Repeatability and inter-observer variation of choroidal thickness measurements using swept-source optical coherence tomography in myopic danish children aged 6-14 years.

purposeTo estimate repeatability and inter-observer variation of choroidal thickness measurements in myopic Danish children aged 7-14 years using swept-source optical coherence tomography (SS-OCT).

methodsThirty-nine children were enrolled. Optical correction was single-vision spectacles (SVS) or orthokeratology lenses (OKL). Three repeated 7 × 7 mm 3-dimensional SS-OCT macula scans and three repeated 9 mm SS-OCT line scans were collected for each child using a DRI OCT Triton. Choroidal thickness was measured using three different methods: line scan method 1 (LM1), line scan method 2 (LM2) and 3D macula scan method (3DM). Segmentation was adjusted if needed. Coefficients of repeatability (CR) and limits of agreement (LoA) were calculated.

resultsThe CRs ranged from 13.4 to 23.9 µm, 14.5 to 26.2 µm and 5.2 to 10.7 µm for LM1, LM2 and 3DM, respectively. The LoA ranged from -22.9 to +31.5 µm, -23.3 to +32.2 µm and -10.2 to +12.4 µm for LM1, LM2 and 3DM, respectively. Segmentation was adjusted in most scans (63%-92%). Mean choroidal thickness ranged from 142.2 ± 47.2 to 253.8 ± 60.9 µm and 190.1 ± 64.0 to 299.0 ± 55.8 µm for the SVS and OKL groups, respectively, measured by 3DM.

conclusionThe 3DM was the most repeatable method in this paediatric population. It yielded a CR of 10.7 µm, confidence interval 2.4 µm, which makes the minimal detectable difference between two measurements 13.1 µm. Most inter-observer variation could be explained by the intramethod variation. Segmentation adjustment on 3D macula scans did not increase CR on a group level.