Your prescription has probably gone up over time (usually becoming more farsighted/less nearsighted in the 50's) and the lens hazes and stiffens over time due to UV light absorption (of course, your intraocular lens implant does not "flex" like your natural lens).
The midrange focusing ability changes usually around the mid-fifties which is when most people need to get the trifocal or progressive multifocal to try to help at that distance. It's best if patients can start in a progressive in the beginning and they will never notice those midrange troubles. I usually prescribe the Ovation brand of progressives or one of the other newer brands for my patients. The el-cheapo progressives many opticals advertise are based on 20 year old lens designs that are not nearly as clear and smooth as the newer designs. As with everything else, you get what you pay for.
Mine are what ever Lens Crafters offers. Being blue eyed I know about the need for the UV protection..it is unfortnate I can't wear sunglasses...they create the same condition as night time resulting in very low vision. I've tried all different colors, the yellow/amber creates the least problems, but still knocks my vision down quite a bit.