A Nomogram Reality Check

by Guy M. Kezirian, MD, MBA, FACS

June 2014


We don’t want to be presented with numbers that give us an artificial sense of comfort…we want a true nomogram. – Vance Thompson, MD

Be careful what you believe, and even more careful what you wish for.

I submit that before SurgiVision® DataLink (and its predecessor, the Refractive Surgery Consultant), there were no validated nomogram tools available for refractive surgery. To my knowledge there still are no others.

Paper nomograms, linear regression algorithms, percentage adjustments, and all the other approaches that I am aware of have serious flaws. Our work, which spans nearly two decades and has engaged some of the best minds in ophthalmology (including Jack Holladay, MD, MSEE and many of you), has improved outcomes predictability to an amazing extend and has greatly facilitated surgical logistics.

SurgiVision® DataLink nomogram development has been done using validated methodologies, and in close coordination with the engineers who designed the laser systems that our software supports. I believe it would be impossible to develop valid nomograms otherwise. I know of no other company that has. Valid nomograms must be based on laser specific algorithms, they must be Surgeon-Specific, they must be “fed” with postop data on a continuous basis and they cannot be shared.

SurgiVision® DataLink is a collaborative effort. The program has been an unprecedented success, with the largest known registry of refractive data in the world and an unparalleled library of valid nomograms. It is the first and largest collaborative effort to improve global outcomes in ophthalmology, to my knowledge. Where else to surgeons contribute data that they know will help other surgeons doing the same procedure?

Yet some surgeons do not understand nomogram technology and do not adequately evaluate alternative sources for nomograms. I am concerned that some surgeons are willing to delegate the most important parts of refractive surgery (including surgical planning) to technicians and ODs. I think in many cases the two events are related – important decisions are being driven by techs and ODs, and not surgeons. Surgeons should always be the ones making surgical decisions. It is their job.

SurgiVision® DataLink has truly been a true collaborative effort. The collaboration continues. My goal has been to improve outcomes and provide the analysis as a fait accompli, but it is still vital for surgeons to know what is happening behind the scenes. This series of articles is an attempt to maintain that engagement.