Buckingham Palace says Queen Elizabeth II had successful eye surgery to treat a cataract last month.

The palace made the announcement Friday after the queen was seen wearing sunglasses at a number of recent public engagements. It was not announced at the time of the procedure.

The 92-year-old monarch was treated as an outpatient at King Edward VII’s hospital in central London.

Cataract surgery has become quite common and often helps people suffering from blurry vision. The surgery involves replacing a cloudy lens inside the eye with an artificial one.

It is performed under local anesthetic and is usually concluded within 40 minutes.

(AP)