Corneal endothelium – Specular microscopy

Abstract

AbstractCorneal endothelium is a single layer of hexagonal cells covering the inner surface of the cornea and maintains the corneal deturgescence by continuous pumping of water and ions from the stroma to the aqueous humour. This mechanism is necessary to preserve the transparency of the cornea. The corneal endothelium is derived from the neural crest. Endothelial cells are arranged in a mosaic pattern of mostly hexagonal shaped cells. The cells can be characterized by different size (polymegathism) and different shape (pleomorphism). These parameters may reflect a compromised endothelial functional status.The corneal endothelial cell layer does not capable for regeneration, a constant and age‐dependent loss of corneal cells present during lifetime. Extensive injury of corneal endothelium leads to permanent corneal swelling and bullous alterations on the corneal surface. If left untreated and in chronic cases inflammation, later on permanent scarring may occur leads to loss of corneal transparency and finally decreased vision.Generally, a healthy cornea has about 1500–3500 endothelial cells/mm2 in the central area (age 40–75). The gold standard for the evaluation of endothelial cell density is endothelial microscopy, based on specular reflection, when light is reflected from the interfaces of materials with different indices of refraction. In addition, in vivo confocal microscope can also be used to visualize the endothelium, along with other tissue components of the cornea.Different forms of corneal damage by inflammatory processes or by mechanical trauma following intraocular surgery can lead to additional endothelial cell loss. Evaluation and proper examination of corneal endothelium and endothelial cell density is important and has clinical relevance in aging, corneal preservation, phacoemulsification, and post‐keratoplasty corneas.