As you can see, not everybody is allowed to take cataract surgery, sometimes if people have the following problems, they are forbidden. First, is BP, patients with high BP would not be ok. Next, if your blood sugar is too high, your are also forbidden. Also, if your eyes have got some infections, also not ok. Anyway, you should get a overall medical exam before taking the surgery.
If you have too high or too low blood pressure, you should not have cataract surgery. If your crystal has been dislocated or half dislocated, you should not have cataract surgery. If the optic nerve and retinal have pathological change, you should not have cataract surgery. If your eyes have inflammation, you should cure it before having cataract surgery.