strong glasses; powerful spectacles
Refers to glasses with a high prescription (strong lenses). The phrase is a noun-like expression often used in everyday conversation.
He wears strong glasses.
With strong glasses, your eyes can sometimes look smaller.
An adjective phrase meaning 'having a strong prescription'; used to describe lenses or glasses, e.g., 度が強いレンズ.
The general word for 'glasses'; 度の強い眼鏡 specifies glasses with strong lenses.
A compound phrase: 度 (ど, 'degree' or 'prescription strength') + の (possessive particle) + 強い (つよい, 'strong') + 眼鏡 (めがね, 'glasses'). The phrase literally means 'glasses of strong degree'.