New techniques allow phaco and corneal transplantation through a cloudy cornea

Corneal transplantation method combines descemetorhexis with EK and the John technique of ‘upside-down phacoemulsification.’

Issue: September 1, 2007

ByThomas TJ John, MD

Descemetorhexis with endokeratoplasty, or DXEK, is a new and evolving surgical procedure that has gained widespread acceptance among corneal surgeons in the United States and in several countries around the world. Unlike traditional penetrating keratoplasty, this new method of corneal transplantation has removed the full-thickness corneal wound and sutures from corneal transplantation with significant benefit to the patient. However, it becomes somewhat of a challenge when performing a combined procedure, namely, DXEK with phacoemulsification and posterior chamber IOL implantation through a cloudy cornea. I will present a new surgical technique that I call “upside-down phacoemulsification” with posterior chamber IOL implantation, which can be performed through a cloudy cornea without any significant risk of posterior capsular tear during the procedure.

Thomas John

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 cotton swab tip or with a 5 mL syringe.

Alternatively, peribulbar, retrobulbar or general anesthesia may be used.

Step-by-step surgery

DXEK. The temporal, perilimbal, bare sclera is exposed, and hemostasis is achieved. A 5-mm limbal incision is made, and a pocket is created. Through a side-port incision, descemetorhexis and roughening of the peripheral exposed stroma is carried out. Next, upside-down phacoemulsification is performed.

Figure 1. Schematic representation of upside-down phacoemulsification (John technique). A: Following a large capsulorrhexis, the cannula is placed on the right side of the nucleus. B: The cannula is moved posteriorly and to the left. C: The lens begins to turn on its horizontal axis within the capsular bag. D: The nucleus is completely flipped into the anterior chamber. The posterior lens surface now faces the endothelium and the anterior lens surface faces the iris. E: Vertical groove is created with the phaco tip starting posteriorly and progressing anteriorly. F: “Automatic” lens splitting without a second chopping instrument. G: Removal of right hemi-section of the nucleus by upside-down phacoemulsification technique. H: Final aspect of lens removal with the phaco tip.

Images: Reproduced with permission from Jaypee Brothers Medical Publishers

Upside-down phacoemulsification. The initial steps are similar to routine phaco, except the wound is at the limbus. A 3.2-mm keratome blade is used to enter the anterior chamber. Following a large capsulorrhexis, hydrodissection is carried out to fully loosen the nucleus from the capsular bag. The same hydrodissection cannula is used to flip the nucleus into the anterior chamber, and the posterior lens surface now faces the corneal endothelium (Figure 1 and Figure 2). This is a complete 180° nucleus flip on its horizontal axis.

Before starting phacoemulsification, viscoelastic material is injected beneath the nucleus, through the pupil to push the posterior capsule away posteriorly and between the nucleus and iris to create a space.

The phaco tip is then introduced into the space between the nucleus and the iris, such that the phaco tip is facing up toward the nucleus. Phacoemulsification is carried out in a linear manner making a vertical groove (Figure 1 and Figure 2), moving up gradually through the substance of the nucleus toward the endothelial surface. The vacuum should be increased to pull the lens nucleus down to the phaco tip. This technique of grooving from the posterior to the anterior direction will automatically split the lens nucleus into two large segments every time. This “automatic” (without the assistance of a second chopping instrument) splitting happens due to the dynamics in this closed system.

As the groove deepens within the lens nucleus, it creates a triangular area of nuclear removal. The triangle has the base toward the iris, and the apex points to the corneal endothelium. As the apex of the triangle reaches closer to the nuclear surface (ie, posterior lens surface facing the endothelium), the nucleus will automatically split (Figure 1 and Figure 2), similar to splitting wood with a triangular metal wedge. If the groove is centrally located within the nucleus, this will result in splitting the nucleus into two hemi-segments. Attention is then directed to one of the hemi-nucleus. A posterior groove is similarly created in this hemi-nucleus by this upside-down phaco technique, and phacoemulsification is carried out in a similar fashion until the segment automatically cracks into two segments. Each of these segments is then removed by continuing the upside-down phaco technique (Figure 1 and Figure 2). After phacoemulsification, a foldable posterior chamber IOL is placed in the capsular bag (Figure 2), and the pupil is constricted with Miochol-E (acetylcholine chloride, Novartis Ophthalmics) or Miostat (carbachol, Alcon). The surgeon then completes the DXEK procedure, namely, the attachment of the donor corneal disc to the patient’s cornea.

