Femtosecond laser-assisted lamellar keratoplasty (FSLK) for anterior corneal stromal diseases. Int Ophthalmol. 2013;May 24; [Epub ahead of print]. [PMID: 23703704 DOI: 10.1007/s10792-013-9794-7]

Femtosecond laser deep lamellar keratoplasty

We aimed to develop a novel and effective technique for creating a smooth deep lamellar dissection of the cornea using a femtosecond (FS) laser for deep anterior lamellar keratoplasty (DALK), we conducted a retrospective eye bank study. Thirteen fresh human corneas were mounted on an artificial anterior chamber, and deep lamellar cuts were made with a 500-kHz VisuMax FS laser at a level of 50-80 μm anterior to the Descemet's membrane (DM). A posterior diameter of 8 mm with a side cut angle of 110° was used for the anterior penetrating side cut. The anterior lamellar tissue was bluntly dissected. The residual posterior stromal beds and side cuts were examined with microscopy and intraoperative optical coherence tomography (OCT) and post-cut endothelial cell evaluations. All corneas revealed a smooth residual posterior stromal bed without any visible irregularities or ridges by microscopy and OCT imaging. Six corneas were suitable for post-cut endothelial cell evaluation 2 days after laser cut, with no significant endothelial cell loss post-laser and blunt dissection of the posterior stroma. FS laser deep lamellar keratoplasty utilizing an ultrafast laser to produce a smooth deep stromal dissection followed by blunt dissection and removal of the anterior stromal tissue yields a consistent and smooth residual stromal bed. The creation of a smooth lamellar dissection in the deep posterior cornea may result in more consistent DALK without the need for air bubble or manual baring of DM that has the risk for DM perforation.

Tuck In Femtosecond Laser Assisted Anterior Lamellar Keratoplasty (T-FALK) for the Management of Superficial Anterior Corneal Scars-A Modified Technique

PURPOSE

To report a modified sutureless and glue-less technique, termed tuck in femtosecond laser assisted anterior lamellar keratoplasty (T-FALK), and to achieve a good graft-host junction apposition.

METHODS

This is a prospective interventional case series of 15 eyes of 15 patients who underwent T-FALK. Depth of the anterior corneal scar was assessed using anterior segment optical coherence tomography (ASOCT). The donor and recipient lenticules were prepared using femtosecond laser. After removing the recipient anterior scarred lenticule, the transparent donor lenticule was positioned on the recipient bed and margins tucked in under the recipient cornea. A bandage contact lens was applied for 3 weeks. Postoperatively, topical antibiotic and steroid combination eye drops were given, and the assessment of healing of the graft-host junction was done using ASOCT.

RESULTS

A total of 15 patients (8 men and 7 women) underwent T-FALK. Six patients had superficial corneal opacities after healed microbial keratitis, 5 patients had spheroidal corneal degeneration, 3 patients had Salzman nodular degeneration, and 1 patient had vortex keratopathy. No intraoperative or postoperative complications were noted during T-FALK. All patients had good graft-host junction apposition postoperatively, as demonstrated by ASOCT.

CONCLUSIONS

Sutureless and glue-less T-FALK can be the best way ahead for management of superficial anterior corneal scars with good visual outcome.

Laser-assisted corneal transplantation surgery

Corneal transplant surgeries have a broad range of indications with outcomes largely dependent on surgeon experience. Traditional manual techniques have certain limitations pertaining to the preparation of donor tissue and the recipient bed that might affect the predictability of visual outcomes. Use of lasers for keratoplasty procedures not only improves the repeatability and consistency of the technique, but also enables the surgeon to control the thickness and shape of the transplant tissue tailored to the specific condition. Despite the advantages, cost-effectiveness and technical know-how remain the major challenges. We discuss the various techniques of laser-assisted keratoplasties with respect to their methods, precision, and efficacy in various corneal indications.

Sutureless Femtosecond Laser-Assisted Anterior Lamellar Keratoplasty Using a Bioengineered Cornea as a Viable Alternative to Human Donor Transplantation for Superficial Corneal Opacities

PURPOSE

To evaluate the safety and efficacy of a bioengineered corneal implant using femtosecond laser-assisted anterior lamellar keratoplasty for superficial corneal opacities.

METHODS

Six eyes of 6 consecutive patients with superficial corneal stromal opacities involving <220 μm owing to various pathologies were included in the study. Preoperatively, all patients underwent anterior segment optical coherence tomography (Visante; Carl Zeiss Meditec AG) to evaluate the depth of the corneal opacity. All patients underwent sutureless femtosecond laser-assisted anterior lamellar keratoplasty using a bioengineered collagen corneal implant (linkcor). Visual indices, refraction, and keratometry were evaluated preoperatively and 12 months postoperatively.

