1. 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. 2  The authors have no financial interests or relationships to disclose. Financial Disclosure

3. 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. 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. 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. 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. 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. 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. 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. 10 Donor featuresGroup 1Group 2P-value Age (years) 36.5±16.429.4±7.9 0.29 Graft rating Excellent Very good Good Fair 8 10 5 4 28622862 0.51 Endothelial cell density (cells/mm 2 ) 2849.4±648.52685.3±507.3 0.43 Death-to-preservation time (hours) 10.8±5.510.7±7.8 1.0 Mean storage time (days) 3.4±4.13.7±1.20.89 Table 1: Donor data in DALK groups

11. 11 Table 2: Scotopic and photopic contrast sensitivity (dB) in the DALK groups Spatial frequencyGroup 1Group 2P-value 1 cpd Scotopic 17.39±1.5314.75±3.77 0.04 Photopic 17.30±1.3014.83±3.56 0.02 2 cpd Scotopic 18.52±3.0915.92±4.87 0.11 Photopic 18.78±2.6614.92±5.74 0.04 3 cpd Scotopic 18.22±4.3116.33±5.50 0.27 Photopic 18.74±4.7115.42±5.18 0.06 6 cpd Scotopic 15.61±4.9413.50±5.60 0.26 Photopic 15.78±5.2111.83±5.39 0.04 12 cpd Scotopic 9.74±5.297.83±4.99 0.31 Photopic 10.61±5.377.25±4.73 0.08 20 cpd Scotopic 5.35±3.464.58±3.66 0.55 Photopic 6.30±4.025.0±2.920.33

12. 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±137.6635±198.8737±65.8 <0.001 0.050.01 Middle 548.7±101.2568.2±78.9604.4±54.6 0.04 0.471.0 Posterior 306.1±99.0579.7±95.3602.4±46.4 <0.001 1.0<0.001 Endothelial cell density (cells/mm 2 ) 2621.2±388.22333.1±450.92987.2±327.7 <0.0010.002<0.0010.06 Hexagonality (%) 53.6±7.857.3±8.355.3±7.8 0.331.0 0.42 Polymegethism (%) 31.5±5.231.2±7.534.0±5.60.200.360.411.0

13. 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