Sudden nearsightedness with snowflake formation in one eye may be caused by cataracts. Sudden onset of myopia with snowflake formation in one eye, which is often characterized by unclear vision and dark shadows in front of the eyes, may be caused by cataracts. Patients with cataracts may experience discomfort such as myopic drift and blurred vision due to uneven clouding of the lens and swelling of the lens, which affects the patient’s visual function. Various reasons such as aging, genetic, local nutritional disorders, immune and metabolic abnormalities, trauma, poisoning, radiation, etc., can cause metabolic disorders in the lens, resulting in cloudy lens protein denaturation, called cataract. Because light is blocked by the cloudy lens and cannot be projected on the retina, patients may experience blurred vision. Patients with vision loss are advised to visit the hospital in time to assess their condition and under the guidance of the doctor.