Central Retinal Vein Occlusion

Figure 15 is a graphic representation of cumulative chances of developing various types of neovascularization (NV) in ischemic CRVO.

Figure 15

On the X axis are the days from the onset of ischemic CRVO, and on the Y axis is the cumulative chance or probability of developing neovascularization. The various graphs are, from above down, for iris neovascularization, angle neovascularization, neovascular glaucoma, disc neovascularization and retinal neovascularization, These graphs provide very important information on a number of issues, including the following:

• Not every eye with ischemic CRVO develops ocular neovascularization because it depends upon the severity of retinal ischemia - more the ischemia, higher the chances of developing neovascularization.
• When ocular neovascularization develops, the commonest site is the anterior segment, much less frequently the posterior segment.
• The greatest risk of developing anterior segment neovascularization is during the first 7 months, after which the risk falls dramatically to minimal. This is extremely important information in the management of these cases; they need to be monitored very frequently during the first 7 months and if they do not develop neovascularization of the anterior segment during this period, then the risk of neovascular glaucoma drops to minimum.
• The commonly held belief that every eye with CRVO that develops iris neovascularization or angle neovascularization is destined also to develop neovascular glaucoma is wholly wrong. In fact, about one-third of the eyes with iris neovascularization and about one-quarter of the eyes with both iris and angle neovascularization never develop neovascular glaucoma.

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