Glasses Design Concept

Design of glasses in regards to children with the 'buy-one, give-one' scheme can create problems in terms of the childs growth and how that affects their glasses. 

If a child is given a pair of glasses with the 'buy-one, give-one' scheme, do they then have to buy a new pair of glasses once grown out of them?
Can families afford to buy a new pair of glasses every time their child grows out of them?

To solve this issue we could look at the glasses design and how we can 'grow' the glasses with the growth of the child.

Examples of this in existing products:

Triple Skin BMX Helmet by Phillip Leyten
The helmet is segmented to allow movement to fit all head shapes and sizes, using a BOA tension system.

Wishbone furniture 

Products are able to adjust with the growth of the child

Shoes by Kenton Lee which can adjust to the growth of children's feet.