Help! Specific problems or just old age?

[bug.dragon]

My friend has a rat named Zookie who is a female, ruby-eyed, beige hooded rat who also happens to be 3 1/2 years old. She's NEVER had any health issues, and up until a month ago, was fat, happy, healthy, and active. However, lately these have been the following symptons:
1.) Climbing to the 2nd level of her cage and hanging her head off the side
2.) Sleeping with her eyes open/not blinking when you touch her eyes/face
3.) Weight loss
4.) Getting "upset" (no longer exploring like usual, hiding, bracing herself against objects) when outside her cage
5.) No longer grooming herself
6.)Overall behavior change
I think it's safe to say that she's blind, and I'm fairly confident that these problems are all just related to old age and other than feeding her tasty fatty foods, and trying to keep her comfortable, there's nothing that can be done, but I thought I'd check here too to see if anyone had any advice. Any foods/ comforting things that anyone can think of?

[Addicted2Rats]

I've heard alot of people mention giving Ensure to the older rats who are losing weight and not eating as much as usual.  Zookie sure is an ol gal, living to 3-1/2 years old!  She must be taken really good care of! 

Deb