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DXEK exchanges corneal disc after failed penetrating keratoplasty
New method of sutureless transplantation retains the shape of the patient’s cornea.
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Descemetorhexis with endokeratoplasty, or DXEK, is a new form of sutureless corneal transplantation that has gained widespread acceptance among corneal surgeons in the United States and in several countries around the world.
The acronym DXEK is synonymous with Descemet’s stripping automated endothelial keratoplasty (DSAEK). This surgical procedure has eliminated the traditional full-thickness corneal wound and corneal sutures, thus retaining the shape of the patient’s cornea after this procedure.
In this column, I describe a technique of removing a failed donor corneal disc and replacing it with a donor corneal disc containing healthy donor corneal endothelium. This procedure is performed on a previously failed penetrating keratoplasty, with a failed DXEK graft (Figure 1). There is also significant peripheral anterior synechiae that has resulted in DXEK graft deformity and partial rolling-in of the DXEK graft edge (Figure 1).
 Intraoperative view of a failed PK graft and a well-adherent, failed DXEK graft with bullous keratopathy and distorted corneal light reflex. The PK wound is visible (upper left); Magnified view displaying the peripheral anterior synechiae and secondary DXEK graft-edge deformity and inward rolling of the graft (upper right); A sterile Q-tip is used to apply 2% lidocaine jelly to the cornea surface (lower left); Ocular surface is evenly covered with 2% lidocaine jelly (lower right). |  Loosely adherent, edematous corneal epithelium is removed by using dry Weck-Cel sponges in a to-and-fro windshield wiper motion (upper row); Corneal epithelium is excised along the margins of the PK wound using Vannas scissors. Peripheral perilimbal epithelium is retained (lower row).Images: John T | |
 After complete hemostasis of the temporal scleral region, an inked caliper is used to mark a chord length of 5 mm close to the surgical limbus (upper left); A fixed-depth diamond blade is used to make a curvilinear groove at a depth of 350 µm (upper right); The completed view of the groove with cut nylon sutures (lower left); A corneo-scleral pocket is created using a crescent blade (lower right). |  The anterior chamber is entered to the right and left of the temporal groove incision using a 15° super blade (upper row); Anterior chamber is filled with Healon (lower left); A reverse Sinskey hook is used to gently release the anterior synechiae (lower right). | |
 The reverse Sinskey hook is moved to the right and left to gently define and release the distal margins of the well-adherent donor disc from the previous PK graft. The reverse Sinskey hook is maintained within the plane of the donor-recipient (PK graft) interface to avoid any damage to the recipient inner corneal surface (PK graft). |  The donor corneal disc is gently released from the host cornea, namely the PK graft. Avoiding any excessive force will help prevent potential separation of the previous PK wound that is clearly visible in these intraoperative photographs. | |
 The reverse Sinskey hook is introduced within the donor-recipient interface, and it is moved to the right and left in a windshield wiper-type of motion to assist in the release of the donor corneal disc from the recipient failed PK graft. |  The anterior chamber is entered using a 3.2-mm keratome blade (upper left); The John Super-Microforceps in its open position is displayed (upper right); The John Super-Microforceps is introduced into the anterior chamber, and the proximal edge of the donor corneal disc is grasped firmly (lower left); The donor corneal disc is gently pulled out through the temporal limbal wound (lower right). | |
 Removal of the failed donor corneal disc using the John Super-Microforceps (upper left); Magnified view of the failed, deformed donor corneal disc (upper right); John DXEK/DSAEK scrubber is used to roughen the peripheral region of the failed PK graft 360° (lower left); Healon from the anterior chamber is removed using an irrigation and aspiration unit. The corneal surface is irrigated with sterile balanced salt solution to augment the view of the anterior chamber through the cloudy, failed PK graft (lower right). |  A small amount of Healon is placed on the central endothelial surface of the donor corneal graft (upper left); The donor corneal graft is folded like a taco and held with the John DXEK/DSAEK insertion forceps (upper right); The temporal wound is closed using three 10-0 nylon interrupted sutures after placing the folded donor corneal disc within the anterior chamber (lower left); Completed view of the procedure showing well-centered donor corneal disc that is adherent to the inner corneal surface of the previous PK graft (lower right). | |
Anesthesia
I routinely use topical anesthesia with monitored anesthesia care. Xylocaine 2% jelly (lidocaine HCl, AstraZeneca) is applied to the ocular surface with a sterile Q-tip (Figure 1) or with a 5 mL syringe.
Alternatively, peribulbar, retrobulbar or general anesthesia may be used.
Donor corneal preparation
The donor cornea is mounted within a Moria automated lamellar therapeutic keratoplasty system, and the artificial anterior chamber is pressurized. A Moria CB microkeratome with a 300-µm head is used to excise a donor corneal cap after removal of the corneal epithelium. Trypan blue (Vision Blue, Dutch Ophthalmic Research Center) is used to stain the exposed donor corneal stroma. The free-cap is then replaced onto the donor corneal stroma and aligned to the surface markings made before excising the corneal cap.
The donor cornea is then removed from the artificial anterior chamber and placed in the well of a Hanna trephine (Moria), and trephination of the donor lamellar graft tissue is carried out from the endothelial side, with the trephine blade landing within the trypan blue-stained region of the donor cornea. The blue coloration helps in trephine centration and prevents eccentric trephination of the donor corneal disc. The diameter of the disposable trephine that was used has the same diameter as the PK graft on the recipient cornea (Figure 1).
