Abstract
Purpose :
Chorioretinal anastomosis (CRA), abnormal connections between the choroidal and retinal vasculature, represent an advanced manifestation of ocular neovascularization that is often refractory to treatment. CRA occurs in ~15% of neovascular age-related macular degeneration and can also arise in macular telangiectasia, Coats, and other diseases. The pathophysiological mechanisms of CRA remain poorly understood. We use two-photon excited fluorescence (TPEF) microscopy and computational methods to investigate the formation of CRA and hemodynamics in a Col4a1 mutant mouse model of neovascularization. We develop analytical methods that provide insight into CRA and will be broadly useful for investigations of aberrant neovascularization.
Methods :
Vascular imaging in fixed eyes was performed with Lectin-Dylight649 staining and TPEF microscopy. Intravital imaging and blood flow measurements were performed with retro-orbital injection of fluorescein-dextran and TPEF microscopy. Three-dimensional (3D) structure analysis was conducted with IMARIS and self-developed R/MATLAB scripts to quantify vessel diameters, density, branching level, branching angle, and segment length. Blood flow was quantified using cross-correlation of blood cell movement in sequential line- or full-frame scans.
Results :
CRA in Col4a1 mutants originated from the choroid (81.8% sprouts) or retina (18.2% sprouts) and formed arborized configurations anchored at the choroid. 3D analysis of CRA uncovered bimodal groupings of vessel diameters, where CRA contained larger vessels and were identifiable within 6 branching levels from the choroid. Col4a1 mutants had decreased blood flow, and abnormal vessels harbored aberrant hemodynamics including flow stagnation and reversals.
Conclusions :
CRA can originate from either the choroid or the retina and progressively remodel into select enlarged vessels. Chorioretinal blood flow in Col4a1 mutants is decreased, and CRA have significant alterations in vascular structure and hemodynamics including flow stagnation and reversal. We develop analytical methods that provide detailed characterization of CRA which will be broadly useful for other investigations of aberrant neovascularization.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.