作者研制了一种易泪管逆行环钻刀，现报告如下。逆行环钻刀的制备：用直径分别为2．0mm、2．5mm、3．0mm和3．5mm，长度均为5．0mm的4种规格的实心不锈钢圆柱。分别在圆柱两端均做成直径为1．0mm，长为1．5mm的同心圆柱，并在其两端的表面各钻一直径为0．5mm的孔。然后在中间段 The authors developed an easy-to-tear retrograde ring drill, which is reported below. Preparation of retrograde ring drill: Four sizes of solid stainless steel cylinders with diameters of 2.0 mm, 2.5 mm, 3.0 mm, and 3.5 mm, both having a length of 5.0 mm, were used. A concentric cylinder with a diameter of 1.0 mm and a length of 1.5 mm was formed at both ends of the cylinder, respectively, and a hole having a diameter of 0.5 mm was drilled on the surfaces of both ends thereof. Then in the middle section