Abstract
Purpose :
The retina has been recognized as a promising site of investigation for psychiatric disorders. We have shown retinal anomalies using the electroretinogram (ERG) in major depression (1), schizophrenia (2) and offspring of patients (3). However, the ERG is performed with bulky expensive equipment and a corneal electrode which may cause some discomfort. The proper placement of an electrode such as the DTL demands some expertise and is also prone to displacement which can affect results. Recently an ambulatory portable device was proposed (RETeval; LKC Gaithersburg MD) along with a novel skin electrode allowing easy recordings in an less invasive manner. In this research we evaluated ERG using the RETeval in healthy controls and patients suffering from schizophrenia. Our goal was to verify if we would obtain the same result as per those published using an Espion system (Diagnosys LLC, MA, USA) and a DTL electrode in 105 patients with schizophrenia (2).
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Methods :
The ERG was performed in non-dilated eye using a skin electrode (RETeval sensor strips) in 16 healthy controls and 15 patients with schizophrenia. A cone ERG was obtained with the RETeval background set at 80 cd/m2 and flash luminance of 7.5 (20 flashes set at 500 ms interval) followed by 20 min of dark adaptation before performing a mixed rod-cone ERG at luminance 1 cd/m2.s (20 flashes set at 5s interval).
Results :
A cone a-wave reduction (p=0.008) and b-wave latency delay (p=0.001) were observed in schizophrenia patients when compared to controls. The rod a-wave (P=0.0009) and b-wave amplitude (p=0.002) were significantly reduced in patients. These are the same anomalies reported in the larger sample of 105 patients (2).
Conclusions :
We confirm the ERG performed with the RETeval using a skin electrode, can detect the same retinal anomalies in schizophrenia as those reported using the Espion system and a DTL electrode. This portable device and the skin electrode demand very little training to perform the test (our patients were tested by 6 different research assistants) and generate less anxiety for the patient. Even in a small sample, we were able to detect highly significant retinal anomalies in patients. This more affordable technology could greatly enhance research in a psychiatric setting. We hope that the discovery of ERG anomalies could shed new light onto the underlying pathophysiology of psychiatric disorders.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.