I Am an AME and can tell you that, despite having more than +5 or -5 lateral phoria, from an FAA standpoint, as long as the airman doesn't exhibit diplopia on exam, the AME handbook states that the deficiency should be noted in block 60, the certificate should be issued, and the airman informed that the FAA may contact him to request additional ophthalmologic evaluation. My mentor, who has been doing firsts for >30 years tells me he has never had an airman called back to request anything additional, (including those with amblyopia so severe that they were not able to place the line on the scale to establish a degree of eso or exophoria. [the feds just say "enter 9, and note your findings in block 60"])
So, at least on this side of the pond, I think there's still some hope...