When does the 2nd eye's cataract usually worsen after the initial cataract surgery?

Varies: Every cataract progresses at different rates. It can be weeks, months or years.

Variable: Most often the cataracts are of the same severity. There is no way to predict how fast the second eye will need surgery, but usually at the same time as the first or shortly there after. Especially once you see the improvement in the first eye.

Varies: Some patients need surgery in both eyes upon initial presentation. Others need the second eye within 6-12 months. Others need it years later.