EyeWorld Asia-Pacific
The News Magazine of the Asia-Pacific Association of Cataract & Refractive Surgeons (APACRS)

DEVICESVolume 8 Number 3

EndoGlide inserter technique for DSAEK surgery

by Donald Tan, FRCOphth
Donald Tan, FRCOphth, takes a detailed look at the technique for using the single-use tissue insertion device he helped develop

Several different inserter devices have become available to help the surgeon during implantation of the donor lenticule during DSAEK/ DSEK. However, despite their use for over 2 years, there are very few published clinical studies demonstrating the outcomes of their use. One of the few inserters that has been used clinically that is both FDA and CE approved and with published clinical outcomes is the Tan EndoGlide (Angiotech, Reading, Pa., USA). The device is a single-use delivery system for simplified insertion of DSAEK donor tissue, which minimizes endothelial cell damage, with reported endothelial cell loss in the region of 15% at 6 months postop. Two versions of the EndoGlide are now available: the EndoGlide Classic for normal thickness donors and the EndoGlide Ultrathin (UT) for ultrathin DSAEK.

DSAEK surgery using the EndoGlide Classic

Recipient preparation: Donor insertion with the EndoGlide is performed through either a shelved 4.5-mm temporal scleral wound or through a 5mm clear cornea temporal tunnel. An anterior chamber (AC) maintainer is useful and may be placed at one side of the incision. A 1.5- mm nasal paracentesis is used to allow introduction of the curved EndoGlide insertion forceps to pull the donor tissue into the AC.

Donor loading into the EndoGlide: Donor loading is best performed under the operating microscope with the preparation base positioned on a stable, sterile surface. The EndoGlide comes with the donor cartridge preloaded on the preparation base. A small volume of balanced salt solution is first injected into the inner chamber of the cartridge for lubrication. The precut donor cornea, comprising both anterior and posterior lenticules, is then placed endothelium up within the well of the preparation base. It is useful to gently loosen the lenticules from each other prior to donor placement. The EndoGlide is designed to enable insertion of a corneal donor up to 10.0 mm in diameter and up to 250 microns in thickness. A small strip of dispersive viscoelastic is placed on the endothelial surface of the posterior lenticule. The EndoGlide straight loading forceps is introduced through the anterior opening of the cartridge into the chamber and is used to grasp the leading stromal edge of the posterior lenticule, which can then be carefully pulled into the cartridge. As the donor enters the capsule, it will coil, and the sides of the donor will naturally curl upward along the inner sidewalls of the cartridge. It is important to facilitate this coiling process by gently flipping up the tissue edges as they coil, using a cannula or Sinskey hook (Figure 1). As the donor coils in, the coiling edges will encounter a central inner ridge on top of the cartridge and automatically roll inward, creating a double coil configuration that prevents endothelial-stromal contact. The donor tissue is pulled through until the leading anterior edge just reaches the anterior opening of the cartridge, and the forceps can be carefully withdrawn. The anterior lenticule left behind is then removed from the well of the preparation base, and the introducer handle (with the word “CORONET” facing up) is slid into position, engaging the posterior end of the cartridge, until there is an audible click indicating the introducer is locked onto the cartridge and fully seals the back end of the cartridge (Figure 2). The loaded cartridge, with the introducer attached, may now be removed in its entirety from the preparation base and is turned right side up for the proper orientation and is ready for insertion into the recipient eye. Donor insertion: With the AC maintainer on low to moderate flow, the flat anterior glide portion of the cartridge is inserted through the temporal wound and advanced into the AC. The flat surface of the glide prevents iris prolapse through the wound. The cartridge is advanced until the entire opening of the cartridge is advanced all the way into the AC, providing a tight seal. With one hand holding the EndoGlide, the curved EndoGlide insertion forceps is inserted into the AC through the nasal paracentesis with the other hand. The forceps is advanced over the glide into the anterior opening of the capsule, used to grasp the stromal edge of the donor, and then used to gently pull the donor tissue out of the cartridge chamber into the AC (Figure 3). Once the donor tissue is fully removed from the cartridge, it will automatically start to uncurl, endothelial side down. While still holding onto the donor with the forceps, the EndoGlide cartridge is then removed from the wound. Gentle sideways shaking of the donor with the forceps as well as tapping on the corneal surface will assist in full uncoiling of the donor. While still holding onto the donor, a small air bubble is injected beneath the donor, through the wound, to prevent descent of the donor onto the iris, and only then should the donor be released from the forceps. Full wound closure, centration of the donor, a complete air tamponade, and completion of the DSAEK procedure may then be performed in the usual manner.

EndoGlide Ultrathin (UT) version

With increasing use of thinner donor tissue (ultrathin DSAEK) to sub-100-micron thicknesses, which may result in better vision, a second version of the EndoGlide, EndoGlide Ultrathin (UT), has been designed, with improved ease of donor coiling for thinner tissues between 50-100 microns. It incorporates a detachable coiling saddle with a conical front end that enables easy coiling without the need to stroke the sides of the donor upward in most cases, unless the donor is less than 50 microns. The EndoGlide UT also has a higher donor well platform, which allows for placement of just the posterior lenticule in situations where only the posterior lenticule is supplied by the eye bank. The EndoGlide UT may also be used for thicker donor tissue (100-250 microns).

Technique of donor loading using the EndoGlide UT: Fill the well and the cartridge with balanced salt solution and place both the anterior and posterior lenticules of the donor in the well. Gently remove the anterior lenticule and position the posterior lenticule adjacent to the cartridge opening. Once the donor is close to the entrance, it may then be further drawn toward the cartridge opening by wicking away balanced salt solution from the front of the cartridge, using a dry Weck cell sponge placed at the front open end of the cartridge. As fluid is drawn forward through the cartridge chamber into the sponge, the donor will usually also be drawn by capillary action right up to the entrance of the cartridge. Place a thin strip of dispersive viscoelastic onto the donor, and pull the donor into the cartridge with the straight loading EndoGlide forceps (Figure 4). As the donor tissue enters the capsule, the sides of the donor tissue will naturally curl upward, without wrinkling, along the upward curving walls of the saddle tunnel, and the tissue will form a double coil configuration in the cartridge. Unlike the EndoGlide Classic, it is usually unnecessary to use a cannula to stroke the edges of the donor upward along the sidewalls of the chamber, unless the donor is extra thin (e.g., sub-50 microns). Remove the detachable transparent saddle, and attach the introducer to the back of the cartridge and remove from the preparation base for insertion.

Early clinical results with the EndoGlide UT have been encouraging with no cases of graft dislocation or graft failure in the first 20 cases (unpublished data). Another advantage of the EndoGlide donor inserter is the possibility of precut and preloaded donor delivery by eye banks, which further simplifies DSAEK surgery for surgeons. A recent study presented at the 2012 ASCRS•ASOA Symposium & Congress showed there was minimal cell damage after the donor corneas were stored for 24 hours preloaded in the EndoGlide. Following our initial wet lab work, we are using precut and preloaded donors for our clinical cases. More data will be required to confirm our early positive safety and efficacy results. EWAP

Editors’ note: Dr. Tan is medical director, Singapore National Eye Centre. He has financial interests with Angiotech, Alcon (Fort Worth, Texas, USA/Hünenberg, Switzerland), Bausch + Lomb (Rochester, NY, USA), Santen (Osaka, Japan), Moria (Antony, France), Carl Zeiss Meditec (Jena, Germany), AcuFocus (Irvine, Calif., USA), and Technolas Perfect Vision (Munich, Germany).

Contact information
Tan: snecdt@pacific.net.sg

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