This is an NSAID eye drop. Like all NSAIDs, diclofenac has a mechanism similar to Motrin or Advil and is good for inflammation. This class of medications is often used after cataract surgery to decrease the chance of retinal swelling (macular edema). This drop is also known under the trade name Voltaren. Diclofenac has gone generic, so it is much cheaper to obtain these days … though most of my patients tell me it is pretty harsh going in.