De or het dagblindheid?

The correct Dutch article is:

de dagblindheid

Rule Words ending in -heid: almost always de. See the rule

How to use dagblindheid

the dagblindheidde dagblindheid
this dagblindheiddeze dagblindheid
that dagblindheiddie dagblindheid
our dagblindheidonze dagblindheid
your dagblindheidjouw dagblindheid
every dagblindheidelke dagblindheid
which dagblindheid?welke dagblindheid?
a big dagblindheid / the big dagblindheideen grote dagblindheid, de grote dagblindheid