Authors' objectives:

This report evaluates the safety, effectiveness and cost-effectiveness of multifocal multichannel objective perimetry (MMOP) for the diagnosis of visual field defects.

Authors' results and conclusions: Safety There is a paucity of data relating to the safety of MMOP. However, as the test is noninvasive the risks to subjects should be minimal. The frequency of skin irritation or minor trauma caused by the scalp electrodes used for MMOP is unknown. Effectiveness Due to the limitations of the available evidence it is unclear whether MMOP is equivalent to static automated perimetry (SAP) in terms of diagnostic accuracy in patients with undiagnosed visual field defects. Overall, the diagnostic accuracy of MMOP could not be established as there were wide variations in the sensitivity (75 to 100 per cent) and specificity (45 to 97 per cent). Sensitivity results were highly dependent on the MMOP thresholds of positivity used. Such variations may affect the use of multifocal visually evoked potentials (mVEP) in practice as it is unclear which threshold is most likely to be used and which is most likely to give an accurate result. Specificities were usually dependent on the population. For example, they were highest in studies that included normal controls and lower in those studies which used glaucoma suspects as controls. The ability of MMOP to diagnose pre-perimetric patients was not adequately addressed in any of the studies due to the unknown disease status for the majority of patients. In order to determine the true predictive value of mVEP, longitudinal data would be necessary to determine if patients actually developed disease. In general, 80 per cent of the validity criteria outlined in Table 5 were unmet. Furthermore, it is unclear where the true diagnostic accuracy of MMOP lies, given that these results are subject to study bias. The majority of patients were pre-diagnosed based on their visual field results and other diagnostic criteria, the reference test was not applied independently of test results and assessment of results was not blinded. Due to the high potential for additional clinical information to influence the overall diagnostic results in these studies, it is unclear whether mVEP can be used as a stand-alone test given. In patients for whom the test is indicated, it is uncertain what the diagnostic value of MMOP would be since none of the studies recruited an appropriate spectrum of subjects. Furthermore, since the majority of studies recruited glaucoma patients, it is uncertain how these results can be applied to those with visual field defects resulting from other pathologies. Indeed, MMOP may be of limited use in the diagnosis of other diseases where damage is not localised to the visual cortex. For example, Klistorner (unpublished) showed that MMOP may be a poor test for the diagnosis of quadrantinopic patients when damage was in the extrastriate area.

Authors' recommendations: Multifocal multichannel objective perimetry for the diagnosis of visual field defects appears to be safe but there is insufficient evidence to demonstrate that it is as effective as alternative technologies. Therefore, its cost-effectiveness could not be determined. MSAC does not recommend public funding.

Authors' methods: Systematic Review

Project Status: Completed

URL for project: http://www.msac.gov.au/reports.htm

Year Published: 2005

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: Australia

Organisation Name: Medical Services Advisory Committee

Contact Address: MSAC (MDP 107), GPO Box 9848, Canberra, ACT 2601, Australia. Tel: +61 2 6289 6811; Fax: +61 2 6289 8799.

Contact Name: msac.secretariat@health.gov.au

Contact Email: msac.secretariat@health.gov.au

Copyright: Medical Services Advisory Committee (MSAC)