RESULTS

Corrected distance visual acuity improved significantly in all patients (P = 0.02). A significant decrease was seen in refractive astigmatism postoperatively (P = 0.04). Flat keratometry reduced significantly 12 months after the intervention (P = 0.04). No intraoperative or early postoperative complications were noticed. All implants were fully covered by healthy epithelium within a month after the surgery and remained clear at follow-up visits. The results of this procedure remained stable throughout the follow-up period. In 1 patient, mild inferior collagen melting and epithelial defect formation occurred at 1-year follow-up. Despite frequent topical corticosteroid therapy the melting progressed, the collagen tissue was removed and the patient was treated accordingly with good visual outcomes.

CONCLUSIONS

Femtosecond laser-assisted anterior lamellar keratoplasty with bioengineered corneal (linkcor) implantation is an effective treatment for improving vision quality in anterior stromal opacities. This procedure reduces the need for human donor tissue and avoids human donor-related and suturing complications.

Femtosecond Laser-Assisted Ipsilateral Rotational Lamellar Autokeratoplasty

PURPOSE

To describe the surgical technique and report the outcomes of 2 patients treated with femtosecond laser-assisted ipsilateral rotational lamellar autokeratoplasty in central corneal scars.

METHODS

The corneal scar depth was mapped using preoperative optical coherence tomography. An eccentric lamellar lenticule was cut with a femtosecond laser and rotated to decenter corneal opacity and free the pupil area in 2 patients with nonprogressive central corneal scars. The surgical plan was set after simulating lenticule rotation with a digital corneal image and computer software.

RESULTS

In both cases, the corneal scar was decentered inferiorly, out of the pupillary area, with increased postoperative visual acuity but visual outcome limitations secondary to corneal irregularities and residual deep opacity.

CONCLUSIONS

Femtosecond laser-assisted ipsilateral rotational lamellar autokeratoplasty is effective for shifting central corneal opacities and can be considered in appropriate cases.

Current techniques of lamellar keratoplasty for keratoconus

In recent years, there has been a considerable interest regarding the concept of lamellar keratoplasty (LK), which contributed in spreading the use of this procedure in the treatment of keratoconus. This is a new frontier in corneal surgery that minimizes trauma on the recipient patient since it works on a "closed bulb". The LK surgery, in fact, aims to selectively replace diseased corneal stroma, leaving the healthy endothelium. The main advantage of LK is to avoid major causes of failure of penetrating keratoplasty as immunological rejection, and the late mismatch in the transplanted cornea, thus increasing the life of transplantation. In the last decade, several techniques of LK have been proposed, depending on how the anterior portion of the recipient cornea is removed. This article, through a literary research reviews the various emerging techniques of anterior lamellar surgery for the management of keratoconus, analyzing their indications, visual outcomes, and rate of complications.

One-stage femtolaser-assisted lamellar keratoplasty and foreign body removal

PURPOSE

To report the use of femtosecond laser platform to remove a glass foreign body (FB) and remove scar by performing sutureless lamellar keratoplasty.

CASE REPORT

A 34-year-old man presented with a posttraumatic anterior stromal scar and retained corneal glass FB after injury to his left eye, sustained in a prior vehicular accident. Right eye examination was essentially normal. Best-corrected visual acuity of the left eye was 20/320. He underwent femtosecond laser-assisted sutureless anterior lamellar keratoplasty using the 500-kHz femtosecond laser machine. The host bed and donor lenticule diameters were 7.9 and 7.8 mm and the thickness of the lenticule was 125 and 150 μm, respectively. The recipient lenticule was obtained by placing the lamellar incision that encompassed the FB. When the recipient lenticule was lifted, partially embedded FB present in the stroma was removed after dislodging it with a 26-gauge needle. The femtosecond-dissected donor button was placed onto the stromal bed with a snug fit. No sutures were taken. Postoperatively, best-corrected visual acuity improved to 20/50 at 1 month and 20/30 at 7 months of follow-up.

CONCLUSIONS

Femtosecond laser-assisted sutureless anterior lamellar keratoplasty is a promising modality for lamellar keratoplasty, and as the depth of the incision can be obtained with precision, impacted stromal FBs can be removed in a single procedure along with scars.

Femtosecond laser-assisted anterior lamellar keratoplasty for the treatment of stromal corneal pathology

BACKGROUND

To describe the initial outcomes and safety of anterior lamellar keratoplasty (ALK) assisted by a femtosecond laser for stromal corneal pathology.

METHODS

A non-comparative case series of 14 eyes (13 patients) with various stromal corneal diseases underwent ALK with a femtosecond laser. Femtosecond laser settings, technique, uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), and endothelial cell density (ECD) were measured.

