gms | German Medical Science

Purpose: EDI-OCT is an advanced application developed from spectral domain-optical coherence tomography (SD-OCT), which allows for better visualization of deeper tissue layers. The aim of this study was the evaluation of the morphology of choroidal tissue by use of EDI-OCT in comparison with SD-OCT.

Methods: Examinations were performed using simultaneous confocal scanning laser ophthalmoscopy (cSLO) and spectral domain-optical coherence tomography (SD-OCT, 870 nm, 40.000 A-scans/sec) in a combined instrument (Spectralis HRA+OCT, Heidelberg Engineering, Heidelberg, Germany). EDI-OCT scans were recorded with the identical resolution as in SD-OCT scans (7 µm depth resolution, 14 µm lateral resolution). Healthy eyes as well as eyes of patients with various chorioretinal diseases were assessed using this new imaging device. Choroidal thickness was measured.

Results: Choroidal thickness shows a great variability with regard to the vertical extent at the posterior pole in healthy eyes. Dependent on the refractive error choroidal thickness decreases with the increase of myopia. The choroidal margins, the highly reflective BM/RPE-layer as well as the demarcation towards the sclera, could be clearly identified. The very thin choriocapillaris layer could not be delineated within the choroidal tissue. By means of the reflectivity-dependent identifiability of the anterior and the posterior margins of the choroidal tissue the choroidal thickness can be quantified in the range of microns.

Conclusions: The new EDI-OCT-technology might prove to be useful to further elucidate the involvement of choroidal alterations in the pathophysiology and natural history of various diseases at the posterior pole. EDI-OCT can be used not only for routine diagnostics but also for monitoring disease process after therapeutic interventions.