"… I require something that will help stop me from breaking them when I lay on my pack and put all the weight on the glasses :)"
Check out the plumbing aisle in Home Depot. A small section of PVC plastic pipe and two slip on plastic pipe caps should do the trick. The diameter and length of the PVC pipe would be wholly dependent on the size of your glasses.
It won't be the lightest but in the diameter that you'd be using I would think that it would be pretty hard to crush this "PVC eyeglass case" while inside of your pack.
Just a thought, try drilling some lightening holes through the PVC pipe to reduce the weight. This only works if you are trying to keep the glasses from being crushed and not completely protected from the elements.
Give some thought to the plastic mailing tubes pictured in my post above. If placed well inside of your pack they may do the trick and at less overall weight.
Party On,
Newton

