Thanks ConElPueblo, Is it possible that it was converted during Wordwar1 ? the case is old and looks like it was made to fit this timepiece. I am adding 2 more photos.
No, the case is much later than WWI era. The only part of this watch that was likely made by Omega is the movement. The rest is inauthentic and the value of the watch is almost nothing as such conversions are both common and not sought-after.