Abstract
Purpose:
We have previously succeeded in recording melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) response to light stimuli from human eyes using four-primary illumination system, which modulates stimulus levels to the ipRGC and cones independently (Fukuda et al. 2010; 2012). The aim of this study was to attest effect of the blue light cut-off filter, which can selectively remove the wavelengths including the peak spectrum sensitivity of melanopsin on the electroretinogram (ERG) obtained from ipRGCs using our system.
Methods:
We used the four-primary illumination system to stimulate ipRGCs independently of other photoreceptors using four kinds of light-emitting diodes (LEDs) and the filter (380-495nm, cut-off 50%) to cut-off blue light in this study. The peak wavelengths of the four LEDs 633 nm, 593 nm, 507nm and 468nm and the light stimulus with sinusoidal wave modulation was used. Six subjects (age, 30.2±2.6 years) were recruited. Power and phase spectra of ipRGC responses were calculatedby using Fast Fourier Transformation (FFT). The power indicates degree and the phase expresses latency of the response.
Results:
The power (mV rms) without and with filter was 1.44±0.73 and 0.77±0.37, respectively. The phase (degree) without and with filter was 217.5±92 and 262.2±62.2, respectively. The reduction of power with filter was 41.8±21.6% and the phase did not show homoscedasticity, there were significant differences between with and without filter (<0.05).
Conclusions:
The effect of blue light cut-off filter on electrical response from ipRGC showed not only the reduction of the power and also the alteration in the phase as well. This results validate the blue light cut-off filter influence on the electrical response of ipRGC in human.