[DALK and penetrating laser keratoplasty for advanced keratoconus]

Femtosecond-Assisted Mushroom Deep Anterior Lamellar Keratoplasty

PURPOSE

The aim of this study was to describe our technique for performing femtosecond laser (FSL)-assisted mushroom configuration in deep anterior lamellar keratoplasty (DALK).

METHODS

We describe our surgical technique for a mushroom-configuration DALK using a femtosecond laser (FSL) both to prepare the graft and to perform a precut of the recipient cornea, as well as the steps for the dissection of the recipient cornea and for donor cornea implantation. Moreover, we show the parameters of energy and spot separation and the external and internal diameters as well as the thickness of the external and internal keratotomy.

RESULTS

We performed a retrospective case series study of 20 patients with a mean follow-up of 4.36 ± 2.54 years. The indication for surgery was leukoma in 15 cases (75%), keratoconus in 4 cases (20%), and stromal corneal dystrophy in 1 case (5%). Four cases had to be converted to penetrating keratoplasty. The overall results were as follows: The mean preoperative corrected distance visual acuity increased from 0.11 ± 0.09 (0.01-0.30) to 0.78 ± 0.22 (0.30-1.0) with spectacles and to 0.92 ± 0.13 (0.5-1.0) with a gas permeable contact lens. The mean final cylinder was 3.90 ± 1.86 (1.25-7.0). The mean endothelial cell count at 6 months was 2033.83 ± 570.53 cells/mm2 (930-3207), and the mean final spherical equivalent was -4.67 ± 2.91 (-0.25 to -9.00).

CONCLUSIONS

FSL-assisted technology is useful to achieve a predictable and safe procedure when using mushroom configuration to perform DALK. Our conversion rate from DALK to penetrating keratoplasty was similar to or even lower than that reported in the literature. In the successful DALK cases, the visual and refractive results were similar to those reported in other studies using FSL-assisted DALK (with a standard or mushroom configuration).

Ultrastructural Examination of the Corneal Interface after Predescemetic Deep Anterior Lamellar Keratoplasty (DALK) - A Case Report with Light and Transmission Electron Microscopy

PURPOSE

To examine corneal buttons with light and transmission electron microscopy (TEM) to visualize the interface area and highlight the ultrastructural corneal changes after deep anterior lamellar keratoplasty (DALK).

METHODS

Two patients underwent excimer laser-assisted penetrating repeat keratoplasty after predescemetic DALK. The corneal buttons were examined by light microscopy and TEM.

RESULTS

The light microscopic examination of the corneal buttons revealed fragments of a second Descemet's membrane in the central and midperipheral areas (Case 1). In both cases, visualization of the interface area was not possible by light microscopy. The donor and host stroma were tightly attached without dehiscence. TEM identified the interface area by irregularities in the collagen distribution between the donor and host stroma. The thickness of the remaining recipient corneal stroma measured approximately 30 µm (Case 1) and 100 µm (Case 2), respectively. In the host stroma, TEM revealed the absence or degeneration of keratocytes, accumulation of amorphous material between the collagen lamellae, and vacuolar inclusions dispersed in the stroma, forming a band-like zone anterior to Descemet's membrane.

CONCLUSION

The interface area after DALK has been mainly investigated by in vivo confocal microscopy. Light microscopy and TEM findings indicate remodeling processes after DALK that are associated with increased keratocyte degeneration and structural alterations of the extracellular matrix in the host stroma. The choice of surgical method may influence the postoperative morphological and functional outcome since these findings were primarily apparent in the remaining host stroma. Therefore, complete exposure of Descemet's membrane is an important prognostic factor for the postoperative visual outcome.

