Inner retinal contributions to the multifocal electroretinogram: patients with Leber's hereditary optic neuropathy (LHON)

In this study we examine the multifocal electroretinogram (mfERG) recorded from patients suffering from Leber's hereditary optic neuropathy (LHON), a degeneration of the ganglion cell and nerve fibre layers of the retina. We compared the mfERGs recorded from 11 patients with LHON, to those from 11 control subjects. The pattern ERG (PERG) was additionally performed with 9 of the patients. MfERGs were recorded and analysed using the VERISTM 3.01 system with a stimulus of 103 equal-sized hexagons. For analysis, hexagons were grouped according to distance from the optic nerve head (ONH) and according to distance from the fovea. Two significant differences were found between the waveforms of the two groups: In the first order kernel, the control group showed a component around 34 ms that decreased with distance from the ONH. This component was reduced in the LHON group of subjects. In the second order (first slice) kernel, the patient group was missing features that decrease with distance from the fovea in the control group. PERG amplitudes showed a significant correlation with the amplitude of the second order mfERG kernel. The results show that the damage to ganglion cells and nerve fibres caused by LHON can be detected in mfERG recordings and indicate that activity from the inner retina can contribute significantly to first and second order waveforms.