Recipient corneal surgery
The view of the anterior chamber is limited because of the failed, cloudy PK and the failed DXEK grafts. To improve the visualization of the anterior segment, the loosely adherent, edematous corneal epithelium overlying the failed PK graft is removed using a Weck-Cel triangular cellulose sponge (Medtronic) and Vannas scissors (Figure 2). The Bowman’s layer of the PK graft is left intact (Figure 2).
The temporal, perilimbal, bare sclera is exposed, and hemostasis is achieved (Figure 3). A 5-mm chord length limbal incision is made, and a pocket is created using a bevel-up crescent blade (Alcon Surgical) (Figure 3).
Through a side-port incision, a reverse Sinskey hook is introduced into a Healon-filled anterior chamber, and anterior synechiolysis is gently carried out (Figure 4). The reverse Sinskey hook is moved to the right and left to gently define and release the distal margins of the well-adherent donor corneal disc from the cloudy PK graft (Figure 5). The reverse Sinskey hook is maintained within the plane of the donor-recipient (PK graft) interface to avoid any damage to the recipient inner corneal surface (PK graft) (Figure 5). The donor corneal disc is gently released from the host cornea, namely the PK graft, using the reverse Sinskey hook (Figure 6).
This donor graft separation from the PK graft is performed in a gradual, progressive manner to the right and then to the left side of the graft (Figure 6). After the marginal separation of the graft, the next step is to detach the central region of the donor graft from the recipient PK graft. This is achieved by introducing the reverse Sinskey hook into the donor-recipient interface, and it is then moved to the right and left in a windshield wiper-type of motion (Figure 7). This results in the complete detachment of the failed DXEK graft (Figure 8).
The anterior chamber is then entered with a 3.2-mm keratome blade (Alcon Surgical). The failed DXEK graft is firmly grasped at its proximal edge, and it is removed from the anterior chamber using the John Super-Microforceps (ASICO) (Figures 8 and 9). The deformed, cloudy DXEK graft is displayed in Figure 9. The continued progression of the peripheral anterior synechiae (Figure 1) resulted in the deformity and rolled margin of the failed DXEK graft (Figure 9).
To facilitate donor graft adhesion to the recipient cornea, the John DXEK/DSAEK scrubber (ASICO) is used to roughen the peripheral band of the failed PK graft. It is essential to remove all of the Healon (sodium hyaluronate, Advanved Medical Optics) from the anterior chamber using an irrigation and aspiration unit (Alcon Surgical) before placing the donor graft in the anterior chamber (Figure 9). A small amount of Healon is placed in the central region of the endothelium before folding it into a taco shape (Figure 10).
The donor disc is then held with the John DXEK/DSAEK insertion forceps (ASICO), and it is introduced into the recipient anterior chamber (Figure 10). The temporal wound is closed with three interrupted 10-0 nylon sutures. Filtered air is used to unfold and attach the donor corneal disc to the recipient cornea (PK graft). After 8 minutes, the air-bubble diameter is decreased. The completed view of the procedure with a well-centered and well-adherent donor corneal graft to the recipient cornea is displayed in Figure 10.
Surgical pearls and tips
Remove the epithelium in cases of epithelial edema with bullae to improve visualization. Use a Weck-Cel cellulose sponge to prevent any damage to the Bowman’s layer.
Complete hemostasis of the temporal wound is essential before entering the anterior chamber. This will prevent any introduction of blood into the donor-recipient interface that will delay visual recovery after surgery.
The donor corneal disc is gently released from the host cornea, namely the PK graft. It is important not to use excessive force because it can result in the separation of the PK wound with aqueous leak and collapse of the anterior chamber.
Fully release the failed donor corneal graft from the PK graft before opening the temporal wound to remove the failed DXEK disc.
Scrubbing the peripheral PK graft with the John DXEK/DSAEK scrubber will facilitate donor graft adhesion to the recipient PK graft. The unique design of this instrument allows easy completion of this surgical step.
Allow a minimum of 8 minutes for the initial adherence of the donor graft.
Treatment
Preoperatively, a prophylactic antibiotic, Iquix (levofloxacin 1.5%, Vistakon), is used. Postoperatively, a topical steroid, Pred Forte 1% (prednisolone acetate 1%, Allergan), and levofloxacin 1.5% are used four times daily. Also, a nonsteroidal anti-inflammatory drug is used preoperatively, namely Xibrom 0.09% (bromfenac ophthalmic solution, Ista Pharmaceuticals) twice daily, and it is continued after surgery. For globe protection, the patient is asked to wear glasses or an eye shield during the day and a shield at night for the operative eye.
For more information:
- Thomas John, MD, is clinical associate professor at Loyola University at Chicago and is in private practice in Tinley Park and Oak Lawn, Ill. He can be reached at 708-429-2223; fax: 708-429-2226; e-mail: tjcornea@gmail.com. Dr. John has a small financial interest in some of the surgical instruments mentioned in this article and is a speaker for ASICO. He is also a speaker and has served as a consultant for Vistakon Pharmaceuticals.
References:
- John T. Surgical Techniques in Anterior and Posterior Lamellar Corneal Surgery. New Delhi, India: Jaypee Brothers Medical Publishers; 2006.
- John T. Step by Step Anterior and Posterior Lamellar Keratoplasty. New Delhi, India: Jaypee Brothers Medical Publishers; 2006.
- John T. Selective tissue corneal transplantation: A great step forward in global visual restoration. Expert Rev Ophthalmol. 2006;1:5-7.
- John T, Taylor DA, Shimmyo M, Siskowski BE. Corneal hysteresis following descemetorhexis with endokeratoplasty: early results. Ann Ophthalmol. 2007;39:9-14.