Will the green laser prostate treatment eliminate bladder fluid retention? I'm due in surgery next tuesday.

Hopefully. Green laser should remove obstructing prostatic tissue so the bladder can empty more easily, this in turn should correct the urinary retention.
Laser treatment. If you have significant urinary retention, laser treatment to the prostate may not remove enough tissue to relieve the obstruction. At 83 yrs of age, i would recommend traditional turp.