A new surgical technique for deep lamellar keratoplasty with single running suture adjustment

Analysis in Results of Microbiologic Exam Related to Donor Corneas

Purpose: This study analyzed the microorganisms identified in donor corneas and their clinical significance.Methods: The medical records of 94 patients (114 eyes) who underwent keratoplasty and microbiological tests of the donor corneas from October 2008 to December 2020 at our hospital were reviewed retrospectively. During keratoplasty, we conducted microbiological tests of the corneoscleral rim of the donor cornea and preserving solution Optisol™-GS (Bausch & Lomb, Rochester, NY, USA), and examined the antibiotic susceptibility of bacterial isolates from the cultures.Results: Some isolates of domestic donor corneas revealed bacteria, but none of the imported corneas did. Gram-negative bacilli were detected from the corneoscleral rim in three eyes (2.6%): two cases of Acinetobacter baumannii/haemolyticus and one case of Pseudomonas aeruginosa. In one case (0.9%), Acinetobacter baumannii/haemolyticus was identified from preserving solution, with no bacteria found in the corneoscleral rim. Antibiotic susceptibility tests showed multi-drug resistance, except to colistin. In all cases where bacteria were detected, there was no keratitis or endophthalmitis after corneal transplantation.Conclusions: Although rare, bacteria can be identified from donor corneas or the preserving solution used in corneal transplantation. Therefore, caution is needed in all processes dealing with donor corneas. Empirical antibiotics that have sufficient antimicrobial activity to suppress multi-drug resistant bacteria should be selected in corneal transplantation.

Femtosecond laser-assisted big bubble for deep anterior lamellar keratoplasty

PURPOSE

To assess the utility of a femtosecond laser-assisted stromal channel to assist the creation of a big bubble (BB) for deep anterior lamellar keratoplasty (DALK) surgery in cadaveric corneas.

SETTING

L V Prasad Eye Institute, Hyderabad, India.

DESIGN

Experimental study.

METHODS

An attempt to create a BB was made on 10 donor pairs of human cadaveric corneoscleral tissues. The 20 corneas were split into 2 groups: Group A underwent femtosecond laser pretreatment and Group B had conventional manual deep lamellar technique. Laser pretreatment was performed using the VisuMax femtosecond laser system to create a stromal channel using the intracorneal ring segment treatment module for direct insertion of the 27-gauge air cannula for pneumodissection at a predetermined depth.

RESULTS

Of the 20 corneas studied, type 1 BB was achieved in 9 of 10 corneas in Group A and in 7 of 10 corneas in Group B. One cornea from Group A had a combined type 1 and 2 BB, whereas no BB was achieved in 1 cornea.

CONCLUSIONS

Creation of an intrastromal channel using a femtosecond laser at a predetermined depth seemed to be a promising option to increase the chances of achieving a BB when compared with the conventional air injection technique of BB DALK.

Two-step keratoplasty for deep vascularized corneal opacity with severe peripheral thinning following Acanthamoeba keratitis

PURPOSE

In cases of corneal opacity with vascularization and peripheral thinning, traditional keratoplasty techniques have several risks and drawbacks. We report the results of a two-step surgical strategy consisting in performing a large diameter tectonic lamellar keratoplasty (TLK) to restore appropriate corneal thickness and an avascular recipient bed, followed by central optical PK within the lamellar graft at a later date.

METHODS

This single-institution study analyzes the results of 7 eyes of 7 patients who received PK after large diameter TLK. All patients were affected by deep post-infectious corneal opacity with persistent stromal vascularization and peripheral thinning. The main outcomes measured were graft survival, visual acuity, refraction, and endothelial cell density.

RESULTS

TLK was performed in all cases with 10/10.1-mm diameters. After a mean interval of 14 months, central PK was performed with a median host-graft diameter of 7.75/8.25 mm. Mean follow-up after PK was 52 months. At last follow-up, 6/7 (86%) grafts were clear. Endothelial rejection occurred in 5/7 (71%) eyes, with one patient having multiple episodes and subsequent graft failure. At 2 years, all patients had a visual acuity ≥ 20/40, with an average refractive astigmatism of 3.75 diopters.

CONCLUSION

Optical PK within a previous TLK is a safe and efficient technique for treating deep corneal opacity associated with extensive vascularization and peripheral thinning. Extended follow-up period is necessary to assess endothelial cell loss and long-term efficacy of the procedure.

