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Definitive anterior segment reconstruction after ocular trauma can prevent complications
Targeting solutions to address each component of the traumatized eye enables encouraging visual and anatomical long-term results.
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On a worldwide basis, the spectrum and burden of ocular trauma are enormous and constitute a major segment of eye care emergencies confronting all ophthalmologists. In the U.S. alone, more than 2.5 million eye injuries occur annually, and about 50,000 of these result in functionally significant vision loss. Interestingly, 44.1% of these injuries occur at home. Moreover, 47.6% affect younger individuals, aged 18 to 45 years, and 73% occur in men.
While the prevention of traumatic ocular injuries remains paramount, it is equally important to optimize the surgical care of these severely injured eyes. Proper planning and enlisting a menu of surgical options to deploy depending on the extent of ocular tissue damage are essential. Although in other corneal contexts keratoplasty has evolved toward tissue-specific deep anterior lamellar keratoplasty and Descemet’s stripping automated endothelial keratoplasty, penetrating keratoplasty remains an integral and essential skill in the corneal transplant surgeon’s repertoire. In the ocular trauma setting, not only does the cornea need replacement, but frequently the entire anterior segment must be restored for visual function as well as structural and cosmetic purposes.
In this column, Kenyon describes various techniques he has devised to restore and rehabilitate the severely traumatized eye.
Thomas John, MD
OSN Surgical Maneuvers Editor
Kenneth R. Kenyon
Despite meticulous primary repair of penetrating corneoscleral injury, secondary sequelae related to wound healing can be equally devastating. Such problems include corneal scarring and astigmatism, glaucoma of various mechanisms but often consequent to iridocorneal synechiae, vitreous incarceration within perforating wounds, and pupillary and cyclitic membranes plus retained lens fragments (Figure 1). The overall principle of “one-stop shopping” remains especially relevant in these situations because definitive repair prevents secondary complications. The surgeon is obligated to creatively choreograph several of the following techniques, thereby composing a definitive and meticulous reconstructive plan.
Penetrating keratoplasty
The open-sky aspect afforded by penetrating keratoplasty greatly facilitates performance of the other important surgical elements. When IOL implantation or replacement is anticipated, an iris- or scleral-sutured IOL is preferable.
For scleral suturing of the IOL, dissection of thin scleral flaps closely posterior to the 12 o’clock and 6 o’clock limbus should be performed prior to corneal trephination. Next, an eight-blade radial marker is imprinted on the corneal surface, and the cardinal suture locations are defined with single cautery spots at the limbus (Figure 1). With such marking plus viscoelastic support, Flieringa rings are seldom required to assure proper tissue and suture alignment. Typically a 7.5-mm recipient trephination is combined with an 8-mm donor disc to preserve adequate anterior chamber vault and limit recurrent synechial angle compromise.
Figure 1. Keratoplasty and anterior segment reconstruction. Several years after perforating injury, the adherent leukoma has been tattooed for cosmesis, but extensive iridocorneal adhesions, lens remnants and vitreous incarceration plus aphakia limit visual acuity to hand motions (top). At initiation of surgery, the eight-blade marker is imprinted, and focal cautery at the limbus reinforces the cardinal suture locations (bottom).
Images: Kenyon KR, John T
Caution in entering the anterior chamber and excision of the recipient cornea is especially necessary if the chamber is shallow and/or broad iridocorneal synechiae are present. Adherent iris remnants can be bluntly dissected with dry Weck-Cel micro-sponges (Medtronic Ophthalmics) from the posterior corneal surface and be utilized for subsequent iris reconstruction (Figure 2). Closure using 10-0 nylon suturing technique varies to suit the situation: If the peripheral recipient cornea is thin or actively vascularized, 16 or more interrupted sutures are most secure. If the corneal periphery remains relatively normal, then combinations of four or eight interrupted plus 16 or 24 bite running sutures are appropriate, the latter especially preferable for astigmatism control.
Figure 2. Keratoplasty and anterior segment reconstruction. Following trephination, iridocorneal adhesions are carefully lysed by blunt dissection to save iris remnants for iridoplasty (top). Peripheral synechialysis is performed with microsurgical sponges, pressing posteriorly while supporting the corneal incision rim anteriorly (bottom). Fibrous membranes are then stripped out of the angle and from the iris surface to open the angle and mobilize tissue for iridoplasty.
Lens removal and replacement
Damage to the lens and/or zonules often may require lensectomy. If the lens capsule and zonules are intact, then standard open-sky extracapsular cataract extraction is straightforward. Following anterior capsulorrhexis, nucleus expression and bimanual cortical aspiration, a posterior chamber IOL is inserted with viscoelastic in the bag. Importantly, a “safety valve” sclerotomy prior to corneal trephination may be performed to manage any potential positive vitreous pressure by creating a 2-mm partial-thickness scleral incision circumferentially over the pars plana (3.5 mm posterior to the limbus). In the event of positive pressure, a minimal automated pars plana vitrectomy without infusion or even an 18-gauge needle aspiration can then be readily performed to restore the lens-iris diaphragm to its normal plane.
In the absence of adequate capsular support, posterior chamber IOL implantation by either scleral- or iris-sutured posterior chamber IOL technique is recommended. For scleral suturing, a posterior chamber IOL with positioning holes on the haptics is preferred, such that a 10-0 Prolene suture on a CIF-4 needle can be tied directly to the haptic and the needle can be carefully passed along the posterior iris surface to exit the ciliary sulcus beneath the previously prepared scleral flaps (Figure 3).
