[Significance of an angiogenic factor (in omental lipid) for the vascularization of the cornea].

The existence of an angiogenic factor in the omental lipid was verified by injecting four different test materials in dosages of 50 microliters into the corneas of New Zealand rabbits. The test substances were: 1) phosphate-buffered saline solution; 2) chloroform-methanol solution; 3) phosphate-buffered saline homogenate of the chloroform-methanol extract of the lipid cake from the rabbit omentum. The experimental results show that the modes of neovascularization after injection of lipid and nonlipid materials into rabbit corneas are very similar. For angiogenesis to be stimulated, the noxious substances must be retained in the cornea for several days. One day after injection the phosphate-buffered saline solution is totally resorbed. The other test substances (2-4), are retained within the cornea for days or weeks. Test substance 1 does not induce any corneal vascularization. The injection of test substances 2-4 causes similar corneal neovascularization: the proliferation of vessels always starts from that segment of the limbus closest to the stimulation. Since the extent of vascularization after injection of chloroform-methanol solution alone is similar to that which occurs after injection of an omental lipid extract, the hypothesis of a specific angiogenic factor is not supported. Fluorescein angiography reveals a large outflow of fluid (leakage) out of the neovascularization.