Hi @sunnyflower, Good question. First of all, I agree with @johnbishop. You should see an ophthalmologist to determine the cause of your diplopia. Once the cause is known a solution will be easier to develop. No guesswork for you. A prism is put in a pair of glasses but those glasses can get very costly. Be aware a prism is not always the answer for finding relief. It all depends on the torsion of the eyes. With the aid of medical tools an ophthalmologist will be able to determine if a prism will help. I went through a total of 8 different prisms and found not one helpful. He later did a test with my eyes and found no prism would offer help. If you get the diplopia on and off a prescription pair of glasses may not be the answer for you. Let the ophthalmologist do an assessment to help you. I hope this information answered your question(s). Toni