Abstract
Purpose: :
The choroid serves as the major vascular supply to the outer retina, helping support its metabolic demand. However, due to its posterior location, clinical imaging of this layer is difficult. Recently, Enhanced Depth Imaging Optical Coherence Tomography (EDI OCT) using existing Spectral Domain OCT (SD-OCT) technology has been described. This allows for fast, non-invasive, cross-sectional imaging of the choroid where the entire choroidal thickness can be visualized and measured. Preliminary studies have correlated changes in choroidal thickness on EDI OCT to a variety of pathologies, indicating the clinical and scientific promise of this imaging technique. EDI OCT studies in the literature have generally been performed on a single SD-OCT model (Heidelberg Spectralis), and few follow-up studies have been done using other available SD-OCT devices. The purpose of this study is to compare choroidal thickness measurements amongst three SD-OCT models: the Heidelberg Spectralis, Topcon SD-OCT 2000, and RTVue Optovue.
Methods: :
Sixty-six (66) eyes of 59 patients, with various retinal diseases were prospectively imaged using EDI OCT on at least two of the three SD-OCT devices at the same sitting. Choroidal thickness was manually measured as the distance from the retinal pigment epithelium (RPE) to the choroidal-scleral junction using the caliper function of the individual scanners. Manual measurements were taken directly below the fovea as well as 2mm nasally and temporally. Measurements from each device were statistically compared using the paired student-t test with a p value <0.05 considered significant.
Results: :
Twenty-five (25) males and 34 females with mean age of 72.7 years were included. Choroidal thickness was greatest at the fovea (217.0 ± 101.1um), slightly thinner temporally (195.4 ± 72.5 um), and thinnest nasally (155.7 ± 77.9). In general, measurements did not differ significantly among the devices, except between the Topcon SD-OCT 2000 and RTV Optovue at both the subfoveal (mean difference 2.39 ± 7.90 um, p=0.03) and nasal (mean difference -3.67 ± 7.50 um, p=0.0005) locations.
Conclusions: :
Our data suggests that choroidal thickness measurements obtained by EDI OCT using various SD-OCT devices generally are comparable and do not differ significantly from each other.
Keywords: choroid • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)