Bilateral, but the onset may be sequential in both eyes, progressive vision loss, sometimes fixed black dots can be seen against a bright background, due to changes in refractive power in different parts of the crystal, there may be polyopia, monocular diplopia, and increased myopia. Clinically, senile cataract is divided into three types: cortical, nuclear and subcapsular. 1. Cortical cataract is characterized by grayish-white clouding of the crystal cortex, and its development process can be divided into four stages: incipient, immature, mature, and overripe stages. Early on, it is yellow in color, and as the clouding increases, the color deepens such as dark yellow and dark brownish yellow, the density of the nucleus increases, the refractive index increases, and the patient often complains of reduced presbyopia or increased myopia. The peripheral cortex is still transparent in the early stage, therefore, the pupil dilates in the dark to improve vision, while the pupil narrows in bright light to reduce vision. 3. Posterior subcapsular cataract, because the clouding is located in the visual axis area, affects vision at an early stage.