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

Introduction

Just like an artist needs good painting brushes to fully express his or her artistic talents, a corneal surgeon requires good surgical instruments to fully optimize his surgical skills. Having excellent machinery such as the operating microscope, phacoemulsification unit, best sutures, artificial anterior chamber and microkeratome, but, without the appropriate state-of-the-art surgical instruments, is like having a superb sound system without the best suited speakers. With this concept in mind this chapter is dedicated to introducing and familiarizing the reader to various surgical instruments that are specially designed for Descemet stripping automated endothelial keratoplasty (DSAEK) surgery [See Section 9, Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK)].

New Concepts in DSAEK Surgery1

In surgical ophthalmology, until now, we have been working on the “floor,” or doing “floor surgery,” meaning, inferiorly directed surgical maneuvers, whether working on the ocular surface, cornea, iris, lens, vitreous or retina that I call as “in-line-with-gravity” surgery (ILGS). In contrast, in DSAEK, for the first time in ophthalmology, we have changed the surgical direction to “against-the-line- of-gravity” surgery (ALGS), namely, we are working on the “ceiling” or “ceiling surgery,” ceiling meaning, the inner dome of the host cornea.1-21 This is a new direction in ophthalmic surgery. Hence, instruments that are designed with the usual “floor surgery” concept does not often work as well as one would like them to, when performing DSAEK surgery or “ceiling surgery.” With this concept in mind I designed several surgical instruments for DSAEK surgery (Table 11-1) and they are described in this chapter.

Additionally, the surgeon has to be cognizant of the anterior chamber volume, namely, large, normal or small and the anterior chamber angle, all of which will have an influence in DSAEK surgery. Similarly, the choice of donor disk diameter, donor disk thickness, the type of fold that is used on the donor corneal disk [eg., taco-fold (bi-fold) [See also Chapter 20, Endothelial Keratoplasty: A Step by Step Guide to DSEK and DSAEK Surgery, Chapter 23, DSAEK Simplified Surgical Technique, Chapter 24, Surgical Technique for Descemet Stripping Automated Endothelial Keratoplasty (DSAEK)]

60/40, 70/30, 80/20, or a burrito fold (tri-fold)] (See also Chapter 25, Descemet Stripping Endothelial Keratoplasty (DSEK, Through a 3 mm Incision using the Tri-fold Technique), surgeon-cut versus eye-bank-technician pre-cut tissue, and the length of the entry wound into the anterior chamber (AC), will all have an influence on the overall outcome of

DSAEK procedure. Additionally, since we are doing ALGS in DSAEK, the donor corneal disk can detach from the patient’s inner corneal dome and fall and rest on the iris. Hence, the use of state-of-the-art DSAEK instruments and proper surgical techniques may be considered as essential ingredients to decreasing, if not, eliminating donor corneal disk detachment in DSAEK surgery.

Surgical Instruments for DSAEK

A list of DSAEK surgical instruments are listed in Table 11-1 and shown in Figures 11-1 to 11-21. The JohninstrumentswerespecificallydesignedtofacilitateDSAEK surgeryandincreasesurgeon-comfortindoingthesenewer corneal procedures. It appeared inappropriate to me, to try to work on the dome of the patient’s cornea with straight instruments from a fixed pivotal point (entry wound). The new instrument design that I developed, is reflected in the Dexatomeandothersimilarinstruments(Table11-1)(Patent Pending). I coined the term “Dexatome” since it is used to scoreanddetachtheDescemet’smembrane(DM),abasement membrane, somewhat in keeping with the term cystatome that is also used to tear a basement membrane namely, the anteriorlenscapsule.TheJohnDexatomeiscurved,andhas a sickle-like profile, so it can rotate to reach the entire inner surfaceofthepatient’scorneathroughasingleentrywound, allowingfor360degreescorringoftheDMwithoutremoving the instrument from the anterior chamber. John Dexatome can then detach the DM as a single disk, leaving a pristine inner host stromal surface, and hence a superior donorrecipientinterface.Suchimprovedinterfacewillcontribute to better quality of vision and faster visual recovery.

John Dexatome DSAEK Spatula

Identification of surgical step: Removal of DM and the corneal endothelium.

Difficulty encountered: Reverse Sinskey Hook (RSH) is difficult to use, as it was not designed to work on the ceiling of the cornea. RSH requires multiple entries into the anterior chamber (AC).

Main benefit: John DSAEK Dexatome Spatula (ASICO Inc., Westmont, IL, AE-2872) (Patent Pending) (Figures 11-1A to C) allows for DM and endothelium to be removed as a single disk almost every time (few exceptions) without exiting the AC (Figures 11-2 to 11-4). A DM tear that is 360 degrees is possible with a single AC entry. John Dexatome (Figures 11-1A to C) special design (Patent Pending) allows access to almost every point in the inner-corneal dome without exiting the AC. Currently, there is no other such instrument

available commercially that will easily permit contact with all areas of the inner corneal dome with a single entry wound. John DSAEK Dexatome spatula is the only instrument that is currently available with which the DM can be removed as a single disk without scraping or touching the inner, central, stromal surface of the patient’s cornea. This is possible since the John Dexatome spatula is only in contact with the folded DM during the removal process (Figure 11-20), similar to rolling a carpet without touching the floor on which the carpet rests. Since there is no contact with the central stromal surface, it results in the best stromal interface and thus facilitates optimal postoperative vision for the patient.

