Variant of the big bubble technique in deep anterior lamellar keratoplasty

We describe a variant of the big-bubble technique that involves placement of a stromal corneal nick and nontraumatic intrastromal insertion of a blunt cannula following anterior lamellar keratectomy. The goal of this technique is to reduce the risk for intraoperative corneal perforation and to obtain a large air bubble between Descemet's membrane and the corneal stroma. Deep anterior lamellar keratoplasty is easier and safer with this technique.     

Optical coherence tomography of Descemet membrane separation by the big bubble technique

PURPOSE: To image Descemet membrane separation by the big bubble technique in human corneas by using anterior segment optical coherence tomography (OCT). METHODS: Five human corneoscleral rims were placed on an artificial anterior chamber and partially trephinated. A 23-gauge needle was inserted into the stroma under slit-lamp control and air was injected. The procedure was continuously imaged by anterior segment OCT. RESULTS: In all corneoscleral rims, a big bubble was created. The spread of air seemed to follow the interlamellar spaces without crossing lamellae. It involved mainly the inner layers of the stroma while sparing the outer 212 +/- 41 microm of the cornea (range, 168-271 microm). Intrastromal pressure build-up forced air above the Descemet membrane, creating tiny air bubbles of approximately 355 +/- 111 microm (range, 210-560 microm). When the pressure inside those bubbles reached a certain level, the bubbles spontaneously coalesced to form a big bubble. CONCLUSIONS: OCT is useful in imaging intracorneal air spread. The main obstacle to creating a big bubble is the impermeability to air of the imperforated posterior stromal lamellae.     

飞秒激光辅助的大气泡法深板层角膜移植治疗圆锥角膜

目的评价飞秒激光辅助的大气泡法深板层角膜移植术治疗圆锥角膜临床效果及安全性。方法系列病例研究。9例（11眼）圆锥角膜患者采用飞秒激光辅助进行大气泡法深板层角膜移植手术。供体及受体角膜均采用500 kHz VisuMax飞秒激光进行垂直边切,术前超声测量角膜最薄点厚度,角膜厚度为（359.7±49.8）μm,术前UCVA为指数～0.1,术前BCVA为指数～0.12,供体直径为（7.51±0.14）mm,受体直径为（7.38±0.10）mm,随访时间为（7.70±2.88）个月。结果所有患者手术顺利,术中无并发症,术后早期所有角膜植片透明。角膜厚度为（481.4±51.3）μm,角膜地形图恢复正常形态。术后最后1次随访,UCVA为0.15～0.40,BCVA为 0.30～0.80。结论飞秒激光辅助的大气泡法深板层角膜移植对于圆锥角膜患者具有良好的临床效果及安全性。     

Standardized "no-touch" technique for descemet membrane endothelial keratoplasty

We describe a standardized technique for "no-touch" isolated Descemet membrane transplant, ie, Descemet membrane endothelial keratoplasty (DMEK). All essential steps, including patient preparation and descemetorhexis as well as DMEK graft implantation, orientation, unrolling, centering, appositioning, and fixation, are described in detail. In the management of Fuchs endothelial dystrophy, the technique may provide a best-corrected visual acuity of 20/25 or better (≥ 0.8) in three-quarters of cases and an endothelial cell density of about 1800 to 2000 cells/mm(2) at 6 months after surgery. No-touch DMEK may therefore be a safe and effective procedure for the treatment of corneal endothelial disorders, making endothelial keratoplasty accessible to most corneal surgeons without requiring major investments while providing an unprecedented visual rehabilitation rate and outcome.     

The "sandwich technique" for iris-fixated phakic intraocular lens implantation

PURPOSE: To describe a new technique of implantation of the Artisan/Verisyse phakic intraocular lens (PIOL). METHODS: After PIOL insertion into the anterior chamber, a bolus of a high viscosity ophthalmic viscosurgical device (OVD) is placed over the optic, separating it widely from the endothelium. RESULTS: The technique decreases the chance of endothelial damage during enclavation. CONCLUSIONS: A bolus of a high viscosity OVD placed on the anterior surface of the Artisan/Verisyse PIOL may make enclavation safer.     

