That... would do it honestly and yeah, and nearsighted, from the way its all too common to come up, is just too detrimental in its current state (and that 20% feels more like 40% when all of my girls keep suffering from it). I do look forward to v2.75 (or whatever future version comes) when it comes out.
On a different note, I'm partially thinking you could add 'Farsighted' to affect those in the front ranks to balance out 'Nearsighted' affecting only the back ranks and for the two to be mutually exclusive. Just that one's an issue in the front, and one's an issue for the back.