Retinal Management of Dropped Lens as a Complication Of Phacoemulsification Surgery

Tips for the posterior-segment surgeon

VICTOR M. VILLEGAS, MD • AARON S. GOLD, OD • ANDREA WILDNER, CRA • FIONA EHLIES, CDOS • TIMOTHY G. MURRAY, MD, MBA

The first-generation small-gauge vitrectomy system (25-gauge) was developed and marketed to minimize conjunctival and scleral manipulation, decrease surgical procedure time, diminish pressure fluctuation intraoperatively, and improve postoperative recovery time.

Initially, the most obvious advantage was the decreased need for wound suturing associated with 20-gauge sclerostomies because 25-gauge incisions were usually self-sealing.

However, lack of rigidity in the instrumentation discouraged many surgeons who adopted the new technology.¹ This excessive flexibility limited the surgeon’s comfort and safety in complex cases, such as retained lens material after cataract surgery.

IMPROVEMENTS IN SMALL-GAUGE INSTRUMENTATION

The 23-gauge system was developed to address the concerns associated with the first-generation 25-gauge systems.² The popularity of the 23-gauge vitrectomy system has increased significantly since its development because it has all of the advantages of 25-gauge systems without the increased flexibility. Nevertheless, the incorporation of smaller-gauge systems in cases of retained lens material after cataract surgery has been more challenging.

The advantages of increased functionality and decreased ocular trauma during surgery have led to significant small-gauge instrumentation research. Rapid progression since the inception of the first-generation vitrectomy systems has resulted in a new generation of 25-gauge vitrectomy systems that have improved rigidity and less flexibility than previous systems. However, small-gauge fragmatome development for retained lens fragments management has lagged.

The purpose of this article is to describe the current small-gauge pars plana vitrectomy techniques for the management of retained lens material after cataract surgery.

PREOPERATIVE CONSIDERATIONS

Upon initial evaluation, the surgeon should pay particular attention to signs of increased intraocular inflammation, infection, increased IOP, and vitreous traction. Peaked corectopia should raise suspicions of vitreous in the anterior chamber and possible wound incarceration.

We routinely perform preoperative B-scan and ultrasound biomicroscopy (UBM) to evaluate vitreous traction and lens placement, especially in cases in which corneal edema limits the view, or lens placement is a concern (Figure 1).

Figure 1. Ultrasound biomicroscopy showing a centered IOL in the posterior chamber.

The surgeon should consider aggressive management of IOP and inflammation to minimize corneal changes that could affect posterior-pole visualization. We routinely use topical prednisolone acetate 1% every two hours preoperatively to minimize both macular edema and intraocular inflammation.

In all cases of retained lens fragments, we routinely perform IOL calculations for both eyes, even if an IOL is well centered at the time of evaluation. This practice gives us further flexibility to exchange the implant if the positioning is in doubt or to place a primary lens if the patient is aphakic.

Small and Large Fragments

Small (<2 mm) lenticular fragments might be observed while the patient is on topical corticosteroid and glaucoma treatment. We perform routine spectral-domain OCT at all follow-up appointments in patients undergoing medical management to evaluate macular edema.

Persistent inflammation, especially if associated with macular edema, and uncontrolled IOP are indications for early surgery. Larger fragments should be surgically removed (Figure 2, page 46).

Figure 2. Ultrasound B-scan displaying a crystalline lens in the posterior segment of the eye, resting on the retina.

Patients with rubra cataracts, phacodonesis, lens dislocation, traumatic cataracts, pseudoexfoliation syndrome, or other significant risk factors for posterior capsule breaks may benefit from primary cataract surgery by a vitreoretinal surgeon.

TROCARS

Small-gauge trocar systems (23-/25-/27-gauge) have evolved significantly over the last decade. The advantages of these trocar systems include improved safety by reducing iatrogenic breaks due to peripheral traction during insertion and removal of instrumentation through the trans-scleral cannula system.³

Retinal detachment after pars plana vitrectomy has been a significant concern for vitreoretinal surgeons.^4-6 Surgery for retained lens material is usually complicated due to significant traction on the peripheral retina and vitreous base at the time of lens fragment loss and during surgical removal. Trocar systems allow for less traction on the peripheral retina, especially during pars plana sclerostomy instrumentation entry.

