Ординатура / Офтальмология / Английские материалы / Corneal Endothelial Transplant (DSAEK, DMEK & DLEK)_John_2010

Figure 27-3: Arrow shows fluid drainage from the donor-recipient corneal interface associated with the slitincision in the temporal quadrant of the cornea.

on the recipient cornea. The author reserves the slit-incision to those occasional cases, where there is entrapped fluid in one quadrant, with 360 degrees of peripheral attachment of the donor disk to the recipient cornea. In such a case, the author performs one-slit that corresponds to the quadrant of “loculated” interface fluid.

Roughening the Peripheral Circular

Area of Recipient Corneal Stroma

Terry M first described this technique of roughening the peripheral circular area of the recipient exposed corneal stroma, after DX to increase the donor disk attachment to the recipient cornea. We know from the deep lamellar endothelial keratoplasty (DLEK) experience that there is good adherence between the roughened host corneal stromal surface to the roughened manually dissected donor

Figure 27-4: Intraoperative photograph showing 4-slits (asterisks), one in each quadrant to drain any interface fluid and increase adherence of the disk to the recipient corneal stroma. Also seen is the double-ring sign (arrows) of a well centered donor corneal disk. The outer ring represents the border of the air bubble inside the anterior chamber and the inner ring represents the margin of the attached donor corneal disk. The donorrecipient interface is very smooth and uniform without any interface debris or donor corneal folds in DSAEK surgery.

corneal disk, during the time prior to the use of a microkeratome in posterior lamellar keratoplasty (PLK). During that period of DLEK surgery, the roughened stroma also included the central area of visual axis. Postoperatively, the interface was quite pronounced at the slit-lamp, but such interface haze and opacity fully cleared over time, often 1 year or less after a DLEK procedure.

This concept of increased stromal adherence when the stromal surface is rough, is carried over from DLEK surgery to DSAEK surgery, except the central region of the host cornea including the visual axis is not roughened. Only a narrow peripheral band of the recipient corneal stroma is

roughened inside the circle of the host DX. Such a surgical step, is thought to further augment the adherence of the peripheral area of the donor disk 360 degrees. The author has designed a special instrument called the John DSAEK Stromal Scrubber (ASICO Inc., Westmont, IL, AE-2878,

Patent Pending) (Figures 27-5A and B) (See also Chapter 11, New/Useful Surgical Instruments in DSAEK) to facilitate this procedure. This instrument takes advantage of the special design of the John DSAEK Dexatome Spatula (ASICO Inc., Westmont, IL, AE-2872, Patent Pending) (See also Chapter 11, New/Useful Surgical Instruments in DSAEK) that permits the John DSAEK Stromal Scrubber to complete the circular scrubbing process with a single entry into the AC. The John DSAEK Stromal Scrubber has a hemispherelike tip which is roughened by sand-blasting technique, makes a narrow band of roughened area within the DX circle. The curvilinear design of this instrument allows for easy access to the inner corneal dome. The author used this surgical technique to further augment the adhesion of the donor disk in combination with a large air bubble (see below).

Use of Large Air Bubble

The author consistently uses a large air bubble within the recipient AC (Figures 27-6 and 27-7) to enhance disk attachment. This is usually combined with a preoperative laser peripheral iridotomy (PI) procedure in the inferior aspect of the iris (Recommended by Elizabeth Davis, MD, personal communication). This is performed in an attempt to prevent postoperative pupillary block glaucoma attack. He combines such a procedure often with peripheral scrubbing of the recipient peripheral corneal stroma (see

Figure 27-6: The use of a large air bubble in the recipient anterior chamber is displayed in DSAEK surgery.

above). These techniques have significantly decreased the disk detachment rate to about 2%. One may consider an acceptable disk detachment rate to be about 5% or less.

