title: Effect of infusion air pressure on visual field defects after macular hole surgery.
abstract: OBJECTIVE
  A defect in the visual field is one of the serious complications of macular hole surgery. We investigated the relationship between the occurrence of visual field defect and the location of infusion cannula and air pressure during fluid-air exchange.
  
  
  METHODS
  We studied 100 eyes from 90 patients with macular holes. All patients underwent preoperative and postoperative visual field testing. Vitreous surgery was performed in a standard three-port fashion, with surgically induced posterior vitreous detachment, fluid-air exchange, and sulfur hexafluoride gas injection. We analyzed differences in surgical methods in three groups. In group A, the infusion cannula was placed inferotemporally, and the air pressure was set at 50 mm Hg. In group B, the infusion cannula was placed inferonasally, and the air pressure was set at 50 mm Hg. In group C, the infusion cannula was placed inferotemporally, and the air pressure was set at 30 mm Hg.
  
  
  RESULTS
  Eighteen eyes (18%) showed visual field defects after vitrectomy. The defect was always located contralateral to the infusion cannula. There was no statistically significant difference in the incidence of visual field defects in groups A and B. Decreased air pressure reduced the occurrence of visual field defects significantly (24% in group A versus 4% in group C, P = .011).
  
  
  CONCLUSIONS
  The location of the visual field defect correlated with the location of the infusion cannula. The incidence of this visual field defect was influenced strongly by the infusion air pressure. The visual field defect may be caused by the mechanical damage of air infusion.
authors.affiliation: Department of Ophthalmology, Kumamoto University School of Medicine, Kumamoto, Japan. ahirata@kaiju.medic.kumamoto-u.ac.jp
authors.forename: A
authors.initials: A
authors.lastname: Hirata
authors.forename: N
authors.initials: N
authors.lastname: Yonemura
authors.forename: T
authors.initials: T
authors.lastname: Hasumura
authors.forename: Y
authors.initials: Y
authors.lastname: Murata
authors.forename: A
authors.initials: A
authors.lastname: Negi
mesh_terms: D000368:Aged; D000388:Air; D002404:Catheterization; D005260:Female; D006801:Humans; D008297:Male; D011312:Pressure / Q000009:adverse effects*; D011446:Prospective Studies; D012167:Retinal Perforations / Q000601:surgery*; D013459:Sulfur Hexafluoride / Q000008:administration & dosage; D014786:Vision Disorders / Q000209:etiology* / Q000517:prevention & control; D058609:Visual Field Tests; D014794:Visual Fields; D014821:Vitrectomy / Q000009:adverse effects* / Q000379:methods
chemical_list: D013459:Sulfur Hexafluoride