Vitrectomy is a surgical procedure which involves removal of vitreous gel from the eye. In this procedure small ports are created in the sclera for introduction of the instruments inside the eye. With the assistance of Vitrectomy machines and fine instruments like cutters which delivers high speed cut rates surgery is performed when the gel vitreous along with membranes proliferated on the retina is removed. For visualisation inside the eye we use light probes and to coagulate the retina and retinal blood vessels we use endolaser probes during the surgeries. Other micro instruments and drugs are also used during the surgery which aid in the complete removal of retinal membranes and proliferations on the retina. For visualisation during the surgery which is essential to perform a optimal and complete vitrectomy we use a special wide angle lens which is fitted to the higher end operating microscope which gives a wide angle view of the retina.
With the Rapid development of instrumentation for these types of surgeries we are using smaller gauge instrumentation like 23G; 25G and 27G instruments where the incision size is reduced to 0.6mm, 0.5mm and 0.4mm respectively which gives us an essentially sutureless surgeries with less discomfort to the patient post operatively. The advantage of smaller gauge instruments are that we can go very close to the retina without much turbulence and tissue damage intraoperatively. These surgeries are called Microincision Vitrectomy Surgeries (MIVS).
Before invention of MIVS, traditionally 20 gauge instruments were used where the scleral openings used to be 1.4mm on size.
We make three scleral incisions using valved trochars and cannulas during the surgery one in the inferotemporal quadrant which secures the infusion inside the eye. The infusion line helps us to maintain the intraocular pressure throughout the surgery and avoid globe collapse intraoperatively. Two more incisions are made in the superotemporal and in the superonasal quadrants where we introduce the cutter and the light probes for the surgery.
Sometimes during retinal detachment and trauma cases the vitrectomy surgery is accompanied by scleral buckle placement which gives additional external support the retina. Membrane surgeries, Internal Limiting membrane peeling and Laser during the surgeries are used as adjuvant steps dung the surgeries. Intraoperatively sometimes we use triamcinolone acetonide for staining the vitreous which helps in the visualization of the transparent vitreous during the surgery. Other agents like brilliant blue green dye is used which stains the internal limiting membrane of the retina and assists its removal during macular hole surgeries and epiretinal membrane removal surgeries. Perfluorocarbon liquids is a heavy liquid used to flatten the retina intraoperatively in retinal detachment cases which helps in the reattachment of the retina and identification of any residual traction on the retina intraoperatively. Tamponading agents used after vitreous surgeries are Air; Expansile gases like (Perfluoropropane C3F8 and Sulfur Hexafluoride SF6) and Silicone oil. These agents are used to provide surface tension across the retinal breaks which prevent the migration of fluid into the subretinal space till the retinal heals. Air or Gas gets absorbed spontaneously in a few days to weeks post procedure during which the patient is advised to avoid air travel. Silicone oil when used as a tamponade needs a second surgery for its removal after 3 to 6 months. When a tamponade is used inside the eye, strict prone positioning is advised to the patient for good results.