In all DSAEK procedures, the surgeons use an air bubble to attach the donor disk to the recipient cornea. The attachment of the donor disk may be compared to “slapping” a pizza on to the ceiling and holding it in place with two hands (See also Chapter 31, Comparison of Wound

Architecture in DLEK versus DSAEK). The author is of the opinion that the diameter of the air bubble within the recipient AC should be greater than the diameter of the donor corneal disk to prevent disk detachment (Figures 27-6 and 27-7). If the air bubble has a smaller diameter than the disk diameter there is increased risk of disk detachment (Figure 27-8). The author usually leaves a large air bubble in the AC at the end of the procedure. The globe is palpated intraoperatively to assure that the intraocular pressure (IOP) is within the acceptable range. The IOP with the air bubble in the AC will also depend on the scleral rigidity, the configuration of the AC, etc. The potential downside to a large air bubble includes pupillary block glaucoma attack on the evening of surgery. The preoperative laser PI as described above should prevent pupillary block glaucoma. There is usually no such risk of a pupillary block glaucoma attack the next day, since the air bubble consistently is at or above the horizontal meridian bisecting the central pupil through the visual axis (Figure 27-9). Thus, the disk detachment rate is correlated to the relative size of the air bubble within the AC to the donor disk diameter (Figure 27-10). However, when a peripheral scrapping is performed, this surgical step helps in the disk attachment to the recipient cornea and the size of the air bubble may be decreased in such cases. There is increased risk of donor

Figure 27-10: Schematic representation of the relative size of the air bubble in the anterior chamber to the size of the donor corneal disk. Top

– there is increased risk of donor corneal detachment when the air bubble diameter (ABD) is smaller than the donor corneal disk diameter (DKD). Middle – When ABD=DKD there is still increased risk of disk detachment. Bottom – When ABD>DKD there is decreased risk of disk detachment.

disk detachment when the air bubble diameter is equal to or smaller than the donor disk diameter (Figure 27-10), while, there is decreased risk of disk detachment when the air bubble diameter is greater than the donor disk diameter (Figure 27-10). A double-ring sign with equal spacing between the two rings suggests that the donor corneal disk is well centered on the recipient cornea (Figure 27-4).

In high risk cases of potential acute glaucoma attack with air in the AC, such as those patients with a small corneal diameter, with hyperopia and convexity to the iris surface and narrow angles, the author performs two NdYAG laser peripheral iridotomies (PIs) preoperatively. The site of the laser PIs are located inferiorly as suggested by Dr. E. Davis (personal communication). The inferior peripheral iridotomy is preferred since the air bubble rises in the patient upright position, and this will not usually block the inferior iris openings made with the laser. In patients with pre-existing PIs, there usually is no risk of an acute pupillary block glaucoma attack associated with a

large air bubble within the AC. Although air may be considered to have a deleterious effect on the host corneal endothelium, in the author’s experience there has not been any endothelial decompensation that has been attributed to the air in the AC. In some cases, where there may a slight increase in the intraoperative tactile IOP check, oral Diamox sequels may be given following the DSAEK surgery if the patient has no medical contraindications to its use and has no allergy to sulfa medications. It is essential to dilate the pupil intraoperatively in all cases of DSAEK.

Inconclusion,diskdetachmentisatrueconcernfollowing DSAEKsurgery.Hence,anysurgicaltechniquethatpossibly reduces the disk detachment rate should be entertained by thesurgeon.Anyoftheabovementionedsurgicaltechniques by itself or in combination, should help reduce the rate of disk detachment following DSAEK surgery.

References

1. John T. Corneal disk detachment. Annals of Ophthalmol 2006; 38:169-84.

2. John T. Selective tissue corneal transplantation: A great step forward in global visual restoration. Expert Rev Ophthalmol 2006;1:5-7.

3. John T. Descemetorhexis with endokeratoplasty. In: Surgical Techniques in Anterior and Posterior Lamellar Corneal Surgery. John T (Ed.). Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India, 2006; 411-20.

4. John T. Descemetorhexis with endokeratoplasty (DXEK). In: Step by Step Anterior and Posterior Lamellar Keratoplasty. John T (Ed.). Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India, 2006;177-96.

