Indications

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The indications for the choice of vitrectomy as the primary method for managing retinal detachment is quite varied among surgeons. Some believe that it should be used in every case, and others feel that a scleral buckle should be attempted first in all cases before vitrectomy is done. Until the clinical evidence can be established for each end of the spectrum, I have chosen an approach that is somewhat more conservative and that balances the risks of vitrectomy with its benefits.

Table 5.1. Indications for vitrectomy in primary retinal detachment

1.

Vitreous opacity - hemorrhage, pigment/debris, uveitis,

asteroid hyalosis

2.

Undetected retinal breaks

3.

Large posterior retinal tears usually associated with lattice

degeneration

4.

Posterior retinal breaks in high myopia, colobomas,

and staphylomas

5.

Failed pneumatic retinopexy

6.

Subretinal gas

z.

Selected cases of retinoschisis

8.

Giant retinal tears

9.

Proliferative vitreoretinopathy

1G.

Retinal detachment following open globe injury

Primary management with vitrectomy is reserved for selected types of retinal detachment that are more difficult to manage with scleral buckling alone. These types of retinal detachment are often more complicated using an external episcleral approach and are listed in Table 5.1. An internal approach allows better visualization of the retinal breaks, better removal of traction on the retina, or better repositioning of the detached retina (Figs. 5.1,5.2). In some cases, an encircling scleral buckle may also be necessary to support the area of the vitreous base. A more detailed discussion of each situation follows below.

Opacification of the vitreous may be sufficient to prevent adequate examination of the peripheral retina. These opacities may result from vitreous hemorrhage, pigment or debris, uveitis, or asteroid hyalosis. When a dense vitreous hemorrhage is present, there is a higher chance that proliferative vitreoretinopathy (PVR) will develop. The reason for this is not completely understood. Does the hemorrhage introduce cytokines that activate the proliferative processes, or is it the type of retinal tears (usually large flap tears)

Fig. 5.1. When the retinal detachment is bullous (left), adding perfluoro-carbon liquid after removing the central cortical vitreous can help to flatten and immobilize the retina, creating additional space to excise the peripheral vitreous. There is less likelihood of damage of the peripheral retina as instruments enter through the sclerotomy incisions

Fig. 5.1. When the retinal detachment is bullous (left), adding perfluoro-carbon liquid after removing the central cortical vitreous can help to flatten and immobilize the retina, creating additional space to excise the peripheral vitreous. There is less likelihood of damage of the peripheral retina as instruments enter through the sclerotomy incisions that allow more retinal pigment epithelial cells to be liberated? Clearing the vitreous opacity allows more accurate identification of the retinal breaks and removal of stimulatory factors for PVR.

In approximately 1-4% of retinal detachments, retinal breaks are not visualized. There are several reasons. In some cases, despite careful funduscopic examination with indirect ophthalmoscopy and contact lens examination, retinal breaks causing the retinal detachment cannot be found. Eyes that have undergone cataract surgery (aphakic or pseudophakic) are more likely to have small retinal breaks in the vicinity of the vitreous base. In other cases, anterior segment changes limit the visualization of the fundus. These include cortical lens opacities in phakic eyes, or capsular phimosis or peripheral capsular opacities in pseudophakic eyes. Microcornea or a small pupil may also prevent adequate evaluation of the retina. There is a worse prognosis in cases where a retinal break cannot be found when treated with scleral buckling alone.

Fig. 5.2. The vitreous is excised along the vitreous base and traction around the flap of the retinal tear is removed. Scleral depression is used to assist in visualizing the anterior vitreous base

Failure of retinal reattachment has been reported for 31-43% of these cases [4,5]. Vitrectomy allows better visualization of the peripheral retina intraoperatively and offers a better chance to identify the breaks and treat them.

Some retinal detachments are associated with large posterior retinal breaks, usually in lattice degeneration (Fig. 5.3). These breaks may occur in lattice degeneration with differing antero-posterior levels. Sometimes a portion of the retinal tear extends posterior to the equator. When the breaks are multiple, with long patches of lattice degeneration, a wide posterior scleral buckling element may be difficult to suture to the sclera and may deform the shape of the globe, resulting in diplopia and anisometropia. Often these eyes are highly myopic with thin scleral tissue. Thus, it may be preferable to select vitrectomy and endophotocoagulation to reduce the amount of surgical trauma in these cases.

Fig. 5.3. A large posterior retinal tear developing along postequatorial lattice degeneration (left). Postoperatively after the gas bubble has reabsorbed, the retinal tear is sealed by laser photocoagulation (right). No scleral buckle was placed, because of the tear's posterior location

Posterior retinal breaks, such as macular holes in highly myopic eyes and retinal breaks within the colobomatous area, are best managed initially with vitrectomy and gas tamponade. Placing a scleral buckle in these eyes may be difficult and more likely to have complications.

Our experience in cases of failed pneumatic retinopexy often reveals that vitrectomy with or without scleral buckling is necessary. There may be persistent vitreous traction or even new retinal breaks that are better managed with vitrectomy. In cases that fail from gas bubbles expanding in the subretinal space, the best way to manage this situation is vitrectomy with the use of perfluoro-carbon liquids to express the bubble from the subretinal space.

Full thickness retinal detachments are seen in patients with retinoschisis when both, an inner layer and an outer layer retinal break, are present. In selected cases where the outer layer breaks are posteriorly located, vitrectomy may be preferable to scleral buckling. In cases where the breaks are peripherally located, scleral buckling is effective in reattaching the retina.

Giant retinal tears and retinal detachment with PVR are complex forms of retinal detachment that are routinely managed with vitrectomy and scleral buckling. Giant tears with an inverted posterior retinal flap are best repositioned with perfluorocarbon liquids after core vitrectomy. Giant tears that do not have a rolled posterior flap might be managed with scleral buckling alone. While PVR usually develops as a complication of prior retinal surgery, it is occasionally seen primarily. Such situations might result from a delay in diagnosis, or in eyes with vitreous hemorrhage or choroidal detachment. Vitrectomy is necessary if the epiretinal traction prevents the retinal breaks from flattening on the scleral buckle.

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