[Stage-appropriate treatment of keratoconus]

Keratoconus (KC) is a progressive cone-shaped corneal protrusion that causes paracentral thinning at the apex of the cone and typically occurs asymmetrically on both sides. After a careful anamnesis and classification of the degree of severity a targeted treatment appropriate to the stage of the disease is available. If the visual acuity is no longer sufficient, rigid gas-permeable contact lenses (CL) are fitted by a specialist. Riboflavin UVA cross-linking (CXL) is recommended in cases of progression and visual acuity that is still useful for the patient. Intracorneal ring segments (ICRS) are indicated for CL intolerance in cases of reduced visual acuity and a clear central cornea. If the stage is more advanced, deep anterior lamellar keratoplasty (DALK) or penetrating keratoplasty (PKP) is recommended. A PKP is contraindicated in acute KC but deep stromal sutures for readaptation of the Descemet tear with gas filling of the anterior chamber can considerably shorten the course. Almost no other eye disease is nowadays as easily accessible for an early instrument-based diagnosis and stage-appropriate treatment as KC.

[Excimer laser-assisted DALK: a case report from the Homburg Keratoconus Center (HKC)]

Indikationen

Ziel der Excimerlaser-gestützten DALK (Excimer-DALK) ist, wie bei der mechanischen DALK, die Behandlung von Keratektasien (Keratokonus und pellucide marginale Degeneration), stromalen Narben oder stromalen Hornhautdystrophien. Voraussetzung für die Operation ist die Abwesenheit von (prä)descemetalen Narben sowie ein gesundes Endothel.

Operationstechnik

Nach der Excimerlaser-gestützten Trepanation auf 80 % der kornealen Dicke an der Trepanationsstelle, einer intrastromalen Lufteingabe (sog. „Big-Bubble“) sowie einer lamellären Hornhautpräparation erfolgt eine lamelläre anteriore Transplantation des endothelfreien Spendergewebes. Diese Technik kombiniert die Vorteile einer DALK und einer Excimerlaser-Trepanation. Wir beschreiben die Schritte einer Excimer-DALK aus unserem Homburger Keratokonus Center (HKC).

Schlussfolgerungen

Die Excimer-DALK stellt bei Patienten mit gutem Endothel eine gute Behandlungsmöglichkeit dar. Bei einer intraoperativen Perforation bleibt die Möglichkeit einer sog. Konversion zur Excimer-PKP mit allen Vorteilen der Excimerlaser-Trepanation.

Video online

Die Online-Version dieses Beitrags (10.1007/s00347-021-01342-3) enthält ein Video.

"Sclero-DALK": New approach for treatment of superficial corneal leukoma

Purpose

Present a new technique to perform a deep anterior lamellar keratoplasty (DALK) that could be an alternative to the "Big Bubble" or the Melles technique.

Observations

The case concerns a 48 years old man who presents superficial corneal leukoma in the left eye secondary to ocular trauma 14 years ago. Sclero-DALK is performed under general anesthesia obtaining an excellent visual and refractive result.

Conclusions and Importance

Sclero-DALK is a novelty in surgical treatment of corneal surface opacities. It offers the same advantages than conventional DALK since it is also a non-penetrating extraocular technique. Better final visual acuities are expected with this technique in comparision with PK and the conventional DALK because less residual stroma can be remained since we acces directly to the predescemetic space.

[Modern methods of surgical treatment of keratectasias]

Keratectasia (KE) ranks as one of the main causes of impaired vision. The pathology is characterized by progressive thinning of the cornea, which causes its deformation, the appearance of irregular astigmatism, and the reduction of vision acuity. The article reviews modern surgical methods that can be used to prevent the progression and treat various types of KE.

Penetrating Keratoplasty for Keratoconus - Excimer Versus Femtosecond Laser Trephination

BACKGROUND

In case of keratoconus, rigid gas-permeable contact lenses as the correction method of first choice allow for a good visual acuity for quite some time. In a severe stage of the disease with major cone-shaped protrusion of the cornea, even specially designed keratoconus contact lenses are no more tolerated. In case of existing contraindications for intrastromal ring segments, corneal transplantation typically has a very good prognosis.

