I am 59 with worsening vision more in one eye than the other. While assessing for cataracts (early stages), the ophthalmologist said my optic nerves were swollen and listed optic nerve edema OU (after nuclear sclerosis OU). I am to have an MRI brain scan in 4 days. I have found about six conditions that could cause this (along with the doc's comment that "some people just have swollen nerves for no reason," which I didn't wholly believe). For people say over 50 years old with optic nerve edema in the US and no comorbid conditions such as MS, what are the top 4-5 causes and the percentage rate for each -- e.g. no reason 30%, brain tumor 15%, infection 10%, etc...?