On the mission field, often you don't have the privilege of having BSS in 500 ml bottles.
We have found that a good alternative is to use Lactated Ringers with a mix of bicarb, epi and Vancomycin for cataract surgery.
Here is the recipe that we have been using:
500 cc L.R. solution
10 cc sodium bicarbonate
0.9 cc dextrose 50%
0.3 cc adrenaline 1:1000
0.6 cc Vancomycin 50mg/ml (500 mg diluted in 10cc normal saline)