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From the HEIR database

From the HEIR database it reveals for the surgeon when the incarcerated vitreous has been severed (see Chap. 2.5).2

Table 2.7.4 provides a summary of questions that need to be answered during the examination.

2.7.3 Specific Conditions 2.7.3.1 Dislocation

The lens is either partially (subluxation) or completely (luxation) torn from the zonules; in the latter case, it may be still inside the eye or extruded3. Both subluxation and luxation can occur anteriorly (AC) or posteriorly (vitreous cavity), and both can happen in the context of open or closed globe trauma.

2 This is especially important in a phakic eye with corneal open globe trauma: traction on the peripheral retina must be prevented by severing the vitreous bridge reaching into the wound, but iatrogenic lens damage should also be avoided (see Chap. 2.5).

3 The lens may be under the conjunctiva (see Fig. 2.12.2) or completely lost.

Table 2.7.4 Diagnostic questions related to lens injury Is the lens extruded?

Is the lens dislocated/luxated into the AC? Are there lens particles in the AC? Is the lens swelling?

Has vitreous prolapsed into the AC? If yes, is it also incarcerated into the wound? Has the anterior capsule been breached?

What additional anterior segment pathologies are present? What is the IOP?

Is there an IOFB inside the lens?

Is there a cataract? If yes, is it partial or complete?

Has the posterior capsule been breached? If yes, has the vitreous prolapsed into the lens?

Is the lens subluxated/luxated into the vitreous cavity? If luxated, is the lens fragmented?

What posterior segment pathologies are present?

If the eye has an open globe injury, many of these questions will be answered during, rather than before, surgery

Whether, when, and what type of intervention is necessary are primarily determined by the type of injury4, the visual acuity, the position of the lens, and the severity of secondary complications including vitreous prolapse, cataract, and glaucoma. Obviously, the range of independently coexisting pathologies is endless.5

5 Indications for, and types of, intervention for pathologies other than the lens are discussed in the appropriate chapters; this chapter focuses on the implications of the lens trauma itself.

2.7.3.1.1 Subluxation

If the visual acuity is normal and there is no vitreous incarceration into the wound, no treatment is necessary. If the lens needs to be removed, the type of intervention should be determined by a careful consideration of all variables.

• Phacoemulsification or ECCE is acceptable if there is no vitreous prolapse into the AC or into the lens - this is why it is crucial to preopera-tively determine whether the posterior capsule is intact.

• If there is a small vitreous prolapse into the AC and it can first be removed with the vitrectomy probe, or if only a small posterior capsular lesion is present and viscoelastics6 can effectively keep the vitreous from prolapsing, careful phacoemulsification may be attempted. The surgeon must keep in mind that the viscoelastic plug covering the capsular breach may be dislodged and the vitreous prolapse may recur; TA should periodically be used to check for vitreous reprolapse.

• A capsular tension ring can be inserted if the area of zonular rupture is verifiably small. A Cionni ring may be used if the zonular damage extends for a few clock hours.7 Since the ring, and thus the capsule, is suture-fixed to the sclera, the capsular bag is given extra stability [1, 5].

6 A small amount of cohesive viscoelastic injected behind the lens capsule. Such use of viscoelastics, however, is a double-edged sword. It may be able to keep the vitreous behind the posterior capsule, but it also makes recognition of vitreous reprolapse even more difficult.

7 The damaged zonular area must not exceed 12 clock hours.

O Cave

If the surgeon cannot be absolutely certain that vitreous has not prolapsed into the lens, phacoemulsification or ECCE must not be the method of choice to remove a subluxated or cataractous lens. Lensec-tomy using vitrectomy instrumentation is recommended to avoid exerting traction on the peripheral retina via aspirating vitreous. It must also be emphasized again that once lens removal has started, recognition of vitreous presence becomes difficult, and when it is recognized, it is often too late.8

• Intracapsular cataract extraction is recommended if most or all of the zonules are torn; again, the surgeon must make sure that there is no vitreous present before the cryoapplicator is applied.

• Lensectomy is the preferred method if vitreous is confirmed or suspected to have prolapsed into the lens.9 Lensectomy is very safe and can be combined with IOL implantation [7].

