A case can be long enough for your glasses and still fail to close without pressure. The folded frame has height and depth as well as width, and those dimensions vary considerably between styles. A curved sunglasses frame often needs a different interior from a flat, narrow optical frame.
Fold the glasses in their normal sequence and measure the widest and deepest points. If the manufacturer supplies a suitable case, use its interior as a reference when shopping for a replacement. External case measurements are less useful because shell thickness and padding take up space.
Closing should not reshape the frame
Place the glasses inside and lower the lid gently. It should close without pushing the bridge, lenses, or arms out of their resting position. A snap that engages only after pressing firmly is a warning to reassess the fit, not a sign of secure protection.
Check the lining for seams, exposed hard parts, or loose debris. A soft surface can still cause problems if grit is trapped inside. Keep the case clean according to its instructions, and avoid storing keys or coins with the glasses.
Ray-Ban's general care guidance recommends a designated hard or soft case to help protect frames and lenses from scratches. That does not mean every case offers the same resistance to crushing. Choose the structure according to where you will carry it, and avoid assuming a fabric pouch can bear the load of heavy objects in a bag.
Opening in the place you use it
A rigid clamshell may be reassuring in a backpack but bulky in a small shoulder bag. A narrow sleeve can save space, yet require two hands to remove the frame carefully. Try the opening motion with the bag or pocket where the case will live.
If you alternate between two pairs, check both rather than assuming the larger case fits each equally well. Very loose contents can move around, and a divider or separate cases may be preferable to stacking frames together.
Do not leave eyewear exposed to unnecessary heat simply because it is inside a case. Storage location and the lens maker's care instructions still matter.
The right case allows the folded frame to rest naturally, closes without force, and is convenient enough that you actually use it. An attractive exterior is a bonus after those basic requirements are met.
