Initially, a 1-piece 360° Intacs ring was used in the procedure, but it proved difficult to insert. The design was later changed to 2 segments of 150° arc each. The segments have a fixed inner diameter of 6.80 mm and an outer diameter of 8.10 mm, and they are available in various thicknesses: 0.210, 0.250, 0.275, 0.300, 0.325, 0.350, 0.400, and 0.450 mm. The degree of correction achieved is related to the thickness of the ring segments; thicker ring segments are used for greater correction. Manually operated surgical equipment or a femtosecond laser can be used to create the channels.
Excerpted from BCSC 2020-2021 series: Section 13 - Refractive Surgery. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.