Delayed reversal of ONS distension- late post-treatment scan. ONUS performed four hours after first measurement depicted in Figure 4. The ocular globe is the hypoechoic structure in the upper part of the images and the ONS the linear hypoechoic structure behind the globe. Caliper A identifies a point 3 mm behind the retina while Caliper B measures the ONSD. ONSD is 0.40 cm, suggestive of normal ICP. Simultaneously recorded ICP from EVD was 13 mmHg.