Iris neovascularization can be directly differentiated from fibrovascular membrane without the need for differential diagnosis with other diseases. The clinical course of iris neovascularization can be divided into 3 stages: Stage 1: Early, when neovascularization first appears in the iris near the pupillary margin and in certain areas of the atrial angle. The surface of the iris is visible as tiny curved and irregular red lines in the brown iris that require careful examination to detect the iris corneal angle examination to see that the width of the atrial angle is still normal The duration of this phase varies with the cause of the disease; those with central retinal vein obstruction develop rapidly and this phase lasts only a few weeks or months; however, the iris neovascularization that occurs in diabetic retinopathy can often be maintained for several years without progression. Stage 2: Iris neovascularization continues to increase and fuse with each other until the entire iris surface becomes reticulated with neovascularization, and the iris corneal angle also has more neovascularization, but there are no or only a few areas of peripheral anterior iris adhesions. Stage 3: The iris surface is generally obscured by the neovascular membrane; the pupillary rim pigment layer is ectropioned due to contraction of the fibrovascular tissue, which pulls the pigment layer forward; the iris angle has extensive peripheral anterior adhesions, leading to a sharp increase in intraocular pressure and significant mixed congestion in neovascular glaucoma. The affected eye has severe pain, and vision is only light perception. In the case of iris neovascularization, the affected eye often has anterior chamber hemorrhage, which can occur at a rate of 25% or more. The amount of hemorrhage varies, but is often prolonged and difficult to absorb. In addition to slit lamp examination, fluorescence angiography of the iris can be performed to clearly show the iris blood circulation in light colored irises. Under normal conditions, the iris vessels are regularly arranged in a radial pattern. In contrast, the neovascularization of the iris surface is irregularly linear or reticulated and fluorescein rapidly leaks in large amounts from the neovascularization into the anterior chamber.