<prompt> Corneal endothelium seen by ?PachymeterKeratometerTonometerSlit lamp bio-microscope  <response>: Ans. is d i.e., Slit lamp bio-microscope Corneal Endothelium: It consists of single layer of polygonal mainly hexagonal cells. They are visualized by slit lamp bio-microscope and appear like mosaic. The cell density is 3000 cells mm2 in young adults and deceases with age. These cells contain active pump mechanism. Note: Confocal microscope can be used to study all layers of retina. 