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Pre Descemet’s endothelial keratoplasty (PDEK) is a kind of endothelial keratoplasty, where the pre descemet’s layer (PDL) along with descemet's membrane (DM) and endothelium is transplanted. Conventionally in a corneal transplantation, doctors use a whole cornea or parts of the five layers of the cornea to perform correction surgeries. In May 2013, Dr Harminder Dua discovered a sixth layer between the stroma and the descemet membrane which was named after him as the Dua's layer. In the PDEK technique, doctors take the innermost two layers of the cornea, along with the Dua's layer and graft it in the patient's eye. ==Definition== The normal cornea (Fig 1) has from the front to the back the following layers: 1. Epithelium 2. Bowmans membrane 3. Stroma 4. Pre Descemets layer 5. Descemets membrane 6. Endothelium For the human eye to see, the cornea or the front window of the eye should be clear or transparent. For that to happen the inside corneal layer the endothelium pumps out water from the cornea so that the cornea remains transparent and light can pass into the eye and one can see. If the endothelium is bad the cornea starts having lot of water and gets damaged which is called Bullous Keratoplasty. Thus PDEK helps in replacing the non function endothelium in bullous keratopathy. PDEK is different from the whole cornea transplantation in which the transplantation of entire donor cornea to the recipient is done. Normal corneal thickness is about 520 to 540 microns in the centre and 600 to 620 microns in the periphery. Pre descemet’s layer which is dissected in PDEK, measures about 10.15±3.6 microns thick. The descemet membrane (DM) measures about 16±2 microns (range 13-20µ) thick and the normal endothelium is about 5 microns thickness. Hence the overall thickness of the PDEK graft will be about 32 to 44 microns. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pre-Descemet's Endothelial Keratoplasty」の詳細全文を読む スポンサード リンク
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