Abstract
Abstract: :
Purpose: To evaluate the role of objective perimetry using multifocal visual evoked potentials (mVEP) in glaucoma practice, and to assess its utility in patients with inconclusive standard automated perimetry (SAP) performance Methods: A retrospective case series of 436 consecutive subjects referred for glaucoma investigation who were tested with the AccuMap system within a defined 12 month period. All patients tested during the study period were included regardless of their subjective field performance. Sensitivity was determined using SAP as reference standard (in those with reproducible SAP fields) and also in a subgroup using masked stereo optic disc photos as an alternative reference standard. Overall clinical diagnostic outcomes were assessed. Results: The mVEP changes were correlated with both stage of disease and with Humphrey MD (r =0.78). The overall sensitivity for detecting glaucoma with established subjective field loss was 97.5%, (early glaucoma 95%). In contrast 92.2% of low risk suspects had normal mVEPs. In high risk suspects 21% were abnormal. When masked disc assessment alone was used for diagnosis of abnormality, sensitivity for both mVEP (80.6%) and HVF (81.9%) were similar, but mVEP specificity was higher(89.2% vs 79.5%). The mVEP was particularly useful in assessing excessive subjective field loss (45 eyes) showing a much closer correlation with the clinical findings/disc appearance. A patient flow model shows the distribution of subjects included and the outcomes of each group including those with variable SAP who would usually be excluded from analysis. Conclusions: MVEP is an effective method for detecting visual field loss in glaucoma and does reflect SAP findings in the majority of cases. It provides a valuable aid to the clinician in categorising patients with unreliable, variable, unconfirmed or excessive subjective field loss.
Keywords: visual fields • electrophysiology: clinical • clinical (human) or epidemiologic studies: outcomes/complications