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

Figure 23-53: Fuchs’ corneal dystrophy with cloudy cornea.

Figure 23-54: : Good corneal clearance of edema following DSAEK.

Figure 23-55: Profile view of the cornea following DSAEK for pseudophakic bullous keratopathy (PBK) showing good uniform adherence of the donor corneal disk to the patient’s cornea.

Figure 23-56: Epithelial removal to increase intraoperative visualization of the donor corneal disk and the anterior chamber.

Figure 23-59: Descemetorhexis can be difficult due to scarring following penetrating keratoplasty (PKP) and a failed corneal graft.

Figure 23-60: DSAEK surgery is often more difficult in eyes following a filtering bleb.

(Figures 23-57 and 23-58). Descemetorhexis can be difficult due to scarring following penetrating keratoplasty (PKP) and a failed corneal graft (Figure 23-59). DSAEK surgery is often more difficult in eyes following a filtering bleb (Figure 23-60). It may be advisable to avoid doing DSAEK surgery in aphakic eyes depending on the level of surgeon experience in DSAEK surgery, since there is a higher risk of the donor corneal disk falling into the vitreous cavity and on to the retinal surface. The same applies to eyes with a very large complete peripheral iridectomy without any PC IOL partially covering the iris opening.

DSAEK surgery has been simplified with the use of Healon in the anterior chamber and not using fluid for the initial steps in this surgical procedure. Additionally,

improved surgical instruments and surgical textbooks have all helped the corneal surgeon to transition from fullthickness penetrating keratoplasty to STCT, namely DSAEK.

References

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

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

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

Introduction

The surgical technique of Descemet stripping automated endothelial keratoplasty (DSAEK) for corneal endothelial failure and secondary corneal edema is explained with clinical pearls to facilitate the use of this technique. DSAEK is a novel procedure that replaces full-thickness penetrating keratoplasty (PKP) for corneal endothelial disease. The visual results of DSAEK exceed those of PKP.

Historic Perspective

Penetrating keratoplasty has been the standard of care for cornealtransplantationforover50years(See also Chapter 14, History of Lamellar and Penetrating Keratoplasty). Modern microsurgical techniques and improved eye banking has resulted in a very highly successful operation, especially if the measures of outcome is a clear cornea. PKP is a fullthicknesscornealprocedureandapplicableforalargerange of diseases including corneal decompensation from endothelial failure, stromal scars and corneal ectatic diseases. However, visual results with PKP are highly variable, unpredictable and often very delayed. Unacceptableastigmatismbothregularandirregularlimitsspectacle correctionfollowingPKP.Full-thicknesstrephinationsand longtermsuturescontributetotherefractivedilemmasand surface disease. The susceptibility to traumatic wound dehiscence and loss of vision remains permanent. Clearly, aprocedurethatnotonlyimprovestheanatomy(i.e.corneal clarity),butalsoconsistentlyandreproducibilityimproves thefunction(i.e.visualacuityasmeasuredbybestcorrected spectaclevisualacuity(BCSVA)ishighlydesirable.DSAEK, by avoiding full-thickness trephinations and long term cornealsutures,avoidsthefunctionalshort-comingsofPKP and results in a rapid high quality visual recovery. DSAEK isa“focused”surgeryforendothelialdisease,suchasFuchs’ corneal endothelial dystrophy, pseudophakic or aphakic bullouskeratopathy,priorendothelialgraftfailurefollowing aPKPortheirido-corneal-endothelial(ICE)syndrome.Isit not applicable for stromal scars or ectatic disease?

The origins of DSAEK stems from the work of Dr. Gerritt Melles (See also Chapter 14, History of Lamellar and Penetrating Keratoplasty). His original technique of posterior lamellar keratoplasty (PLK) involved a large limbal incision and deep manual lamellar corneal dissections with excision and transplantation of a similarly dissected donor corneal disk. Next evolved a smaller (5 mm) clear cornea temporal incision and a “taco-fold” donor corneal insertion into the recipient anterior chamber (AC). Dr Mark Terry renamed the procedure Deep Lamellar Endothelial Keratoplasty (DLEK) and has been instrumental in promoting the superior outcomes of DLEK. PLK (DLEK) requires extensive surgical skill to master the arduous lamellar dissections

on both the patient and donor corneas [performed using an artificial anterior chamber (AAC)].

