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Complications of Macular Surgery

Ximena Vazquez Eric P. Jablon John B. Kerrison Monica Rodriguez-Fontal D. Virgil Alfaro III

The advent of small-gauge vitreous surgery has produced new forms of intraoperative and postoperative complications of pars plana vitrectomy. The reader is well aware that vitreous surgery increases the rate of cataract formation, related to vitreous aquadynamics, vitreous changes, and decreasing temperatures of the vitreous cavity, all thought to play a role in postoperative cataract. Patients should be properly educated on this fact as macular surgery is discussed.

The goals of this chapter are to elucidate the many complications of small-gauge surgery and to provide logical and helpful information on how to resolve these issues as they present during surgery.

COMPLICATIONS OF TROCAR PLACEMENT

The goals of trochar placement are to provide access to vitreoretinal pathology via self-sealing wounds. The surgeon should determine at what clock hours to place the trochars based upon the vitreoretinal pathology at hand. For instance, a retinal detachment with a horseshoe tear at 12 o’clock will require laser surrounding the break; trochar placement at 3 and 9 o’clock will facilitate access to the tear during endolaser.

An intact conjunctiva after vitreous surgery is helpful to a speedy postoperative recovery and in diminishing the risk of postoperative endophthalmitis. We prefer gentle manipulation of the conjunctiva with a cotton-tipped applicator, since it easily displaces the conjunctiva and allows for globe stabilization while the trochar is placed. In aphakic and pseudophakic patients the trochar is placed 3.5 mm posterior to the surgical limbus; the length 4.0 mm is measured from the surgical limbus in phakic eyes patients.

Currently, three systems are used internationally: Alcon, Bausch and Lomb, and Dorc. All three recommend trochar placement that suggests the formation of a shelved, self-sealing wound that is produced after the trochars are removed. The reader should determine the exact angle used for entering the eye as well as subtle trochar manipulation that ensure surgical goals. During placement, the trochar tip should be pointed toward the midvitreous cavity, since these authors have injured the crystalline lens with the trochars during placement.

Small-gauge infusion cannulae are not sutured to the eye wall, resulting in several potential issues during surgery. We have found that taping the canula into proper position after it is connected to the trochar is a significant step in the setup for small-gauge surgery. The weight of the infusion tubing may cause the tip of the infusion canula to point toward the anterior segment of the eye during surgery, irritating the iris and causing intraoperative miosis. These authors have also encountered an inordinately deep anterior chamber, intraocular lens (IOL) malpositioning, damage to the crystalline lens, iridodialysis, hyphema, and iris trauma from an improperly placed infusion canula.

Subretinal canula tips and canula tips located in the suprachoroidal space have been documented during small-gauge surgery. They both represent potentially catastrophic problems and should be prevented by ensuring trochar and canula placement before starting infusion. A subretinal canula tip is made apparent by subretinal gas bubbles or a billowing retinal detachment. After the canula tip has been determined to be in the subretinal space, infusion is stopped immediately. Plugs are placed to prevent hypotony. The infusion canula trochar is removed and the surgeon determines where to place it so that infusion can be restarted. If a total retinal detachment has developed and the patient is phakic, perfluorocarbon liquid may be implemented to stabilize the retina until the infusion trochar canula is repositioned. Subretinal infusion canula tips are often associated with retinal tears, with the breaks located in the same clock hour as the canula.

Suprachoroidal placement of the canula tip may be diagnosed by the presence of a choroidal effusion with or without choroidal hemorrhage. This is more commonly seen in eyes with more severe vitreoretinal disease such as retinal detachment and choroidal effusions from hypotony. Repositioning of the canula to an area where the peripheral retina is normal is fundamental in resolving this issue. Subretinal and suprachoroidal placement of the canula can be prevented by understanding the pathoanatomy of the eye and by direct visualization of the canula tip before starting infusion.

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