When you choose cheap glasses, you should consider their material of the fraames and lenses to ensure good quality. As for glasses frames, titanium glasses frames are the best choices for you due to their good properties. They arehypoallergenic, lightweight, strong, corrosion resistant. And polycarbonate lenses are also of high quality. Glasses with polycarbonate lenses are lightweight and impact resistant. Finally, determine the type of coating you want to add to your lenses.
To choose a pair of good quality glasses, you shall consider you the quality of frames, lenses as well as lenses coatings. There are many materials that applied to glasses frames such as plastic, metal and titanium etc. Among them, titanium frames are considered to be all around high quality because they are hypoallergenic, lightweight, strong and corrosion resistant.
As for the lenses, you shall choose Polycarbonate lenses that are general considered as the best choices that impact resistant and light weight.
What's more, Anti-reflective coating and scratch resistant coating necessary for a pair of good glasses.