Canal plane dynamic visual acuity in superior canal dehiscence

OBJECTIVE: 1) To characterize normal, horizontal active dynamic visual acuity (DVA) and passive canal plane head thrust DVA (htDVA) across ages to establish appropriate control data and 2) to determine whether horizontal active DVA and passive canal plane htDVA are significantly different in individuals with superior canal dehiscence syndrome (SCDS) before and after surgical repair in the acute (within 10 d) and nonacute stage (>6 wk). STUDY DESIGN: Prospective study. SETTING: Tertiary referral center PATIENTS: Patients diagnosed with SCDS (n = 32) and healthy control subjects (n = 51). INTERVENTIONS: Surgical canal plugging on a subset of patients. MAIN OUTCOME MEASURES: Static visual acuity (SVA), active horizontal DVA, and canal plane htDVA. RESULTS: Visual acuity (SVA, active DVA, and htDVA) declines with age. In SCDS, SVA and active DVA are not significantly affected in individuals after surgical canal plugging; however, htDVA in the plane of the affected canal is significantly worse after canal plugging. CONCLUSION: Age-based normative data are necessary for DVA testing. In SCDS, htDVA in the plane of the affected canal is normal before surgery but permanently reduced afterward.