Cirurgia de vitrectomia com equipamento de 27 gauge

Abstract

In the following video, we will show two pars plana vitrectomies using a 27-gauge system. The equipment used was the constellation® (Alcon, USA). These are the first two surgeries performed using this system in Brazil. They were undertaken at the Parana Eye Hospital (Hospital dos Olhos do Parana) in Curitiba, Parana State, and at the Brazilian Vision Center (Centro Brasileiro de Visao) in Brasilia, Distrito Federal. The 27-gauge system is thinner and more delicate compared with other such systems. It allows making incisions as small as 0.4 mm. Previously, the thinnest system available was the 25gague system, allowing 0.55-mm incisions. Smaller incisions induce less inflammation, do not require suturing, and allow faster recovery. The first case presented is that of a patient with vitreous hemorrhage due to proliferative diabetic retinopathy, an operation which was completed using only the new 27-gauge system. Contrary to what is expected, dense vitreous opacities can be removed with an instrument with a smaller-diameter opening. To do so, we simply follow Poiseuille's law that states that the flow velocity of a fluid in a system is directly related to the pressure exerted for its withdrawal and has an inverse correlation with the viscosity of the material. The new 27-gauge systems exhibit a high suction pressure, reaching up to 600 mmHg. In addition, their cutting speed is up to 7500 cuts per minute, i.e., if we perform the vitrectomy using these systems, we can achieve a flow rate similar to that achieved with devices with larger diameters, such as the 25- or 23gauge systems. It is the cutting speed on the vitreous that allows dense vitreous to be removed quickly. Note that the surgery is in real time and all bleeding is aspirated at a constant rate; this is similar to previously used systems. Although the 27-gauge system is more delicate, it allows performing peripheral vitrectomy without bending the tip of the device. Experienced surgeons will have no difficulty performing this procedure. In addition to the thinner cutter tip, the 27-gauge system comes with all accessories with the same diameter, including the laser that is used at the end of the procedure. In the second case, we show the surgery on a patient with a macular hole. With the high vacuum pressure exerted on the vitreous, the posterior hyaloid membrane is removed easily and safely. Once the posterior hyaloid is removed, the inner limiting membrane is stained with brilliant blue so that it may be removed using suitable forceps. At the end of the surgery, fluid–gas exchange is performed.