Main benefit: In these more difficult cases such as a failed corneal graft, the use of a John DSAEK Descemet’s Stripper (ASICO Inc., Westmont, IL, AE-2874) (Patent Pending) (Figures 11-5A and B) will facilitate the procedure and it requires only a single AC entry to remove the DM as a single disk from patient’s cornea. Usually need only one instrument to remove the DM disk, namely, John Dexatome (see above). However, in complicated cases like multiple failed PK with scarring, John Descemet’s stripper, John Super-microforceps and John Super-microscissors (Table 11-1) will facilitate smooth and sucessful completion of the procedure.

John DSAEK Descemet’s Stripper

Identification of surgical step: Complications with DM and endothelium removal.

Difficulty encountered: Complications include, irregular tears in DM especially in failed cornea grafts, creation of unwanted stromal strands, inability to consistently remove DM as a single disk due to scarring from penetrating keratoplasty (PKP), and having to enter AC more than once to complete the 360 degree DM tear. Need three instruments to remove DM, namely, the RSH and two different strippers.

John Retrocorneal Super Micro Forceps

Identification of surgical step: Complications related with DM and endothelium removal.

Difficulty encountered: Very difficult to remove fragments of DM without damaging the stroma.

Main benefit: Very “user-friendly” instrument, namely, John Super Micro Forceps (ASICO Inc., Westmont, IL, AE-4962) (Figures 11-6A and B) to complete the removal of the DM and endothelium especially in the regions of corneal stromal scarring after a PKP.

A

B

Figures 11-5A and B: (A) John DSAEK Descemet’s Stripper (ASICO, Westmont, IL; AE-2874) (Patent Pending); (B) Unique design of the John DSAEK Stripper is displayed. The tip of this instrument has a horizontal T-Bar that is clearly seen in this magnified image.

A

B

Figures 11-6A and B: (A) John Retrocorneal Super Micro Forceps (ASICO, Westmont, IL; AE-4962) is displayed. Round, smooth handle allows for side-to-side rotation of the super-microforceps for holding, pulling and retracting tissues at different angles within the anterior chamber (AC) at the retrocorneal plane. Additionally, it permits the holding of tissues within the AC, in a closed system; (B) Magnified image of the tip of the John Retrocorneal Super Micro Forceps.

John Retrocorneal Super Micro Scissors

Identification of surgical step: Complications related with DM and endothelium removal.

Difficulty encountered: Very difficult to remove fragments of DM without damaging the stroma.

Main benefit: Very “user-friendly” instrument, namely, John Super Micro Scissors (ASICO Inc., Westmont, IL; AE-5762) (Figures 11-7A to C) to complete the removal of the DM and endothelium especially in the regions of corneal stromal scarring after a PKP. The round, smooth handle of this instrument allows for side-to-side rotation for cutting at different angles within the AC at the retrocorneal plane without damaging the adjacent tissues. It allows for cutting of the back surface of the cornea without making a large limbal opening in to the AC. Additionally, it works in a closed system within the AC.

A

B

C

Figures 11-7A to C: (A) John Retrocorneal Super Micro Scissors (ASICO, Westmont, IL; AE-5762) is displayed; (B&C) –Shows a higher magnification of the closed (B) and open (C) profile of the John Retrocorneal Super Micro Scissors.

John DSAEK Stromal Scrubber

Identification of surgical step: To increase the adhesion of the donor corneal disk to the patient’s cornea and thus to decrease the rate of donor detachment.

Difficulty encountered: RSH was used to roughen the peripheral exposed stroma within the area of the Descemetorhexis of the patient’s cornea. However, it was difficult to use, since it was not designed to work on the ceiling of the cornea.

Main benefit: John DSAEK Stromal Scrubber (ASICO Inc., Westmont, IL, AE-2878) (Patent Pending) (Figures 11-8 to 11-10) is easy to use, and effectively roughens the inner corneal stroma within the circle of the Descemetorhexis in the inner surface of the patient’s cornea.

John DSAEK Inserting Forceps (AE-4227)

Identification of surgical step: Insertion of taco-folded donor corneal disk into the recipient AC.

A

B

Figures 11-8A and B: (A) John DSAEK Stromal Scrubber (ASICO Inc., AE-2878) (Patent Pending); (B) Higher magnification image of John DSAEK Stromal Scrubber.

A

B

C

Figures 11-11A to C: (A) John DSAEK Inserting Forceps (ASICO, Westmont, IL; AE-4227) is shown; (B) Higher magnification of John DSAEK Inserting Forceps (ASICO, Westmont, IL; AE-4227) with the tips open, displaying the holding platforms that are oriented 90o to the handle of this instrument to facilitate easy insertion of the folded donor taco-disk into the recipient anterior chamber; (C) Higher magnification of John DSAEK Inserting Forceps (ASICO, Westmont, IL; AE-4227) with the tips closed.

Difficulty encountered: Kellman Forceps holds the folded disk in the horizontal plane and the hand must be rotated in or out for insertion and release of the taco-folded disk within the recipient AC. Other forceps with tissue clearance are also oriented to hold the disk in the horizontal plane. Also, the blades of these forceps release the disk less easily, especially when the AC is not deep enough for this maneuver.

Main benefit: John DSAEK Insertion Forceps (ASICO Inc., Westmont, IL, AE-4227) (Figures 11-11 to 11-13) has vertically oriented platforms to hold the folded donor disk without any significant damage to the donor endothelium. No hand rotation is required. The special design of this forceps allows for more natural, smooth, “fluid-motion” of inserting the folded donor disk into the AC without causing any iris or pupillary damage.

John DSAEK Fixation Hook

Identification of surgical step: Fixation of the donor corneal disk prior to unfolding the donor disk within the recipient AC.