Are the iris muscles opposing muscles?

Yep, pupil reflex (constriction and dilation of pupil) involves 2 muscles in iris: circular muscle and radial muscle.
Are they "opposing muscles" (antagonistic muscles, to be a bit formal), or does this term only apply to "skeletal muscles"??

I know they carry out opposite actions in dim/bright light (sth like circular muscle contracts and radial relaxes in bright light to reduce the size of the pupil.)