Tetracaine

All surgical procedures were performed by the same experienced surgeon (PL) under topical anaesthesia (combination of tetracaine 0.1% and oxybuprocaine 0.4%, Alcon, Fort Worth, TX, USA). The femtosecond laser platform FS 200 (Alcon Laboratories, Inc, Fort Worth, TX, USA) was used to create the corneal incision and tunnels. The tunnels were created at 70% of corneal depth ensuring that at least 100 μm of corneal tissue was present under the tunnel. Keraring segments (Mediphacos, Belo Horizonte, Brazil) were implanted in all cases, with a selection of the number of segments to implant as well as their diameter (SI5 or SI6), arc length and thickness according to the manufacturer’s nomogram and the scotopic pupil size measured. Table 1 summarizes the parameters used in the femtosecond laser platform for the different type of ring segments implanted. Topical antibiotics (Moxifloxacin 0.3%, Alcon Laboratories Inc., Fort Worth, TX, USA) were instilled at the time of implanting ICRS and at the end of the surgery. No stitches and/or therapeutic contact lenses were needed. A plastic protector was placed in the implanted eye to avoid the manipulation of the operated eye. Topical tobramycin 0.3% combined with sodium dexamethasone phosphate 0.1% (Tobradex, Alcon Laboratories Inc, Fort Worth, TX, USA) was instilled in the operated eye 4 times per day for 15 days.