Seems you don't know the power in your current glasses. If you know your power by chance, you can try online stores. They don't need prescription. dealnews.com/Goggles4-U-Prescription-Eyeglasses-for-4-5-s-h/488750.html 

I usually go to Walmart, get the prescription and order glasses from Nepal. If urgent, shipping from EMS service (Sundhara) costs around $16 for up to 500 grams.