A layer of white fog in the eyes may be caused by the following diseases: First, cataracts. When the crystal is transparent at birth, the lens density gradually increases with age, the transmittance begins to decrease, the crystal becomes cloudy, and cataracts gradually occur. At the early stage of cataract, the refractive power will change, resulting in mild myopia, easy visual fatigue, darkening and blurring of vision, and gradual loss of vision, resulting in a white fog-like feeling in front of the eyes. Mild cataracts do not require treatment, and should be observed on a follow-up basis. When going out, avoid strong ultraviolet radiation and wear sunglasses. Moderate to severe cataracts affect vision more obviously and require surgery for complete eradication. Secondly, keratitis, diseases of the cornea often cause a decrease in the transmittance of the cornea, causing blurred vision. If keratitis is in the inflammatory phase, there is often also a foreign body in the cornea, inflammation of the cornea, accompanied by photophobia, foreign body sensation, stinging pain, vision loss, blurred vision, and the feeling of seeing things like a layer of white mist. Some keratitis can leave behind corneal white spots that cause blurred vision and a feeling like a layer of white fog.