Origin of the ASCRS online post-refractive IOL power calculator

Virtually all cataract surgeons face the problem of calculating IOL power in patients who have undergone various forms of corneal refractive surgery. Until recently, this meant for every patient the time-consuming chore of manually performing multiple calculations. As a result, Warren Hill, MD, Li Wang, MD, Ph.D. and I (and many others) began receiving a growing number of e-mails from physicians seeking help. Regrettably, this calculation is an imprecise science, and consequently a large number of formulas have been developed, each possessing unique strengths and limitations, and often complementing one another. Clearly, there was a need to streamline the calculation process and to assist surgeons in selecting the most accurate formulas.

Warren Hill developed an elegant spreadsheet that included those formulas that were either well established by peer-reviewed publications or he had personally found to be of value in his large series of cases. Li and I had a similar experience, both in developing four formulas and in using many others. Warren's spreadsheet cut our workload by 75 percent, and it occurred to me that this should be made available to ophthalmologists worldwide. I suggested the idea to ASCRS, which immediately endorsed the idea and provided the funding and technical support to make it happen. It's also available on the ONE network.

The final spreadsheet was derived from Warren's original spreadsheet, and additional formulas have been added as these have become validated.  Li Wang and her husband Jianzhong Ma then took on the biggest task - to design and develop the calculator in a web format that would be clear and user friendly. The result is an elegant design that categorizes formulas in way we find most useful, that is according to the data required for the calculations:  historical data only, a combination of historical refractive data and contemporary measurements or contemporary measurements alone. 

The calculator is in constant evolution as new information becomes available. We are particularly grateful to Wolfgang Haigis, MS, Ph.D., who so generously provided his two formulas to us, and to the many individuals who developed other formulas that are on this Web site. We welcome suggestions regarding how we can improve it further. Contact me at, dkoch@bcm.tmc.edu