Modified technique aspirates interface fluid in DSAEK

A special cannula helps avoid pushing the button away when aspirating fluid from the interface during DSAEK.

Issue: September 15, 2007

ByTakeshi Ide, MD, PhD

BySonia H. Yoo, MD

Endothelial keratoplasty is an exciting surgical alternative to standard penetrating keratoplasty.

The currently popular method of endothelial keratoplasty is Descemet’s stripping automated endothelial keratoplasty (DSAEK), aimed at selectively replacing diseased corneal endothelium.

PK is often complicated by a variety of postoperative problems, including prolonged healing time, irregular or high astigmatism necessitating hard contact lens wear for visual rehabilitation and late wound dehiscence with trauma. In addition, whereas PK is more difficult and time-consuming, the DSAEK procedure is easier to perform and less time-consuming.

One of the most frustrating problems in DSAEK is the dislocation of the donor lamellar corneal button after surgery. One early series reported a dislocation rate of 50% in the researchers’ first four cases of Descemet’s stripping endothelial keratoplasty performed in 2004. The same 50% dislocation rate was found in the first 10 cases of Descemet’s stripping endothelial keratoplasty by Price and Price. Clearly, despite surgeons’ extensive prior experience with endothelial keratoplasty (deep lamellar endothelial keratoplasty/posterior lamellar keratoplasty), there is a fundamental difference in tissue adherence between deep lamellar endothelial keratoplasty and Descemet’s stripping endothelial keratoplasty surgeries. The reason for this dislocation is controversial. Terry and colleagues attributed this mainly to the absence of recipient stromal fibrils to initially bind to the donor stromal fibrils. Price et al speculated various potential factors: viscoelastic in the graft interface, geometric mismatch between donor and recipient curvatures that cause a portion of the donor to arc away from the recipient, trapped fluid in the graft interface that prevents tight apposition, reduced viability due to excessive manipulation, even patients’ squeezing or rubbing the eye, and others.

Although the exact causes of the dislocation were uncertain, we routinely aspirated fluid from the graft interface using a 30-gauge blunt needle. Unfortunately, we experienced some DSAEK cases in which we pushed the DSAEK button away into the anterior chamber because of the difficulty in holding the needle and syringe in a stable orientation (Figure 1). Therefore, we designed a special instrument to establish a stable technique for fluid aspiration from the interface and asked Rhein Medical to make this prototype. Here we report a modification of the technique and of the needle.

Surgical technique

The donor tissue for DSAEK was routinely prepared using Moria’s automated microkeratome head with the 300-µm blade depth and an artificial chamber. After microkeratome-assisted excision of the anterior corneal tissue, the stromal surface was marked with a skin marker. The remaining donor tissue was punched out from the endothelial side using a Hessburg-Barron trephine (Katena). Descemet’s membrane was removed from the host cornea, as described by Melles et al. The endothelial side of the donor lenticule is protected with a small amount of ophthalmic viscosurgical devices before it is folded. We inserted this DSAEK button into the anterior chamber using inserting forceps through a 4.5-mm to 5-mm-wide incision. After that, the anterior chamber was filled with filtered 100% air, and we made four ventilation incisions along the centered 5-mm diameter circle using a diamond paracentesis blade, and then we manipulated this button through limbal paracentesis incisions with a reverse Sinskey hook (Katena).

Before finishing the DSAEK procedure, we drained fluid from the ventilation incision using this DSAEK cannula prototype.

Figure 1: Normal cannula can push the donor tissue away from the host cornea during aspiration of the interface fluid
Normal cannula can push the donor tissue away from the host cornea during aspiration of the interface fluid.

Figure 2: Ide DSAEK cannula with stopper
Ide DSAEK cannula with stopper. This can prevent pushing the tissue away with the stopper.

Figure 3: Image captured from surgical video

Image captured from surgical video. The instrument allowed surgeons to aspirate as much fluid as possible from the host-and-donor corneal interface.

Images: Ide T

Discussion

The DSAEK procedure is gaining popularity and has many advantages compared with conventional PK. At the same time, however, donor graft detachment still occurs and re-injection of air into the anterior chamber is required to attempt reattachment. The air injection is a simple and safe technique, but anterior chamber air damages the corneal endothelium. Therefore, an injection of air should be avoided as much as possible.

There are many factors affecting graft dislocation after surgery. One factor of significant importance is the interface fluid. We asked Rhein Medical to make this prototype to establish a new stable technique for aspirating interface fluid. Rhein fabricated several prototypes according to our specifications and modifications. After some trial and error, we decided to use a 30-gauge needle, with a 2-mm length stopper and 0.9-mm to 1.5-mm tip length (Figure 2). Although we cannot compare the efficacy of cases with or without using this instrument, and therefore we cannot tell whether this works well for the purpose of reducing the dislocation rate, this simple instrument allowed the surgeons to easily and consistently aspirate as much fluid as possible from the host-and-donor corneal interface (Figure 3). Theoretically, this DSAEK cannula helps the corneal endothelium work better for interface adhesion after DSAEK. What is most important is that we do not need to worry about pushing the cornea away into the anterior chamber, if we accidentally push the needle.

For more information:

Terrence P. O’Brien, MD, can be reached at Bascom Palmer Eye Institute, 7108 Fairway Drive, Palm Beach Gardens, FL 33418; 561-515-1544; fax: 561-515-1588; e-mail: tobrien@med.miami.edu. Dr. O’Brien and Dr. Yoo have no direct financial interest in the products discussed in this article, nor are they paid consultants for any companies mentioned. Dr. Ide has a direct financial interest in the Ide DSAEK 30G.

Rhein Medical Inc., manufacturer of the Ide DSAEK 30-gauge cannular prototype, can be reached at 5460 Beaumont Center Blvd., Suite 500, Tampa, FL 33634; 800-637-4346; fax: 813-885-9346; Web site: www.rheinmedical.com.

References:

Eiferman RA, Wilkins E. The effect of air on human corneal endothelium. Am J Ophthalmol. 1981;92:328-331.

Kim EK, Cristol SM, et al. Corneal endothelial damage by air bubbles during phacoemulsification. Arch Ophthalmol. 1997;115:81-88.

Melles GRJ, Eggink FAGJ, et al. A surgical technique for posterior lamellar keratoplasty. Cornea. 1998;17:618-626.

Melles GRJ, Lander F, Nieuwendaal C. Sutureless, posterior lamellar keratoplasty: a case report of a modified technique. Cornea. 2002;21:325-327.

Melles GRJ, Lander F, et al. Preliminary clinical results of posterior lamellar keratoplasty through a sclerocorneal pocket incision. Ophthalmology. 2000;107:1850-1856.

Melles GRJ, Wijdh RHJ, Nieuwendaal C. A technique to excise the Descemet’s membrane from a recipient cornea(descemetorhexis). Cornea. 2004;23:286-288.

Price FW, Price MO. Descemet’s stripping with endothelial keratoplasty in 200 eyes: Early challenges and technique to enhance donor adherence. J Cataract Refract Surg. 2006;32:411-418.

Price, FW, Price MO. A nonsurgical treatment for donor dislocation after Descemet’s stripping endothelial keratoplasty. Cornea. 2006;25:991.

Terry MA, Hoar KL, Wall J, Ousley P. Histology of dislocations in endothelial keratoplasty (DSEK and DLEK). A laboratory-based, surgical solution to dislocation in 100 consecutive DSEK cases. Cornea. 2006;25:926-932.