METHODS

In case of advanced keratoconus - especially after corneal hydrops due to rupture of Descemet's membrane - penetrating keratoplasty (PKP) still is the surgical method of first choice. Noncontact excimer laser trephination seems to be especially beneficial for eyes with iatrogenic keratectasia after LASIK and those with repeat grafts in case of "keratoconus recurrences" due to small grafts with thin host cornea. For donor trephination from the epithelial side, an artificial chamber is used. Wound closure is achieved with a double running cross-stitch suture according to Hoffmann. Graft size is adapted individually depending on corneal size ("as large as possible - as small as necessary"). Limbal centration will be preferred intraoperatively due to optical displacement of the pupil. During the last 10 years femtosecond laser trephination has been introduced from the USA as a potentially advantageous approach.

RESULTS

Prospective clinical studies have shown that the technique of non-contact excimer laser PKP improves donor and recipient centration, reduces "vertical tilt" and "horizontal torsion" of the graft in the recipient bed, thus resulting in significantly less "all-sutures-out" keratometric astigmatism (2.8 vs. 5.7 D), higher regularity of the topography (SRI 0.80 vs. 0.98) and better visual acuity (0.80 vs. 0.63) in contrast to the motor trephine. The stage of the disease does not influence functional outcome after excimer laser PKP. Refractive outcomes of femtosecond laser keratoplasty, however, resemble that of the motor trephine.

CONCLUSIONS

In contrast to the undisputed clinical advantages of excimer laser keratoplasty with orientation teeth/notches in keratoconus, the major disadvantage of femtosecond laser application is still the necessity of suction and applanation of the cone during trephination with intraoperative pitfalls and high postoperative astigmatism.

Traumatic globe rupture after deep anterior lamellar keratoplasty-A novel management technique

A traumatic wound dehiscence can occur many years after surgery in 2-6% of all keratoplasties. Intraocular tissue prolapse can lead to severe visual loss. Deep anterior lamellar keratoplasty (DALK) leads to higher wound stability because of the intact Descemet membrane. We report a case of a novel management of wound dehiscence following DALK. A 59-year-old patient underwent uncomplicated DALK for advanced keratoconus. Eighteen months later he experienced a traumatic wound dehiscence (globe rupture) after a fall. Visual acuity decreased to light perception on the affected eye, the iris and prolapsed vitreous were incarcerated, and no retinal details were recognizable. The corneal graft was dehiscent over eight clock hours, the Descemet membrane was ruptured, and the stroma dissolved over 30% of its surface in a bell shape. Primary wound closure was performed with nylon 10-0 single interrupted corneal sutures. One day after emergency treatment, a 23-gauge pars-plana-vitrectomy for vitreous hemorrhage was conducted and a retinal tear was treated with laser photocoagulation. The Descemet membrane was repositioned using a 23 g vitrectomy probe under air and the globe was filled with SF₆ gas. Postoperatively, visual acuity increased to 6/15 and the cornea cleared up. Corneal graft and Descemet membrane repositioning after trauma can avoid a further keratoplasty and the risk of immunological rejection of donor endothelial cells. Clin. Anat. 31:56-59, 2018. © 2017 Wiley Periodicals, Inc.

Comparison of visual and topographic outcomes of deep-anterior lamellar keratoplasty and penetrating keratoplasty in keratoconus

AIM

To compare visual, surgical and topographic outcomes of deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) for keratoconus (KC).

METHODS

In this multicenter, prospective, randomized clinical trial 76 eyes of 71 KC patients operated between January 2011 and July 2014 in 2 tertiary referral hospitals were included. Consecutive patients were alternately selected to receive one of the two surgical methods. Thirty eight eyes underwent DALK with the big-bubble technique and 38 eyes underwent PK.

RESULTS

Mean best spectacle corrected visual acuity (BSCVA) at the first postoperative week (P=0.012) and the first postoperative month (P<0.001) was statistically significantly higher in DALK group. The mean BSCVA at 12mo was not significantly different for DALK (0.30±1.99 logMAR) versus PK (0.40±0.33 logMAR) (P=0.104). The 76.3% of the eyes had a BSCVA over 0.5 in DALK and 47.4% in PK group (P=0.009). The 7.9% of the eyes had a BSCVA of 1.0 in DALK and 5.3% in PK group (P=0.644). Mean spherical equivalent was -2.94 D in DALK and -3.09 D in PK group. Mean topographic astigmatism was 4.62 D and 4.18 D respectively. Regular topographic patterns were observed in 31 (81.6%) of DALK and 29 (76.3%) of PK (P=0.574). The most frequent topographic pattern was oblate asymmetric bow tie, seen in 39.5% in DALK and 23.7% in PK.

