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Use of En Face Swept-Source Optical Coherence Tomography Angiography in Identifying Choroidal Flow Voids in 3 Patients With Birdshot Chorioretinopathy

Importance Patients with birdshot chorioretinopathy (BSCR) can experience a delay in diagnosis owing to the challenges of identifying the condition prior to evolution of characteristic choroidal scars. An objective, noninvasive method for detecting early lesions in BSCR might have an effect on preventing vision loss in these patients. Objective To test the feasibility of swept-source optical coherence tomography angiography (SS-OCTA) in the detection of BSCR choroidal lesions and to use en face image analysis of choroidal layers to localize lesion depth. Design, Setting, and Participants Prospective, longitudinal, observational case series of 3 patients diagnosed as having BSCR at 1 of 2 tertiary care uveitis centers between August 2017 and October 2017. Exposures Widefield SS-OCTA and indocyanine green angiography (ICGA). Main Outcomes and Measures En face SS-OCTA slabs through the choroid were evaluated for the presence of flow voids corresponding to hypocyanescent lesions by ICGA. Baseline and posttreatment images were compared. Results Six eyes of 3 patients with previously undiagnosed and untreated BSCR were imaged at baseline and after initiation of immune modulation treatment. Two patients had a history of recent-onset BSCR, and the third patient had a history of chronic untreated disease of at least 5 years’ duration. All patients were white and between the ages of 50 and 67 years. All eyes demonstrated multiple flow voids on en face SS-OCTA images that corresponded with hypocyanescent lesions by ICGA. Analysis of serial depth en face SS-OCTA flow images identified that in the acute-onset patients, flow voids were located adjacent to large vessels in the Haller layer and regressed with treatment. In the patient with chronic, untreated disease, full-thickness choroidal flow voids were identified that did not regress with treatment. Conclusions and Relevance For these 3 patients, SS-OCTA provided a noninvasive method for identifying early BSCR lesions previously visible only with ICGA. The depth information provided by SS-OCTA suggests acute lesions originate in the Haller layer, and that in the absence of treatment, damage extends up thorough the superficial choroid, and ultimately to the retinal pigment epithelium and retina. Swept-source OCTA may represent a new and noninvasive method for detecting and monitoring disease activity in BSCR.