The most common symptom is a cloudy vision.
Another would be your vision getting affected, like your short-sightedness increasing: as if the near objects are clear but the far ones keep on getting blurrier and blurrier over time. This means you have to keep on going to your optician, who keeps on increasing the degree. That's one symptom of cataracts.
Other symptoms include double vision, where you see things or images are doubled or more dispersed. The top telltale sign would be blur vision.
