Miyake analysis of anterior vitrectomy techniques

Purpose: To study the efficacy and safety of anterior vitrectomy with the Miyake system. Setting. Miyake Laboratory, IOLAB, Claremont, California. Methods: Four pig eyes and three human eyes were transected equatorially. The anterior segments were glued to a glass slide and placed on a stage for anterior and posterior videography. Phacoemulsification was performed, and the posterior capsule was intentionally ruptured. Three different vitrectomy techniques were studied: anterior vitrectomy with coaxial infusion sleeve, anterior vitrectomy with separate limbal infusion, and pars plana vitrectomy with limbal infusion. Results: All techniques showed that vitreous could be safely and effectively removed without undue stress on the retina whenever the vitrectomy instrument was held directly beneath the iris and not placed peripherally to the iris root. Only the pars plana site allowed access to the entire posterior aspect of the iris for removal of vitreous gel. Conclusion: Anterior vitrectomy can be performed safely and effectively with any of the three approaches studied. The pars plana technique permitted removal of gel beneath the superior iris. This has important clinical implications because irido-vitreous adhesions tend to form superiorly after limbal vitrectomy.