7.2 MICS in Special Cases (on CD): Vitreous Loss

27.Kwartz J (1996) Implantation of foldable intraocular lenses in the presence of anterior capsular tears. Eye 10(Pt 4): 529–530

28.Perez-Arteaga A (2008) Step by step to biaxial lens surgery. Jaypee Brothers Medical Publishers, New Delhi, India

7.2MICS in Special Cases (on CD): Vitreous Loss

Jerome Bovet

Core Messages

ßAs soon as the surgeon recognizes the presence of a posterior capsule rupture and vitre-

ous loss, it is best to remove all the instruments from the eye with care.

ßTriamcinolone may be injected inside the anterior chamber to visualize the vitreous.

ßBimanual anterior vitrectomy or sutureless pars plana bimanual vitrectomy can be performed.

ßBoth the techniques result in faster visual rehabilitation and better visual outcomes in patients

with posterior capsule rupture and vitreous loss during MICS.

7.2.1 Introduction (Fig. 7.51)

MICS surgery has been the preferred method of cataract extraction during the last décade [1, 2]. A major advancement in the management of cataracts is early surgery, when the nucleus is still soft and before it becomes more dense. However, there are patients who already have mature cataracts at the time of the first examination. This obviously creates difficulties during surgery. Other ocular conditions that may present alone or in combination with cataracts are pseudoexfoliation syndrome (PEX), iridodonesis-phacodonesis, zonulolysis, lens subluxation, and posterior polar cataracts. All of these may be addressed as the precursors of a probable intraoperative complication along with the mature white cataracts [3–5].

Vitreous loss is probably the most frequent serious complication encountered by cataract surgeons. A vitreous loss may increase the risk of cystoid macular

Fig. 7.51 Triamcilonone acetonide anterior chamber injection

edema and retinal detachment [6]. Luxation of the nucleus material is not a rare complication of phacoemulsification procedures (0.3–1.1%), and it often requires vitreoretinal surgical intervention [7–9].

As soon as the surgeon recognizes the presence of a posterior capsule tear or a zonulysis, he should immediately change some parameters on the phaco machine and inject triamcinolone acetonide inside the anterior chamber to localize the vitreous strands [10–12].

Fluidics inside the chamber should be kept to a minimum so that the lens material and possibly the capsule are not aspirated too quickly, offering the surgeon more precise control of the complication and more time to think and react. As this is being done by the surgeon, the assistant should already prepare the bimanual gauge 23 vitrector. [13, 14]. Even when a vitreous loss occurs, proper management of this complication can facilitate IOL implantation in the sulcus or even in the capsular bag and therefore can provide an excellent visual outcome [15].

7.2.2Posterior Capsule Tears and Vitreous Prolapse (Figs. 7.52–7.54)

When vitreous loss through a capsular tear is present, the early detection of vitreous prolapse is the key to a successful outcome. The goals should be to maintain capsular support for a posterior chamber implant, and to limit the risk of retinal complications [16]. The likelihood of achieving these goals decreases with increased manipulation of the vitreous.

When a posterior capsule break is identified, the first maneuver should be to determine the presence or the absence of the vitreous. A vitreous prolapse should be suspected in the absence of a visible posterior capsule break if there are indirect signs of vitreous traction. Careful inspection of the anterior segment will establish vitreous prolapse if there is any abnormal peaking or configuration of the pupil margin or the margin of the capsular break. If there is suspicion of vitreous prolapse, the first maneuver is to inject 0.5 mL triamcinolone acetonide on a solution of 4 mg/mL to the anterior chamber. Triamcinolone is then washed carefully with BSS, which will stain all the vitreous strands in the anterior chamber, white. All the old maneuvers such as sweeping of the anterior chamber with a cyclodialysis spatula or the weck-cel at the wound margin should be avoided [17]. Special care should be taken not to pull on the vitreous, which can enlarge the capsule tears.

If the presence of the vitreous material is confirmed, any further manipulations should be deferred until the vitreous has been completely removed. Inadequate removal of vitreous from the anterior chamber and corneal wound increases the likelihood of immediate and long-term complications. If a vitreous traction stays around the pupil margin postoperatively, it will increase the chance of cystoid macular edema (IrvineGass syndrome) [18].

Newer 23 gauge bimanual vitrectomy techniques with single-use air vitrector and irrigation cannula are more efficient than the old magnetic vitrectors. The 23 gauge vitrector and the 20 gauge irrigation cannula are placed into the anterior chamber through the same enlarged paracentesis that is done at the beginning of the MICS procedure for irrigation-aspiration. The irrigation cannula is directed away from MICS incision site in order to achieve a stable anterior chamber, constant intraocular pressure, and prevent hydration of the vitreous. Continuous infusion and aspiration through the anterior vitrectomy cutter and corneal incision increase vitreous prolapse into the corneal wound. For this reason, the cutting rate should be relatively high, while the irrigation, aspiration, and vacuum levels should be maintained at a minimum [19–22]. (Figs. 7.55 and 7.56). Furthermore, it tends to hydrate the vitreous and exerts more traction on the peripheral vitreous, which then increases the risk for postoperative retinal detachment [23].

Vitrectomy done through the pars plana approach on the other hand, is a better alternative. When the vitrectomy is performed via the pars plana, the vitreous is

Fig. 7.54 Residual vitreous meshwork after IOLXchange

being drawn out of the anterior chamber space, thus applying less tension on the vitreous base. In contrast, a corneal approach pulls the vitreous forward through the tear, creating more tension and increases the chance of enlarging the tear. Additionally, the vitrector is much less likely to disturb any of the anterior chamber structures if it is not inserted through the anterior chamber.

The pars plana vitrectomy in this situation begins by removing all instruments from the anterior chamber and injecting either a viscoelastic or balanced salt solution. Two 20-Gauge oblique trephinations without conjunctival relaxing incision are made to allow access to the posterior vitreous 4.0 mm, behind the limbus. For a superiorly-placed cataract incisions, the 11 o’clock and 1 o’clock meridian provide a more comfortable hand positioning, than placing the incisions directly behind the wound. When operating temporally, the pars plana incision may be placed slightly inferotemporal. A sclerotomy is created with a 20-Gauge microvitreoretinal trephine and the tip is visualized through the pupil after it has passed through the tutor cannula into the pupillary space. The 23 gauge vitrectomy tip is then placed a few millimeters behind the posterior capsular tear, and the foot pedal is engaged, drawing the vitreous out from the tear. The handpiece should be held relatively still with only a few slow movements. Once no anterior segment movement is detected and vitreous is no longer present, more triamcinolone acetate can be injected until all the tractions have been removed. Once

Fig. 7.55 Anterior vitrectomy after transforming MICS for IEC

Fig. 7.56 Residual vitreous meshwork after closing the IEC

vitrectomy is complete, removal of remaining lens material can be achieved [24–26] (Figs. 7.57–7.60).