Blurred eyes from chemotherapy for breast cancer may be a side effect of chemotherapy or caused by overuse of eyes, but the possibility of brain metastasis of breast cancer cannot be excluded. It needs to be diagnosed clearly and take general treatment, radiotherapy and chemotherapy to improve. 1. Side effect of chemotherapy: blurred eyes in chemotherapy for breast cancer may be the side effect of chemotherapy drugs. Some chemotherapy drugs can cause mild damage to optic nerve, resulting in blurred vision, but it is mostly transient damage, which can be relieved after the end of chemotherapy. 2. Excessive use of eyes: If the blurring of eyes is caused by excessive use of drugs, patients should pay attention to the rationality of eye use, avoid reading e-books or watching TV for a long time, and go out to look at green plants to improve visual fatigue. 3. Brain metastasis of breast cancer: Sudden blurring of eyes caused by breast cancer may also be caused by brain metastasis of breast cancer. After diagnosis, timely treatment is needed, and common treatments include radiotherapy and chemotherapy, which can improve the quality of life and prolong the survival time. For patients with blurred eyes after chemotherapy for breast cancer, they should consult a doctor for examination and choose the appropriate way of treatment.