RT Journal Article SR Electronic T1 Quantitative trabeculectomy JF British Journal of Ophthalmology JO Br J Ophthalmol FD BMJ Publishing Group Ltd. SP 67 OP 67 DO 10.1136/bjo.67.1.67 VO 67 IS 1 A1 Roger A. Hitchings YR 1983 UL http://bjo.bmj.com/content/67/1/67.1.abstract AB