Effects of unsteady fixation on multifocal electroretinogram (mfERG)

Abstract

These results suggest that mfERG amplitude is not substantially affected if fixation is maintained within the central stimulus hexagon. We conclude that, for patients with poor fixation, the accuracy of mfERG results may be difficult to interpret and the use of a fixation-monitoring system is desirable for ideal measurement. The depth of depression at the blind spot area may be another useful parameter to interpret the accuracy of mfERG results in patients with poor fixation.

Comparison Between Multifocal Electroretinography and Microperimetry in Age-Related Macular Degeneration

“…[35][36][37] For the 103-hexagon stimulus pattern used in this study, fixation errors (which are more profound in eyes at early stages of AMD than in eyes of control participants 24 ) can further limit the ability to sensitively and topographically assess functional changes. Although patient fixation was monitored using the fixation monitoring system in this study, fixation drifts still could not be corrected, unlike fundus tracking used in microperimetry.…”

Multifocal Electroretinography

“…Eccentric fixation may distort the central responses and may even create a plateau-like appearance of the central peak of the mf ERG responses. 8 Various technical factors may influence the mf ERG and may be related to specific conditions of individual laboratories. Therefore, each laboratory must develop its own parameters of normal, taking into account the stimulus employed, the level of interference, and the type of electrode used for the recording.…”

“…Therefore, each laboratory must develop its own parameters of normal, taking into account the stimulus employed, the level of interference, and the type of electrode used for the recording. 8,12,15 The quality of the study also depends on the ambient limitations of the laboratory. Nevertheless, the incorrect placement of the electrodes constitutes the most common cause of poor quality recordings.…”

“…7 Others have considered that loss of photoreceptors and ganglion cells over time may be primarily responsible for changes in the mf ERG in older individuals. [8][9][10][11] Incomplete degradation of the outer segments of the photoreceptors and loss of function of ABCA4 gene (found in Stargardt's patients) may provoke the accumulation of lipofucsin in the retinal pigment epithelium and may also be a factor. 12 Other authors have attributed the loss of the amplitude to the loss of bipolar cells as well as Muller cells with age.…”

“…10 Extra ocular movements or poor fixation will compromise the topographic correlation of the stimuli with specific areas of the retina. 8,19 In patients with eccentric fixation or poor cooperation, as well as in children, the multifocal ERG results are less reliable. Moreover, the size of the fixation target influences the foveal response.…”