Effects of text contrast polarity on the retinal activity in eyes with myopia and emmetropia

The results of a study by Sandra Wagner and Torsten Strasser from the Applied Vision Research Group at the Institute of Ophthalmic Research have been published in the journal "Scientific Reports" https://www.nature.com/articles/s41598-023-38192-9

Previous studies showed that reading black text on a white background leads to a thinning of the choroid, which is associated with the development of myopia. On the other hand, reading text with inverted contrast (white-on-black) induced a thickening of the choroid, which may help to prevent myopia. In the present study, the effects of text contrast polarity on the retinal activity in eyes with myopia and emmetropia were exploratively assessed. A novel protocol for pattern electroretinogram (pERG), a measure of the electrical activity of the retina in response to visual stimuli, was used. Stimuli were composed of a dead leaves stimulus (DLS - s. Figure) with overlaying text elements of both contrast polarities of different size and shape (6deg circle, 12deg circle, 6-12deg ring). The pERG recordings revealed that the retinal responses of myopic eyes were smaller than those of emmetropes during stimulation with inverted contrast in foveal and parafoveal regions, but not perifoveally around 6-12deg. This suggests that myopic eyes may have a different way of processing visual information on text contrast polarity compared to emmetropic eyes, with a special role of the peripheral retina. The presented approach might be a first step to explain how nearwork promotes the eye’s elongation. Given a causality between text contrast polarity and myopia onset, using reading material in the inverted contrast form might be a simple method to support myopia management treatment in the future.