Different approaches in ICRS implantation in keratoconus are based on either spherical equivalent refraction or topographic values. No well established nomograms for ICRS implanatation are available as of now. Contact lens fitting maybe started as soon as 6 weeks after surgery but vision may fluctuate till 6 months. At the end of the procedure, the incision is closed with a 10-’0’ nylon suture which is removed after 6 weeks to 3 months depending on the result attained. If any resistance or wave like appearance of the corneal tissue is noted, insertion should be stopped and it should be ensured that the segment is being placed in the right plane. The segment is placed in the tunnel and advanced slowly with the distal end being placed at least 1 to 2 mm beyond the incision site to prevent extrusion. The creation of the intrastromal tunnel with the femtosecond laser is completed smoothly without manipulation of the cornea. The inner to outer diameter of the Intacs tunnel is from 7.0 to 8.3 mm depending upon various factors.
The applanation cone of the femtosecond laser is applied to the cornea to fixate the eye and help maintain the precise distance from the laser head to the focal point. The segments are implanted at 70% -80% corneal depth.
Alternatively, the femtosecond laser can be used for the same using pre-programmed parameters. The incision may be made mechanically with a diamond knife and a tunnel created by a dissector into which the ring segments are placed. The corneal centre is marked and topical anesthesia applied.
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