Use of a "small-bubble technique" to increase the success of Anwar's "big-bubble technique" for deep lamellar keratoplasty with complete baring of Descemet's membrane

PURPOSE: To describe a quick and simple "small-bubble" technique to immediately determine the success of attaining complete Descemet's membrane (DM) separation from corneal stroma through Anwar's "big-bubble" technique of deep anterior lamellar keratoplasty (DALK) for complete stromal removal. METHODS: A partial trephination was followed by a lamellar dissection of the anterior stroma. Deep stromal air injection was then attempted to achieve the big bubble to help separate the stroma from the DM. To confirm that a big bubble had been achieved, a small air bubble was injected into the anterior chamber (AC) through a limbal paracentesis. If the small bubble is then seen at the corneal periphery, it confirms that the big-bubble separation of DM was successful because the convex nature of the bubble will cause it to protrude posteriorly, forcing the small AC bubble to the periphery. If the small AC bubble is not seen in the corneal periphery, this means that it is present in the centre, beneath the opaque corneal stroma, and therefore the big bubble has not been achieved. RESULTS: We used the small-bubble technique to confirm the presence of the big bubble in three (one keratoconus, one interstitial keratitis and one dense corneal scar) out of 41 patients who underwent DALK. The small-bubble technique confirmed that the big bubble was achieved in the eye of all three patients. Complete stromal removal with baring of the DM was achieved, and postoperatively all three eyes achieved best corrected vision of 6/6. CONCLUSION: The small-bubble technique can be a useful surgical tool for corneal surgeons attempting lamellar keratoplasty using the big-bubble technique. It helps in confirming the separation of DM from the deep stroma, which is important in achieving total stromal replacement. It will help to make the transition to lamellar keratoplasty smoother, enhance corneal graft success and improve visual outcomes in patients.     

Modification in descemet-stripping automated endothelial keratoplasty: "Hitch suture" technique

PURPOSE: To describe a new modification in Descemet-stripping automated endothelial keratoplasty, using a "hitch suture" to unfold the donor lenticule inside the recipient's eye. METHODS: The technique was used in 2 eyes of 2 patients with bullous keratopathy after complicated cataract surgery. A hitch suture was created in both the donor lenticules before inserting the folded graft in the recipient's anterior chamber. The hitch suture was pulled through a limbal stab incision to unfold the donor lenticule in both cases. RESULTS: No intraoperative problems were encountered. The grafts were well centered with corneal edema. The central part of the graft cleared over a period of 10 to 14 days. CONCLUSION: The technique of using a hitch suture to unfold the graft eliminates the problems associated with this difficult step of the surgery. The hitch loop can be easily made at the edge of the graft and can be pulled using a Sinskey hook through 1 of the stab incisions. We believe that this simple modification in this surgery would help simplify the learning curve of the procedure and increase its chances of success.     

Excimer laser "corneal shaping": a new technique for customized trephination in penetrating keratoplasty

PURPOSE: The aim of the presented experimental work was to develop a technique for congruent trephination of donor and recipient corneas in free form using a 193-nm excimer laser and to study the clinical follow-up after the application of the technique in a rabbit model. METHODS: In 12 New Zealand White rabbits homologous penetrating keratoplasty was performed. Trephination of donor buttons and recipient beds was achieved in six animals by conventional mechanical trephination and in six by excimer laser trephination with a guided laser beam in a non-circular geometry. The surgical procedure and its applicability to human subjects were evaluated and the postoperative clinical course was followed for 6 months. RESULTS: The surgical procedure of full-thickness excimer laser trephination could be performed reproducibly in the animal model both for dissection of the donor buttons and for preparation of the recipient beds. Keratoplasty was performed with kidney-shaped transplants after trephination in free form with the guided laser beam. Postoperative clinical follow-up did not show any differences between the two trephination groups that could be related to the applied trephination technique. After 6 months we observed well-adapted and clear corneal grafts, kidney-shaped in the excimer trephination group and circular in the mechanical trephination group. No side effects on the crystalline lens and the central retina could be clinically observed following excimer laser trephination. CONCLUSION: We present the first experimental study of keratoplasty with freely selected transplant geometry and perfect congruence of donor button and recipient bed. The application of this technique in certain corneal disorders in humans will offer improved treatment options in the future.