Characterization of Birdshot Chorioretinopathy Using Extramacular Enhanced Depth Optical Coherence Tomography

Abstract

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, agematched 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] m) than for controls (337 [74] m) (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.

Choroidal Findings in Eyes With Birdshot Chorioretinitis Using Enhanced-Depth Optical Coherence Tomography

“…In other prior studies of BSCR, Keane et al 10 found choroidal thinning, discrete hyperreflective foci, focal depigmentation, and presence of a suprachoroidal hyporeflective space on EDI-OCT scans from 12 individuals. The authors had the impression that birdshot lesions on fundus photographs were focal areas of ''choroidal depigmentation'' suggested by increased scleral reflectivity on the OCT images.…”

“…Using EDI-OCT, Mrejen and Spaide 9 demonstrated hyporeflective zones in the choroid of eyes with BSCR. Keane et al 10 subsequently reported choroidal depigmentation and hyperreflective foci in the choroid and speculated that these findings were most likely inflammatory in nature. Other choroidal findings by EDI-OCT included thinning of the Sattler layer, generalized choroidal thinning, focal depigmentation, and presence of a suprachoroidal space.…”

“…Other choroidal findings by EDI-OCT included thinning of the Sattler layer, generalized choroidal thinning, focal depigmentation, and presence of a suprachoroidal space. 10,11 The clinical relevance of these findings remains poorly understood. To expand our iovs.arvojournals.org j ISSN: 1552-5783…”

Structural changes of the choroid in sarcoid- and tuberculosis-related granulomatous uveitis

“…5,42,44 In a recent study, extra-macular scans performed in eyes diagnosed with birdshot chorioretinitis demonstrated generalised choroidal thinning outside the macula. 18 Although factors including age and disease activity were well matched between the good (o0.3 LogMAR) and poor (≥0.3 LogMAR) VA groups, other confounders are possible.…”

“…[15][16][17] Several early studies have indicated how OCT-derived choroidal images can be useful in uveitic disorders. For example, OCT has been used (1) to describe characteristic features of specific uveitis entities, including thinning of Haller's large vessel layer of the choroid in idiopathic panuveitis and extra-macular choroidal changes in birdshot chorioretinopathy; 18,19 (2) to identify distinct stages of a disease process as illustrated by punctate inner choroidopathy; 20,21 (3) objective measurement of vitreous inflammation; 22 and (4) to monitor response to therapy, exemplified by a reduction of subfoveal choroidal thickening with corticosteroid therapy in Vogt-KoyanagiHarada disease. 23 Additionally, the potential of OCT angiography in uveitic diseases has yet to be realised.…”