CONCLUSION

Big bubble DALK provides an earlier visual improvement compare to PK. However, visual and topographic outcomes are similar to those in PK at 1y. Postoperative complications including rejection and intraocular pressure elevation are more frequent in PK. DALK is a safer alternative to PK for KC. However, intraoperative perforation of the Descemet's membrane is a significant complication.

[Update: Deep anterior lamellar keratoplasty (DALK) for keratoconus. When, how and why]

BACKGROUND

The treatment of keratoconus has been significantly expanded in recent years. In addition to the previous options for correction by fitting hard contact lenses and penetrating keratoplasty (PK), corneal cross-linking and lamellar transplantation techniques have been added.

OBJECTIVE

The aim of this review article is to highlight currently available options for minimization of complications and standardization of deep anterior lamellar keratoplasty (DALK) for keratoconus.

MATERIAL AND METHODS

This article summarizes our own data and gives a review of the literature in PubMed.

RESULTS

Performing DALK can provide keratoconus patients with corneal grafts with considerably longer graft survival and a reduced risk of complications.

CONCLUSION

The DALK procedure provides numerous advantages over PK, especially the reduced intraoperative opening of the eye, which thus reduces the risk of serious intraoperative complications. A further benefit is the complete absence of postoperative endothelial immune reactions as the recipient's endothelium remains untouched. The absence of endothelial immune reactions is especially advantageous for young patients with keratoconus and patients with an increased risk of graft rejection, e.g. in atopic dermatitis; however, there are also typical complications of DALK that do not occur during PK. The outlined strategies for standardization of DALK and avoidance of intraoperative and postoperative complications should make DALK safer and more reproducible and lead to possible establishment as a standard procedure in keratokonus.

[Complications of deep anterior lamellar keratoplasty. Avoid, recognize and treat]

Deep anterior lamellar keratoplasty (DALK) offers tremendous advantages over penetrating keratoplasty (PK). Intraoperative safety is increased due to reduced opening of the eye interoperatively and the fact that no endothelial graft rejection can take place as the patient's own corneal endothelium is retained. Despite these advantages the number of DALK procedures performed each year in Germany remains constant at a low level. One reason could be that the DALK technique offers some complexity and at the same time intraoperative conversion to PK has to be performed in some cases due to rupture of Descemet's membrane. Moreover, interface-related and DALK-specific complications exist which can contribute to an unfavorable visual outcome. Most of these complications, such as incomplete attachment of Descemet's membrane or opacification within the interface between Descemet's membrane and the posterior corneal stoma can be resolved by adequate measures making PK for revision barely necessary. As visual acuity does not differ between PK and DALK, the benefits of DALK - lack of endothelial immune reaction and increased ocular stability during surgery - outweigh the risk of additional complications and DALK should therefore be performed whenever appropriate.

In Vivo Confocal Microscopic Imaging of the Cornea After Femtosecond and Excimer Laser-assisted Penetrating Keratoplasty

PURPOSE

To examine the microstructure of the cornea after excimer and femtosecond laser-assisted penetrating keratoplasty (ELAK and FLAK) in eyes with Fuchs' dystrophy and keratoconus.

METHODS

Fifty-seven patients were divided into four groups according to corneal disease and surgical technique: Fuchs' dystrophy and ELAK (n = 9; mean age: 70.4 ± 10.6 years); Fuchs' dystrophy and FLAK (n = 13; mean age: 64.3 ± 11.2 years); keratoconus and ELAK (n = 9; mean age: 47.4 ± 13.9 years); and keratoconus and FLAK (n = 9; mean age: 43.5 ± 13.8 years). The control group comprised individuals without ocular disease (n = 17; mean age: 39.9 ± 17.3 years). In vivo investigation of the corneal graft and graft-host junction zone was performed with confocal corneal microscopy.

