Toyota has extended warranty for certain models for this same problem, but not for Prius. My car has 117,000 miles and this problem has been going on for at least the last 25,000 miles (based upon orange warning triangle). According to dealer, problem is with rings (which is the recall for other Toyota cars). Also, according to dealer, this is a real problem for other Prius owners with 100,000+ miles.
Concave lenses in glasses correct this shortfall by spreading out the light before it reaches the eye, thereby enabling the person using them to see distant objects more clearly. Cameras. Camera manufacturers use combinations of concave and convex lenses to improve the quality of photographs.
The simplest, cheapest and safest way to correct short sight is with glasses. Concave prescription lenses (called minus lenses) are used to bend light rays slightly outwards to counteract the over-focusing tendency. As a result, the light rays focus further back in the eye on the retina.