VESGEN analysis of human macular microvasculature in venous occlusive disease imaged in vivo with AOSLO FA

Abstract

 

Purpose

 

Cardiovascular disease processes such as diabetes mellitus, hypertension and vascular occlusion disrupt the microvasculature, leading to ischemia and end organ damage. Two-dimensional, high-resolution imaging of human macular microvasculature using adaptive optics scanning light ophthalmoscope fluorescein angiography (AOSLO FA) offers a platform for studying these systemic pathological changes. Here we establish VESsel GENeration Analysis (VESGEN) software as an analysis tool of vascular patterning in AOSLO FAs.

 

Methods

 

AOSLO FAs of 1 healthy control eye (25 year old male), 1 non-ischemic central retinal vein occlusion (CRVO; treatment history of multiple intravitreal bevacizumab injections) affected eye and its fellow unaffected eye (55 year old male without significant past medical history) were acquired. For each eye, simultaneous reflectance (790 nm) and fluorescence (488 nm) image sequences were recorded using a 1.75° field-of-view at a frame rate of 15Hz to map a 6° square area centered at the fovea, 10 minutes post-ingestion of 20mg/kg fluorescein dye. After sinusoidal distortion and eye motion were removed, registered averaged images with high signal-to-noise ratio were stitched together to create larger microvascular perfusion images. Binary (black/white) vascular patterns extracted from the images as reported for vascular tree-network composites (Anat Rec 292:320) were automatically mapped by VESGEN (Figs 1-2) to assign branching generations (Gx) according to weighted vascular rules for bifurcational branching, vessel diameter and tapering, and fluid mechanics of laminar blood flow. Maps were quantified to obtain key vascular parameters that include the fractal dimension (Df) and densities of vessel length (Lv, E+2 μm-1), number (Nv) and area (Av).

 

Results

 

Overall vascular density by Df and Lv decreased from 1.85 and 4.29 in the control to 1.83 and 3.61 in the fellow eye, and 1.77 and 2.45 in the CRVO eye.

 

Conclusions

 

Our proof-of-concept study demonstrates the potential usefulness of VESGEN for characterization of ‘signature’ changes in vascular patterning that occur in different types of cardiovascular disease. The approach has significant clinical implications for earlier, more sensitive diagnosis and individually tailored management of disease.

 

 

Fig 1 Vascular map of control eye by VESGEN (legend, G1-G8).

 

 

Fig 2 VESGEN maps of fellow and CRVO eyes (legend, Fig 1).

 

Keywords: 688 retina • 749 vascular occlusion/vascular occlusive disease • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)