Total or subtotal full thickness recipient bed cut to repair donor-recipient curvature disparity in cases of DM rupture with manual DALK

PURPOSE

To report how to manage a specific type of Descemet's membrane (DM) rupture during manual DALK with a concurrent donor-recipient disparity of curvature.

METHODS

Case report of two patients that had DM rupture during manual DALK with a concurrent donor-recipient disparity of curvature; the recipient bed was flatter (post-infectious scar, case 1) and steeper (keratoglobus, case 2) than the donor. Preoperative diagnosis, clinical exam, and best spectacle correct visual acuity (BSCVA) have been reported. A subtotal full-thickness circular cut of the recipient bed was performed to resolve a persistent double AC in case 1 (recipient flatter than donor). A total full-thickness circular cut of the recipient bed, creating a graft made by a DALK allograft and a "DSEK autograft," was performed to avoid a refractory double AC in case 2 (recipient steeper than donor). Evaluated outcomes included postoperative BSCVA, endothelial cell count (ECC), graft clarity, rejection, and presence/absence of double AC.

RESULTS

Surgery was successful in resolving/avoiding double AC. VA improved in both cases. No episodes of rejection were recorded. Graft remained clear at the last follow-up (6 years for case 1 and 4 years for case 2).

CONCLUSION

The existence of a donor-recipient curvature disparity should be investigated as a possible underlying mechanism of refractory double AC. Total or subtotal full thickness recipient bed cut may be considered to repair donor-recipient curvature disparity in cases of DM rupture occurring during manual DALK. Repairing the DM rupture and avoiding a conversion to PK in high-risk transplant cases are crucial.

Approaches toward enhancing survival probability following deep anterior lamellar keratoplasty

The greatest advantage of deep anterior lamellar keratoplasty over full-thickness corneal transplantation is the elimination of graft failure caused by endothelial rejection. Despite this advantage, a deep anterior lamellar keratoplasty graft can fail because of several factors, such as complications related to the donor-recipient interface, graft epithelial abnormalities, graft vascularization, stromal graft rejection, and recurrence of herpetic keratitis. Increased deep anterior lamellar keratoplasty graft survival is mainly built upon optimization of the ocular surface to provide a hospitable environment for the graft. Any predisposing factors for graft epithelial abnormalities, corneal neovascularization, and preexisting vernal keratoconjunctivitis should be identified and treated preoperatively. Prompt recognition and appropriate treatment of interface-related complications and stromal graft rejection usually result in good anatomic outcomes, with no detrimental effects on vision.

Novel Technique For The Management Of Macroperforation During Deep Anterior Lamellar Keratoplasty

Purpose

To describe the outcomes of a case series of patients who underwent a novel technique for managing macroperforation during deep anterior lamellar keratoplasty (DALK).

Methods

Nine eyes of 9 patients with advanced keratoconus who underwent DALK comprised the case series. A macroperforation occurred in all eyes during DALK. The stromal patch suturing technique was used to manage all cases; a large piece of the previously excised stromal tissue was sutured to the edge of the trephine to seal the perforation. The technical aspects of the procedure are described and data are presented on the visual outcomes, endothelial microscopy, and postoperative complications at last postoperative visit (average 18 months; range, 7 to 23 months).

Results

All 9 cases were managed successfully with the stromal patch suturing technique. Postoperatively, the graft was clear in all cases. At day 1, seven eyes had a Descemet’s membrane detachment, 3 of these eyes resolved spontaneously within 2 weeks and 4 required air bubble injection for successful reattachment. At last follow up seven eyes had a corrected distance visual acuity of 20/30 or better and 2 eyes had 20/40 vision. The average endothelial cell count was 2162 cell/mm². There were no cases with excessive inflammation or vascularisation during the postoperative follow-up.

Conclusion

The stromal patch suturing technique was successfully used to manage intraoperative macroperforation during DALK. This technique resulted in endothelial changes that were consistent with uncomplicated DALK and function visual acuity of 20/40 or better in all cases with no postoperative sequelae.

Graft rejection-like reactions in the early postoperative period after deep anterior lamellar keratoplasty for keratoconus: a retrospective study

Background

Deep anterior lamellar keratoplasty (DALK) is indicated to correct high astigmatism in patients with keratoconus (KC) and no evidence of Descemet’s membrane rupture. However, some patients with KC experience graft rejection-like inflammatory reactions within 2 months (usually in the first week) after DALK. The aim of this study was to identify the characteristics and influencing factors of these reactions by reviewing the records of patients who underwent DALK or penetrating keratoplasty (PKP) for KC or other corneal problems.

