If you really want to know, I suggest contacting your recruiter/ BI, whatever they are called.  I believe that 20/400 is considered leagally blind, so you may have an issue.  Find out before you invest your time in something that may end up being a futile pursuit. 

Cheers.

I used to work for the FBI in a support role and know alot about the SA application process having gone through it myself. I think you will have a problem with the vision requirement. Your uncorrected vision is high. The Bureau usually uses an outside medical office to do the physical exam. when you get to the eyetest you will probably look through a viewfinder on a machine. If you put your hands up to the viewfinder near your eyes and stretch the corners of your eyes outward with your fingers you will find the tension on your eyeballs will flatten your cornea and and this will  clear your vision enough to read the chart. Make sure you use eye drops before doing this as the combination of this with the technique I described will temporarily clear your vision enough to read the chart which might consist of letters of shaded circles. I know an applicant who had horrible eyesight, worse than 20/400 and used this or a similar method to pass the eye exam. This about 12 years ago. She is an FBI Special Agent today.... Good luck, don't forget the use of laser vision correction is also an option if you really want this job. I did it and got a great LE job from it. The Bureau may frown on this procedure, I don't know. But there is no way they can detect it.....  Good luck........exssg........

I am in a similar situation like yours.  Did you pass the vision test?  Thanks