Confocal scan study of corneal grafts following Descemet-on versus Descemet-off deep anterior lamellar keratoplasty Zare M, Feizi S, Rezaie M, Hoseini B. MDs Hasani H, MD Shahid Beheshti University of Medical Sciences WCC VII -2015

2  The authors have no financial interests or relationships to disclose. Financial Disclosure

3 To compare confocal and biomechanical features of grafts following deep anterior lamellar keratoplasty (DALK) using a donor without Descemet’s membrane (DM) versus a full-thickness donor with intact DM. Purpose

4 Design: non-randomized cross-sectional comparative study. 45 eyes with keratoconus who underwent DALK using the big-bubble technique were enrolled. Of which, 27 received a donor without DM (group1) while in 18 eyes; a full-thickness donor with an intact DM was used (group 2). A group of normal eyes (n=28, group 3) served as controls. Methods

5  Confocal microscopy was used to determine cellular profiles of grafts and the features of donor-recipient interface.  Additionally, corneal hysteresis (CH) and corneal resistance factor (CRF) were measured.  The results were compared between the study groups using ANOVA test.

6  Mean follow-up duration was 20.2±8.6 months and 29.6±17.0 months in groups 1 and 2, respectively (P=0.13).  CH was 9.82±1.93 mmHg in group 1, 9.51±1.22 mmHg in group 2 and 9.84±1.59 mmHg in group 3 (P=0.76). Results

7  CRF was 9.57±1.87 mmHg, 9.04±1.55 mmHg and 9.89±1.73 mmHg, respectively (P=0.24).  Confocal scan demonstrated that the keratocyte profiles and distribution were more similar to normal corneas in group 2.  Additionally, significantly more severe interface haziness was observed when donor DM was retained.

8 The density and distribution of keratocytes in group 2 look like the normal group. But, group 1 shows reduction in keratocyte density in anterior and posterior stroma.

9 Donor-recipient interface.: Confocal scan illustrates sheets of hyper reflective and amorphous extracellular deposits together with high- contrast micro-dots at the interface. These deposits are more prominent in group 2 compared to group 1.

10 Donor featuresGroup 1Group 2P-value Age (years) 36.5± ± Graft rating Excellent Very good Good Fair Endothelial cell density (cells/mm 2 ) ± ± Death-to-preservation time (hours) 10.8± ± Mean storage time (days) 3.4±4.13.7± Table 1: Donor data in DALK groups

11 Table 2: Scotopic and photopic contrast sensitivity (dB) in the DALK groups Spatial frequencyGroup 1Group 2P-value 1 cpd Scotopic 17.39± ± Photopic 17.30± ± cpd Scotopic 18.52± ± Photopic 18.78± ± cpd Scotopic 18.22± ± Photopic 18.74± ± cpd Scotopic 15.61± ± Photopic 15.78± ± cpd Scotopic 9.74± ± Photopic 10.61± ± cpd Scotopic 5.35± ± Photopic 6.30± ±

12 Table 3: Anterior, middle, and posterior stromal keratocyte density, and endothelial cell density and morphology in the three study groups ParametersGroup 1Group 2Group 3P (ANOVA) P1P1 P2P2 P3P3 Keratocyte density (cells/mm 2 ) Anterior 499.5± ± ±65.8 < Middle 548.7± ± ± Posterior 306.1± ± ±46.4 < <0.001 Endothelial cell density (cells/mm 2 ) ± ± ±327.7 < < Hexagonality (%) 53.6± ± ± Polymegethism (%) 31.5± ± ±

13  Two techniques of donor preparation for DALK provide comparable results in terms of graft biomechanics.  However, graft cellular profiles and healing response at the donor-recipient interface can profoundly be affected depending on whether donor DM is removed or retained. Conclusion