Clinical Anaiysis Of Patiellts With Hyper-reflective Corneal Endothelial Nuclei Imaged By Confocal Microscopy After Penetrating Keratoplasty

Objective To observe the morphological changes in endothelial cells of corneal grafts after penetrating keratoplasty (PKP) by in vivo confocal microscopy. The morphologic characteristics and variation of hyper-reflective corneal endothelial nuclei were studied, and the potential risk factors, its clinical significance and possible mechanism of this phenomenon were investigated.Methods This was a retrospectively case-series study. The patients who received the first PKP surgery in Sir Run Run Shaw hospital from April1999to April2008and were regularly followed up at least1year were included. The main measurements included the initial time of exhibiting hyper-reflective corneal endothelial nuclei and the changes of morphologic characteristics detected by in vivo confocal microscopy. Corneal endothelial cell density, cell area, coefficient of variation of cell area, percentage of hexagonal cells, and corneal endothelial cell loss were also analyzed. The graft survival, postoperative complications, and subsequent surgeries were recorded.Results Ninety-four eyes of94patients were enrolled. The mean follow-up duration was41.2±15.2months. The mean corneal endothelial cell density was2365.1±313.6cells/mm2at1month after the surgery, with regular arrangement, similar size, and no visible endothelial nuclei imaged by in vivo confocal microscopy. Corneal endothelial cell density and percentage of hexagonal cells decreased and cell areas increased with visit time. At the last visit, hyper-reflective corneal endothelial nuclei were identified in16eyes (16/94,17.0%) of16patients. There were9males and7females, the mean age was41.3±14.5years. The mean time of initial observation of the bright corneal endothelial nuclei was26.2±11.6months after surgery. The mean corneal endothelial cell density, cell area, coefficient of variation of cell area, percentage of hexagonal cells, and cell loss were878.2±193.9cells/mm2,1140.3±296.4μm2,46.8±9.7%,32.6±12.1%, and61.6±16.8%, respectively, which was significantly different with the patients without showing hyper-reflective corneal endothelial nuclei. Confocal images showed that corneal endothelial cells exhibiting bright nuclei manifested as increased cell areas, cellular pleomorphism and polymegathism. The bight corneal endothelial nuclei were round or oval, with an approximately size as10-12μm. Multinucleated cells were noted in several corneal endothelial cells with greater cell areas. Secondary glaucoma, rejection episode, and subsequent surgeries were statistically related with hyper-reflective corneal endothelial nuclei using by Cox proportional hazards model.Conclusion This study firstly investigate the confocal microscopic characteristics, variation and risk factors of the hyper-reflective corneal endothelial nuclei imaged by in vivo confocal microscopy after PKP. When corneal endothelial cell density decreased to900cells/mm2, bright endothelial nuclei were detected by in vivo confocal microscopy. Whether the exhibition of hyper-reflective corneal endothelial nuclei may indicate that the compensation function of endothelial cells is closed to the critical status need further investigation.