1. Long-term Follow-up for Intrastromal Cornea Ring Segments in Early to Severe Keratoconic Patients Omer Trivizki 1,Eliya Levinger 1,2, Irit Bareqet 2, Ami Hirsh 2, Israel Kremer 2, Shmuel Levinger 2 1 Department of ophthalmology, Tel Aviv Medical Center, Israel 2 Enaim Medical Center, Jerusalem, Israel

2. I have no financial interests or relationships to disclose

3. Purpose To report the safety and the efficacy of a long term follow-up of intrastromal corneal ring segments (ICRS) implantation in early to severe keratoconic patients

4. Methods Retrospective nonrandomized study PMMA, crescent-shaped arc length of 150 degrees, Inner diameter is 6.8 mm and the outer diameter is 8.1 millimeter ICRS were implanted using either by femtosecond laser technique The evaluation included: Uncorrected distance visual acuity (UDVA) Corrected distance visual acuity (CDVA) Refraction Average keratometric values

5. Results The study included 221 keratokonic eyes of 221 patients Median age 32.17 ± 8.94, 124 males 154 (69%) of the procedures were made using femtosecond laser and inasmuch as only 67 were done manually Mean follow-up period was 26.8 ± 30 months ranging between 1 to 148 months Patients were grouped according to keratoconus stage

6. Results There was a statistically significant improvement in postoperative LogMAR UDVA of more than 3 lines from 0.95 ± 0.40 to 0.64 ± 0.37 (P < 0.005), respectively Mean LogMAR CDVA was changed from 0.29 ± 0.30 to 0.38 ± 0.40 (P=0.85) Change in the UCVA after Intacs implantationChange in the BCVA after Intacs implantation

7. Results The mean spherical equivalent (SEQ) was -3.36 diopters (D) preoperatively and -1.20 D postoperatively (P<0.005) Average keratometry decreased by 2.2 D from 47.08 ± 3.12 to 44.82 ± 3.48 (P<0.001) Change in cylindrical refraction post-implantation Change in spherical refraction post-implantation

8. Results The mean spherical equivalent (SEQ) was -3.36 diopters (D) preoperatively and -1.20 D postoperatively (P<0.005) Average keratometry decreased by 2.2 D from 47.08 ± 3.12 to 44.82 ± 3.48 (P<0.001) Change in cylindrical refraction post-implantation Change in spherical refraction post-implantation

9. Results Stage post-implantationTotal (%) 1234 Stage pre- implantation 1 117420123 (55.5%) 2 222111 51 (23.2%) 3 51133 22 (10%) 4 1112 25 (11.4%) Total (%) 144 (65.5%)47 (21.4%)12 (5.45%)17 (7.73%)221 Change in keratoconus stage post-implantation according Amsler- Krumeich Classification for Grading Keratoconus Ɨ Most did not change, 52 improved, 31 deteriorate Improvement was found statistically significant in the female group (p<0.001) Ɨ Ophthalmologica. 1946 Feb-Mar;111(2-3):96-101.

10. Results Change in VA and refraction post-op, grouped by initial according Amsler- Krumeich Classification Ɨ VA improved in all groups, so did refraction values Yet, it was found statistical significant only in stage 1 disease (p<0.001) Ɨ Ophthalmologica. 1946 Feb-Mar;111(2-3):96-101.

11. Complications Change ring location 5 Adding segment 13 Removing segment 8 Removing rings 4 Cornea transplantation 1 Total31 31 patients needed re-operation for ring change (Table 1) 1 patient needed corneal transplantation 65 patients needed a secondery refraction surgery (Table 2) Table 1Table 2 LASEK+ CROSSLINK 41 LASEK 18 PRK 2 ICL 4 Total65

12. Conclusion As far to our knowledge, this is the first study evaluating effectiveness of ICRS for such a long term follow-up period ICRS implantation is both safe and efficient in keratoconus management over the long-term period of time