Vitreo-retinal Surgery

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Suprachoroidal Hemorrhage. One of the more feared complications for all eye surgeons is an intraoperative massive suprachoroidal hemorrhage. The incidence of suprachoroidal hemorrhage during vitrectomy surgery has been estimated to be 0. If the IOP is significantly lowered in a short period of time, especially if it is initially elevated, the short or long posterior arteries may rupture, giving rise to a severe suprachoroidal hemorrhage.

This can lead to even more bleeding as the forced separation of the choroid away from the sclera will avulse more blood vessels. Intraoperative management of suprachoroidal hemorrhage is aimed primarily at stabilizing the IOP and preventing extrusion of intraocular contents. Increasing the IOP to 60 mmHg or more can usually be instantaneously accomplished by depressing a pre-determined switch on the vitrectomy foot pedal. The infusion line should also be checked frequently to make sure that the infusion cannula has not entered the subretinal space.

Drainage posterior sclerotomies can be considered in more severe cases or when intraocular tissues are incarcerated. It is often impossible, however, to drain all of the hemorrhage, as there is usually a persistent localized blood clot. Moreover, it does not appear to have any significant beneficial effect on the long-term visual outcome. Additionally, there is an increased incidence of retinal detachment, secondary glaucoma and eventual hypotony. Iatrogenic Phototoxicity. Iatrogenic macular phototoxicity was first described on six patients who developed a characteristic macular lesion following cataract extraction.

Tungsten filament sources have been found to cause more oval-shaped lesions, whereas fiber optic microscope illuminators usually produce a more homogenous, round lesion. Iatrogenic phototoxicity during vitrectomy has been reported both from the operating microscope as well as the endoilluminator See Figure 3.


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One study with long-term follow up of patients with iatrogenic phototoxicity following either cataract or vitrectomy surgery found the average duration of surgery to be minutes. The intensity of the light source should also be titrated only to the level that is sufficient for the surgeon to accomplish the procedure and no higher.

Vitrectomy: Procedure, complications, and recovery

This is especially important in regards to the recent advent of xenon and mercury vapor light sources, where inadvertent exposure to potentially extremely high light intensities is likely to increase the incidence of iatrogenic phototoxicity. Nitrous Oxide. In patients with pre-existing intraocular gas bubbles that have undergone vitreoretinal surgery, the use of nitrous oxide during general anesthesia by the anesthesiologist in subsequent surgical procedures can lead to intractable elevation of IOP and an eventual central artery occlusion.

This will cause a net rapid expansion of the existing intraocular gas bubble and subsequent elevation of IOP, which in many cases can lead to a central artery occlusion and permanent visual loss See Figure 4.

These findings were independently confirmed using a mathematical model, and the authors of the study concluded that if ventilation with nitrous oxide is discontinued at least 15 minutes before the gas-fluid exchange, the volume of gas would only expand by 15 percent. Three eyes had no light perception. It is very important, therefore, to notify the anesthesiologist ahead of time before performing an air-fluid exchange under general anesthesia, to insure that nitrous oxide is not used as an anesthetic.

Patients undergoing vitreoretinal surgery requiring intraocular gas bubbles should also wear a special wrist band postoperatively until the gas bubble is completely reabsorbed in order to notify the anesthesiologist if the patient needs a subsequent surgical procedure requiring general anesthesia.

Air-fluid Exchange Complications. A fundamental maneuver in vitreoretinal surgery for repairing retinal detachments, macular holes and any other procedure requiring gas tamponade, is the air-fluid exchange, where fluid in the vitreous cavity is replaced by air. Though the maneuver is typically completed within minutes and usually signals a satisfactory completion of vitrectomy, complications can still occur. One such complication is damage to the retina associated with air infusion.

If the IOP immediately preceding the infusion of air is elevated, as can occur iatrogenically with the vitrectomy foot pedal, the pressure of the air infusion can be high enough to cause damage to the retina contralateral to the infusion cannula. With the infusion cannula placed inferotemporally in most cases, damage to the retina from air infusion is usually seen as whitening of the retina in the superonasal quadrant See Figure 5.

Vitreoretinal Disorder Surgery

One group performed air-fluid exchange in vitrectomized rabbit eyes with an air pressure of 25 and 40 mmHg for 30 seconds. No morphological changes were seen in rabbit eyes that underwent vitrectomy alone. Another complication during air-fluid exchange is mechanical trauma to the optic nerve head during aspiration. Three patients in one report underwent vitrectomy with air-fluid exchange and subsequently developed permanent peripheral temporal visual field defects.

