The main symptoms of cataracts include: First, a decline in vision, which is the most obvious and significant symptom of cataracts. Second, a decrease in contrast sensitivity, particularly noticeable at high spatial frequencies in cataract patients. Third, changes in refractive power. Nuclear cataracts lead to increased lens power due to an increase in the lens and refractive index, causing nuclear myopia. Fourth, monocular diplopia or polyopia due to uneven refractive power across different parts of the lens, similar to the effect of a prism, resulting in monocular diplopia or polyopia. Fifth, glare. Sixth, changes in color perception. Seventh, varying degrees of visual field defects.