Sorry to hear about your dog's problem
I've read that some topicals/drops can cause damage to the eyes which would eliminate the option of surgical removal of cataracts at a later date, while not doing anything to dissolve the cataracts. IIRC some topicals can cause uveitis.
Check with the vet school closest to you; the specialists would know of studies and the newest drugs and procedures. IME
the costs are similar or less than the local vet. There were some studies a few years ago, the specialists would know the results.