This is when the lens of the eye becomes cloudy and hard to see through. In a normal eye, the lens is almost transparent. Its job is to focus the things we are looking at onto the retina at the back of the eye so we can see objects at different distances clearly. Cloudiness of the lens causes dimming of the eyesight and fuzzy images. Cataracts are usually caused by exposure to too much sunlight or by aging. In young infants with galactosemia, cataracts may be caused by the buildup of galactose and other substances in the blood.