Einfluss der Akkommodation auf die Aderhautdicke: eine Pilotstudie

Abstract

Purpose. The aim of this study is to characterise the changes in choroidal thickness during and after a prolonged accom­ modation period using optical coherence tomography (OCT). Subjects and Methods. This study used 24 test subjects (age 28.2 ± 2.6 years), with n = 18 assigned to the moderate myopic group (MSE: ­2.6 ± 1.76 D) and n = 6 to the emmetropic group (MSE: ­0.07 ± 0.24 D). The test subjects underwent an accommodation relaxation phase (ten minutes), an accom­ modation phase (twenty minutes of continuous accommoda­ tion), and another relaxation phase (ten minutes). Seven OCT scans (Topcon Corporation, Tokyo, Japan) were taken along a horizontal axis on each eye at five­minute intervals. For each tomogram, the subfoveal, temporal and nasal choroidal thick­ ness was determined manually at three measurement points (2 mm apart) using a measurement tool. To trigger the process of accommodation, a mobile phone was attached to the side of the OCT device and the display was projected into the measurement beam path of the OCT via a semi­transparent mirror (demand of accommodation = 5.0 D). Results. During accommodation, the choroidal thickness decreased significantly by an average of ­8.06 ± 7.33 µm in the subfoveal region, ­4.00 ± 11.00 µm in the nasal region, and ­5.29 ± 12.52 µm in the temporal region (each with p < 0.01). Furthermore, emmetropic eyes showed a significantly strong­ er decrease in the subfoveal region (­13.08 ± 8.58 µm) than myopic eyes (­6.39 ± 6.06 µm). In the ten minutes following the accommodation phase, the choroid returned to its initial thickness, showing no significant difference (p = 0.80) in the degree of recovery between myopic and emmetropic eyes. Conclusion. The study shows that the process of accommo­ dation is associated with a decrease in choroidal thickness. The results further suggest that accommodation in myopic eyes entails a smaller decrease in choroidal thickness than in emmetropic eyes. The apparatus design developed spe­ cifically for this study to project a smartphone display into the measurement beam path of the OCT device is suitable for stimulating accommodation over a longer period while performing repeated OCT scans. Keywords myopia, accommodation, choroidal thickness