I have the older RCBS powder dispenser and Powder Pro Scale, both made by PACT. I love it, but it is an older version, and slower, I understand, than the newer versions. It is faster than balance beam weighing, but not exceedingly fast. Where it is great, it won't overcharge, and you don't have to bend and squint and dribble the powder. This makes it much easier, and less tension. The scale has to be warmed up for about 20 min before use, or the zero will wander. This is not a problem, just plug it in 20 minutes before use, and do something else. Both have to be calibrated, so I don't use them for small jobs (about 10-15 charges), instead use the balance beam scale. For 15 -30, I use the dispenser and scale exclusively. For larger jobs, I use a volumetric measure to charge about 1 or 2 grains light, and let the dispenser - scale trickle the final powder to get to the charge desired. Since I bought the scale/dispenser, I measure every charge.
The problem is not your eyes or age, I have the same problem. I have found out that the manufacturer of dials, and books cause the print to shrink as they get older. I have found that the sights on my guns are also deterioriating, and are now fuzzy. They used to be sharp, I assume I have worn them out with use over the years.