Vimto,
As it turned out, friends diagnosis was exactly as you had, Centreal Serous Retinopathy, which is a lot more comforting when compared to the Macular Oedema.
It would appear there it is far more prevelant in males 30 - 45 years and one of the causal factors seems to be stress. (this is probably due to the fact that your kids are teenagers by the time you hit that age)
The treatment advised is simply let it run it's own course and in most cases 2 -4 months will see a full recovery.
Laser treatment may be recommended where the condition does not improve after this time.