Abstract
Purpose :
Previous research found that reading white text on black background increased the choroidal thickness in young adults, possibly inhibiting myopia (Aleman et al., 2018). We have already shown that prolonged reading of conventional text (black-on-white) leads to a thinning of the ciliary muscle (CM) in both emmetropes and myopes (Wagner et al., 2019). We aim to assess whether the contrast polarity of the reading material affects the CM structure and whether this differs between emmetropic and myopic eyes.
Methods :
Optical coherence tomography (OCT) is used to image the subjects’ CM at baseline and after having read binocularly white text on black background on an ebook reader for a continuous 30-min period at 25cm distance. Before and after the nearwork task, a minimum of 3 OCT images of the right eye’s CM is taken while subjects first fixate a far (0D), then a near target (4D) with their left eye, respectively. OCT images are analyzed using custom-developed software to achieve CM thickness (CMT) profiles and selective CMT readings.
Results :
Preliminary results with 6 adults (3 myopic, 3 emmetropic; age 19-43) showed that the CMT profiles of myopic eyes decreased after the 30-min reading period, while CMT profiles of emmetropes were rather thicker afterwards, especially for the 4D condition. Analysis of CMT changes (pre-post) likewise showed a thinning in myopic, but a CMT increase in emmetropic eyes in both target conditions (median emm/ my: 0D: -35.29µm/ 38.28µm; 4D: -12.70µm/ 57.19µm; Fig.).
Conclusions :
Stimulating predominantly retinal ON pathways by presenting white-on-black text was previously found to produce a thickening of the choroid (Aleman et al., 2018). Our preliminary data suggests that the CM is also affected by the text’s contrast polarity, however differing depending on the eye’s refractive error. Emmetropic CM becomes rather thicker after reading white-on-black text, being in line with the previous finding of increased choroidal thickness. In contrast, the CM structure of myopic eyes, being thinner after the near task, seems to be unaffected by the contrast polarity, since post-task thinning has equally been measured for black-on-white text previously (Wagner et al., 2019). We further intend to increase the sample size to consolidate the preliminary outcome. A longitudinal dataset would allow to test whether the text polarity only affects the CM prior to myopia onset.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.