The most frequent case in “bespectacled” — breaking the joint of a pair of glasses. Sometimes there are such designs that any can replace or repair is not possible.
Offer a universal method that is suitable for any points. You need to take the appropriate diameter of a tube of electrical insulation and cut it on the handle and the rest of the hinge. This flexible “denture” keeps the glasses when worn and does not interfere with folding them to put into the spectacle case.