EyeWorld India June 2013 Issue

48 EWAP rEfrActivE June 2013 Is efficacy ratio the new 20/20? by David J. tanzer, MD There are new expectations and new ways to measure success after laser vision correction S everal factors in combination have made 20/16 or even 20/12 uncorrected vision a possibility after laser vision correction. These include modern lasers and improved pre-op, intra- op, and post-op procedures. A study conducted by Steve Schallhorn, MD, evaluated the relationship between patients’ mean satisfaction after surgery as a function of uncorrected visual acuity. He found a statistically significant correlation between uncorrected visual acuity and overall satisfaction. Patients with uncorrected visual acuity of 20/12 Pre-op BCVA Post-op UCVA Efficacy ratio 20/20 20/25 0.80 20/20 20/20 1.00 20/20 20/16 1.25 20/20 20/125 1.6 Source (all): David J. Tanzer, MD were more satisfied with their outcomes than those with 20/20 and 20/25 uncorrected visual acuity. Additionally, multiple studies in different settings have demonstrated that rates of 20/20 uncorrected vision are consistently at or near 100%. So, if 20/20 is no longer a differentiator, a new benchmark or metric may be needed. In the past, the key benchmark has been uncorrected and best- corrected visual acuity. Today, we are paying closer attention to other metrics, such as the efficacy ratio. The efficacy ratio allows surgeons to compare how well a patient sees corrected before surgery to how well he or she sees uncorrected after surgery. For example, if a patient sees 20/20 before surgery with glasses and is now 20/20 uncorrected, the ratio is 1. Very often, patients are seeing better after surgery uncorrected than they were before surgery best-corrected, so the efficacy ratio would actually be 1+ (see table). These outcomes are possible because of advances in the excimer laser coupled with the femtosecond laser. Many patients have concerns about the flaps, specifically whether they can be displaced with minor trauma. Today, the femtosecond laser allows surgeons to create reverse beveled flaps, which are much stronger and safer than previous flap configurations. 1 Additionally, today’s excimer lasers are faster and smoother, have larger optical zones and better blend zones, and have less induction/actual reduction of aberrations. Surgeons also provide better patient care through more effective patient screening methods and post-op management.