Could tretinoin have caused eyebrow hair loss? (photos)

Last week I noticed a bald patch in my eyebrow. I hadn't realized until then that my eyebrows had gotten so thin. I looked at old pictures and saw they were fine last May, then started thinning after that. I began 0.025 tretinoin in June last year for acne. I also started spironolactone, but only have eyebrow hair loss, so I don't think it's the spiro causing it. Do you think it was the tret? Will my eyebrows come back if I stop using it and how soon? Anything to speed up the process? Thank you!