I was watching Blassreiter and I noticed that the back of Hermann's jacket has the same eyes as Senketsu from Kill la Kill.
Are those eye patterns mean something or if they are just a playful nod from one anime to another?
It could just be one coincidence, they do share some similarities and some large differences. This was asked on the Kill La Kill reddit 3 years ago and remains unanswered. I guess you would have to get the character artists and ask them...
My assumption would be that it is just a coincidence, the lines from the tops of the eyes, both showing, multiple layers and the pupil being the main differences.
A large part of Kill La Kill's plot is the Life Fibers, which make up the clothes. Eyes being on the clothes is a design choice, which makes sense as they are living.