Feasibility of swept-source OCT for active birdshot chorioretinopathy

Purpose To assess the feasibility of swept-source optical coherence tomography (SS-OCT) for clinical follow-up of patients with birdshot chorioretinopathy (BC). Methods Prospective longitudinal, observational, 12-month case-control study in a tertiary care center. The study population included 12 patients (24 eyes) diagnosed with BC and 21 age- and sex-matched healthy controls (42 eyes). The macular areas in both affected and healthy eyes were prospectively analyzed with SS-OCT at 1050 nm, using 2D 12.0-mm radial and horizontal scans and the 3D raster scan protocol (12.0 x 9.0 mm). Anatomical and structural abnormalities, as well as retinal and choroidal thickness (measured automatically), were evaluated and compared with visual field (VF) testing and indocyanine green angiography (ICGA). Results The most common qualitative abnormalities in the retina were thinning/loss of architecture and outer retinal hyperreflective foci, and in the choroid they were focal depigmentation, thinning/absence of Sattler's layer, generalized thinning, and hyperreflective foci. The most significant changes in the retina from baseline to the 12-month follow-up were decreases in intraretinal cysts, subretinal fluid, and hyaloid thickening. In the choroid, focal depigmentation decreased significantly, while vascular pattern loss increased. Compared to the healthy volunteers, patients with BC had thinner choroids and retinas at both baseline and study end. Retinal thickness decreased significantly in BC patients over the 12-month study period, but choroidal thickness remained unchanged. Findings from ICGA, VF, and SS-OCT were perfectly correlated in most (approximate to 60%) patients. Conclusions SS-OCT is a non-invasive, rapid method of assessing choroidal and retinal changes in patients with birdshot disease. This technique provides a simple method of monitoring the course of the disease that can be used to complement conventional tests.