Imaging technique may help understanding of chronic CSCR

By Laura Cowen, medwireNews Reporter

Swept-source optical coherence tomography (SS-OCT) identifies the morphological features implicated in the underlying physiopathological mechanisms of chronic central serous chorioretinopathy (CSCR), researchers report.

The high-speed, enhanced-depth, three-dimensional scanning technique, conducted at 1050 nm wavelength, allows characterisation of pathological features of the retinal pigment epithelium (RPE) and choroid in eyes with chronic CSCR not usually captured with standard spectral domain OCT.

Jay Duker (Tufts Medical Centre, Boston, Massachusetts, USA) and colleagues studied the en face SS-OCT morphology of the RPE and individual choroidal layers of 15 eyes from 13 patients (mean age 51 years, 85% men) with chronic CSCR. All patients reported visual symptoms in the affected eye for at least 6 months (mean 13.6 months).

The researchers explain that the non-invasive, en face imaging allowed virtual sectioning of the macular area in consecutive scans 3.5 μm apart, from the vitreous cavity to the sclera.

At the RPE level, the team observed an absence of signal corresponding to RPE detachment or RPE loss in all of the eyes they studied. Furthermore, the changes observed on these images corresponded with pathological changes seen on cross-sectional SS-OCT and multimodal imaging, including fundus autofluorescence and angiography.

Large hypoechoic spots were identified at choriocapillaris level in eight (53%) of the 15 eyes. Duker et al comment that this finding suggests “the presence of enlarged vessels”. However, they add that it was unclear whether the absence of identifiable choriocapillary changes in the remaining seven eyes “was related to a limitation in image resolution, given the smaller vascular lumen and the complex vascular anatomy at this level, or the true absence of vascular engorgement.”

At the level of Sattler’s layer, the en face SS-OCT highlighted dilation of medium-sized choroidal vessels in two distinct patterns; there was focal choroidal dilation in eight (53%) eyes and diffuse choroidal dilation in seven (47%).

This pattern was repeated at the level of Haller’s layer, with three (20%) and 12 (80%) eyes showing focal and diffuse choroidal dilation, respectively.

Of note, the choroidal vascular abnormalities were seen just below the areas of RPE abnormalities in all affected eyes. They cannot, however, be seen on cross-sectional OCT images, which suggests that “en face imaging is superior to cross-sectional imaging for visualizing these features”, Duker and co-authors remark.

Reporting in Ophthalmology, they add: “Although the physiopathologic significance of focal versus diffuse choroidal dilation is still to be determined, our original results may lead to new insights related to disease mechanisms.”

This could in turn “contribute to the diagnosis and management of chronic CSCR,” the team concludes.

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