RESULTS

All corneal grafts were transparent and no rejection reaction could be observed during the follow-up period. Confocal microscopy revealed no difference in basal epithelial cell density compared to controls. Anterior keratocyte density was lower than in the control group (818 ± 131 cells/mm(2)) in all four treatment groups (596 ± 174, 586 ± 113, 529 ± 75, 552 ± 91 cells/mm(2)). Langerhans cells could barely be seen; there was no difference in the cutting edge configuration and wound integrity.

CONCLUSIONS

In vivo confocal microscopy provided evidence that good alignment of graft-host junction could be created with both techniques. The excimer laser was not inferior to the femtosecond laser in performing corneal cuts. The low density of Langerhans cells revealed well-controlled cellular immunological response and sustained corneal integrity in both laser groups.

[Current treatment options with artificial corneas: Boston Kpro, Osteo-odontokeratoprosthesis, Miro Cornea® and KeraKlear®]

BACKGROUND

Although corneal transplant surgery in avascular normal risk eyes is becoming even more minimally invasive and successful, treatment options for difficult to treat patients with high risk eyes are still limited. In these cases HLA typed allogeneic transplants and artificial corneas (keratoprostheses) can be used.

METHODS

This article combines a review of the literature in PubMed and own clinical experiences on the use of artificial corneas in high risk eyes. Osteo-odontokeratoprosthesis (OOKP), Boston Kpro, Miro Cornea® and KeraKlear® corneas were used as clinical keratoprostheses.

RESULTS

Worldwide, the most experience exists for the use of Boston Kpro and OOKP in high risk eyes. Miro Cornea® and KeraKlear® are new procedures where only preliminary results are available and further evaluation is necessary. The longest experience and best anatomical long-term results have been achieved with OOKPs. Comparable cohorts are available for the Boston Kpro. The function of all keratoprostheses is threatened by secondary glaucoma. Implantation of the KeraKlear® prosthesis remains difficult. The Miro Cornea® shows an initially stable integration behavior.

CONCLUSION

Keratoprostheses, such as the Boston Kpro and OOKP are valid treatment options for eyes which are not open to therapy with allogeneic corneal transplantation. Modern implants such as KeraKlear® prosthesis and Miro Cornea® need further prospective clinical evaluation.

Deep anterior lamellar keratoplasty using irradiated acellular cornea with amniotic membrane transplantation for intractable ocular surface diseases

Purpose

To report the clinical outcomes of deep anterior lamellar keratoplasty (DALK) when sterile gamma-irradiated acellular corneal tissues (VisionGraft) are used in combination with amniotic membrane transplantation (AMT) for intractable ocular surface diseases.

Methods

The medical records of fifteen patients who had DALK with AMT were retrospectively reviewed. Indications for surgery included ocular burn, bacterial keratitis, herpes simplex virus keratitis, corneal opacity with Stevens-Johnson syndrome, Mooren's ulcer, idiopathic myxoid degeneration of corneal stroma, and recurrent band keratopathy. DALK was performed using partial-thickness acellular corneal tissue and a temporary amniotic membrane patch was added at the end of the operation.

Results

All cases that underwent DALK with AMT became epithelialized within 2 postoperative weeks. Twelve patients showed favorable outcomes without graft rejection, corneal opacification, or neovascularization. The other three grafts developed corneal opacification and neovascularization, and required additional penetrating keratoplasty (PK). Unlike the results of previous PKs, there were no graft rejections and the graft clarity was well-maintained in these three cases for at least 8 months after PK.

Conclusions

DALK using sterile acellular corneal tissues in combination with AMT may be a good therapeutic strategy for treating intractable ocular surface diseases because of lowered immune rejection, fibroblast activation, and facilitation of epithelialization. Furthermore, DALK can help stabilize the ocular surface, prolong graft survival, and may allow better outcomes when combined with subsequent PK.