Abstract
Abstract: :
Purpose:Changes in the biomechanical properties of the lamina cribrosa (LC) and of the peripapillary sclera might play a role in the pathogensis of glaucoma. Glyceraldehyde is a substance which is an advanced glycation end product and increases with the ageing process. Aim of the study was to assess the influence of glyceraldehyde on the mechanical properties of the LC. Methods:From 20 enucleated porcine eyes and from 8 pairs of enucleated human eyes three stripes of 1 mm width were cut from each eye. One stripe contained the LC and the other two the adjacent peripapillary sclera. The stripes of 10 porcine eyes and 8 human eyes (one of each pair) were incubated in DMEM and 0.5 M glyceraldehyde for 6 days. The other stripes served as control and were placed in DMED for the same time. The stress strain relation was measured in the stress range of 0.02 – 6.0 MPa by a biomaterial tester with a prestress of 0.02 MPa and a velocity of 2mm/min. The distance between the clamps was 3 mm. Results:Stress values at 20% strain of the human LC were 0.89±0.67 MPa without glyceraldehyde and 1.53±0.72 MPa after incubation with glyceraldehyde (P=0.029), and 0.92±0.17 MPa and 1.86±0.78 MPa (P=0.031) for porcine LC, respectively. The stress values of human peripapillary sclera without glyceraldehyde were 2.91±2.2 MPa and 6.33±3.79 MPa after incubation with glyceradlehyde (P =0.047), and 3.3±1.21 and 5.26±1.06 (P=0.027) for porcine peripapillary sclera, respectively. In comparison the stress values and Young’s moduli of the untreated peripapillary sclera at 10 % strain from the literature are: human 0.83±0.66 MPa (E=13.4 MPa), monkey 1 MPa (E=6.3 MPa), rabbit 0.7 MPa (E=6.0 MPa), porcine 0.63±0.3 MPa (E=14.2MPa). Conclusions:The stress/strain relations of human and porcine LC and peripapillary sclera are not statistically different. Glyceraldehyde increases the stiffness of the LC and of the peripapillary sclera in humans and in porcine. Glyceraldehyde affects changes in the extracellular matrix according to the Maillard reaction as it occurs during the ageing process or diabetes. CR: None
Keywords: lamina cribrosa • optic disc • aging