Alberto, the whole point of the Vis/RVR conversion table is for situations where only Vis is reported, you can convert it to RVR, provided you stick with the requirements of the table. So for a standard ILS Cat1, minima is 550 RVR, then if RVR equip U/S, you convert Vis to RVR, f.ex. 400 x 2 as above, and you land. However, if RVR is reported, you cannot convert the Vis and you have to apply reported RVR.