John Berdahl, MD is a board-certified ophthalmologist practicing in Sioux Falls, SD. He is widely regarded as one of the leading international cataract surgeons. He is one of the very few surgeons in the United States who is also fellowship-trained in cornea, glaucoma, and refractive surgery. Dr. Berdahl has already performed more than 25,000 eye surgeries around the globe. His published work has primarily focused on the fundamental causes of glaucoma, minimally invasive glaucoma surgery, and astigmatism management during and after cataract surgery.

He has been involved in numerous FDA-monitored clinical trials on some of the most exciting technologies in ophthalmology. He also founded Equinox, which is developing the first non-surgical, non-pharmacologic way to lower eye pressure for glaucoma treatment. He co-invented the MKO melt, which provides sedation during cataract surgery without the use of an IV. Additionally, he created astigmatismfix.com which helps thousands of surgeons per month fix residual astigmatism after cataract surgery. Finally, in an effort to improve access to care, he co-founded expertopinion.md which provides online opinions to patients from top doctors around the world.