astigmatic power lens #01135BT: OIMLDF: lens bringing a paraxial pencil of parallel rays to two separate line foci mutually at right angles and hence, unlike a spherical lens, having two principal powersNA: One of these powers may be zero, with the corresponding focal line at infinity. Lenses referred to as toric lenses, sphero-cylindrical lenses and cylinder lenses are all astigmatic.NC: ID: 01135NC: reference: R093:1999 3.10