Effects of Defocus on Choroidal Thickness in Children and Adults



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Purpose: The choroid responds to short exposures of defocus in a bidirectional manner, demonstrating thickening with imposed myopic defocus and thinning with imposed hyperopic defocus. This study investigated the choroidal response to myopic defocus in children and adults using spectral domain optical coherence tomography (SD-OCT). Methods: Participants ages 6-45 years (n = 46) were enrolled. Measurements took place between 8:00 am and 10:00 am to minimize effects of diurnal variation. Baseline measurements included biometry and autorefraction. Participants wore their distance correction with an additional +0.50 D both eyes and viewed a black and white movie on a screen at 2 m for 10 min. Two SD-OCT images were collected for each eye, then +3 D was added over the distance correction to the left eye. Participants continued to watch the movie, and SD-OCT images were collected of both eyes every 10 minutes for 50 minutes. SD-OCT images were manually segmented to determine choroidal thickness at each time point, and analyzed with repeated measures ANOVA to assess changes in choroidal thickness by age group (6-17, 18-30, and 31-45 years). Results: Data are presented for 37 subjects. Over the 50-minute experimental session, the choroidal thickness of the left experimental eye (mean ± SEM) significantly increased from 338.7 ± 12.5 μm to 346.6 ± 12.6 μm, representing an increase of 7.9 ± 1.5 μm (P < .001). The choroidal thickness of the right control eye significantly decreased from 349.1 to 337.4 μm, representing a decrease of 11.7 ± 1.3 μm (P < .001). The relative thickening of the experimental eye compared to the control eye at 50 minutes was 19 ± 2.1 μm. There were no significant interactions between time and age group (P > .05 for both eyes and the relative difference). Conclusion: The findings demonstrate that the choroid of children and adults significantly thickens in response to short-term, full-field myopic defocus. The magnitude of the response was similar in children and in adults. Findings will contribute to our understanding of the role of the choroid in ocular responses to the visual environment.



Myopia Control, Choroid,