Please ask your engineers to find out if the end user follows the correct procedures or solution for cleaning.
The 1st thing factory suspect is the cleaning method and solution used, also if they have dropped or mis-handled the iris fame before, it may not be obvious, but after long time of wear and tear the lines will appear.
Please ask user to refer to section4 in the user manual.
I also attached some important cleaning solution information, and things to avoid.”