title: Effect of simulated dynamic intraocular pressure on retinal thickness measured by optical coherence tomography after cataract surgery.
abstract: OBJECTIVE
  To investigate the effect of simulated dynamic intraocular pressure (SDIOP) during uncomplicated phacoemulsification on postoperative macular and peripapillary retinal nerve fiber layer (RNFL) thickness.
  
  
  METHODS
  Macular and RNFL thicknesses in one eye of patients (n=30) undergoing uncomplicated phacoemulsification were measured by optical coherence tomography preoperatively and 1 week postoperatively. The best-corrected visual acuity, SDIOP, irrigation time (IT), effective phacoemulsification time, entire surgical duration, blood pressure, and heart rate were recorded.
  
  
  RESULTS
  The mean SDIOP and IT was (74.9 ± 27.4)cmH(2)O and (178.4 ± 21.6) seconds respectively. We divided our patients into two groups based upon IT with greater than 90cmH(2)O (P(>90)IT). In Group A (n=14), the P(>90)IT was greater than the mean P(>90)IT, and in Group B (n=16), the P(>90)IT was less than the mean P(>90)IT. For all patients there was a significant increase in macular thickness one week after cataract surgery (P=0.001). While the RNFL thickness tended to increase, the change was not significant. The postoperative macular thickness of Group A, (277.8 ± 13.7)µm, was significantly thicker than that of Group B, (267.9 ± 15.0)µm (P=0.004). The postoperative peripapillary RNFL thickness of Group A, (96.8 ± 10.8) µm, was not significantly different from Group B. For Group A, the change in macular thickness was positively correlated with P(>90)IT (R(2)=0.524, P=0.02). There was no statistical difference in postoperative visual acuity between Groups A and B.
  
  
  CONCLUSIONS
  After uncomplicated phacoemulsification, increased macular thickness is associated with the IT under high SDIOP. The effect of high SDIOP is limited to the sub-clinical level.
authors.affiliation: Eye Hospital, Wenzhou Medical College, Wenzhou 325027, Zhejiang Province, China.
authors.forename: Ding
authors.initials: D
authors.lastname: Chen
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
authors.forename: Jin
authors.initials: J
authors.lastname: Li
authors.forename: Xi-Xia
authors.initials: XX
authors.lastname: Ding
authors.forename: Fan
authors.initials: F
authors.lastname: Lu
authors.forename: Yun-E
authors.initials: YE
authors.lastname: Zhao
keywords: intraocular pressure; optical coherence tomography; phacoemulsification; retina