Evaluation of the effects of circular Descemet's membrane incision on the biomechanical, topographic and optical properties of rabbit corneas

Background: Prospective interventional animal case series to investigate quantitatively changes in corneal light-scattering, corneal hysteresis, keratometry and pachymetry induced by circular Descemet's membrane incision. Methods: Thirty mature New Zealand White rabbits were divided into three study groups: (i) surgical intervention with circular Descemet's incision; (ii) surgical control; and (iii) medical control. Group 1 eyes had two paracenteses placed 120 degrees apart and an 8.5-mm-diameter Descemetorhexis was created with a reverse Sinskey hook. Group 2 eyes had two paracenteses placed 120 degrees apart. The main outcome measures were scatterometry, corneal hysteresis, pachymetry and keratometry measurements, which were performed prior to and 2weeks following the interventions. Histology and transmission electron microscopy were performed post-mortem in representative eyes. Results: Eyes that had undergone circular Descemet's incision had significantly decreased mean keratometry (43.9±0.7 dioptres [mean±standard deviation] preoperatively vs. 43.5±0.9 dioptres postoperatively, P=0.007). Circular Descemet's membrane incision did not significantly change corneal hysteresis (4.4±1.1mmHg preoperatively vs. 4.6±0.9mmHg postoperatively, P=0.664). Corneal light scattering decreased after Descemet's scoring (0.00254±0.00059 preoperatively vs. 0.00206±0.00031 postoperatively, P=0.0025). Pachymetry measurements remained relatively stable (341.3±18.6μm preoperatively vs. 330.6±20.0μm postoperatively) without postoperative oedema. Conclusions: Circular Descemet's scoring flattened the corneal curvature by a mean of 0.4 dioptres without affecting corneal hysteresis in rabbit corneas. These findings may have important implications for ongoing developments in endothelial keratoplasty.