Abstract
Presentation Description :
New angle-based surgical procedures in glaucoma for intraocular pressure (IOP) lowering has renewed interest in anterior segment glaucoma clinical and basic research. Aqueous humor outflow (AHO) is taught using two-dimensional cross-sectional images and, when generalized into a three-dimensional eye, implies uniform AHO that circumferentially radiates away from the limbus. Prior bench research analyzing the structural pathways for AHO or documenting tracer movement has instead suggested segmental AHO around the limbus.
Aqueous angiography is a new imaging modality that derives from retinal intravenous angiography (IVA). Retinal IVA is performed routinely in clinical care of patients with vascular retinal disorders and involves placing tracers in peripheral veins (indocyanine green [ICG] of fluorescein) to visualize retinal blood flow with angiographic cameras. In aqueous angiography, the same tracers are introduced into the anterior chamber and imaged with similar angiographic cameras to follow AHO instead.
Aqueous angiography was first developed in the laboratory using post-mortem eyes from pigs, cows, and humans. Aqueous angiography demonstrated segmental AHO in all species. Like retinal IVA, real-time movies documenting AHO can be recorded. Sequential angiography with ICG followed by fluorescein allowed for interventional testing. In post-mortem human eyes, segmental regions of initially low angiographic flow could be rescued and improved by trabecular bypass.
Modified for the operating room, aqueous angiography was translated to intact eye of living non-human primates and human patients undergoing routine cataract surgery. Aqueous angiography confirmed segmental AHO seen in the laboratory and also showed a pulsatile and novel dynamic flow characteristic.
Aqueous angiography is a new AHO imaging modality that follows where aqueous humor moves in an individual eye. Further investigation regarding segmental AHO may allow for individualized placement of trabecular bypass glaucoma surgeries. Angiographic end-points could be used for pharmacological screening of candidate conventional outflow glaucoma drugs. Aqueous angiography and evaluation of high/low flow regions in normal/glaucoma eyes may allow for greater insight into pathological outflow in disease.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.