High-frequency-ultrasound Annular Arrays for Ophthalmic Imaging

The goal of this study is to develop and evaluate advanced annular-array transducer technology for rapid, high-definition imaging. The study will assess high frequency ultrasound (HFU, 40 & 20 MegaHertz) annular arrays in imaging posterior vitreous detachments (PVDs) associated with diabetic retinopathy, the leading cause of blindness in the US working-age population according to Prevent Blindness America. Current HFU instruments do not use linear arrays for such applications because of a variety of technical and cost reasons. Instead, current HFU instruments use mechanically scanned, single-element transducers, which provide fine-resolution images over a very limited depth of field (DOF). For ophthalmic applications, a shallow DOF causes most ocular anatomy to be imaged with poor definition compared to the in-focus region; therefore, because only a small portion of the eye is in focus at a given time, detection and assessment of ocular conditions such as PVD are prone to inaccuracies and false-negative determinations. Annular-array transducers offer a promising approach to significantly extend DOF and to increase the depth range over which fine-lateral resolution is provided. The investigators will validate system performance using animal experiments and human-subject examinations. First, in vivo animal experiments will be conducted to evaluate a 40-MegaHertz (MHz) annular array for anterior-segment imaging and a 20-MHz annular array for posterior segment and full-globe imaging. The investigators will test the hypothesis that 20-MHz annular arrays improve detection of PVD. Validation of this hypothesis will significantly improve our ability to assess disease status in diabetic retinopathy.