Assessing machine independence of quantitative ultrasonography to evaluate vision degrading myodesopsia

Abstract

Vision degrading myodesopsia (VDM) results from clinically significant vitreous opacities that reduce contrast sensitivity (CS) and visual quality of life (VQOL). Previous studies with a single clinical system for quantitative ultrasonography (QUS) found correlations with CS and VQOL as measured by the N.E.I. Visual Function Questionnaire (VFQ). Here, we evaluated a cohort of patients to determine if VDM as evaluated by QUS is machine independent. 28 eyes from 14 patients (age 56 ± 14 years) experiencing VDM were scanned with two different clinical ophthalmic ultrasound systems in succession: one with a 15-MHz single element transducer (23mm focal length, 7 mm aperture) and one with a 20 MHz annular array (five elements, 22 mm focal length, 9 mm total aperture). Images were acquired as a longitudinal plane through premacular vitreous in temporal gaze. Three QUS parameters and a composite score were computed from the vitreous region within each set of log-compressed envelope data and averaged over artifact-free frames. A linear regression comparing QUS parameters computed fromeach system showed statistically significant correlations (R ≥ 0.86, p < 0.001). Moreover, QUS parameters from both systems were correlated with CS and VFQ scores. The results from this study suggest the QUS parameters are independent of scanner and could be universally applied to assess VDM.