An experimental study of retinal endovascular surgery with a microfabricated needle.

PURPOSE To study the feasibility of performing retinal endovascular surgery with a microfabricated needle-based cannulation system at the level of the retinal microvasculature. METHODS A total of 40 retinal vein vessels, and 40 porcine eyes were used, and the eyecups were prepared under an operating microscope. Twenty retinal veins each were pierced with a microfabricated needle having an outer diameter of 50 μm and with a micropipette having an outer diameter of 50 μm, respectively, and each vessel that was successfully pierced was injected with a solution. The piercing success rates and injection success rates were calculated, and a histologic examination of the site was performed in each eye. RESULTS Piercing and injection with the microneedle were successful in all 20 eyes (100%). Histologic examination showed that the retinal vasculature was well preserved in all eyes in which piercing had been performed with the microneedle. Piercing with the micropipette, on the other hand, was successful in only 8 eyes (40%), and injection with the micropipette was successful in only 5 eyes (25%). The tip of the micropipette broke in 12 vessels during piercing and in 3 vessels during injection. CONCLUSIONS; The feasibility of performing microvascular piercing and intravascular injection of retinal veins with a microneedle was demonstrated in porcine eyes. It may be possible to administer solutions into retinal vessels more effectively with a microfabricated needle, and that may contribute to improving retinal endovascular surgery in human eyes.