If you have a particularly strong prescription, we will automatically upgrade the eyeglasses lenses in your order from standard index to high index. These lenses are thinner and lighter than our standard polycarbonate, and can more efficiently refract light, thus preventing the "magnifying glass" effect created by thicker lenses. The cost for a high index lens upgrade is an additional $40 per pair. If you enter your prescription directly, you will see the change in your order total immediately. If you upload your prescription, send it to us after you place your order, or request that we call your doctor, we will process the additional charge once we submit your prescription to our lab. If you would like to decline this option, simply uncheck the box for high index lenses.