EX-PRESS(®) Implant Position and Function: Comparative Evaluation with Ultrasound Biomicroscopy and Optical Coherence Tomography

PURPOSE: This study evaluated the feasibility of anterior segment optical coherence tomography (OCT) and ultrasound biomicroscopy (UBM) for the imaging of EX-PRESS(®) implant. MATERIALS AND METHODS: This nonrandomized comparative case series was performed at the Department of Ophthalmology of the University Hospital of Heraklion, Crete, Greece. The Ellex Eye Cubed (40 MHz) UBM and the Zeiss Visante OCT systems were used. The filtering bleb morphology (BL), aqueous outflow (AS), and tube position (TB) were evaluated by two independent observers using a quality scale of 1 (worst) to 4 (best). Data were also collected on corneal and iris clearance from the tip of the tube (CC and IC, respectively). Data from both the devices were statistically analyzed. P < 0.05 was considered as statistically significant. RESULTS: Ten eyes of 10 patients (6 males) with EX-PRESS(®) implant were examined. TB, AS, and BL scores using UBM were 2.40 ± 0.39, 3.45 ± 0.72, and 2.45 ± 0.64, respectively. TB, AS, and BL scores for OCT were 3.35 ± 0.41, 1.55 ± 0.43, and 2.55 ± 0.55, respectively. AS was significantly higher with UBM whereas the opposite was true for TB. Differences in BL between OCT and UBM were not statistically significant (P > 0.05). CONCLUSION: Imaging of the EX-PRESS(®) implant is feasible with both UBM and OCT. Both modalities allow visualization of the position of the implant tube in relation to the iris or cornea and delineate the internal structure of the filtering bleb.