Effect of simulated dynamic intraocular pressure on retinal thickness measured by optical coherence tomography after cataract surgery

AIM: To investigate the effect of simulated dynamic intraocular pressure (SDIOP) during uncomplicated phaco- emulsification 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)cmH2O and (178.4±21.6) seconds respectively. We divided our patients into two groups based upon IT with greater than 90cmH2O (P>90IT). In Group A (n = 14), the P>90IT was greater than the mean P>90IT, and in Group B (n=16), the P>90IT was less than the mean P>90IT. 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>90IT (R 2=0.524,P =0.02). There was no statistical difference in postoperative visual acuity between Groups A and B. CONCLUSION: 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.