1. CORNEAL ENDOTHELIAL PROFILE AFTER FERRARA RING IMPLANTATION Leonardo Torquetti, MD, PhD Paulo Ferrara, MD, PhD Paulo Ferrara Eye Clinic Belo Horizonte - Brasil Financial Disclosure: The authors of this poster have received research funding and travel expense reimbursement from Ferrara Ophthalmics

2. Purpose: To evaluate corneal endothelium changes after the implantation of Ferrara intrastromal corneal ring segments (ICRS) (Ferrara Ophthalmics, Belo Horizonte, Brazil). Methods: One-hundred and two eyes of 81 patients with keratoconus, pellucid degeneration and post-LASIK ectasia who had completed at least one year of follow-up (mean follow-up ± SD, 45.7 ± 16.4 months, range 13 to 71 months) were retrospectively studied. One or two Ferrara ring ICRS were inserted in the cornea, embracing the keratoconus/ectasia area. The corneal topography was obtained from EyeMap (Alcon ®, USA) and Pentacam (Oculus Pentacam ®, USA). Corneal endothelial cell analysis was performed with a non-contact specular microscope (SP-3000, Topcon ®, Japan). Endothelial cell images were collected at the central region of the cornea. Statistical analysis included preoperative and postoperative keratometry and endothelial characteristics (cell count, average cell size and coefficient of variation). Results: The mean cell count decreased from (mean ± SD) 2714 ± 372 cells/mm 2 to 2562 ± 406 cells/mm 2 (p < 0.001). The calculated exponential cell loss rate over the mean interval of follow-up (4 years) was 1.4% per year. The average cell size increased from (mean ± SD) 375 ± 56 µ 2 to 399 ± 61 µ 2 (p < 0.001). The coefficient of variation increased from (mean ± SD) 0.22 ± 0.075 to 0.26 ± 0.010 (p = 0.001). There was significant corneal flattening as showed by keratometry changes. The mean K decreased from 47.70 ± 2.29 (range 43.70 to 53.80) to 44.86 ± 2.02 (range 41.20 to 51.20) (p = 0.0001). Conclusion: There are some endothelial changes after Ferrara ICRS implantation, without clinical relevance.

3. To evaluate possible endothelial changes after implantation of the Ferrara intrastromal corneal ring segments (ICRS) * The Ferrara ICRS has not been approved by the U.S. Food an Drug Admnistration (FDA)

4. - Retrospective study: chart review of 102 eyes of 81 patients, consecutively operated and followed for at least 1 year; - Surgical technique: standard (manual technique); - Studied parameters: endothelial cell count (ECC), endothelial cell size (ECS), coefficient of variation (CV) and keratometry (K); - Follow-up: 45.7 months (mean) (range: 13 to 71 months);

5. - Topography: EyeMap (Alcon ®, USA) and Pentacam (Oculus Pentacam ®, USA); - Corneal endothelial cell analysis: non-contact specular microscope (SP-3000, Topcon ®,Japan) -Statistical analysis: preoperative and postoperative anterior e posterior keratometry, endothelial characteristics (cell count, average cell size and coefficient of variation); - Student t Test (paired sample) and Pearson’s correlation coefficient: Minitab Software (Minitab Inc.).

6. Distribution of diagnosis of operated patients (I, II and III refer to keratoconus classification)

7. Endothelial cell parameters and Keratometry (mean) PreoperativePostoperative p Cell count (cells/mm 2 ): 2714 ± 372 2562 ± 406 0.001 Cell size (µ 2 ) 375 ± 56 399 ± 61 0.001 Coefficient of variation 0.22 ± 0.075 0.26 ± 0.010 0.001 Keratometry (anterior) 47.70 ± 2.29 44.86 ± 2.02 0.001 Keratometry (posterior) - 6.76 ± 0.70 - 6.80 ± 0.45 0.667

8. FIGURE 2.1 and 2.2 – Preoperative (2.1) and Postoperative (2.2) Scattergram of Keratometry and Endothelial cell count Pre and Postoperative Cell Count

9. ParametersPreop KmPreop ECCPostop KmPostop ECC Preop Km1-0,2890,6820,060 Preop ECC-0,2891-0,2700,383 Postop Km0,682-0,2701-0,005 Postop ECC0,0600,383-0,0051 Bold values are different from 0 with a level of significance of.05. ECC = endothelial cell count, Km = mean keratometry p values ParametersPreop KmPreop ECCPostop KmPostop ECC Preop Km00,041< 0,00010,681 Preop ECC0,04100,0580,006 Postop Km< 0,00010,05800,972 Postop ECC0,6810,0060,9720 There is no correlation between the pre and postoperative keratometry and the ECC pre and postoperatively. Pearson’s correlation coefficient

10. Calculated exponential cell loss rate over the mean interval of follow-up (4 years): 1.4% per year

11. - Consensus: gradual decrease in cell density occurs with increasing age. Abib FC, Barreto Junior J. Behavior of corneal endothelial density over a lifetime. J Cataract Refract Surg. 2001;27(10):1574-8. - Endothelial cell loss rate: Patients < 18 years old): 1.1% ± 0.8% per year loss Patients > 18 years old): 0.6% ± 0.5% per year loss Bourne WM, Nelson LR, Hodge DO. Central corneal endothelial cell changes over a ten-year period. Invest Ophthalmol Vis Sci 1997;38:779-782 After PK, ranging from 4.2% to 9.4% per year, at the long-term follow-up Langenbucher A, Nguyen NX, Seitz B. Predictive donor factors for chronic endothelial cell loss after nonmechanical penetrating keratoplasty in a regression model. Graefe’s Arch Clin Exp Ophtalmol. 2003;241:975-981.

12. The endothelial cell loss after Ferrara ICRS implantation is slightly higher than the expected cell loss in normal eyes