Functional evaluation of corneal endothelium by combined measurement of corneal volume alteration and cell density after phacoemulsification

PURPOSE: To assess a new method of functional evaluation of corneal endothelium using combined measurement of corneal volume alteration and cell density (CD) after phacoemulsification. SETTING: Nippon Medical School Hospital, Tokyo, Japan. METHODS: Phacoemulsification was performed in 28 cases. The corneal volume within 3.0 mm and 10.0 mm circles of the cornea was measured using Scheimpflug imaging (Pentacam, Oculus, Inc.) and the cell density, using specular microscopy (Noncon Robo, Konan Medical). The volume stress index (VSI), a parameter for measuring functional evaluation, was calculated by dividing the volume increase within the 3.0 mm circle (preoperative corneal volume - corneal volume at time of measurement) by the central cell density value. The resulting value is indicative of the amount of postoperative increase in corneal volume with which each corneal endothelial cell should be able to cope. RESULTS: Three months after surgery, the 3.0 mm corneal volume returned to preoperative values, while the 10.0 mm corneal volume remained significantly higher than preoperatively. The cell density values did not significantly change throughout the study. The VSI showed a significant decrease by 7 days after surgery followed by a gradual decrease until the end of the study. At 3 months, the VSI value was significantly smaller than at 1 day. CONCLUSION: The corneal volume increase after surgery may be indicative of the degree of the endothelial damage in the area; thus, the VSI may be useful in the functional assessment of the corneal endothelium.