I also have lymphedema. Fortunately not in my watch arm. However, the loop bands are ideal for this! You can adjust them all day if you want/need, and you can get the Milanese loop style or the leather loop style. I like them so much better than any kind of buckle now.
That's what I was thinking! Fortunately I rarely have swelling (my armpit is my main problem area but when that gets bad my arm starts to swell), but I've had some lately. I actually like to have something with a band on that wrist (Fitbit Flex > Misfit Flash > Apple Watch). The band fitting tighter than normal often warns me of swelling before I can physically feel it. Then I can get on the MLD before it gets worse. I'm so glad there are band options that adjust easily.
Just another way my Watch is helping my health.