title: Positive vitreous pressure: Pathophysiology, complications, prevention, and management.
abstract: Positive vitreous pressure occurs during anterior segment intraocular surgery associated with acute hypotony and is characterized by forward displacement of the lens-iris diaphragm with shallowing of the anterior chamber resistant to reformation, repeated iris prolapse, and, in severe cases, zonular rupture and vitreous or lens prolapse that can lead to a cascade of intraoperative complications. Positive vitreous pressure is particularly common during penetrating keratoplasty, conventional nuclear expression cataract extraction, and repair of anterior open-globe injury. Hypotony resulting from aqueous loss leads to elevated vitreous pressure from 3 possible causes: external scleral compression, acute intraocular intumescence, or rarely acutely increased vitreous volume. Understanding the pathophysiology of positive vitreous pressure helps in its prevention and management.
authors.affiliation: Department of Ophthalmology, University Hospitals and School of Medicine, Geneva, Switzerland. Electronic address: aris_c@web.de.
authors.forename: Argyrios
authors.initials: A
authors.lastname: Chronopoulos
authors.affiliation: Department of Ophthalmology, University Hospitals and School of Medicine, Geneva, Switzerland.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Thumann
authors.affiliation: Department of Ophthalmology, University Hospitals and School of Medicine, Geneva, Switzerland.
authors.forename: James
authors.initials: J
authors.lastname: Schutz
mesh_terms: D000867:Anterior Chamber / Q000503:physiopathology*; D007431:Intraoperative Complications; D015814:Ocular Hypotension / Q000209:etiology / Q000503:physiopathology*; D013508:Ophthalmologic Surgical Procedures / Q000009:adverse effects*; D014822:Vitreous Body / Q000503:physiopathology*
keywords: akinesia; choroidal detachment; choroidal effusion; choroidal hemorrhage; open intraocular surgery; positive vitreous pressure; vitreous pressure