Not sure if it is old age, but in my younger years I had a thick set of eyebrows. Now that I’m an old man, the eyebrows are still there but it is definitely thinning. border line guynan from star trek.
What I found works well : i have a nose hair trimmer, I used it to clean up my eyebrows and it did a decent job. The trimmer does cut all the way down, so I leave the main portion of the eyebrows in place but clean the strays with it.