Purpose
To investigate alterations in the neurosensory retinal morphology secondary to acute retinal ischemic conditions. The observations were documented by spectral domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF) imaging.
Methods
SD-OCT images and FAF were used to observe the retinal structure. 26 subjects (36 - 96 years) with acute monocular visual impairment due to retinal ischemia were included. The main focus of attention was set on the transition of the outer nuclear layer (ONL) to outer plexiform layer (OPL). SD-OCT images were aquired with a combined SD-OCT and scanning laser ophthalmoscope (SLO) imaging system using a linear cross hair scan and a 6 line radial scan of 6 mm length (ART mode on; average of 20 frames)
Results
SD-OCT revealed an additional highly reflective band located within the OPL. Morphological characteristics of this hyperdense band were a decreasing intensity with distance from the fovea, partially segmental occurrence and manifestation limited in time. FAF showed areas of increased and decreased signal intensity within the vessel arcade at the posterior pole. The regions of decreased FAF corresponded to perivenous regions and resemble the “frosted branches” sign seen in fluorescein angiogaphy in patients with ocular iscemia
Conclusions
The additional hyperreflective band observed in SD-OCT could represent a marker for retinal ischemia in subjects without the presence of a complete arterial occlusion. The mid retinal localization of the band within the OPL represents the locus of transition from retinal to choroidal oxygen supply where oxygen diffusion is weakest. Histopathologically the observed structure could represent activated microglial tissue induced by the hypoxia driven upregulation of inflammatory molecules aimed at ischemia repair
Keywords: 572 ischemia •
550 imaging/image analysis: clinical •
436 blood supply