Correlation of corneal thickness and volume with intraoperative phacoemulsification parameters using Scheimpflug imaging and optical coherence tomography

PURPOSE: To evaluate post-phacoemulsification corneal edema using central corneal thickness (CCT) and central corneal volume (CCV) derived from Scheimpflug imaging, optical coherence tomography (OCT), and ultrasound (US) pachymetry and to correlate CCV with phacoemulsification parameters. SETTING: Department of Ophthalmology, Boston Medical Center, Boston, Massachusetts, USA. DESIGN: Prospective case study. METHODS: Scheimpflug imaging (Pentacam HR), OCT (Cirrus HD-OCT), and US pachymetry (Pachmate) were used to measure the CCT, CCV, and phacoemulsification parameters after uneventful phacoemulsification over a 1-month follow-up. RESULTS: In the 16 eyes assessed, the Scheimpflug CCT was less than the US CCT preoperatively (P=.01) and 1 week postoperatively (P=.02). The OCT CCT was less than the US CCT at 1 week and 1 month (both P<.01). At 3.0 mm, the CCV was increased at 1 day and 1 week (both P<.01) but returned to preoperative levels by 1 month (P=.09). However, the 7.0 mm CCV remained elevated at 1 month (P<.01). There were strong correlations between the change in the 7.0 mm CCV and the estimated fluid used (r = 0.76) and phacoemulsification time (r = 0.61). CONCLUSIONS: Scheimpflug imaging and OCT underestimated the CCT in normal eyes compared with US pachymetry, with a trend toward thicker measurements in acutely edematous corneas. Although the CCV returned to preoperative values at 1 month, the peripheral cornea remained edematous, possibly because of a correlation with the estimated amount of fluid used and phacoemulsification time.