Corneal Wound: Architecture and Integrity

1. Corneal Wound: Architecture and Integrity 1 Magill Research Center for Vision Correction, Storm Eye Institute, Medical University of South Carolina, Charleston, SC, USA Luis E. Fernández de Castro, M.D.1 Helga P. Sandoval, M.D., M.S.C.R.1 Kerry D. Solomon, M.D.1 Disclosure: L.E. Fernández de Castro-D: Alcon, Allergan, AMO; H.P. Sandoval-D: Alcon, Allergan, AMO; K.D. Solomon–A,C,D: Alcon, Allergan, AMO, Advanced Medical Research, B&L, InSite Vision, Eyemaginations Supported in part by NIH/NEI EY-014793 (vision core) and an unrestricted grant to MUSC-SEI from Research to Prevent Blindness, New York, NY, USA

2. Introduction • Surgeons transitioning from larger to smaller micro-incisions • Incision construction is key for preventing hypotony, wound leaks, and ingress of microorganisms (endophthalmitis)

3. Purpose • To compare different incision sizes on clear corneal incision (CCIs) and to determine which incision width creates a square or nearly square arquitecture

4. Materials and Methods • A prospective study of 4 human cadaver eyes using different incisions (4) were analyzed • Particular attention was given to ensure that the wound had a square or near square configuration • Scanning electron microscopy was used to evaluate wound architecture in each group 3.2 mm 2.8 mm 2.6 mm 2.2 mm

5. Materials and Methods • After the CCIs • Corneas were fixed in 2% CacodylateGlutaraldehyde • Processed and examined using SEM at the Medical University of South Carolina, Charleston, SC • Imaging was performed using a magnification factor of 50x, 100x, and 200x • Each specimen was examined and then photographed according to a standard protocol • The outer and inner corneal wound surface were evaluated

6. Results • Qualitative observations • On the epithelial side • All incisions were adequately apposed • Large incision width • Rectangle configuration • Small incision width • Square configuration

7. 3.2 mm Incision Tear of Descemet membrane Epithelial cell loss Apposed Gapping Outer Inner

8. 2.8 mm Incision Epithelial cell loss Apposed Gapping Outer Inner

9. 2.6 mm Incision Epithelial cell loss Gapping Apposed Tear at the edge Outer Inner

10. 2.2 mm Incision Apposed Gapping Outer Inner

11. Smaller incision widths permit a nearly squared or squared configuration Larger incision widths prevent a square configuration 3.2 mm 2.6 mm 2.6 mm 3.2 mm 2.2 mm 2.8 mm 2.2 mm 2.8 mm

12. Conclusion • Larger incision widths often preclude a square construction due to infringement on the visual axis • Smaller incision width permit a nearly square or square construction • Square incisions can be more stable than rectangular • Reducing risk of hypotony • Reducing risk of wound leakage • Reducing ingress of microorganisms • Irregular apposition and minimal gapping in endothelial edges due to direct mechanical trauma • Clinically shown to improve over time • Ongoing study to determine wound integrity