I've been using a hydrocortisone and now my eye is puffed up. is using hydrocortisone the cause?

No but maybe: Hydrocortisone should decrease eye swelling. I assume that you are using either a topical cream or Hydrocortisone pills. Neither should cause eye swelling unless certain things occur: 1. The cream went into the eye itself and you are reacting not to Hydrocortisone but to a stabilizer or inactive ingredient 2. The oral steroids are causing you to retain fluid and therefore causing eye swelling.

Diagnosis: The question cannot be answered without knowing (1) for what purpose are you using Hydrocortisone (2) are you using it on your skin or taking it internally (3) if applied to the skin, are you putting in on your eyelid (4) what is the concentration of the Hydrocortisone (5) how often is it used (6) how much is used each time. In general, eyelid puffiness is an unusual adverse effect for this drug.