We cannot provide a definite answer unfortunately as it depends upon numerous factors such as how old the cataracts are, how well established and how large they are, how old the person/pet with the cataracts is, their general health etc etc
Some people/pets get results quickly, some might take several months, but in our opinion and reinforced by customer feedback, the greater the percentage of the active ingredient in the eye drops - N-Acetyl-Carnosine - the quicker results will be achieved, which is why Cataract Clear 2% NAC Ultra contains TWICE AS MUCH and Cataract Clear 4% NAC XTRAMAX contains FOUR TIMES as much N.A.C as most other N.A.C based eye drops.
Unlike taking an aspirin for a headache which then goes in a hour or so or anti biotics for an infection that goes after a few days, consistent use of Cataract Clear is the key. Please bear in mind you are trying to tackle an issue from "the outside" of the eye which then has to penetrate the cornea of the eye, make it's way to the lens of the eye and then break down the cataract material. IT WORKS, but, in some cases, it can take a little time, so persistence is key.