Statistical Significance vs Clinical Significance—That Is the Question

Abstract

Microincision cataract surgery, defined as wounds of around 2 mm or smaller, have been shown to reduce surgically induced astigmatism compared with smallincision cataract surgery wounds of 3 mm or greater. 1 Therefore, cataract surgeons have intuitively concluded that the smaller the wound, the better, with regard to wound stability and topographic neutrality. However, 2.2-mm incisions have been shown to increase small Descemet membrane detachments (DMD) on postoperative day 1 compared with 2.85-mm incisions and, in 1 study, these detachments translated into slower visual recovery for patients. 2 To address these concerns, Dai et al 3 studied trapezoidal wound construction where the internal wound is 3 mm, while the external wound remains at 2.2 mm. They showed a reduced incidence of DMD vs conventional incision design on postoperative day 1 but no sustained difference in the number of DMD or any other clinical measure between groups. Although their study design and execution are to be congratulated, one is left to wonder about the clinical significance of these findings. There are 3 main reasons why the clinical relevance may be limited including the study concept, a shortterm anatomic difference without clear impact on clinical outcomes, and generalizability.