| | Femtosecond Laser–Assisted Sutureless Anterior Lamellar KeratoplastyReceived 23 July 2007; received in revised form 4 October 2007; accepted 25 October 2007. published online 03 January 2008. PurposeTo report the technique and small case series results of femtosecond laser–assisted sutureless anterior lamellar keratoplasty (FALK) for anterior corneal pathology. DesignRetrospective, noncomparative, interventional case series. ParticipantsTwelve consecutive eyes from 12 patients with anterior corneal scarring. InterventionFemtosecond laser–assisted sutureless anterior lamellar keratoplasty. Main Outcome MeasuresMeasured parameters included femtosecond laser settings, technique, uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), and complications. ResultsMean follow-up was 12.7 months (range, 6–24). No intraoperative complications were found. Uncorrected visual acuity (VA) improved in 7 eyes (58.3%) compared with preoperative VA. The mean difference between preoperative and postoperative UCVAs was a gain of 2.5 lines (range, unchanged–7 lines). Best-corrected VA was unchanged or improved in all eyes compared with preoperative levels. The mean difference between preoperative and postoperative BCVAs was a gain of 3.8 lines (range, unchanged–8 lines). In 2 eyes, adjuvant surgical procedures were performed (one treated with phototherapeutic keratectomy and the other with photorefractive keratectomy). Six patients (50%) developed dry eye after FALK, which improved during the follow-up period. No graft rejection, infection, or epithelial ingrowth was found in this series of patients. ConclusionsFemtosecond laser–assisted sutureless anterior lamellar keratoplasty could improve UCVA and BCVA in patients with anterior corneal pathology. Available online: January 20, 2008. Anterior lamellar keratoplasty (LK) is a partial-thickness corneal transplantation used in eyes with pathology limited to the anterior layers. Superficial corneal scars after trauma/keratitis or corneal epithelial/anterior stromal dystrophies are the major indications for anterior LK.1, 2, 3 Anterior LK provides several advantages over conventional full-thickness keratoplasty in these cases. Avoiding a full-thickness trephination minimizes potential intraoperative complications and allows for faster visual and refractive recovery. Maintaining the recipient endothelial layer decreases the rate of graft rejection. Furthermore, with the advancements in Descemet's stripping endothelial keratoplasty, anterior LK provides us the ability to perform multiple lamellar (anterior, stromal, posterior–endothelial) corneal transplantations from one donor's cornea.4 The major limitations with anterior LK are the technical challenges of performing manual dissections and the resulting stromal interface irregularities between the donor and recipient interface that could result in stromal interface haze, induced irregular astigmatism, and loss of best-corrected visual acuity (BCVA). The improvements in automated microkeratomes and artificial anterior chambers (ACs) minimize these difficulties.5, 6, 7, 8, 9 Recently, femtosecond laser technology (IntraLase, Irvine, CA) has been introduced in corneal surgery, providing a new surgical modality. Accuracy, safety, and efficacy of this new technology have already been described for several corneal procedures.10, 11, 12, 13, 14, 15, 16, 17 Theoretically, the femtosecond laser increases the precision of anterior LK because of the highly reproducible dimensions of the cuts at the graft–host junction and the vertical (in comparison with horizontal using the mechanical microkeratome) side cut orientation. The surgeon can better customize the shape and corneal dimensions of the donor and recipient, improving the resulting fit and leading to less induced irregular astigmatism and interface haze. These features may result in faster and better wound healing, without the need for sutures. In this study, we report our experience with femtosecond laser–assisted sutureless anterior LK (FALK) in patients with anterior corneal scarring. Materials and Methods  Twelve eyes of 12 patients (6 men and 6 women) ages 11 to 72 years with anterior corneal scarring underwent FALK. Anterior corneal scarring resulted from corneal infections in 10 patients and from trauma in the remaining 2. Patients with severe corneal scars totally obscuring visualization of anterior segment structures, corneal scarring leaving <250 μm of posterior residual corneal bed thickness, and <6 months' follow-up were excluded from this study. Surgical Technique All procedures were performed under topical anesthesia (proparacaine hydrochloride 0.5%). Anterior segment ocular coherence tomography (OCT; Visante OCT, model 1000, Carl Zeiss Meditec, Dublin, CA) was used in all