Steady-state PERG, not only the amplitude evaluation to detect inner retinal dysfunction.

What is it about?

We developed a new electrophysiological test, that we call RE-PERG, a variation of Steady-STATE erg pattern. Briefly, We found a simple and fast protocol for identification of retinal ganglion cell dysfunction and we discovered that our test can detect inner retinal impairment in glaucoma or other neurodegenerative diseases. The morphology of the wave obtained is an aspect of the response of the bioelectric potential, which is due to both signal-to-noise ratio (type or position of the electrodes, gain, etc.) and the signal quality. Being a result of the average of the events acquired, morphology should be better as the repeatability of the events is greater. Increasing temporal frequency of the stimulus, in healthy patients the peaks obtained gradually approach each other until a sinusoidal wave is obtained. Therefore, if the events are not perfectly repeatable, the morphology of the sinusoidal wave will be altered. In RE-PERG, in which a very high number of events is used, the alterations of the morphology of the waves we found (ie, intrinsic phase variability) are, in our opinion, due to a real variability of the electrophysiological events, that is, a marker of neuronal performance impairment. Because of the variability of PERG amplitude due to nonspecific causes, the implication for glaucoma is that a worsening of the quality of the visual stimulus, as in CP, may display nonspecific PERG amplitude reductions due to stimulus deterioration, but not increased intrinsic variability of steady-state perg phase, which remains related only to the disease.

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Why is it important?

Based on the outcome of this study, we suppose that increased phase variability in RE-PERG could be the expression of the lower ability to follow stimuli due to RGCs’ preapoptotic synaptic dysfunction in glaucoma and other neurodegenerative diseases.