Table 1.

Extended reality device types, details, and clinical applications.

Extended Reality Classification	Hardware Examples	User Interface	Technical Strengths	Technical Limitations	Clinical Applications
Virtual Reality	• Oculus Rift • HTC Vive	• Handheld motion-tracked controllers	• Superior 3D graphics performance and highest resolution	• User has no direct view of physical environment • Requires controller inputs	• The Stanford Virtual Heart • The Body VR • MindMaze
2D Augmented Reality (Indirect)	• iPhone • iPad • Android Devices	• Touchscreen	• Widely available, inexpensive	• Phone or tablet must be held or mounted • Requires touch input	• Echocardiographic probe orientation (Kiss, 2015)
2D Augmented Reality (Direct)	• Google Glass	• Side-mounted touchpad • Voice	• Lightweight head mounted display	• 2D display • UI does not interact with physical environment	• First-In-Man use in Interventional Cath (Opolski, 2016)
3D Augmented Reality	• Microsoft HoloLens • Magic Leap • RealView Holoscope	• Voice • Gaze • Gestures	• Touch-free input • 3D display • Full visibility of surroundings	•Narrow field of view for 3D graphics	• HoloAnatomy • EchoPixel • RealView • Intraprocedural scar visualization (Jang, 2018) • Enhanced Electrophysiology Visualization and Interaction System (Silva, 2017)