Corneal endothelial protection

Brauweiler P. Bimanual irrigation/aspiration. J Cataract Refract Surg 1996 22 1013-1016 Bresciani C, Lebuisson DA, Eveillard M, Grossiord JL, Drupt F, Montefiore G. Dynamic viscosity and corneal endothelial protection with Healonid, Healon GV, Proviso and Viscoat during phacoemulsification. J Fr Ophthalmol 1996 19 39-50... 

Ravalico G, Tognetto, Baccara F, Lovisato A. Corneal endothelial protection by different viscoelastics during phacoemulsification. J Cataract Refract Surg 1997 23 433-439 Raymond L, Jacobson B. Isolation and inhibitory cell growth factors in bovine vitrous. Exp Eye Res 1982 34 267-286... 

As was seen in in-vitro and animal studies, 1% sodium hyaluronic acid, 10 8c 20% chondroitin sulfate and 1% HPMC solutions protected the corneal endothelial cells from potential injury from direct contact of the lOL or instruments with corneal endothelium (Hammer 8c Burch, 1984 Miyauchi 8c Iwata, 1984). There is, however, no viscoelastic capable of shielding the corneal endothelium from sharp instruments, accentuating the importance of creating and maintaining a deep an-... 

Fig. 74. The higher-viscosity cohesive agent (green) rapidly leaves the eye during phacoemulsification. The smooth layer of the lower-viscosity dispersive agent (violet) will be left to serve as a protection for the corneal endothelial cells...

Kerr Muir MG, Sherrard ES, Andrews V, Steel ADM. Air, methylcellulose, sodium hyaluronate and the corneal endothelium endothelial protective agents. Eye 1987 1 480-486 Kim JH. Intraocular inflammation of denatured viscoelastic substance in cases of cataract extraction and lens implantation. J Cataract Refract Surg 1987 13 537-542 Kirkby GR, Gregor ZJ. The removal of silicone oil from the anterior chamber in phakic eyes. Arch Ophthalmol 1987 105 1592... 

Nguyen LK, Yee RW, Sigler SC, Ye H-S. Use of in vitro models of bovine corneal endothelial cells to determine the relative toxicity of viscoelastic agents. J Cataract Refract Surg 1992 18 7-13 Nimrod A, Ezra E, Ezov N, Nachum G, Parisada B. Absorption, distribution, metabolism, and excretion of bacteria-derived hyaluronic acid in rats and rabbits. J Ocular Pharmacol 1992 8 161-172 Norn MS. Peroperative protection of cornea and conjunctiva. Acta Ophthalmol (Copenh) 1981 59 587-594... 

Microscopically, the cornea shows a rather simple and multilayered structure that can be divided into six layers the epithelium, basement membrane, Bowman s layer, stroma, Descemet s membrane, and endothelium. The corneal tissue consists of three different cell types epithelial cells, keratocytes (corneal fibroblasts), and endothelial cells. The outermost corneal surface is covered with the preocular tear film, which is functionally associated with the cornea. The epithelial surface must be kept moist and smooth, a role played by the tear film in conjunction with a spreading function of the eyelids during blinking motions. Furthermore, the tear film provides a protection against infectious agents that may gain access into the eye. 

In 1976, I received a telephone call from a former clinical fellow at the Retinal Foundation, David Miller, who was now the Head of Ophthalmology at Beth Israel Hospital in Boston. He remembered that in the late 1960s, we tested Healon in eye surgery during corneal transplantation to protect the thin layer of endothelial cells on the inside of the cornea from mechanical damage. These cells die when mechanically injured and do not regenerate in adults. Their function is to pump water... 

Following damage, corneal epithelial cells can regenerate. A thick protective layer of glycoprotein from mucous secretions protects the epithelium from mechanical trauma. Endothelial cells, however, do not have the same potential to regenerate (e.g., mitosis). 

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