Methods

We retrospectively reviewed the medical records of patients who underwent DALK for KC (DALK/KC), PKP for KC (PKP/KC), or DALK for other corneal problems (DALK/non-KC) at Ban Buntane Hotokukai Hospital between January 2006 and December 2015 and who were followed for more than 1 year. We collected data on the characteristics and incidence of severe inflammatory graft reactions in the early postoperative phase (ie, within 2 months after keratoplasty) and visual outcomes after these inflammatory reactions.

Results

Postoperative inflammatory reactions characterized by persistent epithelial defects, loose suture with infiltration, and vessel invasion occurred in seven of eleven DALK/KC patients, three of 50 DALK/non-KC patients, and none of five PKP/KC patients. These reactions were nonresponsive to topical steroids, and suture removal was required. Although a clear corneal graft in the pupillary area was obtained and best-corrected visual acuity was good after the resolution of inflammation, a risk of corneal astigmatism remained.

Conclusion

The incidence of these reactions in the early postoperative period is high after DALK for KC. These reactions do not respond well to topical steroids, and suture removal may be required, which may cause high astigmatism after the inflammation subsides. Lamellar keratoplasty should be considered carefully for patients with KC.

Lamellar keratoplasty techniques

Lamellar keratoplasty (LK) has revolutionized corneal graft surgery in several ways. Deep anterior LK (DALK) has eliminated risk of failure due to endothelial rejection. Endothelial keratoplasty (EK) has almost eliminated induced astigmatism and the “weak” graft–host junction as seen with penetrating keratoplasty (PK) and also reduced the risk of endothelial rejection. LK provided new insights into posterior corneal anatomy that led to better understanding and performance of DALK and to the development of another EK procedure, namely pre-Descemet's EK (PDEK). Surgical procedures for LK were further refined based on the improved understanding and are able to deliver better surgical outcomes in terms of structural integrity and long-term patient satisfaction, reducing the need of further surgeries and minimizing patient discomfort. In most specialist centers, anterior lamellar techniques like DALK and EK techniques like Descemet's stripping EK (DSEK) and Descemet's membrane EK (DMEK) have replaced the full-thickness PK where possible. The introduction of microkeratome, femtosecond laser, and PDEK clamp have made LK techniques easier and more predictable and have led to the innovation of another LK procedure, namely Bowman membrane transplant (BMT). In this article, we discuss the evolution of different surgical techniques, their principles, main outcomes, and limitations. To date, experience with BMT is limited, but DALK has become the gold standard for anterior LK. The EK procedures too have undergone a rapid transition from DSEK to DMEK and PDEK emerging as a viable option. Ultrathin-DSEK may still have a role in modern EK.

Cataract surgery after deep anterior lamellar keratoplasty and penetrating keratoplasty in age- and disease-matched eyes

PURPOSE

To assess the efficacy and safety of cataract surgery after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP).

SETTING

Tokyo Dental College Ichikawa General Hospital, Chiba, Japan.

DESIGN

Retrospective case series.

METHODS

Age-matched and disease-matched eyes that had phacoemulsification and intraocular lens insertion after DALK or PKP were studied. Graft clarity was assessed at the final follow-up. The difference in the endothelial cell density (ECD), corrected distance visual acuity (CDVA), spherical equivalence, and refractive error between the expected values and values 1, 3, 6, and 12 months after cataract surgery were compared between the 2 groups.

RESULTS

Indications for keratoplasty were corneal stromal scar (22 eyes), lattice dystrophy (2 eyes), keratoconus (2 eyes), and postherpetic keratitis (4 eyes). All 30 eyes in each group had successful cataract surgery after keratoplasty. Graft clarity rates were 90.0% and 80.0% in the DALK group and PKP group, respectively (P = .47). The decrease in ECD at 12 months was significantly greater in the PKP group than in the DALK group (8.7% [SD] ± 21.7% versus 26.3% ± 27.8%) (P = .043). The CDVA was significantly improved in both groups. At 1 month, the mean refractive error was -0.5 diopter (D) ± 2.4 (SD) in the DALK and -0.4 ± 1.9 D in the PKP groups and remained stable thereafter.

CONCLUSIONS

Cataract surgery was successfully performed in eyes that had DALK or PKP, providing excellent visual and refractive outcomes. In cases of combined cataract and corneal pathology, and in the absence of endothelial involvement, DALK followed by cataract surgery might cause less endothelial damage.