Another study reported on patients with visual field defects after receiving air-fluid exchange and observed optic disc pallor and afferent pupillary defects, further suggesting trauma to the optic nerve as a mechanism for visual field loss. Retained Perfluorocarbon Liquid. Perfluorocarbon liquids are a commonly used surgical adjunct in the management of retinal detachment repair, particularly when dealing with proliferative vitreoretinopathy or giant retinal tears.

Because of their high specific gravity and weight, injection of perfluorocarbon liquids into the posterior chamber will flatten detached retina against the RPE and displace fluid anteriorly through any peripheral breaks, as well as provide counter-traction when peeling epiretinal membranes.

Background

Surgical complications from perfluorocarbons are rare but can occur and are the result of retention postoperatively with subsequent toxicity. Reported toxicities include secondary glaucoma from retained intraocular perfluorocarbon as well as central scotomas from retained subfoveal perfluorocarbon. Sympathetic Ophthalmia. An unusual complication that occurs rarely but has been reported after vitrectomy surgery is sympathetic ophthalmia.

A bilateral diffuse granulomatous uveitis occurring in patients who have sustained previous ocular trauma or surgery, sympathetic ophthalmia has also been reported in patients following vitrectomy. Sympathetic ophthalmia tends to occur between three weeks and six months following vitrectomy and is characterized by bilateral anterior chamber inflammation, vitritis, Dalen-Fuchs nodules and exudative serous retinal detachment See Figure 6. Long-term complications include patchy or diffuse retinal pigment epithelial atrophy and rarely, choroidal neovascularization.

Therapy for sympathetic ophthalmia includes enucleation and immunosuppression. The role of enucleation in the therapy of sympathetic ophthalmia is controversial. Some advocate early enucleation, specifically within two weeks after surgery, 49 while others contend that the timing of enucleation has no effect on the final visual outcome. Wound Leakage Complications. The introduction of ga. Though heralded as decreasing operating times and increasing patient comfort, the new procedure's complications, such as endophthalmitis, appear to be increased compared to the more "standard" ga.

One of the main concerns with small-gauge sutureless vitrectomy is the potential complication of wound leakage and hypotony. A report on consecutive cases using a ga.

EYE EXAMINATION

Several authors have demonstrated superior wound closure using a ga. In addition, the threshold for placing an additional suture in a small-gauge incision should be low.

SURGICAL PROCEDURES

Any hint of bleb formation or wound leakage should prompt the placement of a suture by the surgeon. Aminoglycoside Toxicity. Lastly, a potentially catastrophic but preventable complication is the accidental injection of aminoglycoside antibiotic into the vitreous cavity. Though less commonly used today, aminoglycosides are still used intravitreally for the treatment of endophthalmitis as well as subconjunctivally for antibiotic prophylaxis.

Aminoglycosides have been reported to cause an acute, toxic ischemic retinopathy in high concentrations. Injection of aminoglycosides subconjunctivally has been reported to cause toxicity as well.

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Additionally, we recommend that aminoglycosides not be used as a routine prophylactic antibiotic following vitrectomy surgery. Suitable antibiotics include cefazolin, or if the patient is allergic to penicillin, vancomycin instead. Like all ocular surgery, vitreoretinal surgery may have complications, some of which can be devastating. However, the majority of complications are preventable with careful planning and decision making. Having an open dialogue with the anesthesiologist before surgery begins to discuss the specific needs required of vitreoretinal surgery will prevent unwanted patient movement during critical maneuvers as well the use of nitrous oxide when performing an air-fluid exchange.

Other preventable measures include minimizing exposure to the operating microscope light or endoilluminator and being aware of the intraocular infusion pressure when performing an air-fluid exchange. Aminoglycosides should probably be avoided as a prophylactic antibiotic at the end of the case. Lastly, the surgical team should always label all intraocular fluids used prior to the start of surgery and these should be double-checked by the surgeon before use.

Contact Dr. Ocular perforation following retrobulbar anesthesia for retinal detachment surgery. Am J Ophthalmol ; Inadvertent globe perforation during retrobulbar and peribulbar anesthesia. Patient characteristics, surgical management, and visual outcome. Ophthalmology ; Vitreoretinal surgery after inadvertent globe penetration during local ocular anesthesia. Ocular complications associated with retrobulbar injections. Central retinal artery occlusion without retrobulbar hemorrhage after retrobulbar anesthesia.

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