(O-C2) The Association of Image Gain Intensity to the Accuracy of Point-of-care Ocular Ultrasound

Objectives: To determine the effect on sensitivity, specificity, positive predictive value, and negative predictive value of detecting ocular pathology by stratifying gain settings on ocular point-of-care ultrasound.

Background: Point-of-care ultrasound (POCUS) plays a pivotal role in evaluating ocular complaints in the emergency department (ED). The rapid and non-invasive nature of ocular POCUS makes it a safe and informative imaging modality. Previous studies have investigated using ocular POCUS to diagnose posterior vitreous detachment (PVD), vitreous hemorrhage (VH), and retinal detachment (RD); however, little is known about the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of detecting ocular pathology at stratified gain levels.

Methods: We performed a retrospective review of ED patients who received ocular POCUS examinations and ophthalmology consultations as part of their evaluation for eye complaints at our urban level I trauma center ED from November 2017 to January 2021. 383 out of 706 exams qualified for the study. The primary analysis looked at the ability of ED physicians to recognize any posterior chamber abnormality on ocular POCUS.

Results: The images were found to have an overall sensitivity of 81% (95% confidence interval [CI] 76-86%), specificity of 82% (95% CI 76-88%), PPV of 86% (95% CI 81-91%), and NPV of 77% (95% CI 70-83%). Images acquired with a gain of (25, 50] had a sensitivity of 71% (95% CI 61-80%), specificity of 95% (95% CI 85-99%), PPV of 96% (95% CI 88-99%), and NPV of 68% (95% CI 56-78%). Images acquired with a gain of (50, 75] had a sensitivity of 85% (95% CI 73-93%), specificity of 85% (95% CI 72-93%), PPV of 86% (95% CI 75-94%), and NPV of 83% (95% CI 70-92%). Images acquired with a gain (75, 100] had a sensitivity of 91% (95% CI 82-97%), specificity of 67% (95% CI 53-79%), PPV of 78% (95% CI 68-86%), and NPV of 86% (95% CI 72-95%). Secondary analysis looked at each gain range further stratified by specific pathology (PVD, VH, and RD).

Conclusions: High (75, 100] gain on ocular POCUS has a high degree of sensitivity for detecting any posterior chamber abnormality, as compared to intermediate (50, 75] and low (25, 50] gain levels. All gain levels are highly sensitive and specific for RD. Overall, we recommend incorporating the use of high gain for ocular POCUS to maximize sensitivity without sacrificing specificity. High gain is an effective screening tool for ocular pathologies in acute care settings and may be particularly valuable in resource-limited settings.

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Funding (Optional): None