RT Journal Article SR Electronic T1 Classifying posterior vitreous detachment: a new way to look at the invisible JF British Journal of Ophthalmology JO Br J Ophthalmol FD BMJ Publishing Group Ltd. SP 521 OP 521 DO 10.1136/bjo.81.7.521 VO 81 IS 7 A1 J SEBAG YR 1997 UL http://bjo.bmj.com/content/81/7/521.abstract AB