5. Melles GR. Posterior lamellar keratoplasty: DLEK to DSEK to DMEK. Cornea 2006;25:879-81.

6. Price FW Jr, Price MO. Descemet’s stripping with endothelial keratoplasty in 200 eyes: Early challenges and techniques to enhance donor adherence. J Cataract Refract Surg 2006; 32:411-8.

7. Price MO, Price FW. Descemet’s stripping endothelial keratoplasty. Curr Opin Ophthalmol 2007;18:290-4.

8. Terry MA. Endothelial keratoplasty: History, current state, and future directions. Cornea 2006;25:873-8.

9. Kymionis GD, Suh LH, Dubovy SR, Yoo SH. Diagnosis of residual Descemet’s membrane after Descemet’s stripping endothelial keratoplastywithanteriorsegmentopticalcoherencetomography.

J Cataract Refract Surg 2007;33:1322-4.

10.Terry MA, Hoar KL, Wall J, Ousley P. Histology of dislocations in endothelial keratoplasty (DSEK and DLEK): A laboratorybased, surgical solution to dislocation in 100 consecutive DSEK cases. Cornea 2006;25:926-32.

11.Price MO, Price FW Jr. Descemet stripping with endothelial keratoplasty for treatment of iridocorneal endothelial syndrome. Cornea 2007; 26:493-7.

12.Mearza AA, Qureshi MA, Rostron CK. Experience and 12-month results of descemet-stripping endothelial keratoplasty (DSEK) with a small-incision technique. Cornea 2007; 26:279-83.

13.Price MO, Price FW Jr. Descemet stripping with endothelial keratoplasty for treatment of iridocorneal endothelial syndrome. Cornea 2007; 26:493-7.

14.Cheng YY, Pels E, Nuijts RM. Femtosecond-laser-assisted Descemet’s stripping endothelial keratoplasty. J Cataract Refract Surg 2007;33:152-5.

Introduction

Descemet membrane stripping automated endothelial keratoplasty (DSAEK)1-3 may be associated with complications that may be intraoperative or postoperative and may manifest early or late in the post-surgical period. This chapter will review some of these complications associated with DSAEK. Some of these complications can also occur with other types of sutureless corneal transplant, namely, deep lamellar endothelial keratoplasty (DLEK) and Descemet membrane endothelial keratoplasty (DMEK).

Complications

Intraoperative Complications

1.Blood in the anterior chamber

2.Iris prolapse

3.Fluid in the donor-recipient interface

4.Macro-folds

5.Flipped-disk

6.Disk detachment during unfolding

7.Dropped disk into vitreous cavity

Blood in the Anterior Chamber

It is best to prevent this intraoperative complication by making sure that complete hemostasis is achieved before entering the anterior chamber through the temporal wound. If the anterior chamber is entered with the donor corneal disk while there is active bleeding or if there is blood on the ocular surface while entering the anterior chamber, this blood will easily enter into the anterior chamber and decrease visualization of the donor disk, and more importantly, it can get into the donor-recipient interface and cause postoperative decrease in vision and intracorneal inflammation and possible subsequent scarring. If the donor disk is within the anterior chamber and a small amount of blood is in the anterior chamber this blood should be aspirated using a sterile syringe and a blunt 30gauge or a 27-gauge cannula.

Iris Prolapse

If there is iris prolapse through the anterior chamber, temporal entry wound, it can be due to “premature” entry into the anterior chamber. A premature entry into the anterior chamber through a temporal wound will result in the wound being very close to the iris surface, and hence there can be an increased tendency for the iris to prolapse out of the anterior chamber during surgery. If the iris keeps prolapsing out during surgery, it may be best to close the

wound and make another entry wound further away from the iris surface and use this new site for completion of the surgical procedure. The further the entry wound is away from the iris surface, the less chance of iris prolapse. However, the wound should not go past the surface epithelial circular mark.

