Abstract
Purpose: :
To analyze the morphologic changes of retinal areas with peripheral ischemia identified by fluorescence angiography (FA) and spectral domain optical coherence tomography (SD-OCT) in patients with diabetic retinopathy
Methods: :
Patients were examined with FA and SD-OCT using the Heidelberg Engineering® Spectralis HRA+OCTTM at baseline and one year later. Ischemic retinal areas were identified during the same session and analyzed by obtaining at least one SD-OCT section scan registered on the FA image (FA+OCT). Ischemic areas on FA and on SD-OCT were then compared and analyzed with regard to size, shape, and morphology at both visits
Results: :
Areas of peripheral retinal ischemia in patients with diabetic retinopathy showed one of two clearly distinguished morphologies in SD-OCT: a homogeneous hyper-reflective band or a more hyper-reflective, speckled lesion representing a cotton-whool-spot between and including the ganglion cell layer and the nerve fiber layer. In all patients, the thickness of the lesion in SD-OCT diminished over the course of the follow-up time. The size of the horizontal bands observed in SD-OCT correlated with the diameter of the area of non-perfusion in FA. The OCT beam scattering below theses bands was slightly less than the beam scattering caused by blood in the retinal vessels. The pigment epithelium and the photoreceptor cells below the bands appeared to have a normal morphology as the inner and outer segments, the pigment epithelium and the outer nuclear layer could be identified in detail
Conclusions: :
Ischemic retinal areas can be identified in SD-OCT as individual pathomorphologic entities. Size and shape can be determined in SD-OCT and FA with comparable confidence. The pathologic process of the ischemia seems to be limited to the ganglion cell layer and the nerve fiber layer: the retinal morphology below these layers does not show significant alteration
Keywords: diabetic retinopathy • ischemia • imaging/image analysis: clinical