Seeing white characters on a black background with heavy shadows may be caused by physiological reasons, such as visual fatigue caused by overexertion of the eyes, may also be a symptomatic manifestation of certain diseases, such as astigmatism, strabismus, etc., the patient should consult a doctor to find out the cause of the disease in a timely manner. 1. Physiological reasons: If patients watch electronic products for a long time, look at objects for a long time, stay up late for a long time, etc., visual fatigue of the eyes will be produced, so the symptoms of double vision and false shadow can appear. Patients should pay attention to rest, ensure adequate sleep, and develop good eye habits. 2. Pathological causes (1) Astigmatism: due to the uneven curvature or irregular shape of the cornea, patients with astigmatism may suffer from vision loss, double vision and other uncomfortable symptoms. (2) Strabismus: Patients with strabismus, whose eyes are skewed due to trauma or congenital factors, may experience discomfort such as double vision due to the imbalance between the two eyes. It is recommended that patients with double vision should consult a doctor promptly to evaluate their condition and follow the doctor’s instructions for treatment.