Hi Duncan,

For super comfort for your slippers you could try either Diabetic spec insoles or alternatively the Comfort System Plus socks which have a comfortable cushioning base.(socks: depends how much your feet swell, you may need the next size up)  Both will help considerably with your comfort.

Insoles: http://www.yourfootcare.com/html/insoles_orthotics.html

Socks: http://www.yourfootcare.com/html/socks.html

regards