Characterization of birdshot chorioretinopathy using extramacular enhanced depth optical coherence tomography.

OBJECTIVE: To combine "extramacular" and "enhanced depth" optical coherence tomographic (OCT) scanning protocols to facilitate enhanced characterization of patients with birdshot chorioretinopathy.

METHODS: Spectral-domain OCT images were prospectively collected from 24 eyes of 12 patients with birdshot chorioretinopathy. The images were acquired both from the macula and from 4 peripheral locations: superior and inferior to the temporal vascular arcades, nasal to the optic disc, and temporal to the macula. All images were obtained using enhanced depth scanning protocols. Qualitative and quantitative assessments were performed and compared with those from healthy, age-matched controls.

RESULTS: Generalized loss of the photoreceptor inner segment/outer segment junction was seen more frequently on extramacular OCT image sets. Focal loss of the inner segment/outer segment junction was seen most commonly on inferior extramacular images. Generalized thinning and loss of retinal architecture, accompanied by outer retinal hyperreflective foci, were also commonly seen on extramacular scans. Assessment of choroidal morphology included thinning/absence of the Sattler layer, generalized thinning, discrete hyperreflective foci, focal depigmentation, and the presence of suprachoroidal hyporeflective space. The mean (SD) foveal choroidal thickness was significantly less for patients with birdshot chorioretinopathy (276 [101] μm) than for controls (337 [74] μm) (P = .04).

CONCLUSIONS: The OCT images obtained outside the macula often show significant retinal and choroidal changes in cases for which conventional OCT scans appear unremarkable. Use of extramacular scanning may thus allow improved phenotyping of uveitic disorders such as birdshot chorioretinopathy. Evaluation of the photoreceptor inner segment/outer segment junction, using this approach, may be of value for monitoring disease activity in clinical practice and as a surrogate end point in clinical trials.