Newer Valved Systems

The advent of valved trocars has improved the fluidics of vitrectomy by preventing aqueous reflux through the open cannula. The surgeon may experience difficulty introducing instruments, such as the soft-tipped extrusion cannula, through the valved cannula.

However, the surgeon can overcome this difficulty by using the push-pull technique or displacement of the valved leaflets. The stabilization of the fluid dynamics during surgery outweighs any difficulties, especially when complex pathology is present or when removing retained lens fragments in previously vitrectomized eyes.

Valved systems also help to stabilize IOP during surgery, minimizing the risks of intraoperative and postoperative maculopathy, choroidal detachment, and choroidal hemorrhage.

Patients who have undergone refractive cataract surgery with loss of lenticular material may benefit from the minimal refractive changes and enhanced visual rehabilitation following surgery with small-gauge trocar systems.⁷

SCLEROSTOMIES

One of the most important steps during small-gauge pars plana vitrectomy is the construction of correct wound configuration, which allows the incision to be self-sealing after successful completion of surgery.^3,8,9

However, we routinely modify wound configuration for the management of retained lenticular fragments. Conjunctival displacement before the incision will maximize the possibility that the conjunctiva and scleral wound do not overlie.⁸

We perform perpendicular sclerectomies without conjunctival displacement in these cases, for easier introduction of the fragmatome. This procedure minimizes conjunctival bleeding and postsurgical scaring.

Displacement of the conjunctiva at the sclerostomy sites not used for the fragmatome is still important, to decrease the likelihood of having a vitreous wick at the incision site and preventing access of the tear film into the sclerostomy.⁸

Trocar Positioning

Using an oblique trocar wound incision provides added incision stability and reduces postoperative hypotony.⁹ We recommend suturing all sclerotomies performed with a direct perpendicular incision at the end of the case.

Sclerostomies should be placed to avoid conjunctival scars, filtering blebs, and regions of abnormal pars plana. The placement should maximize the angle for intraocular access and comfort.

The surgeon should place the inferotemporal trocar just below the horizontal meridian to reduce the risk of touching the inferior eyelid when manipulating the globe to visualize the inferior retina.

In cases of retained lens material, we avoid sclerostomies in areas with evidence of vitreous traction or capsular dislocation to minimize the risk of iatrogenic breaks.

FRAGMATOME AND INTRAOPERATIVE TECHNIQUE

A major technical hurdle has been the development of a fragmatome compatible with 23-gauge and smaller cannula systems. The most widely available fragmatome is still 20-gauge, and many surgeons prefer to open a 20-gauge sclerostomy with the vitreoretinal blade to use the fragmatome.

However, we have found that a perpendicular 23-gauge trocar incision allows for the placement of a 20-gauge fragmatome in most cases. If difficulty is experienced during fragmatome introduction, opening the incision site with either the trocar blade or a 20-gauge vitreoretinal blade can be considered.

Our preferred technique is a three-port, 23-gauge pars plana vitrectomy with a widefield viewing system. In cases of intraoperative microcystic epithelial corneal edema, we may switch to a contact widefield lens after removal of the corneal epithelium.

In cases of small lenticular fragments, we perform core vitrectomy, followed by aspiration of the fragments with the vitrector. If extraction is not possible by this technique, switching to the fragmatome becomes important.

In cases of 25-gauge and smaller gauges, opening the primary sclerostomy to allow for introduction of the fragmatome is essential.

LARGE LENS PARTICLES

In cases of large lenticular fragments, we prefer to elevate the nuclear fragments into the pupillary plane if the patient is aphakic, and a large opening is accessible in the posterior capsule. This procedure allows for phacoemulsification to occur away from the retinal surface.

Conversely, if fragmentation is going to occur in the posterior pole, we rotate the globe to distance the macula away from the most posterior aspect of the orbit (Figure 3). With this technique, the lenticular fragments minimize contact with the macular surface.

Figure 3. Fundus image (A) of a crystalline lens in the fundus, overlying the posterior pole. Elevation of lens (B) with the cutter away from the retina for fragmentation.

NEW INTRAOPERATIVE TECHNIQUES

Previous reports have also described the use of perfluorocarbon liquids to distance the lenticular fragments from the macula and elevate the fragments to the pupillary place.¹⁰

This technique has been reported with good visual acuity outcomes and a low complication profile. However, introduction of perfluorocarbon liquids into the eye may not benefit all patients.

