Distribution of FITC-dextran in rabbit eye tissues after uveoscleral drainage surgery

Objective: To study the morphologic changes of aqueous humor outflow pathway after uveoscleral drainage surgery. Methods: Totally 20 Chinese white rabbits were randomly divided into two groups. Uveoscleral drainage surgery was performed in one group and trabeculectomy was performed in the other; only the right eyes were chosen in both groups. Two weeks after surgery, FITC-dextran was perfused intracamerally on the operated eyes. After the rabbits were sacrificed the whole eyeball was extracted and prepared for frozen sections. Distribution of fluorescein was observed under confocal microscope. The normal tissue opposite to the surgical site which was untouched was used as control. Results: In uveoscleral drainage group, fluorescein was most expressed in the anterior and middle parts of the sclera, followed by the anterior uveal tract. In trabeculectomy group, however, fluorescein was most expressed in the anterior uveal tract, and anterior and middle parts of the sclera followed as the second. In both groups, only parts of the posterior sclera and uveal tract were moderately manifested, but hardly any fluorescein could be seen in these parts in their corresponding controls. Fluorescein in the anterior and middle parts of sclera was significantly brighter than that in controls in both groups. Conclusion: There seems to be a multi-pathway of aqueous humor drainage after both trabeculectomy and our devised surgery. There is not only a flow "out" but also an enhanced uveoscleral outflow. Compared with trabeculectomy, uveoscleral drainage surgery may also increase transcleral outflow.