopter Meter

A portable hand operated vision testing device for testing patients to determine if vision correction is needed or the extent to which vision correction is needed said device comprising:

• A) at least one lens unit comprising a first lens element and a second lens element, each of said first and second lens element having a specially designed thickness profile wherein the designs of the thickness profiles are chosen such that small adjustments of the relative positions of the two lenses in directions perpendicular or approximately perpendicular to a viewing direction results in changes in the combined focus of the two lenses of the lens unit;
• B) a frame system adapted to hold said first and said second lens elements and to permit said small adjustments of said relative positions of the two lenses, said frame system comprising:
• 1) an adjustment mechanism comprising a finger controlled adjusting element for adjustment of the position of at least one of the two lens elements relative to the other in a direction generally perpendicular to the viewing direction;
• 2) a scale directly or indirectly associated with the finger controlled adjusting element indicating an extent by which at least one of said lens element has moved relative to the other, said scale being adapted to indicate if vision correction is needed or an extent to which vision correction is needed.