title: Does head positioning influence anterior chamber depth in pseudoexfoliation syndrome?
abstract: OBJECTIVE
  Phacodonesis can occur in pseudoexfoliation syndrome because of impaired zonular support. This study investigates whether the increased mobility of the lens influences anterior chamber depth in patients with pseudoexfoliation while assuming a prone position.
  
  
  METHODS
  Central anterior chamber depth was measured in 39 patients with clinically apparent unilateral pseudoexfoliation and elevated intraocular pressure. Patients were placed in a face-up position for 5 minutes, at which time anterior chamber depth and axial length were measured by A scan, and intraocular pressure was measured by Tonopen (Oculab, La Jolla, CA) in both eyes. The measurements were repeated on both eyes after 5 minutes in a face-down position.
  
  
  RESULTS
  No significant differences in intraocular pressure or axial length between the prone and supine positions were found in either eye. Anterior chamber depth in eyes with pseudoexfoliation decreased from a mean of 3.08 mm in the supine position to a mean of 2.95 mm in the prone position, whereas mean anterior chamber depth in the fellow eyes decreased from 3.01 mm to 2.97 mm. The decrease in anterior chamber depth when facing down in the eyes with pseudoexfoliation was significantly greater than in the fellow eyes.
  
  
  CONCLUSIONS
  In patients with clinically apparent unilateral pseudoexfoliation, the lens seems to be more mobile in the affected eye. This results in a shallower anterior chamber when the head is placed in a prone position. Whether this fact might potentially lead to transient pupillary block when engaging in activities such as facing down while reading warrants further study.
authors.affiliation: Augenklinik und -Poliklinik der Technischen Universität München am Klinikum rechts der Isar, Germany.
authors.forename: I M
authors.initials: IM
authors.lastname: Lanzl
authors.forename: R L
authors.initials: RL
authors.lastname: Merté
authors.forename: A D
authors.initials: AD
authors.lastname: Graham
mesh_terms: D000867:Anterior Chamber / Q000000981:diagnostic imaging / Q000503:physiopathology*; D017889:Exfoliation Syndrome / Q000503:physiopathology*; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D007429:Intraocular Pressure; D007908:Lens, Crystalline / Q000503:physiopathology*; D011187:Posture; D016684:Prone Position; D014463:Ultrasonography