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Andre Heck, Fernando Abib; Theoretical and Clinical Method to quantify the Corneal Suction Pressure from normal corneas during the lifetime. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1671.
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© ARVO (1962-2015); The Authors (2016-present)
To demonstrate a methodology to quantify the Corneal Suction Pressure (CSP) from normal corneas during the lifetime.
The Corneal Suction Pressure (CSP) is defined as the corneal volume that oncotically works through on the summation of the lateral membrane; the CSP is a volumetric unity (µm3) for 1µm of the lateral membrane between 2 contiguous cells. To calculate the CSP in normal corneas will be used clinical results from corneal specular microscopy (CSM) with reliability indexes <0.05, and Pentakan. The endothelial cell density (ECD) and the average of the endothelial cell area (A) are routinely calculated by CSM. The ECD and A of the corneal endothelial cell (CEC) changes during the lifetime. The model will consider all possible ECD (4000 - 500 cells/mm2) and A (250 - 2000 µm2) values during the lifetime. The Corneal Volume (CV) of the 10mm of the corneal diameter is calculated by Pentakan. To demonstrate the theoretical model used to quantify the CSP in corneas, the used range of the CV is from 40 to 70 mm2. Considering that the water flows through the lateral membrane of the CEC, the study will calculate the summation of the perimeter (P) of the estimated total population of the CEC (ΣCEC Perimeter) with the predominant cell morphology - hexagonal. The P of the CEC is calculated by the formula PCEC = 6sCEC and A = 6sCEC2√3/4 . The summation of CEC perimeter will be calculated by the formula: ΣCEC Perimeter = 2πrh.ECD.6sCEC. The model cornea data: radius of the corneal inner surface (r) = 6.93; corneal sagital depth (h) = 3.06; side of the CEC (sCEC); π=3.14159. CSP is defined as the CV/ 0.5ΣCEC Perimeter. The results of the CSP will be present in a table with the corresponding ECD and A values and a graphic model.
The calculated values of the CSP can be able to represent the smaller volume (µm3) of cornea which is correlated functionally with 1 µm of the neighboring lateral cell membrane, which represents the endothelial barrier and endothelial pump to maintain the corneal trasnparency. The calculated CSP values for different corneal volumes is presented in the Table and its behavior in the Graphic 1.
The used methodology was able to calculate the Corneal Suction Pressure (CSP) from normal corneas with different ECD and volumes during the lifetime with results of CSM and Pentacan in clinical situations.
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