- If the limbal route is used, the posterior capsule can usually be preserved.

- If the pars plana approach is chosen, the anterior capsule is preserved.10 The pars plana route has distinct advantages: increased maneuverability and access to potential posterior segment abnor-malities.11

8 The editor recently operated on an eye whose injury (corneal penetrating trauma with an intravitreally located FB causing a visible anterior capsule lesion and cataract; Fig. 2.7.3) made it obvious that the posterior capsule had also been breached. Lensectomy was therefore the selected lens removal method, but the probe malfunctioned: aspiration was applied without cutting (i.e., as if phacoemulsification or ECCE had been done). This was soon realized and the probe was replaced; nevertheless, during vitrectomy (performed in the same surgical setting), a large inferior retinal dialysis was found: an iatrogenic complication, not one caused by the original injury.

9 Prolapse of vitreous into the AC is easier to deal with (see above).

10 A three-piece IOL can be implanted into the sulcus on top of the retained capsule(s).

11 In the HEIR, 48% of eyes undergoing removal of a traumatic cataract had coexisting posterior segment injury, and 79% of these eyes had to undergo vitrectomy.

- Infusion is always needed: an AC maintainer is suitable in all cases. If a pars plana infusion is used, this should not be turned on unless the cannula's position can be verified (see Chap. 2.9). If the surgeon is experienced in bimanual surgery, a good alternative solution is to keep inside the capsular bag a needle attached to the infusion line: this method assures that the vitreous is not unnecessarily violated, the eye remains pressurized, and the lens gets hydrated, making removal easier.

O Pearl

The usual vitrectomy settings need to be modified for the lensectomy procedure.12 The aspiration should be somewhat higher (200 mmHg), as should the infusion pressure be (40 mmHg), and the cut rate is significantly reduced (200 cpm). The low cut rate prevents the escape of lens particles from the aspiration port and the collapse of the globe^, should the port become unoccluded.

2.7.3.1.2 Luxation

A subconjunctivally extruded lens [21] is easily removed with forceps or a cryoapplicator. Anterior luxation of the lens is rare; this, however, requires rather urgent intervention to prevent endothelial damage. Posterior luxation, even if the lens capsules are intact, triggers an inflammatory response; removal is not an emergency but should not be deferred indefinitely. The removal technique depends on the hardness of the nucleus (mostly determined by the age of the patient) and on the surgeon's personal preference.

• Phacofragmentation.14

- The energy of the ultrasound should be set at no more than 20%.

- The infusion pressure must be set at no less than 40 mmHg.

12 As in virtually every trauma case, 20-g systems are recommended (see Chap. 2.9).

13 A preferred alternative is a flow-based system (peristaltic pump; see Chap. 2.9).

14 An ultrasonographic handpiece designed for intravitreal use.

- The aspiration must be linear; if the port is not occluded, instantaneous globe collapse occurs.

- The lens should be lifted into the midvitreous cavity using minimal aspiration and then the ultrasound is turned on. A second instrument,15 inserted into the lens, is very helpful in keeping the lens from falling back onto the retina - even then, smaller lens particles will be falling down and need to be picked up repeatedly. The ultrasound must always be off when the probe is close to the retina. The lens often resembles Emmental ("Swiss") cheese before removal is completed.

- If phacofragmentation is performed for complicationsi® of cataract surgery, the postoperative retinal detachment rate is around 5% [17]; in trauma-related cases the rate is probably significantly higher.

O Pitfall

To reduce the risk of retinal detachment, a complete vitrectomy must be done before the onset of phacofragmentation. If a retinal dialysis or horseshoe tear and then detachment develop shortly after phacofrag-mentation, the surgeon may conveniently blame the complication on the original injury. Such retinal complications, however, may well have been caused by improper surgical techniques.17 As a general rule, the shorter the time between injury/cataract removal8 and the development of retinal detachment, the more suspect the technique of lens extraction is.

