Pilot study: simulating myopic chromatic aberration on a computer screen induces progressive choroidal thickening in myopes

The purpose of this study was to determine whether repeated exposure to a digitally simulated myopic chromatic aberration (“red in focus” filter) on a computer screen, can change axial length (AL) and choroidal thickness (ChT) in young human subjects. Six myopic and four emmetropic subjects worked on a computer screen with a “red in focus” filter for 2 hours per day over 12 consecutive days (days 1–12). The treatment period was followed by 2 days of recovery where subjects performed computer work for 2 hours per day without filtering (days 13 and 14). Before and after each computer work episode, axial length and subfoveal choroidal thickness were measured in both eyes. Additionally, on days 1, 12, and 14, visual acuity and contrast sensitivity were measured in three luminance-matched light conditions: red, blue, and white light. Myopic, but not emmetropic eyes showed progressive thickening of the choroid and shortening of the axial length over 12 consecutive days with the “red in focus” filter (AL:−31 ± 39 µm, p < 0.01; ChT: +18 ± 14 µm, p < 0.0001) with significant recovery when compared to the last days of the treatment period (AL: +10 ± 26 µm, p < 0.05; ChT:−16 ± 10 µm, p < 0.001). Visual acuity improved in both emmetropic and myopic eyes, under all light conditions, however, a significant difference was measured only in emmetropic eyes in red light (−0.03 ± 0.15 vs. −0.19 ± 0.14 LogMAR, p < 0.05). Contrast sensitivity did not significantly change during the entire experiment in emmetropic or myopic eyes. Working on a computer screen with the “red in focus” filter may have an inhibitory effect on myopia progression since it causes progressive thickening of the choroid and associated shortening of axial length over 12 days. However, long-term studies with larger sample sizes are necessary to verify a general effect.