Desktop-based virtual colonoscopy is a proven and accurate process for identifying colon abnormalities. However, it is time-consuming. Faster, immersive interfaces for virtual colonoscopy are still incipient and need to be better understood. This article introduces a novel design that leverages VR paradigm components to enhance the efficiency and effectiveness of immersive analysis. Our approach contributes a novel tool highlighting unseen areas within the colon via eye-tracking, a flexible navigation approach, and a distinct interface for displaying scans blended with the reconstructed colon surface. The path to evaluating and validating such a tool for clinical settings is arduous. This article contributes a formative evaluation using think-aloud sessions with radiology experts and students. Questions related to colon coverage, diagnostic accuracy, and time to complete are analyzed with different user profiles. Although not aimed at quantitatively measuring performance, the experiment provides lessons learned to guide other researchers in the field.