Collocations for opaque - adj.

be, look
become
As the lens becomes more opaque, the patient notices a falling off in vision.

completely
These crystals are completely opaque and nearly black.

almost, nearly
slightly, somewhat
The glasses looked slightly opaque.

with
The windows were nearly opaque with grime.

be
become
remain

extremely, fairly, very, etc.
Both question and answer are rather opaque.
The complex administrative arrangements mean that the decision-making process remains somewhat opaque.

completely
The system is completely opaque to non-specialists.

relatively
a little, slightly, etc.

Opaque is used with these nouns:
glass, tights