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E. Spoerl, A.G. Boehm, L.E. Pillunat; Biomechanical Behaviour of the Lamina Cribrosa Influenced by Various Substances . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3318.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Structural changes in the lamina cribrosa(LC) might be related to changes of optic disc excavation. The aim of the study was to investigate whether the application of different substances influences the biomechanical properties of the LC. Methods:Porcine eyes strips of 1 mm width were cut from the posterior sclera through the LC and incubated in DULBECCO's hat medium with different substances: group 1 with 20% uric acid for 6 days; group 2 with 20% glutamate for 2 days; group 3 with 0.5 M glyceraldehyde for 3 days; group 4 with 0.1 glutaraldehyde for 1 hour; group 5 with collagenase A for 1 day and group 6 with 20% pepsin for 1 day.Each group consisted out of 10 stripes. 10 untreated LC stripes and 10 sclera stripes without LC were used as controls. The stress strain relation was measured in the stress range of 2 - 600 x 104 N/m² by a biomaterial tester. Results: Stress values in 105 N/m² at 20 % strain are 12.9±8.8 for the LC, 33.1±12.1 for the sclera, 12.4±5.1 for uric acid, 9.9±5.6 for glutamate, 18.6±7.8 for glyceraldehyde, 27.5±7.4 for glutaraldehyde, 5.4±2.5 for collagenase and 4.5±2.6 for pepsin. The LC is about 2.5 times more extensible than the sclera. Uric acid and glutamate do not direct influence the biomechanical properties of the LC. Glyceraldehyde as a representant of sugar derivates leads to an increase of stiffness (factor 1.6). The same influence shows glutaraldehyde. Collagenase or pepsin reduce the stability of the LC significantly (factor 0.5) and leads to an increased extensibility. Conclusions: This method is suitable to investigate the influence of various substances to the LC in vitro. The increase of stiffness after application of glyceraldehyde or glutaraldehyde might be explained by crosslinking of collagen and the decrease after application of collagenase or pepsin by reduction of crosslinks. Degradation enzymes or collagenase activators might play an active role in the alteration of the LC collagen and consecutive changes of the optic disc excavation.
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