Mechanical Property Changes of Glial LC and RGC Axons in Response to High Intraocular Pressure

Bochao Ma¹Liu Liu²Yushu Liu³Jifeng Ren¹Xiuqing Qian^1*

• ¹Capital Medical University, Beijing, China
• ²Peking University Third Hospital, Haidian, Beijing Municipality, China
• ³Binzhou Medical University, Binzhou, Shandong Province, China

Pathological high intraocular pressure (IOP) is an important risk factor for glaucoma. The lamina cribrosa (LC) area in the optic nerve head is the initial site of optic nerve injury for glaucoma. LC deformation caused by elevated IOP will compress the retinal ganglion cells (RGC) axons passing through it, thereby leading to the damage of the RGC axons. The deformation of LC is highly correlated with its mechanical properties. Therefore, changes in mechanical properties of LC with the duration of high IOP is of great significance. In this study, the rat models with chronic high IOP were established by cauterizing the superior scleral vein and injecting 5-fluorouracil (5-FU) under the conjunctiva. Linear elastic properties of glial LCs and RGC axons in the high IOP eyes were determined by combining atomic force microscope (AFM) scanning with image segmentation technique. Morphological changes of glial LC were observed by using hematoxylin-eosin staining, immunofluorescence staining, and transmission electron microscopy. The results of elastic properties of glial LC and RGC axons were obtained while the elevated IOP of rats was sustained at 4 weeks, 8 weeks, and 12 weeks. Compared with the control group, the Young's modulus of the glial LC decreased by 35.5%, 74.2%, and 80.6% after 4, 8, and 12 weeks of elevated IOP, respectively; the Young's modulus of RGC axons decreased by 45.6%, 70.9%, and 75.9% after 4, 8, and 12 weeks of elevated IOP, respectively. Our results indicated that the long-term effects of high IOP will damage the structure and mechanical properties of the LC. This study provides a basis to further understand the mechanism of optic nerve injury.