Blurry eyes during the day and normal eyes at night may be caused by over-exertion of the eyes, resulting in visual fatigue. Secondly, there is also the possibility of cataract. 1. Visual fatigue: Visual fatigue is a common disease in ophthalmology, which can cause dry eyes, astringency, blurred vision and even vision loss, affecting people’s work and life. Visual fatigue is mainly caused by excessive use of the eyes, and if you use your eyes in the wrong way, you will experience blurred eyes. After a period of rest, visual fatigue will be relieved and vision will return to normal. 2. Cataract: Cataract is a visual disorder caused by clouding of the lens, the causes of which include aging, heredity, local nutritional disorders and so on. The main symptom is painless progressive vision loss. Due to the clouding of the lens, the night light is darker than the pupil is larger than the daytime, the incoming light will be relatively more, the night will feel to see things clearer than the daytime. If you experience blurred vision during the day and normal vision at night, you should go to the hospital to get a clear picture of the cause of the problem and get treatment under the guidance of your doctor.