The monofocal lens, also called a single vision lens, has been the standard intra-ocular lens (IOL) for routine cataract surgery for many years. During cataract surgery, the cloudy natural lens/cataract is removed, and a new lens takes the place of the cataract. A monofocal IOL may improve your vision at either distance or near, but not both. Also, these lenses do not correct astigmatism. Therefore, if you choose a monofocal lens, you will most likely need to wear glasses/bifocals to correct any astigmatism and reading vision troubles.