Recently, surgeons have found that using a centroid value gives improved outcomes, Dr. Hill noted. A centroid value is the two-dimensional mean of SIA for a series of patients.
Using data from a large physician database of over 35,000 cases, Dr. Hill observed that for the typical temporal clear corneal incision, the calculated centroid value generally ranges from 0.08 D to 0.14 D. If a surgeon has not yet calculated a centroid value for their cataract surgery incision, he advised beginning with a centroid value of 0.12 D when using toric calculators. A centroid calculation can be carried out using the free tool at www.SIA-calculator.com.
Dr. Hill reviewed the currently available toric calculators in the United States, including the Bausch & Lomb Trulign, the Holladay IOL Consultant calculator, the Abbott Medical Optics calculator (Johnson & Johnson Vision Care), the updated Alcon calculator, and the Barrett toric calculator, available on the American Society of Cataract and Refractive Surgery web site.
“The Barrett toric calculator is currently the most advanced one we have,” Dr. Hill said. “Doug Koch gave us the gift of the posterior cornea and Graham Barrett made it practical for all of us.”