Abstract
Purpose :
Light-dependent increases in retinal dopamine (DA) are linked to reduced axial length. Blue light exposure leads to dopamine release in the retina. Dopamine is known to enhance ERG amplitudes. We hypothesize that short-term blue light exposure differentially enhances ERG amplitudes in myopic eyes relative to controls.
Methods :
In a two-visit cross-over design, we compared ERGs before and after 20 minutes of full-field adaptation to long wavelength light (λ; peak 627 nm) or short λ (peak 448 nm) using an Espion ColorDome™ (Diagnosys LLC). Human participants (ages 18-30) were healthy high myopes (≤ -5 D; N=11, 8 female) and emmetropes (-0.25 D to +1 D; N=22, 14 female). Monocular, light-adapted (LA) ERGs were recorded using skin electrodes and a handheld system that adjusted for pupil diameter in real time (RETeval™). ERG stimuli were LA standard white flash and flicker (85 Td.s), presented at 2 and 28.3 Hz, respectively. The amplitudes and implicit times of a-wave, b-wave and flicker ERGs were compared as a function of pre/post adaption (time), adapting stimulus (λ), and refractive error (RE) group using mixed model ANOVAs.
Results :
As expected, pre-adaptation ERG amplitudes and implicit times did not differ between visits (p≥0.23). B-wave amplitudes were reduced by –2.65 ± 4.82 µV following adaptation to both long and short λ (p=0.001), regardless of λ (p=0.907) and RE group (p=0.839). A similar reduction in flicker amplitudes (-1.07 ± 3.47 µV) was observed (p=0.024), regardless of adapting λ (p=0.874) and RE group (p=0.559). Delays in implicit times for b-waves (+0.27 ± 0.58 ms) and flicker (+0.15 ± 0.33 ms) were observed only for long λ adaptation (p=0.003, p<0.001, respectively). Adaptation had no other effects on the ERG parameters measured and there were no differences between the RE groups.
Conclusions :
There is no evidence that chromatic adaptation has a differential effect on post-adaptation ERGs in high myopes. Regardless of refractive error, adaptation to chromatic backgrounds reduces b-wave and flicker ERG amplitudes. Long wavelength adaptation prolongs ERG implicit times, probably reflecting relatively reduced input from the faster long wavelength cone system.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.