• Lensectomy. The vitrectomy probe can also be used to remove the lens, even if the nucleus is hard (e.g., in patients in their sixties). The nucleus is crushed into small pieces between the vitrectomy probe and another

15 e.g., pick light probe

16 i.e., "dropped nucleus" (see below)

17 e.g., the selection of an inappropriate method of lens removal (e.g., phacoemulsification instead of lensectomy)

18 Using phacoemulsification or ECCE

instrument (even the light pipe suffices), and the small pieces are removed one by one. The process is lengthy19 but reduces the risks associated with intravitreal ultrasound use. • Removal in toto. The lens can be extracted using an intraocular cryo-probe or with a vectis after floating it up with PFCL [14]. In the latter case, a complete PFCL fill is necessary, and the initial injection of the PFCL must be carefully done so that it gets underneath, not on top of, the lens. During fill-up, the lens may temporarily disappear from view: the initial shape of the enlarging PFCL bubble is more of a sphere, making the lens slide sideways. For in toto lens removal, a large limbal incision is necessary. Obviously, the eye must be aphakic.20

2.7.3.2 Capsular Breach

A breach in the anterior capsule is usually easy to see at the slit lamp, although good dilatation is needed if the lesion is peripheral. A posterior capsular breach is much more difficult to visualize, although it is often detectable on ultrasonography [12] or even at the slit lamp if posterior cortical material has "sunk" into the vitreous: an empty space is seen in the anterior cortex of the cataract. It is important to remember that a posterior capsular rupture can occur in isolation, i.e., without any other lens or even ocular pathology [16].

Common sense must be used: in the presence of an anterior capsular lesion and a posterior segment IOFB, it is very unlikely that the posterior capsule is intact (Fig. 2.7.3). The surgeon must be prepared for intraoperative surprises regarding capsular injury (Table 2.7.3).

Regarding management, no treatment is necessary for the breach itself, and its presence does not imply that subsequent cataract formation is inescapable since the break may spontaneously seal.

19 Especially because the vitrectomy probe may get clogged and needs flushing repeatedly.

20 This is why in case of a "dropped nucleus" IOL implantation may be ill-advised before the lens is removed (see below).

Fig. 2.7.3 Injury to the anterior lens capsule. The FB caused a corneal penetrating wound, an anterior capsule lesion, and a cataract. The corneal and capsular injuries provide trajectory information: a straight line drawn from the corneal wound and through the two capsular lesions should indicate the location of the potential impact site in the retina

Fig. 2.7.3 Injury to the anterior lens capsule. The FB caused a corneal penetrating wound, an anterior capsule lesion, and a cataract. The corneal and capsular injuries provide trajectory information: a straight line drawn from the corneal wound and through the two capsular lesions should indicate the location of the potential impact site in the retina

2.7.3.3 Fragmentation

If the lens is in pieces, this always causes major inflammation and IOP elevation (see Chap. 2.18). Intervention is urgent.

Regarding management, all lens particles must be removed; the method depends on the location of the particles, the coexisting pathologies, the hardness of the nucleus, and the surgeon's personal preference (see above). Intense anti-inflammatory treatment must accompany the surgical intervention. An admixture of lens particles, vitreous, and blood is a uniquely potent inciter for PVR development.

2.7.3.4 Cataract

This is the most common type of lens injury and the one with the most significant visual consequence.21 It can occur as a result of mechanical as

21 It must be noted that it is not always easy to definitely establish that a cataract is present; even experienced surgeons can err on either side: diagnosing a traumatic cataract when the lens is clear or declaring the lens to be clear when in fact there is cataract.

well as nonmechanical22 trauma. The cataract can be partial (localized, focal) or total; the former may be stationary or progressive. The progression from minor to total lens opacity may take only hours (especially short in children; see Chap. 2.16) or may take years. Swelling with consequent IOP elevation is another factor to consider when the management options (i.e., removal or observation) are contemplated. The decision whether and when to intervene should also be influenced by the presence of, or potential for, posterior segment pathologies (Table 2.7.2).

Regarding management, the various techniques of lens removal have been described previously.

