Fig. 3. The double-pass technique offers the benefits of both the Russian and American techniques. The initial incision is centrifugal and can be expected to create a beveled incision profile at the central optical zone. The blade is then pushed centrally from the peripheral 8-mm optical zone mark, deepening the initial incision until it can no longer be extended centrally. The two-step diamond blade is sharpened only on the bottom 250 μm of the vertical facet. Note the slight undercutting of the central optical zone.