We had this issue with DS. Mostly when he was under 6 months and were told if it didn't clear itself we'd be seeing someone too. But it did clear itself, I suggest saline drops, or those saline eye wash things.
DS is 17 months and I've noticed its started again over the last few days. He's been a little crook so hoping it'll clear soon. I've been flushing with saline, none of those eye drop things. It was semi good when I dropped him at childcare, so hoping it's still good this arvo!
As long as the gunk isn't really green or anything it's just the blockage, but I'd keep flushing to keep it clean anyway.
I hope it clears for you, cos any operation on a bubba is not nice!