Specially designed masks are available from chemists - you would need to purchase several so that there is always one cooled.
Alternatively, a small bag of frozen peas or similar wrapped in a clean cotton cloth will make a good icepack. If ice cubes are used they need to be in a non-leaking clean clear plastic bag.
Sitting upright, put some clean gauze over the eyelids then apply the icepack. This can be cold and you need to hold a cloth in your hand or wrapped around your head in order to secure the icepack.
Try icepack application for 45 minutes every hour during waking hours if possible, but if you cannot manage this, anything longer than 15 minutes every hour is satisfactory.
Continue icepack applications for 3 days after surgery.