Fingernails help!!

This is so random but I’m hoping someone has had a similar problem! For years my husband has struggled with nails like this. With all the rigid indents on his nails he use to have them on every nail but now it’s mostly the middle finger. Excuse the dirt he’s a firefighter and took this pic after a fire!

He went to the doctor when he was younger but never got any help with it. For a few years it cleared it but now it’s back.

Anyone ever had this. Did anything help? Any advice would be appreciated!