Diagnostic sensitivity of Ultrasound Biomicroscopy (UBM) in identifying Clinical Aqueous Misdirection Syndrome

Abstract

Purpose : The diagnosis of aqueous misdirection (AqM) often poses a challenging diagnostic dilemma. The aim of this study was to assess the diagnostic accuracy of ultrasound biomicroscopy (UBM) for identifying clinical Aqueous misdirection syndrome.

Methods : A retrospective assessment of UBM images of 30 patients with clinical AqM and 58 control images was independently conducted by 2 masked observers. Controls included conditions that mimic AqM and normal UBM images. Images were graded as ‘misdirection’, ‘not misdirection’ or ‘uncertain’. Images were eligible in the AqM group if they were of good quality and if patients met the inclusion criteria of: intraocular pressure>21 mmHg, axial anterior chamber shallowing, a patent peripheral iridotomy and absence of any fundus lesion. Receiver operator characteristic curves were plotted to assess diagnostic accuracy and sensitivities at 90% specificity.

Results : The mean (± sd) age of patients in the AqM group was 59 ± 14 years and 44 ± 27 years in the control group (t=2.8, p=0.06). With images graded as ‘uncertain’ classified as ‘no misdirection’, the total area under the ROC curve was 62% for observer 1 and 55% for observer 2. The sensitivity of UBM at 90% specificity was 33% (95% CI: 16—50%) for observer 1 and 19% (95% CI: 10—28%) for observer 2.

Conclusions : UBM is likely to have poor diagnostic sensitivity for identifying patients with clinical AqM. This investigation should be interpreted with caution in patients who have a high clinical suspicion of this condition.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.