Cataracts are caused by the clouding of the lens, leading to a decline in vision. Early symptoms include blurred vision, sometimes seeing black spots, and some patients report a significant decrease in vision in dim light, with both near and distant vision being unclear. As cataracts progress, the decline in vision becomes more pronounced, severely affecting the quality of life. Some patients with cataracts may also experience double vision, changes in color perception, and a significant decrease in vision, requiring surgical treatment.