Alternatively, the iris prolapse may be due to a positive pressure and this can be determined easily by gentle palpation of the globe. If the globe is hard to palpation, then there is a positive pressure within the eye that contributes to the iris prolapse. If that is the case, then first priority is to decrease the intraocular pressure (e.g. by using intravenous Mannitol). Preoperative intravenous Mannitol along with globe compression with a Honan balloon can often prevent intraoperative positive pressure. Alternatively, the intraocular pressure can be decreased by doing a limited anterior vitrectomy. If the positive pressure is excessive, it is also important to rule out a choroidal hemorrhage. If the intra-globe pressure continues to be excessive, it may be safer to close the wound and bring the patient back later in the day or even the next day to complete the surgical procedure.

Fluid in the Donor-Recipient Interface

During DSAEK surgery, following the donor disk adherence to the recipient cornea, there may be fluid within the potential space between the donor and recipient corneas. Price has described the use of slit-incisions passing from the corneal surface to the interface and thus drain the interface fluid and promote adherence of the donor disk to the inner surface of the recipient cornea (Figure 28-1). These incisions are

Figure 28-1: Selective drainage of donor-recipient interface fluid, namely a single slit incision in the temporal region. Fluid draining from the slit incision is seen (arrow).

Figure 28-3: Good adherence of the donor corneal disk following interface fluid drainage in 4-quadrants. Also seen is the double-ring sign of good uniform donor disk adherence to the recipient cornea.

sometimes referred to as “vent” incisions. Price advocated the use of four-quadrant slit-incisions to drain interface fluid during DSAEK surgery (Figure 28-2). Good adherence of the donor corneal disk is usually seen following interface fluid drainage in 4-quadrants (Figure 28-3). Double-ring sign of good uniform donor disk adherence to the recipient cornea may also be seen intra-operatively (Figure 28-3). These slit-

incisions are almost always visible by slit-lamp examination, regardless of the postoperative duration after the initial surgical procedure. Occasionally, there has also been incidence of epithelial ingrowth through these “vent” incisions (Figures 28-4 and 28-5). I do not perform routine slit-incisions in all DSAEK procedures. Total air-filled anterior chamber during the 8 to 10 minutes of intraoperative waiting period often expels most of the interface fluid. Additionally, the corneal dome may be gently massaged with a Lindstrom roller (Figure 28-6) or a John Glider (Figure 28- 7) (ASICO Inc., Westmont, IL) to further drain any interface fluid. Intraoperative surgical slit-lamp can also assist in evaluating the interface for any fluid collections (See also Chapter 10, Role of Surgical Slit-lamp in Endothelial Transplantation and Anterior Segment Surgery). If there is only an area of localized fluid collection, then a single slitincision overlying this area may be used to drain the fluid

(Figure 28-8).

Macro-folds

If there is any macro-folds in the donor cornea after airassisted donor corneal adherence to the recipient cornea, these folds may be diminished or eliminated using the John Glider (Figure 28-7). The amount of relief will depend on the number and severity of the macro-folds.

Figure 28-6: Use of Lindstrom roller to remove any donor-recipient interface fluid.

Flipped-Disk

Every effort should be made to prevent the donor corneal disk from flipping upside down, resulting in the endothelial

surface of the donor corneal disk facing the inner corneal surface of the recipient cornea. If not recognized, the disk may be attached by the wrong surface to the recipient cornea, namely, the donor endothelium at the donorrecipient interface. Flipped disk attachment to the recipient cornea will result in postoperative graft failure. This event when unrecognized at the time of surgery, can only be confirmed when a penetrating keratoplasty is performed and the tissue is available for histopathology showing the donor endothelial cells at the donor-recipient interface.

Options to consider in preventing the wrong surface facing the inner recipient corneal surface include the following:

•Promoting optimal unfolding of the “taco-folded” donor corneal disk

•60/40 or greater underor over-fold

•Steady controlled air injection to unfold the donor corneal disk

•Correct immediately any tendency to unfold the donor corneal disk in the wrong direction