The docs always say that the red/green issue (no matter how mild or severe) is always congenital, and never changes in ones lifetime. The "acquired" problems are usually the "blue/yellow" issue (chemical exposure or cataracts), and if at that point, you will have had way bigger problems with your eyes long before the color vision became the issue.... The mild deutran type Red/Green deficiency is by far the most common, and doesn't change for life (usually doesn't affect their lives until a sensitive color test is taken either, because they have no problems with most real world color discrimination and didn't even know they had any until meeting the FAA...) Yet most people that get screwed by these tests are of this mild type... It's bad science and bad testing methods. Hopefully they keep the wide variety of options, and come up with a one and done method for R/G people stuck in this limbo someday soon.