Purpose
To explore the differences in inter-observer agreement in choroidal and scleral thickness measurements using swept-source and spectral-domain optical coherence tomography (OCT) devices.
Methods
This is a retrospective analysis of OCT images from 100 eyes of 50 consecutive patients who underwent a single horizontal line scan in both eyes using the Heidelberg Spectralis OCT (100 frames, HR, EDI mode) and the Topcon DRI OCT-1 Atlantis (96 frames, 9.0 mm) on the same day. Patient demographics and diagnoses were recorded. Two masked observers measured the distance between the Bruch’s membrane and the: 1. outermost demarcation of the vessels within the choroid (VT), 2. outermost boundary of the choroid stroma (ST), 3. interface between lamina fusca and the sclera (LT) and 4. Interface between the sclera and orbital fat (CS) directly under the fovea. Measurements from the 2 observers were compared using Bland-Altman analysis and the 95% limits of agreement (LOA) were calculated for each device.
Results
The mean age of the cohort was 64 (13-88) years. Six patients had no macula pathology, 10 had bilateral drusen or vitelliform lesions, 14 had neovascular AMD, 6 had diabetic retinopathy, 4 had other retinal vascular diseases and the remaining 10 had a range of other diagnoses. Vessel boundary was visible in 99% and 100% of the scans from Spectralis and Atlantis. The respective LOA for VT were -48 to +45 and -38 to +58 microns. Stromal boundary was visible in 55% and 69% of the scans from Spectralis and Atlantis. The respective LOA for ST were -41 to +26 and -23 to +16 microns. Lamina fusca boundary was visible in 33% and 41% of the scans from Spectralis and Atlantis. The respective LOA for LT were -18 to +15 and -15 to +19 microns. Orbital boundary was visible in 4% and 6% of the scans from Spectralis and Atlantis. The respective LOA for ST were -73 to +30 and -59 to +29 microns.
Conclusions
Subfoveal choroidal stroma and lamina fusca boundaries are not universally seen with swept-source OCT device. However, the tighter inter-observer LOA for ST and LT compared to VT has implications for trial endpoints in defining the preferred boundary for choroidal thickness measurements. Scleral thickness measurement is not feasible in the majority of eyes using either OCT devices.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
452 choroid •
708 sclera