patients to estimate corneal scarring depth in the recipient cornea (Fig 1). To create the donor graft, corneoscleral donor tissue was mounted on a Moria artificial AC. When an entire donor globe was available, it was mounted directly under the laser. Epithelium was removed before the flap creation. A donor graft was created using the 30-kilohertz femtosecond laser (IntraLase) with the following settings: donor lenticule thickness, 160 to 270 μm (thickness of the lenticule adjusted in relation to depth of the lesions according to the anterior segment OCT findings); donor lenticule diameter, 7.5 to 8.2 mm, spiral method; 1.9 to 2.9 microjoules spiral energy; 2.3 to 3.0 microjoules side cut energy; 360° side cut, 70° to 80° side cut angle; tangential spot separation, 11 to 12; and radial spot separation, 9 to 11. Depending on the donor tissue quality and edema, up to 20% additional thickness was added to the donor lenticule to adjust for donor tissue swelling. The range of energy was adjusted according to the severity of the corneal scar, with higher spiral energy and lower tangent and radial spot separation for denser scars. A recipient corneal lenticule was created using similar femtosecond laser settings except that the recipient corneal lenticule was set to be 0.1 mm smaller in diameter than the donor graft diameter. The host corneal button then was removed (Fig 2A [available at http://aaojournal.org]) and replaced with the donor lenticule on the recipient residual corneal stromal bed (Fig 2B). The keratectomy incision was dried with methylcellulose sponges. After approximately 5 minutes (to dehydrate the cornea and improve adhesion), the flap was checked for adhesion by depressing the peripheral host cornea and ensuring that the resulting indentation radiated into the lenticule (similar to checking for flap adhesion after LASIK with the striae test). A bandage contact lens was fitted over the cornea. Patients were then placed on a topical antibiotic and steroid for 1 week, and steroid drops were slowly tapered over several months. Results Mean postoperative follow-up was 12.7 months (range, 6–24). Data of the last follow-up visit of each patient were recorded and selected for analysis. Contact lenses were removed from 3 to 12 days after the procedure (mean, 6.2). Uncorrected Visual Acuity Uncorrected visual acuity (UCVA) was improved in 7 eyes (58.3%) compared with preoperative levels. Pre–femtosecond laser–assisted sutureless anterior LK UCVA was 20/70 or worse in all eyes (range, hand movements [HM]–20/70), whereas at the last follow-up examination 4 (33%) of 12 eyes had UCVA of 20/50 or better (range, 20/200–20/30). The mean difference between preoperative and postoperative UCVAs was a gain of 2.5 lines (range, unchanged–7 lines). Best-Corrected Visual Acuity Best-corrected visual acuity was unchanged or improved in all eyes compared with the preoperative levels. Pre–femtosecond laser–assisted sutureless anterior LK BCVA was 20/50 or worse in all eyes (range, HM–20/50), whereas at the last follow-up examination 10 (83%) of 12 eyes had BCVA of 20/50 or better (range, 20/80–20/25). One eye (8%) maintained the pre-FALK BCVA, whereas the remaining 11 eyes (92%) experienced a gain of 1 or 8 lines at the last follow-up examination. The mean difference between preoperative and postoperative BCVAs was a gain of 3.8 lines (range, unchanged–8 lines). In all patients, both UCVA and BCVA stabilized between 1- and 6-month follow-up examinations. Adverse Effects and Postoperative Complications In 2 eyes, additional surgical procedures were performed. In one eye, due to residual corneal scarring, phototherapeutic keratectomy (PTK; 40 μm deep) was performed (10 months after FALK) after lifting the FALK graft. There were no intraoperative or postoperative complications in this case, whereas a significant improvement in BCVA and corneal scarring was found (Fig 3). The second additional surgical procedure was performed due to anisometropia. Hyperopic photorefractive keratectomy (PRK) over the graft was performed (with attempted correction +1.00+3.00×26) 4 months after FALK. Haze formation was found during the next 3 postoperative months and resolved during the following 9 postoperative months. Six patients developed dry eye (defined as an increase in burning and foreign body sensation; corneal findings, such as superficial punctate keratopathy; and abnormal results of dry eye tests, such as the Schirmer test and tear breakup time) after FALK. All patients were treated with artificial tears and punctal occlusion. An improvement in dryness was found in these patients during the next 3 to 12 months of follow-up. No graft rejection, infection, or epithelial ingrowth was found in this series of patients. Discussion Anterior LK is a treatment