Experimental glaucoma model in two lines of rats using polystyren microspheres (Bead Model)

Purpose The purpose of this study is to develop a method to get simple and reproducible rodent glaucoma model in rats of Wistar and Long-Evans line. The intraocular pressure (IOP) and loss of number of retinal ganglion cells (RGCs) were measured to evaluate the success of model. Methods 20 male rats were used in this study. 7 of them were excluded because of incidence of eye inflammation. Finally 13 rats (6 Wistar rats and 7 of Long-Evans lines with a mass about 200 g) were included. IOP was elevated by injection of polystyrene microbeads into the anterior chamber and measured by Icare TonoLab. For each rat, the right eye was treated with different combinations of polystyrene microspheres with a diameter of 6 and 1 um separately and the left eye was treated as a control. RGCs were labeled retrogradely with a fluorescent marker “FluoroGold” 5 days before euthanasia and after harvested and made slices for a counting of surviving ganglion cells. Results Mean intraocular pressure (IOP) of examined group was 24 mmHg ± 5,4. The highest IOP appeared after injection on 3rd day, and rose a bit lasting till 21st day. The mean IOP in contralateral eyes during experiment was 10,8 mmHg ± 0,5. Mean number of RGCs in eyes with elevated IOP was 3014±655 cells (semiquantitative method was used). In control group it was 4106±852 cells. In examined group values of IOP were significantly higher and number of RGCs was significantly lower according to control eyes. Conclusion“Bead model” method could be used to create rat model of glaucoma with stable increasd IOP. The different size microspheres could provide the IOP with the desired values.