RT Journal Article SR Electronic T1 “TWINCENTRIC” LENSES JF British Journal of Ophthalmology JO Br J Ophthalmol FD BMJ Publishing Group Ltd. SP 116 OP 117 DO 10.1136/bjo.21.3.116 VO 21 IS 3 A1 F. A. Williamson-Noble YR 1937 UL http://bjo.bmj.com/content/21/3/116.abstract AB