Is my dog going blind?????????????????

My dog, Coco, is turning twelve this December. She's part Chihuahua and part Beagle we think, with possibly other breeds in her. She's very healthy and has never had any health problems. For a while now, when light shines in her eyes, instead of the black part being black, in it's depths it's milky white-gray, almost as if there's a foggy film within her eyes. (not a film on the surface of her eyes, but inside of her pupils) I believe that it's gotten worse over time. She doesn't run into stuff i.e., or show signs of blindness, but she's been uncharacteristically clumsy (although this could be because of her old joints). My parents have dismissed her eyes as cataracts, saying that "Old dogs get them." and "We don't have the money to remove cataracts." . Also, as a side note, when I take pictures of my 3 year old dog, JJ, with a flash on, her pupils glow a normal white or red. When I do this with Coco, her pupils are glowing green. I'm really worried. Is she going blind? Can she not see very well? Are they just cataracts? Will cataracts make her go blind? Is there an inexpensive way to fix her eyes? Thank you!