Vitrectomy is a surgery to remove some or all of the vitreous humor from the eye. Anterior vitrectomy entails removing small portions of the vitreous humor from the front structures of the eye—often because these are tangled in an intraocular lens or other structures. Pars plana vitrectomy is a general term for a group of operations accomplished in the deeper part of the eye, all of which involve removing some or all of the vitreous humor—the eye's clear internal jelly. Even before the modern era, some surgeons performed crude vitrectomies. For instance, Dutch surgeon Anton Nuck (1650–1692) claimed to have removed vitreous by suction in a young man with an inflamed eye. In Boston, John Collins Warren (1778–1856) performed a crude limited vitrectomy for angle closure glaucoma.
Anesthesia for vitrectomy
Options for anesthesia for vitrectomy are general anaesthesia, local anesthesia, topical anesthesia and intracameral lidocaine irrigation. Each anesthesia technique has its advantages and disadvantages, and the selection of anesthesia will depend on various factors including the surgeon's and patient's choice, disease and additional surgical steps required.
Pars plana vitrectomy
Although Robert Machemer has historically been credited with developing pars plana vitrectomy, Anton Banko patented the procedure for closed vitrectomy in 1968, predating Machemer's first reported operation by three years. Machemer performed the first reported human closed pars plana vitrectomy in 1970 and subsequently helped establish the technique as a standard approach to vitreous surgery. The original purpose of vitrectomy was to remove clouded vitreous humor—usually containing blood. The success of these first procedures led to the development of techniques and instruments to peel scar tissue (membranectomy) off the light sensing nerves of the posterior eye (the retina) and to provide space for materials injected in the eye. It also made space for surgeons to inject gases or liquid silicone necessary to reattach the retina. It also increase the efficacy of other surgical procedures such as scleral buckle. The development of new instruments and surgical strategies through the 1970s and 1980s was spearheaded by surgeon and engineer Steve Charles. More recent advances have included smaller and more refined instruments for use in the eye, the injection of various medications at the time of surgery to manipulate a detached retina into its proper position and mark the location of tissue layers to allow their removal, and for long term protection against scar tissue formation. Several technologies and systems exist to treat vitrectomy.
Additional surgical steps
Additional surgical steps involved as part of modern vitrectomy surgeries may include: Membranectomy – removal of layers of unhealthy tissue from the retina with minute instruments such as forceps (tiny grasping tools), picks (miniature hooks), and visco-dissection (separating layers of tissue with jets of fluid.) This layer of unhealthy tissue is called an epiretinal membrane and it can occur in anyone, but is more likely to occur in the elderly or in people who have had prior eye disease or eye surgery. If the patient has an epiretinal membrane and is also complaining of symptoms such as decreased visual acuity, then a membranectomy is performed in addition to the vitrectomy. Complications of this additional step are similar to complications of the standard vitrectomy procedure. Fluid/air exchange – injection of air into the eye to remove the intraocular fluid from the posterior segment of the globe while maintaining intraocular pressure to temporarily hold the retina in place or seal off holes in the retina. The air pressure is temporary as the posterior segment will soon re-fill with fluid. Air/gas exchange – In some cases, gas can be used to help hold the retina in place. Gas, or more typically mixed gas and air, is injected through the sclera and into the posterior segment of the globe. This procedure is often referred to as pneumatic retinopexy. Typical gases used are perfluoropropane or sulfur hexafluoride. The gases are mixed with air to neutralize their expansive properties to provide for a longer acting (than air alone) retinal tamponade. The retinal tamponade acts to hold the retina in place or temporarily seal off holes in the retina. The mixed gases disappear spontaneously once they have accomplished their purpose and the posterior segment re-fills with fluid. Silicone oil injection – Similar to an air/gas exchange, or pneumatic retinopexy, the eye can also be filled with liquid silicone to hold the retina in place. In contrast to the pneumatic retinopexy, however, the silicone oil remains in the eye until it is later removed surgically. Oils have less surface tension and buoyancy than gases so the tension exerted by the oil is about 30 times less than that of the gas. Photocoagulation – In cases when there is a tear in the retina, or when there are unhealthy damaging blood vessels (which can be seen in patients with diabetic retinopathy), laser treatment can be used. In such cases, the laser is used to seal the hole or prevent growth of the unhealthy, damaging blood vessels. Scleral buckling – placement of a support positioned like a belt around the eyeball to maintain the retina in a proper, attached position. This is referred to as an "exoplant". Placement of the scleral buckle for patients who have had a retinal detachment has been shown to lead to reattachment approximately 80 to 90 percent of the time after one surgery. In cases of failure, most patients are treated with vitrectomy. Lensectomy – In some cases, a lensectomy, or "cataract surgery", is done in conjunction with the vitrectomy. This extra procedure is performed when the lens of eye is cloudy (cataract), damaged during the vitrectomy, if there is attached to scar tissue, or if the pressure in the eye needs to be lowered (as in the case with some glaucomatous patients).
Indications
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