RESULTS

All eyes were successfully treated without intraoperative complications. The UCVA improved in 11 eyes (78.6%) compared with preoperative UCVA. The mean difference between preoperative and postoperative UCVA was a gain of 1.7 lines (range, unchanged to 6 lines). The BCVA improved in all eyes compared with preoperative levels. The mean difference between preoperative and postoperative BCVA was a gain of 2.4 lines (range, 1-8 lines). In 3 eyes, phototherapeutic keratectomy was performed. The mean reduction in endothelial cell density was 3.7% after a mean 7.3 months of follow-up. No graft rejection, infection, or epithelial ingrowth was found.

CONCLUSIONS

Femtosecond laser-assisted ALK improved UCVA and BCVA in patients with stromal corneal pathology. Our early results indicated that the femtosecond laser produced an effective and smooth dissection through opaque corneas even deeper corneal tissue.

Femtosecond laser-assisted sutureless anterior lamellar keratoplasty for superficial corneal opacities

PURPOSE

To evaluate the visual and refractive outcomes, endothelial cell count (ECC), ocular surface changes, corneal aberrations, and biomechanical profile changes after femtosecond laser-assisted anterior lamellar keratoplasty surgery for superficial corneal scars.

SETTING

Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran.

DESIGN

Prospective case series.

METHODS

Patients with superficial corneal scars had femtosecond laser-assisted anterior lamellar keratoplasty. Visual and refractive results, ECC, ocular surface changes, corneal aberrations, and biomechanical profiles were assessed preoperatively and for 1 year postoperatively.

RESULTS

Nineteen eyes (19 patients) were evaluated. A significant decline occurred in refractive astigmatism and corneal astigmatism after 1 year. There was a nonsignificant reduction in corneal hysteresis and the corneal resistance factor from preoperatively to 1 year postoperatively. The corneal-compensated intraocular pressure (IOP) and Goldmann-correlated IOP increased during the follow-up; the increase was not significant. A statistically insignificant reduction in the root mean square for trefoil and spherical aberrations occurred between 1 month and 1 year postoperatively (P=.1 and P=.4, respectively). The decreases in primary coma and total higher-order aberrations approached significance (P=.08 and P=.07, respectively). There were no significant changes in the central corneal thickness, ECC, or ocular surface parameters. No intraoperative complications occurred.

CONCLUSION

Femtosecond laser-assisted anterior lamellar keratoplasty was an efficient and safe procedure for improving the quality of vision in patients with anterior corneal pathology, and the results remained stable during the 1-year follow-up.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

New perspectives on lamellar keratoplasty

Lamellar (anterior and posterior) keratoplasty entails the surgical replacement of diseased-only corneal tissue, while healthy host corneal tissue is preserved. Selective keratoplasty offers several advantages in comparison to penetrating keratoplasty such as a lower rate of graft rejection, less endothelial cell loss, faster/superior visual rehabilitation and enhanced resistance to closed injury. The surgical approach of "partial corneal transplantation" may be divided into anterior and posterior: techniques including superficial and deep anterior lamellar keratoplasty (SALK and DALK, respectively) and endothelial keratoplasty as well as Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK). These novel surgical procedures are rapidly becoming the preferred therapy option for specific corneal dysfunctions involving the corneal stroma (SALK, DALK), or corneal endothelium (DSAEK, DMEK). During the past decade, the continuing advancement of surgical techniques and the development of innovative surgical instruments have significantly enhanced corneal transplantation. Lamellar keratoplasty techniques facilitate corneal surgery, provide patients with superior outcomes and can successfully restore vision in corneal-related blindness. Nevertheless, more long-term evidence is needed to better evaluate these promising new techniques.

Keratoconus therapeutics advances

Keratoconus is a progressive, usually bilateral disease of the cornea that significantly diminishes visual acuity, secondary to a progressive corneal deformity which is characterized by corneal thinning, variable degrees of irregular astigmatism and specific abnormal topographic patterns. Normally it initiates during puberty and is progressive until the third or fourth decade of life, when normally the progression rate is diminished or waned. There are multiple scales to clinically classify keratoconus. One of the most commonly used is Amsler-Krumeich and recently with the development of morphometric and aberrometric techniques, additional scales have been created that allow keratoconus to be classified according to its severity. Despite certain etiology of keratoconus remains unknown, current treatment options are available in patients with ectatic corneas and they vary depending on the severity of the disease and they include spectacles, contact lenses, intrastromal rings, keratoplasty both penetrant or lamellar, cross-linking, refractive lens exchange with intraocular lens implant, phakic intraocular lenses and the combination of these alternatives. Some authors have been using excimer laser in patients with keratoconus but the safety of the procedure is controversial. Currently, the techniques for the management of keratoconus can be classified in 3 types: corneal strengthening techniques, optical optimization techniques and combined techniques.