Possible tear duct infection

Question
I have a 2 1/2 yr old rat. He is very happy and content even at his old age. He is partially blind. He can not see objects but can seem to see shadows and bright light. He is also deaf. He is still going strong, eating lots, going in and out of his cage to his play area. He doesn't show signs of being uncomfortable, nor scratching his eyes, then again I keep his toenails pretty short by clipping with a baby nail clipper (avoiding the nic).

Within the past 3 days I suddenly noticed that his left eye near the corner of the eye closes towards his nose, where I believe to be where his tear duct is located...there is a small bulbous but not huge nor normal/smooth like bump. His other eyes is normal and healthy looking.

To me it looks like he may have infection. At this point and time there is no discharge. If it doesn't go down naturally by 3-26-09, I will be on the phone making an appointment with the his vet for 3-27-10. I was just curious if you could list some possibilities as to what you may believe what it could be, or have you heard of this happening before in other older rats. I would send you a picture, but I have misplaced my digital camera.

Thanks for your time
-Kim
3-24-10

Answer
I am so sorry for the delay. I feel like a broken record telling my readers that I have been out with food poisoning and trying to get caught up with all of my pending questions....so here goes:

It could be a block tear duct or infection, but without seeing it its hard to say. Is your vet experienced with rats?  Let me know what the outcome is. I would not allow the vet to try to puncture the little mass with a needle though esp if they want to sedate him....not at his age. I would opt for antibiotics first.