Inhibiting myopia development by the digital chromatic filters

Abstract

We had previously found that simulated chromatic defocus, imposed by spatially filtering the RGB channels of the computer screen, induces significant changes in choroidal thickness already after 45 min (Swiatczak and Schaeffel, 2022). In emmetropes, the “red in focus” filter, which blurs the image in the blue channel and simulates myopic chromatic defocus, induced thickening of the choroid and eye shortening, while the “blue in focus” filter, which blurs the image in the red channel and simulates hyperopic chromatic defocus, induced thinning of the choroid and eye elongation. Strikingly, eyes that were already myopic were not responsive to these filters, suggesting that (1) they may no longer detect longitudinal chromatic aberration (LCA), (2) the imposed signal was too weak to induce significant changes in choroidal thickness, or (3) the signal was detected by the retina, but it was not transmitted to the choroidal tissue. To gain a better understanding of the underlying mechanisms and their roles in emmetropization, we measured in emmetropic and myopic subjects (1) the long‐term effect of repetitive exposure to the “red in focus” filter over 12 days of treatment, followed by 2 days of recovery, (2) the accommodation responses to visual targets with simulated myopic and hyperopic LCA, and (3) visual acuity and contrast sensitivity in red and blue light.Our results showed that as previously found for choroidal changes, simulated hyperopic or myopic LCA also affected accommodation. The “blue in focus” filter induced more accommodation than the “red in focus” filter (difference in emmetropes: 0.13D, p < 0.05). Strikingly, accommodation in myopic eyes was not responsive to simulated LCA. Moreover, visual acuity was severely reduced when subjects were looking through a short‐pass blue filter (cut‐off at 490 nm) compared to visual acuity in red light (long‐pass red filter, cut‐off at 610 nm) which was observed in both emmetropic and myopic subjects. Furthermore, emmetropes displayed higher contrast sensitivity in red than in blue light, but this difference was not found in myopes.Our findings confirm that there is a difference in retinal processing between emmetropes and myopes which includes lower sensitivity to LCA in myopes. Furthermore, we showed that these differences show up in both, changes in choroidal thickness as well as accommodation.