Short-Term Myopic Defocus and Choroidal Thickness in Children and Adults

Abstract

Purpose: Studies report conflicting findings regarding choroidal thickness changes in response to myopic defocus in humans. This study aimed to investigate the choroidal response to myopic defocus in children and adults using automated analysis.

Methods: Participants (N = 46) were distance-corrected in both eyes and viewed a movie on a screen for 10 minutes. Two optical coherence tomography (OCT) radial scans were collected for each eye, then +3 diopters was added to one eye. Participants continued to watch the movie, OCT scans were repeated every 10 minutes for 50 minutes, and then recovery was assessed at 60 and 70 minutes. Defocus was interrupted for approximately two out of each 10 minutes for OCT imaging. OCT images were analyzed using an automated algorithm and trained neural network implemented in MATLAB to determine choroidal thickness at each time point. Repeated-measures ANOVA was used to assess changes with time in three age groups (6-17, 18-30, and 31-45 years) and by refractive error group (myopic and nonmyopic).

Results: Choroidal thickness was significantly associated with spherical equivalent refraction, with the myopic group having a thinner choroid than the nonmyopic group (P < 0.001). With imposed myopic defocus, there were no significant changes in choroidal thickness at any time point for any age group and for either refractive error group (P > 0.05 for all).

Conclusions: Findings demonstrate that, using the described protocol, the choroidal thickness of children and adults does not significantly change in response to short-term, full-field myopic defocus, in contrast to several previously published studies.

Figure 1.

Protocol. OCT imaging (eye icon) was performed before and every 10 minutes after monocular imposed myopic defocus for 50 minutes, and then recovery was measured for 20 minutes. For OCT imaging, participants removed the trial frame and looked into the OCT instrument, then replaced the trial frame and again viewed the movie after the scans were captured. Therefore defocus was interrupted for approximately two out of each 10 minutes for OCT imaging.

Figure 2.

(A) Representative infrared fundus image showing the OCT scan protocol (green) and (B) segmentation, including the inner limiting membrane (yellow), Bruch's membrane (blue), and choroid/sclera border (red).

Figure 3.

Baseline choroidal thickness (mean ± SD) of right eyes by age group and refractive error group, *P < 0.05 for post-hoc pairwise comparisons between refractive error groups.

Figure 4.

Bland-Altman analysis for assessment of within-session repeatability for choroidal thickness. Solid red line represents the mean difference between the two scans collected at baseline for each participant; dashed red line represents the limits of agreement, and blue lines represent the inner and outer 97.5% confidence limits for the limits of agreement.

Figure 5.

(A) Choroidal thickness and (B) change in choroidal thickness over time for control eyes (filled symbols) and experimental eyes (open symbols) for all participants (N = 46); red dashed line represents zero change.