Liquefaction of rabbit vitreous by ferrous ions

Intravitreal injection of 0.7 mumol of ferrous chloride in 0.1 ml into the rabbit eye resulted in liquefaction of the vitreous gel and condensation of vitreous collagen fibrils within two weeks; injection of 0.1 mumol did not cause any obvious vitreous degeneration, although retina damage was noted in the posterior pole. Macrophages migrated at the vitreoretinal interface and local posterior vitreous separation was observed after the injection of ferrous solution. This suggests that the least amount of ferrous ions necessary to cause liquefaction of the rabbit vitreous is in the range of 16.8 to 39.2 micrograms of elemental iron, a concentration of 0.3 to 0.7 mM in the vitreous. Since 0.1 ml of blood contains approximately 50 micrograms of iron, it is possible, at least theoretically, that the iron released by hemoglobin following vitreous hemorrhage could induce liquefaction of the vitreous.