"Use the Nagel Anomaloscope as the test standard"
Not a chance. The number of failures amongst current pilots would be astronomical, at the current pass standard. Achieving +/- 4 units on the test standard is no mean achievement; I am -6 on Nagel and only fail the Ishihara by 1 - 2 plates but I am unable to see clearly the microscopic lights on the lanterns any longer (age, I'm afraid, has caused a condition known as 'scatter') so the authorities deem me unsafe (despite having deemed me safe 16 years ago when I COULD see the latern lights).