Hi, Chet,
Sorry to hear about your Chihuahua's eye problems.
I cannot say whether or not cataract surgery would help - it would depend on the type of cataract. If the rest of the eye - ie the retina is OK, removal of the affected lens would produce a return of vision, but if the cataracts are a result of a retinal abnormality, it would not.
I am assuming that you do not live in the UK, so I cannot help you in advising you of a eye specialist to ask to be referred to, but your own veterinarian should be able to refer you.
The cost in the UK of cataract surgery could be as much as $6-700 per eye, without a guarantee of success.
Walter