Figure 3. Keratoplasty and anterior segment reconstruction. Posterior chamber IOL is scleral-sutured into the ciliary sulcus with 10-0 Prolene covered by scleral flaps (top left). Iridoplasty with multiple interrupted 10-0 nylon or Prolene sutures (top right). Deep anterior chamber, round pupil and central posterior chamber IOL await placement of donor cornea (bottom left). Postop 12 months (bottom right).
If adequate iris tissue remains or can be restored, then iris suturing is preferable, although requiring a posterior chamber IOL with positioning holes on the optic through which a special 2-inch 10-0 Prolene on double-armed BV-100 needles (Ethicon) can be girth-hitched and then mattress-sutured through the mid-iris. IOL power determination can be challenging in severely traumatized eyes. If an axial length cannot be obtained, then the axial length of the fellow eye is utilized in concert with the surgeon’s average post-keratoplasty keratometry value (typically approximately 45 D).
Anterior vitrectomy
As facilitated by open-sky access, lens remnants, prolapsed vitreous, organized fibrotic membranes and retained foreign material must be completely removed either manually or with automated vitrectomy, the latter requiring only very low infusion flow. The vitrectomy is concluded when the vitreous level recedes to the level of the iris diaphragm. IOL placement is then performed as previously detailed. In eyes requiring simultaneous vitreoretinal intervention, a temporary keratoprosthesis, such as the Eckhardt or Landers-Foulks designs, allows excellent posterior visualization during performance of closed vitrectomy and other retinal procedures.
Goniosynechialysis and iridoplasty
Once the anterior chamber has been cleared and restored, the most important but often overlooked procedure of goniosynechialysis is performed with two primary foci: lysis of peripheral anterior synechiae to improve aqueous outflow and minimize postoperative glaucoma, then liberation of incarcerated iris tissue for reconstructive iridoplasty. When performing open-sky synechialysis, the anterior chamber must remain devoid of aqueous and viscoelastic, such that dry micro-sponges can be utilized to press the iris posteriorly while the keratoplasty lip is supported anteriorly with tissue forceps (Figure 3). Such anterior-posterior dissection can gently reduce broad peripheral synechiae without incurring additional iris damage. Rarely are forceps, spatula or Vannas scissors required. With the iris surface dried, glassy Descemet’s-like hyalinized and/or fibrocellular membranes proliferating over the anterior iris surface and angle can be identified and then carefully peeled to avoid further fibrotic compromise of the angle.
Following lysis of adhesions, removal of membranes and scar tissue, iris reconstruction is performed to restore a tight iris diaphragm and lessen the risk of recurrent peripheral synechia, improve graft survival by preventing iridocorneal adhesions and glaucoma, reconstruct the pupil to prevent glare and improve appearance, and form a stable iris diaphragm for support of an iris-sutured posterior chamber IOL. Once goniosynechialysis has been completed, it is often remarkable how seemingly minimal residual iris tissue can be recruited for extensive restoration.
Interrupted sutures of 10-0 nylon or Prolene are used in edge-to-edge apposition of sector iris defects to recreate a central small-diameter pupil or can be used to suspend dialyzed iris into the ciliary sulcus (Figure 3). Flaccid atrophic iris tissue can be rendered more taut by tucking with broad interrupted sutures placed tangentially near the iris margin. If the recreated pupil is eccentric, judicious application of focal thermal cautery at the pupillary margin will improve centration. A prosthetic iris, which is not approved by the U.S. Food and Drug Administration, can further extend the iris restorative effort. At this point, the iris diaphragm should be in the normal plane with a small central pupil, the anterior chamber deep and vitreous-free with an open angle, the IOL central and stable, and the visual axis clear of debris or opacity (Figure 3). The keratoplasty is then completed, and the procedure is concluded. At 12 months postop, visual acuity in the eye in Figure 3 was improved to 20/100, keratoplasty was clear, anterior chamber was deep, the IOL remained central, and IOP was medically controlled.
Results and conclusions
Review of our penetrating ocular trauma cases undergoing secondary anterior segment reconstruction has proven encouraging because visual acuity significantly improved in 70% of cases, corneal graft clarity was maintained in 80%, and goniosynechialysis was corrected in 65% with no additional postoperative glaucoma (Figure 4). Although beyond the scope of this brief overview, attention must also be directed to ocular surface problems such as limbal stem cell deficiency, as well as to the glaucoma and vitreoretinal components of each individual case. Yet by individualizing solutions specifically targeted to address each component of the traumatized eye, anterior segment reconstruction produces long-term results that are both visually excellent and anatomically elegant.
Figure 4. Selected cases of keratoplasty and anterior segment reconstruction. Monocular motor vehicle accident victim with central corneal laceration, extensive iris damage and aphakia (left). Following PK with secondary posterior chamber IOL, iris remnants have been utilized to recreate a central pupil (right). Following severe corneal and iris laceration, the lens has remarkably remained clear (bottom left). Anterior segment reconstruction involved PK and minimal pars plana vitrectomy to decompress anterior segment and thereby allow extensive synechialysis and iridoplasty without lensectomy (bottom right).