Point-of-care ocular ultrasound to detect optic disc swelling

Objectives: Emergency physicians (EPs) frequently evaluate patients at risk for diseases that cause optic disc swelling, and they may encounter conditions that make traditional fundoscopy difficult or impossible. The objective was to assess whether EP-performed point-of-care (POC) ultrasound (US) could accurately assess swelling of the optic disc.

Methods: This was a blinded, prospective study using a convenience sample of patients presenting to a neuroophthalmology clinic who were thought to be at risk for conditions associated with optic disc edema. Two EPs performed POC US examinations. Patients then underwent standard clinical assessment by a specialist.

Results: Fourteen patients were assessed with disc swelling noted on dilated fundoscopic exam in 11 of 28 (39%) eyes. A maximum disc height greater than 0.6 mm as measured by US predicted the presence of optic disc edema noted on fundoscopic exam, with a sensitivity of 82% (95% confidence interval [CI] = 48% to 98%) and a specificity of 76% (95% CI = 50% to 93%). A threshold value of 1.0 mm for disc height yielded a sensitivity of 73% (95% CI = 39% to 94%) and a specificity of 100% (95% CI = 81% to 100%). Measurements of disc height as determined by optical coherence tomography (OCT) exhibited good correlation when compared to US measurements (r = 0.836, p < 0.0001, 95% CI = 0.65 to 0.93).

Conclusions: These data suggest that EP-performed POC US can detect clinically apparent optic disc swelling. Because sonography can be performed readily at the bedside, even in cases where fundoscopy is difficult or impossible, this technique may prove to be a valuable tool for the assessment of optic disc swelling in the emergency department (ED).