Intraoperative photographs of upside-down phacoemulsification, temporal approach, surgeon’s view. 2a: Diffuse corneal edema and cataract with a well-dilated pupil and a large capsulorrhexis. 2b to 2d: Initial arc of the C-movement using the cannula to flip the nucleus from the posterior to the anterior chamber. 2d: Left half of the pupillary area is filled with the nucleus and the right half of the pupillary area shows an intact lens capsule. The nucleus is in a vertical position. 2e to 2g: Nucleus is being completely flipped on its horizontal axis (3 to 9 o’clock meridian, photo-temporal approach) and rests in the anterior chamber. 2g: There is complete lens inversion with the posterior lens surface facing the endothelium and the anterior lens surface facing the iris. 2h: Upside-down phacoemulsification is begun, creating a posterior longitudinal groove and gradually proceeding anteriorly toward the endothelium. 2i and 2j: “Automatic” splitting of the lens nucleus into two halves without the aid of any chopping instruments. 2k: Posterior groove is being created in the left half of the nucleus. 2l: Progressive upside-down phacoemulsification of the lens nucleus. 2m and 2n: Segmental division and removal of the nucleus using the upside-down phacoemulsification technique. 2o: Foldable acrylic posterior chamber IOL is being introduced into the capsular bag using the injection cartridge system. 2p: The wound is temporarily closed with a 10-0 nylon suture.

Treatment

Preoperatively, a prophylactic antibiotic, either gatifloxacin 0.3% (Zymar, Allergan) or moxifloxacin 0.5% (Vigamox, Alcon), and dilation drops are used as in routine cataract surgery.

Postoperatively, a topical steroid and an antibiotic, namely gatifloxacin or moxifloxacin, are applied four times a day. 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. Activity limitations include no bending over, no straining and no lifting objects weighing more than 10 lbs.

DXEK surgical tips and pearls

The pupil should be dilated for good exposure of the anterior lens capsule.
Remove the epithelium in cases of epithelial edema with bullae to improve visualization.
To perform upside-down phaco, a large capsulorrhexis is essential. Before phacoemulsification, pushing the posterior capsule away with viscoelastic will help prevent inadvertent capsular tear with the phaco tip.
To prevent accidental iris damage, work within the dilated pupillary area, the “safe zone,” while performing phacoemulsification. Avoid working in the iris area, which is the “danger zone.”
There is no need to crack or divide the lens with a second instrument. As phacoemulsification is carried out from the posterior-to-anterior direction, the lens will automatically divide itself every time, much like dividing a log.
If the lens in the anterior chamber is rubbing against the endothelium, it is not a concern because the endothelium will be replaced with a donor corneal disc during the DXEK surgery.
The corneal incision for upside-down phaco should be as peripheral as possible within the cornea, such that it does not interfere with the DXEK procedure.
Use high vacuum to pull the nucleus toward the phaco tip, as this will effectively decrease the time needed for phacoemulsification to create the posterior grooves.
While working on one segment of the lens nucleus, do not allow the other segments to move freely because a fragment can move posteriorly and result in an accidental posterior capsular tear.
Avoid making multiple fragments simultaneously. Instead, divide the nucleus and use segmental division and removal of the nucleus.

Source: John T

For more information:

Thomas John, MD, is a clinical associate professor at Loyola University in Chicago and in private practice in Tinley Park and Oak Lawn, Ill., and Hammond, Ind. He can be reached at 708-429-2223; fax: 708-429-2226; e-mail: tjcornea@gmail.com. Dr. John has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.

References:

John T. Upside-down phacoemulsification in deep lamellar endothelial keratoplasty. In: Surgical Techniques in Anterior and Posterior Lamellar Corneal Surgery. New Delhi, India: Jaypee Brothers Medical Publishers; 2006;372-379.

John T. Surgical Techniques in Anterior and Posterior Lamellar Keratoplasty. New Delhi, India: Jaypee Brothers Medical Publishers; 2006:1-687.

John T. Step by Step Anterior and Posterior Lamellar Keratoplasty. New Delhi, India: Jaypee Brothers Medical Publishers; 2006:1-297.

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 (DXEK): early results. Ann Ophthalmol. 2007;39:9-17.