Wash and dry your hands
Check which part is loose: temple arms, hinges, nose pads, or screws
Tighten loose screws with a small eyeglass screwdriver
Turn screws clockwise only until snug
Do not overtighten
Use a drop of clear nail polish or thread locker on loose screws if needed
Bend metal temple arms slightly inward for a tighter fit
Adjust plastic frames carefully with warm water if they need reshaping
Tighten or reposition nose pads if your sunglasses have them
Replace stripped or missing screws
Take them to an optician if the frame is damaged or still loose