In vivo retinal vascular cannulation in rabbits.

PURPOSE

To perform in vivo cannulation of retinal vessels for local application of pharmacotherapy to treat central retinal vein occlusion (CRVO), a new method was tested using rabbits. Changes following cannulation were studied histologically.

METHODS

The micropipette used for cannulation was constructed from a glass tube. The outer diameter of the tip was 30-40 microm. Rabbits for the experiment were anesthetized; each had its head stabilized with fixing equipment designed for that purpose. After preparing a port for infusion of balanced salt solution (BSS), the specially designed micropipette was inserted at the pars plana of the ciliary body to puncture the major retinal vein, through which BSS was injected.

RESULTS

We were able to puncture the major retinal vein with the micropipette without causing any serious incident, after which we injected approximately 100 microl of BSS. A small amount of vitreous hemorrhage that appeared after removing the micropipette could be stopped by increasing intraocular pressure by elevating the infusion bottle. Postoperative observation by indirect ophthalmoscopy showed no obstruction in the vein at the puncture site. Light microscopy showed only a slight narrowing of the venous lumen at the site.

CONCLUSION

Cannulation into the retinal vein of rabbits was possible, and invasion was not significant, as determined histologically. Our findings endorse a method of restoring blood flow that involves direct injection of tissue plasminogen activator into the retinal vein of patients with CRVO to dissolve a thrombus.