O Pitfall

The different implications of removing an age-related (elective) cataract vs a traumatic cataract must clearly be understood by the surgeon. In an elective case, preservation of the capsular bag is important; for the trauma surgeon, avoiding iatrogenic damage to the retina is the main goal. It is not whether the IOL is in the bag23 that determines the visual outcome but the integrity of the retina.

If vitrectomy is performed in an injured eye that has a risk high of, or already developed, PVR, and the lens needs to be sacrificed, both capsules must also be removed to reduce the surface ("scaffold") available for the proliferative cells. Preserving the capsule further increases the risk of anterior PVR as well as of phthisis (see Chaps. 2.9, 2.19).

• The lens is removed using a technique required by the eye's condition (see above) or the surgeon's preference. Depending on the surgical technique employed, one of capsules is left intact.

• A complete vitrectomy is performed.

• A capsulectomy is made with the vitrectomy probe or the MVR blade.

22 e.g., electricity/lightning; laser, microwave, thermal, and UV energy

23 As opposed to being in the AC, iris-fixated, or in the sulcus

• Utilizing the capsulectomy, the capsule is grabbed with a forceps, slowly rolled up ("spaghetti technique"24), and carefully removed. If the zonules are especially strong/5 alpha-chymotrypsi^6 should first be injected under the iris, then removed by thorough irrigation. If the capsule tears, the other sclerotomy can be used to regrasp it.

• Scleral indentation is performed to assure that all of the capsule has been removed and the ciliary processes have been freed of all tissues.

The timing of lens removal must be carefully considered. If the injury is a contusion, and the IOP elevation and inflammation can be controlled medically, the decision is easily deferred. If, however, a wound is present and requires acute surgery, the surgeon must weigh the benefits and risks of primary vs secondary lens removal (Table 2.7.5; the flowchart in Fig. 2.7.4 explains the surgical strategy).

If lensectomy is performed and the anterior capsule is retained, it must be polished with the vitrectomy probe at low vacuum (flow)2? and without cutting. The best method to visualize the efficiency of the polishing is to switch off the microscope light, hold the endoilluminator at the limbus, and aim its light at the capsule.2® Preserving the anterior capsule means that the risk of iris damage and constriction of the pupil is reduced during the procedure, and, at least theoretically, the incidence of postoperative synechia formation is also decreased.

2.7.3.5 Iatrogenic Lens Damage

Although the discussion of surgeon-induced trauma is beyond the scope of this book, two important issues deserve to be mentioned briefly here:

24 A term coined by C. Forlini, Ravenna, Italy

25 Such as in young patients

27 If such a vacuuming is carried out, the surgeon must continually keep the probe moving on the back surface of the anterior capsule to avoid aspirating it into the port.

28 i.e., the endoilluminator is outside the eye, and its light enters the eye through the peripheral cornea

Table 2.7.5 Arguments for and against primary removal of a cataractous lens

For

Against

Single surgery: convenience and cost

Diagnosis may be false

Posterior segment immediately visible and surgery can planned according to the injuries found

Optimal surgical conditions not always available: proper equipment, experienced surgeon

Prevention of secondary complications (e.g., IOP elevation)

Increased inflammation

Immediate visual rehabilitation possible

Difficulty to determine optimal IOL power

Postoperative synechia formation will make secondary IOL implantation more difficult

Increased risk of secondary complications such as inflammation (especially if primary IOL implantation is also performed)

• A dropped nucleus during phacoemulsification should not be appreciated as a dreaded complication; inappropriate management of the complication should. Ideally, when lens is lost into the vitreous, the cataract surgeon instantly becomes an ocular traumatologist - or immediately calls for such a colleague's help.

- The only acceptable management is vitrectomy, as described previously; never should "fishing" for the lens particles be performed [2].

- If vitrectomy in the same session cannot be performed, the eye should be closed, anti-inflammatory therapy instigated, and vitreo-retinal consultation sought.

- The cataract surgeon may implant an IOL29, but its disadvantages must be understood: it limits the removal options of the lost lens particle(s) (see above), and may make it more difficult to thoroughly clean the capsular bag.

29 Since it was the original goal of surgery, there is a strong desire on the surgeon's and the patient's part to have an IOL implanted at the termination of a cataract surgery.

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