ISCEV standard for clinical multifocal electroretinography (mfERG) (2011 edition)

Abstract

The clinical multifocal electroretinogram (mfERG) is an electrophysiological test of local retinal function. With this technique, many local ERG responses are recorded quasi-simultaneously from the cone-driven retina under light-adapted conditions. This document, from the International Society for Clinical Electrophysiology of Vision (ISCEV: www.iscev.org ), replaces the ISCEV guidelines for the mfERG published in 2007. Standards for performance of the basic clinical mfERG test with a stimulus array of 61 or 103 hexagons, as well as for reporting the results, are specified.

Fig. 1

a Representative hexagonal mfERG stimulus array with 61 elements scaled with eccentricity. Roughly half of the elements are illuminated at any one time. b Same as in panel A for an array with 103 elements

Fig. 2

Diagram of a mfERG response to show the designation of the major features of the waveform. The arrows show the trough-to-peak amplitude (vertical arrow) and the implicit time (horizontal arrow) of the basic mfERG measures of amplitude and timing

Fig. 3

Sample mfERG trace arrays (field view) with 61 elements (panel A, left eye) and 103 elements (panel B, right eye). c, d. The 3-D response density plots (field view) associated with panels A and B

Fig. 4

The mfERG trace array (left panel, field view) and (right panel) the probability plot from routine automated perimetry (Humphrey Visual Field Analyser, Carl Zeiss Meditec) for a patient with retinitis pigmentosa. The contours for radii of 5 and 15° are shown. The light gray, dark gray, and black squares indicate statistically significant field loss at the 5, 1, and 0.5 percent levels, respectively

Fig. 5

a The mfERG responses in Fig. 3b were grouped by concentric rings (see inset in the middle) and the average response per hexagon within each ring was calculated. That is, the sum of all the responses in a ring is divided by the number of the hexagons in the ring to give the average response per hexagon in nV. b The sum of the responses in a ring is divided by the area of the hexagons in the ring to give nV/degree². R1 is central; R5 peripheral. A similar grouping for the 103 hexagon display would have 6 rings

Fig. 6

Electrical noise. The trace array shows 60 Hz line frequency contaminating the responses

Fig. 7

Eccentric fixation. The subject with normal vision fixated at the + instead of at the center. As a result, the calculated response magnitudes are altered, and there is a false appearance of central retinal dysfunction

Fig. 8

Positioning error

Fig. 9

Weak signals and erroneous central peak. These recordings were obtained from a contact lens electrode placed in a beaker of water. Therefore, there are no mfERG responses in these records. However, the 3-D plot shows an artifactual central peak because the noise level is divided by the stimulus area