Eyeworld

EW CORNEA 40 August 2016 by Mitchell Gossman, MD As with most intraocular surger- ies, local anesthesia offers akinesia and excellent anesthesia, but there is the potential for complications such as globe penetration and extraoc- ular muscle damage, and there is the inconvenience of patching. The local anesthetic use here undoubted- ly exceeds that for cataract surgery, probably because of the greater technical difficulty and less of this procedure being performed. The second question was, "What size incision is closest to what you use for insertion of the donor cornea?" First of a series exploring the methods practicing ophthalmologists use when performing DSAEK D escemet's stripping auto- mated endothelial kera- toplasty (DSAEK), and its related procedure Descem- et's membrane endothelial keratoplasty (DMEK, not the subject of this review), have largely replaced penetrating keratoplasty (PK) for corneal endothelial disease. Because the epithelial and corneal layers are not removed, there are many advantages when compared to pen- etrating keratoplasty, such as lack of issues with superficial sutures, better postoperative refractive results, and quicker visual rehabilitation. While overall graft survival rates are similar between PK and DSAEK, there tend to be fewer rejection episodes with DSAEK. Since first being performed and popularized by Frank Price, MD, I have enjoyed seeing the panorama of methods that have evolved, via videos, articles, and personal communications. This article, the first of a 3-part series, will explore what methods are being used by practicing ophthalmologists. A survey was performed of 23 ophthalmologists who volunteered to participate from the ranks of par- ticipants of the eyeCONNECTIONS online community and volunteers in North America. Responses are anonymous in order to encourage candor. Totals may not equal 100% due to rounding. The first question was, "Anes- thesia preference?" Comparison of methods of performing DSAEK Retrobulbar or peribulbar block 70% Topical 17% General 13% Mitchell Gossman, MD 3.0 mm 4% 3.5 mm 9% 4.0 mm 39% 4.5 mm 4% 5.0 mm 35% 5.5 mm 9% 6.0 mm 0% Smaller incision sizes are asso- ciated with greater endothelial cell loss. However, smaller incision sizes, even as small as 3.2 in one report, are not associated with a difference in graft survival rates at the 1-year point. 1 However, it seems plausible that there may be a greater rate of graft failure in subsequent years if there is greater endothelial cell loss early in the postoperative period. Smaller incisions offer the benefit of greater structural integrity, fewer sutures or even sutureless incisions, less troublesome closure with an air bubble present, and less influence on astigmatism. Viscoelastic 57% Balanced salt solution infusion 35% Air 9% Reverse Sinskey 57% Descemet's stripper 43% Yuri McKee, MD, in private practice, Swagel Wootton Hiatt Eye Center, Mesa, Arizona, prefers a smaller incision. "As eye banks have been able to reliably reduce graft thickness from an average of 150 mi- crons down to 100 microns, smaller incision sizes have become more feasible. My preferred technique is to use a reusable Busin glide via a 3.5 mm incision and pull a thin (100 micron) graft into the eye with forceps from the opposite limbus. This ensures that the graft main- tains the proper orientation during insertion and allows for an immedi- ate air bubble to be placed while the forceps keep the graft in the desired location. I recommend suturing the main incision in all cases of endo- thelial keratoplasty as the graft can unexpectedly eject from the eye when a significant pressure differen- tial exists. Additionally, the patient could inadvertently burp air from the eye with any rubbing. A suture is placed to ensure a stable wound." The third question was, "What do you have in the anterior chamber when removing Descemet's?" Dilated 32% Undilated 68% Most, if not all, surgeons use a reverse Sinskey hook to score the circumference of the recipient endothelium prior to stripping so it is possible to complete the process by peeling Descemet's with the same instrument, which is a convenience, and is the practice of a slight major- ity. I prefer a stripper device because it is less grabby on underlying stro- ma thus there is less damage, and for me it is less prone to tear Descem- et's, which promotes a single, intact Descemet's removal. The fifth question was, "Do you prefer to remove Descemet's with a dilated or undilated pupil?" There are many tradeoffs. Viscoelastic provides excellent anterior chamber maintenance and may already be in the eye if com- bined with cataract extraction but any residual may be entrapped in the graft-recipient interface if not diligently removed. Balanced salt solution infusion requires placement of an anterior chamber maintainer such as a Lewicky, but may be used later for graft insertion anyway with some methods. Air is innocuous for preventing graft adhesion but has a tendency to burp out of the incision during Descemet's removal. The fourth question was, "How do you remove Descemet's?" A dilated pupil may make De- scemet's visualization easier against the red reflex, but if surgery is per- formed without concurrent cataract extraction on the phakic patient, it may be preferable to have a smaller pupil to protect the crystalline lens and stabilize the intraocular lens/ iris diaphragm. In an already pseu- dophakic patient, you can choose a small or large pupil depending on preference. Some surgeons prefer a small pupil to discourage posterior migration of air, and others prefer a dilated pupil for the better visualiza- tion during Descemet's removal. Further comparison of methods will be presented in part 2. EW Reference 1. Price MO, et al. Effect of incision width on graft survival and endothelial cell loss after Descemet stripping automated endothelial keratoplasty. Cornea. 2010;29:523–527. Editors' note: Dr. Gossman is in private clinical practice at Eye Surgeons & Physicians, St. Cloud, Minnesota. The physicians have no financial interests related to their comments. Contact information Gossman: n1149x@gmail.com McKee: mckee@swhec.org Pulse of ophthalmology: Survey of clinical practices and opinion

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