Abstract
Purpose :
Decline in visual sensitivity of specific points on the retina can be measured by microperimetry. However, it is difficult to identify the retinal layer causing this decline. We developed an electroretinogram superimposing seven multifocal hexagonal stimulus arrays on the background of a multifocal array to assist in identifying the affected layer at a specific point on the retina.
Methods :
This apparatus contains illumination and photographic optical systems separated by a mirror with a 4-mm diameter hole. It also has a microperimetry optical system and an ERG optical system separated by a cold mirror. The device consists of an Edmund infrared camera EO-50231, a lens with a 25-mm focal length, a halogen lamp, an objective lens with a 50-mm focal length, 4 double convex lenses with a 100-mm focal length, 2 aperture stops, a mirror, a 45° cold mirror, an 8-inch monitor, and an artificial eye. We deployed a differential amplifier with gain 10, a high-pass filter with a 21.2-Hz cut-off frequency, a 60-Hz notch filter, and 2 non-inverting amplifiers with gains 1001 and 11. Moreover, we used the National Instruments' I/O device USB-6212, the Nihon Kohden's plate electrode NE-113A, the Nihon Kohden's electromagnetic shield sheet Y049, and the LabVIEW 2018 software for data retrieval. The background of the ERG software consisted of 11 layers and 330 arrays, and it uses 7 arrays as the examination target. The center of these 7 arrays has the same area, with an array directly placed under it on the background and the system superimposes these arrays. The ERG software is placed on an HP Pavilion 32-inch HDR display. The software is able to display the adjusted background to provide input of any axial length from 18.0 to 30.0 mm. The software outputs a flicker stimulation as the frequency was changed from 10 to 100 Hz and was designed to reduce the delay time.
Results :
A new ERG-microperimetry system was developed that superimposes 7 stimulus arrays on a larger background array. The system is able to adjust for axial length from 18.0 to 30.0 mm on the monitor and exhibits minimal delay time in the flicker stimulation.
Conclusions :
It is expected that the superimposing ERG function would allow the identification of the retinal layer causing visual alterations at specific points throughout the retina. Further work toward pre-clinical animal testing and clinical evaluation are merited.
This is a 2020 ARVO Annual Meeting abstract.