Authors: Jaroslav Madunicky, MD Katerina Buusova Smeckova, MD, MBA Col. Assoc.Prof. Jiri Pasta, MD, PhD. Iveta Nemcova, MD, PhD. Eva Vyplasilova, MD Kristina Hakucova, MD Department of Ophthalmology of the First Faculty of Medicine of Charles University and Central Military Hospital, Prague None of the authors has a financial interest on the presented data.

Purpose To evaluate the change of change in the refractive error, BCVA, pachymetry and corneal topography of 50 patients, who underwent in our Clinic since 2009 uni- or bilateral implantation of the keraring(s) using the femtosecond laser iFS 150 following Madunicky Formula. To statistically evaluate effect based on the degree of keratoconus (I-IV) and max. keratometry localization. 2

Setting / Venue N° of patients TotalMaleFemale N°of eyes53 Mean age33 (20 ; 55) Preop UCVA0,26(0,05 ; 0,5) Preop BCVA0,63(0,2 ; 1,0) Preop refractive error-1,35()-3,76 [0.00()-1,25; -4,5()-6,25] Preop autorefractometry-4,57()-5,78 [-10,75;+2,50 () -1;-9,75]] Pachymetry459,52 [426 ; 500] Max. keratometry58,21 [48,1 ; 66,7] Degree of keratoconus according to Pentacam ,5%9,5%10%80% Type of ectasia %41%28%18% 3

Methods Prospective, unmasked, non-randomized study of 50 patients with keratoconus (53 eyes), grade 2 to 3-4, who underwent the implantation of SI-5 Keraring/s. Degree of keratoconus and type of ectasia according to the localization of maximal keratometric readings were determined, other pathologies were described. Preoperatively and 1, 6 and 12 months postoperatively UCVA, BCVA, autorefractometry, pachymetry measurements and keratometry readings were obtained. Implantation of keraring/s was performed in local anesthesia implanted into the tunnel created by Intralase iFS 150 set according to the Madunicky Formula. No peroperative complications were reported. Ring was selected according to the currently valid nomogram and preoperative examination of the patient. 4

MADUNICKY´S FORMULA DF = (0.8 TP x AC) - (SC x RC) DF = (0.8 TP x 0.92) - (-20 x 0.5/0.1) DF: Depth of the femtotunnel (µm) TP: Thinnest pachymetry (µm) AP: Applanation coefficient SC: Safety coefficient (µm) RC: Ring coefficient

Results I. Mean UCVA-1M,6M and 12 M after implantation UCVA 12 Months after Procedure 6

Results II: Evaluation of UCVA & BCVA 7 before surgery 1M after 6M after 12M after -1,3Dsf/-2,2Dcyl=0,62 0,41 +/- 0,07 [0,2;0,9] -2,50Dsf/-2,4Dcyl=0,63 0,44 +/- 0,05 [0,2;0,8] -1,81Dsf/-1,82Dcyl=0,63 0,34 +/- 0,03 [0,1;0,7] 0,25 +/- 0,02 [0,05;0,5] -1,34Dsf/-3,76Dcyl=0,63 Improved by 1,61D of SE

Results III. Change in pachymetry Change in K max. and grade 8 Kmax Degree of keratoconus Prior surgery58,2[48,1 ; 66,7]2,9[1,5 ; 3,5] 12M after50,9[44,8 ; 52,8]2,6[1 ; 3,5]

Results IV.: Evaluation of Autorefractometry & Pachymetry 9 before surgery 1M after 6M after 12M after 477,77[453;529] um -2,39Dsf/-2,17Dcyl 471,14[438;527] um -3,45Dsf/-2,75Dcyl 469,14[423;583] um -2,42Dsf/-2,87Dcyl -4,57Dsf/-5,78Dcyl 459,52 [426;500] um Improved by 5,79 D of SEImproved by 18,25 [3;31]

Results V.  In the interval of 1 year of the implantation 2/3 of patients have improved both their UCVA and BCVA. Statistically are the most succesfull group grade II and III. In this group there is no worsening of the BCVA, in 1/3 it only remained unchanged. Vision of 11% of patients in the group grade III-IV got worse during this period.  In a group grade II-III is more expressive the change of the SE, as the flattening of the extasia. Ring dislocation Optical phenomenon 10 Complications

Comparison of possible keratoconus treatments 11

Conclusion Keraring implantation with the iFS 150 following Madunicky Formula and up-to-date nomograms, when performed by an experienced surgeon, seems to be a safe and full-valued treatment, which helps patients on their way to stabilize the disease and to postpone the need to perform a perforative keratoplasty. The effect of implantation is quite individual and it depends on the degree of disease, progression / stability of the disease and the location of the ectasia in the cornea (depth, symetry). On our clinic we perform the implantation of the intrastromal segments only with the femtosecond laser set according to the Madunicky Formula. The results seem to be very perspective. The procedure itself is less stressful for both patient and surgeon and we have not reported so far any case of extrusion or perforation. 12