White/clear gooey buildup in eye?

I've had contacts for 7 years now and I don't take my contacts out very often. I leave them in over night and only take them out to change them or to clean them if they appear slightly blurry from bacteria buildup. My question, however, is why do I get white to clearish buildup under my eye lids? I can feel them and I take them out by dabbing the backside of my finger slightly under my eye lid. They appear like a string of white goo when it retracts onto my finger. It has no smell but it is irritating because I can feel them and it only stops bothering me when I finally get them out. I'm pretty sure it only comes after sleeping.