You would better not to wear eyeglasses when you do some hot yoga to loss weight. Have you ever notice that yoga is a active that relax your body and heart, the yoga coach even has nothing to wear except the light cotton clothing. Yoga ask for meditation and attention, but if you wear your glasses, you need to take care of it when you move your body, worry about if it will drop. It is a distraction to your attention. You can stand near your teacher and remember the movements if you are not in a strong prescription. If you have to wearing glasses as your prescription strong, you would wear contacts for alternative.
As we know that yaga is build body in a gentle way. It is a tender sports. from this point, it is ok to wear glasses. But if you want to do some hot yoga, you'd better get out of your eyeglasses. It will affect your act of yoga. Besides you may sweat when you doing hot yoga that will make you eyes painful if you wear eyeglasses. And the sweat can also cause damages to eyes. So, you'd better not wear glasses to hot yoga.