Final answer:
Various deficiencies of vision can be caused by factors such as astigmatism, vitamin A deficiency, and cataracts.
Step-by-step explanation:
Various deficiencies of vision can be caused by different factors. One common cause is astigmatism, which is an unevenness or asymmetry in the focus of the eye. This can be due to irregularities in the shape of the cornea, lens irregularities, or unevenness in the retina. Another cause is vitamin A deficiency, which can lead to visual impairments ranging from night blindness to total blindness. Cataracts, a clouding of the lens, can also cause vision problems and even blindness.