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.
CONVEX or POSITIVE lenses will CONVERGE or FOCUS light and can form an IMAGE. CONCAVE or NEGATIVE lenses will DIVERGE (spread out) light rays. You can have mixed lens shapes too: See a demonstration (opens a new window) of what happens to the light path when you combine several convex or concave lenses. Perfectly straight, until something bends it. The straight paths of light are called LIGHT RAYS.