First, it is important to understand what cataracts are. Cataracts are the clouding of the lens cortex, which commonly refers to the gradual whitening of the central pupil area, the black part of the eye. Cataracts, based on their stage of development, are divided into early, middle, and late stages. In the early stage of cataract, the vision is slightly impaired. In the middle stage, the cortex becomes moderately clouded, and vision might still be around 0.4 or 0.5. In the late stage, the cataract is severely matured, generally with vision lower than 0.3. Cataract in its early and middle stages might not necessarily require immediate surgery. However, in late stages, when vision drops below 0.3, surgery should be considered. If not treated surgically, the mature cataract can completely block light, progressively decreasing vision and eventually leading to blindness. Therefore, it is advisable to consider surgical treatment for cataracts in the late stage.