The next evolution by Dr Melles was the substitution of the patient’s corneal stromal dissection with Descemet stripping. This pivotal change gave birth to Descemet’s Stripping Endo Keratoplasty (DSEK). Descemet stripping eliminated the manual dissection of the patient’s cornea and my adaptation of the Moria anterior lamellar therapeutic keratoplasty (ALTK) system eliminated the manual dissection of the donor and gave rise to DSAEK

(See also Chapter 14, History of Lamellar and Penetrating Keratoplasty). The elimination of all manual lamellar dissections has resulted in a more consistent and reproducible surgical outcome while simplifying the surgical procedure. Visual recovery is hastened by the two smooth lamellar surfaces.

Surgical Technique

DSAEK is my procedure of choice for all patients requiring corneal transplantation due to corneal endothelial disease. DSAEK surgery is totally dissimilar to PKP surgery and because it is a new and novel procedure, I continue to modify my technique to improve patient outcomes. The “Achilles heel” of DSAEK is donor corneal dislocation and most changes to the procedure are in an effort to reduce this complication. I will describe my present surgical technique (Figures 24-1 to 24-18) and postoperative maneuvers in detail.

Patient Selection

DSAEK is indicated for corneal endothelial disease. Fuchs’ corneal dystrophy comprises the largest cohort followed

Figure 24-1: Cutting the corenal cap using a Moria ALTK system and a 300 micron microkeratome head.

Figure 24-2: Intraoperative photograph showing the surface circular mark of 9.0 mm diameter and temporal 5.0 mm limbus marks with surgical calipers.

Figure 24-3: Diamond blade is used to make the 1.0 mm limbal entry wounds to the anterior chamber.

Figure 24-4: A 2.75 mm keratome blade is used to make a clear corneal incision.

Figure 24-5: Irrigating Descemet stripper used for scoring the inside surface of the cornea, using the surface circular mark as a guide.

Figure 24-6: Descemet stripping is performed using an I and A unit.

Figure 24-7: Stab incisions are made with 1.0 mm diamond blade from the corneal surface to the donor-recipient interface.

by PBK and prior corneal endothelial graft failure. The technique is essentially the same for all diagnoses. All patients must be pseudophakic with a posterior chamber intraocular lens implant (PC IOL). I prefer to do DSAEK as a stand alone procedure, not combined with other surgical

procedures. All phakic patients are rendered pseudophakic even if it requires a clear lensectomy (Editorial Note: Clear lens extraction if performed, should be discussed in detail with the patient prior to the procedure and documented in the patient’s chart). The only exception is a cornea too opaque to perform

Figure 24-8: The clear corneal wound is enlarged to 5.0 mm.

Figure 24-9: Donor endothelium is coated with HealonTM.

Figure 24-10: Intraoperative photograph showing the cornea after stripping the Descemet’s membrane.

phacoemulsification. This deepens the anterior chamber (AC) for donor corneal disk unfolding and avoids future cataract surgery, that is almost inevitable, thereby avoiding phacoemulsification induced endothelial cell loss. All AC IOL is replaced with sutured scleral-fixated PC IOL. Glaucoma must be well controlled and if necessary filtering or shunt surgery is performed pre-DSAEK. The staged procedures are performed approximately 4-6 weeks apart.

Figure 24-11: The donor corneal disk is folded as a 60/40 “taco” fold.

Figure 24-12: Donor corneal disk is inserted into the recipient anterior chamber with the Goosey forceps.

Figure 24-13: Corneal wound is closed with a 10-0 nylon suture.

Preoperative Treatment

A fourth generation fluoroquinolone is started qid the day prior to surgery [Editorial Note: Alternative medication to consider include, levofloxacin 1.5% (Iquix 1.5%, Vistakon Pharmaceuticals, Jacksonville, FL) used qid for 3 days prior to surgery and continued postoperatively]. Topical anesthesia using Lidocaine hydrochloride jelly 2% (Akorn Inc., Buffalo