Two simple animal models of intraocular pressure elevation for testing therapeutic drugs in glaucoma

Purpose Glaucoma is a progressive optic neuropathy and elevated intraocular pressure (IOP) is one of the most important risk factors. Here we present two experimental models of high IOP in rats and rabbits. One is related to the side effects of corticosteroids and the other one on the hypersaline stress. Methods In the rat model, elevation of IOP was induced by instillations of 0.1% dexamethasone twice daily. One group received only saline instillations. The three dexamethasone induced groups received either 0.9% NaCl or brimonidine/timolol (0.2%/0.25%) or latanoprost (0.002%). The IOP was measured using a TonoLab® tonometer. In the rabbit model, elevation of IOP was induced by intravitreal (IVT) injection of 5% saline solution. The first received isotonic saline solution (0.9%) by IVT injection, the other two groups received hypertonic saline solution (5%) by IVT injection, one treated with an instillation of 0.9% NaCl and the other with an instillation of brimonidine-timolol (0.2%/0.25%). IOP were recorded with a pneumatonometer. Results In the rat model, 0.1% dexamethasone instillations induced a significant and chronic increase of the IOP over 35 days. The high IOP significantly decreased after treatment with the IOP-lowering agents. In the rabbit model, the treatment showed a significant and acute increase of the IOP over 30 min to 120 min, after treatment the IOP significantly decreased. Conclusion These two models of high intraocular pressure with simple experimental handling and low cost, can be used as a tool for discovering therapeutic drugs in glaucoma targeting the outflow