WHAT YOU NEED TO KNOW:
Nomograms greatly improve the predictability of refractive surgery outcomes and can reduce enhancement rates to 1% or less.
What Is a Nomogram?
The term “nomogram” is derived from the Greek nomos, meaning law or custom, and gram, meaning measure or weight. Throughout science, nomograms or tabular listings of numbers have been used to plot results and to predict the outcome of those results using two known points. In refractive surgery, nomograms were first used to guide radial keratotomy procedures. They were usually in the form of number tables that listed the desired correction on the left and age of the patient across the top and indicated the number and length of incisions to make. Today’s nomograms for laser-correction surgery are far more sophisticated and take the form of mathematical equations. Variables about the laser, surgical techniques, the patient, laser room environment, and other factors are taken into account to determine the correct numbers to program into the laser. Because lasers, surgeons, and climates vary, nomograms are used to determine which factors are most important for each procedure and to provide specific adjustments for each eye.
*Source of info:
Guy M. Kezirian, M.D., F.A.C.S., is president of SurgiVisionConsultants, Inc., an ophthalmic consulting firm in Scottsdale, Ariz., and Refractive Consulting Group, Inc., a software company that makes the Refractive Surgery Consultant Elite software. Dr. Kezirian is a board-certified ophthalmologist and works extensively to research and validate ophthalmic lasers.