A recent study by Chiang et al reported on the use of the torsional phacoemulsification handpiece without the silicone sleeve through the pars plana sclerotomy.¹¹ The technique has the advantages of reduced lenticular repulsion from the handpiece tip, compared to the fragmatome.¹² These findings have been attributed to the torsional movement of the phacoemulsification handpiece.

KEY TECHNIQUES

At the end of each case, we inspect 360º of the peripheral retina for tears. We treat any tears with endolaser. Retinal detachments should be repaired during the primary vitrectomy. Evaluation of the sulcus, anterior chamber, and vitreous base should be undertaken to look for easily missed fragments. Intravitreal triamcinolone acetonide is injected routinely to minimize postoperative inflammation.

FLUIDICS

Vitreous flow analysis using 20-, 23-, and 25-gauge systems on porcine vitreous showed increased flow obstruction in all systems as the aspiration rate was increased.¹³ These findings have suggested decreased flow in 25-gauge systems compared to 23-gauge systems, as well as concerns regarding traction on the remaining vitreous or retina.³

Recent studies have also shown variability in infusion and extrusion volumes between vitrectomy systems.¹⁴ The different aspiration and infusion capabilities of various systems may be of benefit in select cases in which particular flow settings might be necessary.

INTRAOCULAR PRESSURE AND HYPOTONY

A prospective study that evaluated 95 eyes that underwent 25-gauge PPV without tamponade, using direct and oblique cannula insertion, showed the superiority of oblique cannula insertion in decreasing relative and absolute postoperative hypotony.⁸ Ten percent of patients who had perpendicular insertion had postoperative hypotony, compared to 1% of eyes with oblique insertion.

A recent study by Murray and associates that evaluated 114 eyes that underwent small-gauge PPV found a postoperative hypotony (IOP <5 mm Hg) rate of 3.5%.¹⁵ They reported no cases of endophthalmitis or suprachoroidal hemorrhage.

ENDOPHTHALMITIS

Widespread use of smaller-gauge systems by vitreoretinal surgeons has not progressed as rapidly as expected due to initial concerns of increased incidence of endophthalmitis.^16,17 These concerns may be increased in complex cases, such as when retained lenticular material is present after cataract surgery.

A recent study by the Pan American Collaborative Retina Study Group that evaluated 35,427 cases of PPV had endophthalmitis rates of 0.020%, 0.028%, and 0.021% for 20-gauge, 23-gauge, and 25-gauge, respectively (P=.9685).¹⁸

No significant difference in endophthalmitis rates was detected in the study, suggesting that factors other than gauge may be more important in the development of postoperative endophthalmitis after PPV. Other smaller studies have also had similar results.^19,20

VISUAL ACUITY OUTCOMES

The most common causes of significantly decreased visual acuity following PPV for the removal of retained lens fragments remain cystoid macular edema, corneal edema, and retinal detachment.^4-6

A study performed at the Bascom Palmer Eye Institute found an RD rate of 8% and final VA of 20/40 or better in 54% of eyes.⁵ Other large centers have had similar results.⁶

A recent study that compared same-day vs deferred PPV for retained lens fragments found no statistically significant difference in final visual acuity or complication profiles.²¹ Patients that received earlier surgery had a lower rate of corneal edema at first examination but the same rate of edema at the final follow-up.

Multiple studies have found a trend toward better visual acuity in patients with posterior-chamber IOLs, compared to anterior-chamber lenses.²² Patients with complex disease may benefit from combined PPV and cataract surgery as a primary procedure.²⁴

FOLLOW-UP

We follow up closely those patients who have undergone PPV and lensectomy for retained lens fragments. During the first month, we follow up at one day, one week, and four weeks. We then follow up monthly for the next three months.

We perform macular SD-OCT in all patients at the one-month postoperative visit and at subsequent appointments for the first three months to evaluate for CME. We treat patients with CME with intravitreal triamcinolone acetonide, with excellent results and minimal IOP variation.

CONCLUSION

Small-gauge systems have revolutionized modern vitrectomy. However, management of retained lens material remains challenging. As new technologies in instrumentation crystallize, changes in these procedures will continue to develop. RP

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