Here is a link to a company that sells the verifier:
http://www.lancasterarchery.com
I did a request on another forum this fall asking other bow hunters that normally wore glasses, what or if they new of something that would work. At the time I wore 2 power glasses for reading. Several replied to my request with the link I enclosed. I was recommended by a Lancaster representative to get the #5. They list numbers from 4 to 9, with 9 being the highest. I installed a hooded peep and screwed in the #5 verifier. I am very happy with this set up. A verifier is for clearly viewing your site pins. The company also sells a clarifier which is for distance. In my case, I needed the verifier as I am far sighted. These verifiers are color coded. My #5 is purple.
I just recently purchased a second hooded peep with the same number verifier as I have a new bow ordered which should arrive in a few days. All the best.