option for patients with anterior corneal pathology that combines the advantages of keratoplasty (replacing the diseased corneal tissue) with a less invasive technique. Taking advantage of the refractive experience using microkeratomes and femtosecond laser, surgeons can apply these technologies in anterior LK, potentially improving the safety and efficacy of this procedure. There are several reports in the literature regarding improvements in patients' outcomes with anterior LK after the introduction of automated microkeratomes.5, 6, 7, 8 Vajpayee et al8 reported positive results using automated lamellar therapeutic keratoplasty for diseases affecting the anterior stroma to midstroma of the cornea. In our series, femtosecond laser–assisted anterior LK was performed. An overall improvement in UCVA and BCVA in patients with anterior corneal scarring after FALK was found, without intraoperative complications. All grafts were successfully created in both donor and recipient corneas. No graft rejection was observed during the follow-up period. Additionally, the use of the artificial AC (which provides us the ability to create lamellar donor grafts from corneoscleral donor tissue) and anterior segment OCT (used to estimate the percentage of corneal thickness with corneal scarring) in the current series allows us to perform anterior LK in an accurate way, sparing unaffected corneal tissue. In all patients, lamellar separation was successfully performed despite varying degrees of corneal opacification. The effectiveness of a femtosecond laser in patients with corneal scarring (such as in patients with retreatments in post–radial keratectomy patients) has already been described.18 In cases of denser corneal scarring, femtosecond laser energy adjustments should be considered. Patients with severe corneal scars totally obscuring visualization of anterior segment structures were excluded from this study because of concern that the scars' opacification could scatter laser energy. The fit between donor and recipient lenticules was highly reproducible, allowing all patients to have sutureless anterior LK. There were no late complications during the follow-up period of this study. Six patients developed dry eye with an improvement of dryness during the next 3 to 12 months of follow-up. In 2 patients, additional procedures (PTK and PRK) were needed for residual corneal scarring and anisometropia, respectively. No infection or epithelial ingrowth was found in these patients. In comparison with microkeratome automated anterior LK, FALK enables the surgeon to perform customized graft-thickness procedures.7, 8 Combining FALK with anterior segment OCT findings provides us the ability to estimate the exact depth of the corneal scarring and program the graft thickness in an accurate way.19 In contrast, with automated mechanical microkeratomes only predetermined corneal graft thicknesses are available to surgeons. In addition, the ability to create a vertical side cut with the femtosecond laser could further improve the fit at the graft–host junction. Some potential limitations of this study include a small sample (12 eyes), the retrospective nature of the study, and the lack of a comparison group of patients treated with automated mechanical microkeratome or penetrating keratoplasty (PK). Future prospective comparative randomized studies including more patients are needed to address these limitations. In conclusion, FALK in patients with anterior corneal scarring seems to be an alternative to conventional anterior LK and PK without significant short-term complications. The femtosecond laser, with its ability to perform precise preprogrammed corneal dissections at a variety of depths and orientations, is a powerful tool for anterior LK, especially when combined with anterior segment OCT findings. Improvements in fit between the donor tissue and the recipient cornea at the graft–host junction provided us the ability to perform sutureless anterior LK in this series. Future prospective comparative studies are needed to evaluate the long-term results of this technique. References 1. 1Terry MA. The evolution of lamellar grafting techniques over twenty-five years. Cornea. 2000;19:611–616. MEDLINE |
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Department of Ophthalmology, Bascom Palmer Eye Institute–University of Miami School of Medicine, Miami, Florida.  Correspondence to Sonia H. Yoo, MD, 900 NW 17th Street, Miami, FL 33136.
Drs Yoo and Culbertson received travel grants and speakers' honoraria from IntraLase Corp. No other author has a financial interest. PII: S0161-6420(07)01211-0 doi:10.1016/j.ophtha.2007.10.037 © 2008 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved. | |
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