Progressive glasses have a definite advantage over conventional bifocal glasses; in that they provide clear vision at all distances from infinity to near work. The only disadvantages are its cost, which is high.
2. Cataract (whether congenital or acquired) does not cause pain in the eye. The reason for the eye pain may by something else, which must be evaluated by an ophthalmologist. Technically, blue cataracts are like any other cataract, and require an operation for removal of cataract.