1. Vance Thompson Vision, Sioux Falls, South Dakota, USA
2. Cole Eye Institute, Cleveland Clinic, Cleveland Ohio, USA
3. Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, USA
4. Duke Eye Center, Durham, North Carolina, USA
5. Minnesota Eye Consultants, Minneapolis, Minnesota, USA
6. Prism Eye Institute, Mississauga, Ontario, Canada
7. New York Eye and Ear Infirmary of Mount Sinai, New York, New York