Abstract
Purpose :
The thickness of the choroid changes when the eye is treated with atropine eye drops or exposed to optical defocus. This study investigated whether atropine and optical defocus act on different layers of the choroid.
Methods :
We analyzed Optical Coherence Tomography (OCT) images from our previous study of 20 children (6-14 yrs.), who received 60 min of ±2.00D monocular optical defocus, before and after 1 week of nightly 0.3% atropine eye drops. Layers (Retina, RPE/Choriocapillaris, Sattler’s, Haller’s, Suprachoroid) were segmented using a hard threshold method with symlet filters in the wavelet denoise Plugin, followed by Find Edges tool in ImageJ. Layer areas (A) were calculated using boundary coordinates measured along three central guiding lines 750 µm apart (see Figure). Analyses were performed for atropine alone, optical defocus alone and combinations of atropine & defocus. Data were tested for normality using strict criteria (|kurtosis|≤0.5 and |skewness|≤0.5, then transformed by computing Mean Ratio ln(MR)=(Σ ln(A exposure/A baseline)i )/n to assess change in each layer.
Results :
There were strong correlations between Haller’s thickening and Choroidal thickening for atropine alone (R2=0.548, p=0.0001) and between Haller’s thinning and Choroid thinning for hyperopic defocus alone (R2=0.635, p=0.00001), but not with hyperopic defocus & atropine. Localization of myopic defocus was non-specific. Atropine alone significantly thickened Haller’s Layer: MR = 1.101, 95% CI [1.050, 1.154]. Myopic defocus significantly thickened Sattler’s layer after atropine: MR = 1.181, 95% CI [1.013, 1.377]. Moreover, the RPE/Choriocapillaris was thicker for hyperopic defocus alone: MR = 1.025, 95% CI [1.002, 1.048], but not with hyperopic defocus & atropine: MR = 0.9932, 95% CI [0.965, 1.023]. Other conditions were not statistically significant.
Conclusions :
Our findings indicate that atropine inhibits the choroidal thinning effect of hyperopic defocus because their opposing effects are both localized in Haller’s layer. Myopic defocus thickened Sattler’s layer which added to Haller’s layer thickening after atropine. Higher resolution imaging will aid any future study to confirm changes in the RPE/Choriocapillaris layer.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.