OCT provides minute details of aqueous outflow pathways, motion
Schlemm’s canal and collector channels respond rapidly to changes in pressure gradients.
Take-home message: Schlemm's canal and collector channels respond rapidly to changes in pressure gradients.
Reviewed by Murray A. Johnstone, MD
Seattle-A new optical coherence tomography (OCT) platform goes where others have not gone before, said Murray A. Johnstone, MD.
Analysis of minute tissue structures in the area of Schlemm’s canal and the collector channels shows incredibly rapid responses to changes in pressure gradients, said Dr. Johnstone, clinical professor of ophthalmology, University of Washington, Seattle.
The instrument showed that pressure-dependent opening and closing of collector channels occurs and may be relevant in distal resistance in micro invasive glaucoma surgery.
This became apparent when Murray A. Johnstone, MD, and colleagues evaluated a radial limbal segment facing upward in a Petri dish.
This positioning facilitates the beam having to pass through only the trabecular meshwork and thus effectively image Schlemm’s canal and the collector channels, Dr. Johnstone explained.
“Using radial scans through the limbal region, we can maintain a steady-state gradient by attaching a cannula in Schlemm’s canal to a reservoir and rapidly switch between reservoirs to watch the responses of the tissues to changes in the pressure gradients,” he said.
With OCT scanning through the trabecular meshwork with a cannula in Schlemm’s canal at the distal end, Dr. Johnstone showed that at 10 mm Hg Schlemm’s canal was widely dilated.
“We could actually see the entrances to the collector channels and hinged collagen flaps at each of the entrances to the collector channels,” he said.
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