Air-Guided Manual Deep Lamellar Keratoplasty

Purpose

To evaluate the efficacy of a new modified technique of deep lamellar keratoplasty (DLK).

METHODS

Nine eyes of eight patients with keratoconus of moderate degree were included. All patients underwent DLK with manual dissection from a limbal side port after an air bubble injection in the anterior chamber. The patients underwent a complete ophthalmologic examinations months after the suture removal, evaluating best-corrected visual acuity, corneal thickness, endothelial cell count, and topographic astigmatism.

Results

One case (11.1%) was converted to penetrating keratoplasty because of micro-perforation. In the eight successful cases, 7 eyes (77.8%) achieved 20/30 or better visual acuity 6 months after suture removal. Mean postoperative pachymetry was 604.76μm (SD 46.76). Specular microscopy 6 months after suture removal revealed average endothelial cell count of 2273/mm2 (SD 229).

CONCLUSIONS

This modified DLK technique is a safe and effective procedure and could facilitate, after a short learning curve, this kind of surgery with a low risk of conversion to penetrating keratoplasty.

Air-Guided Manual Deep Anterior Lamellar Keratoplasty: Long-Term Results and Confocal Microscopic Findings

Purpose

To evaluate the long-term results of air-guided manual deep anterior lamellar keratoplasty (DALK) and to perform confocal microscopy on postoperative DALK corneas.

Methods

Seven postoperative consecutive DALK corneas were evaluated 1 year after suture removal. All patients underwent a complete ophthalmologic examination evaluating visual acuity, astigmatism, corneal thickness, and endothelial cell count. Confocal microscopy was performed to examine the corneas of the seven eyes and to obtain the measured interface depth.

Results

Eighteen months after surgery, the mean postoperative uncorrected visual acuity was 20/38 and the mean best-corrected visual acuity was 20/23. Postoperative mean value of residual recipient stroma thickness was 65.57 μm ± 28.74.

Conclusions

Maximum depth DALK can lead to significant advantages for quality of vision when compared to other types of anterior lamellar keratoplasty. Still, it remains a challenging procedure. These results show that a deep dissection without baring Descemet membrane makes good visual results possible, preventing corneal perforation and conversion to penetrating graft.

Updates on Managements for Keratoconus

Purpose

Keratoconus is a progressive disease of the cornea which can lead to blindness as irregular astigmatism increases. Currently, a variety of methods are available for the treatment of keratoconus, and in certain cases, it may be difficult to choose the most appropriate option. This article reviews available treatment modalities for keratoconus to provide the practitioner with practical and useful information for selecting the most suitable option for each individual patient.

Methods

To review treatment methods for different stages of keratoconus, PubMed (United States National Library of Medicine) and Scopus (Elsevier BV) databases were searched using the keywords “keratoconus”, “contact lens”, “cross-linking”, “Intacs”, “keratoplasty”, “gene therapy”, and “irregular astigmatism”, and related articles were reviewed based on disease assessment parameters and treatment methods.

Results

Various methods are available for the treatment of keratoconus: eyeglasses and contact lenses in the early stages, cross-linking for stabilizing disease progression, intrastromal corneal ring segments (ICRS) for reducing refractive errors or flattening the cornea, and penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK), conductive keratoplasty, gene therapy and more recently, bowman layer transplantation (BL transplantation) in advanced stages of the disease. To achieve optimum results, it is essential to choose the best option for each individual patient.

Conclusions

A commonality of the reviewed papers was the advancement of novel diagnostic and treatment methods in ophthalmology, which can delay the need for corneal grafting. A better understanding of keratoconus treatment options can help enhance visual rehabilitation and prevent blindness in keratoconus patients.

New parameters in assessment of human donor corneal stroma

PURPOSE

To provide quantitative parameters for assessment of human donor corneal stroma by imaging stromal features of diseased and normal human corneas with full-field optical coherence microscopy (FFOCM), using confocal microscopy (CM) and histology as reference techniques.

METHODS

Bowman's layer (BL) thickness and keratocyte density were assessed ex vivo in 23 human donor corneas and 27 human pathological corneas (keratoconus and other corneal disorders) with FFOCM, CM and histology. Stromal backscattering was assessed with FFOCM. Additionally, 10 normal human corneas were assessed in vivo with CM.

RESULTS

In FFOCM, the logarithm of the normalized stromal reflectivity was a linear function of stromal depth (R²  = 0.95) in human donor corneas. Compared with keratoconus corneas, human donor corneas featured higher BL thickness (p = 0.0014) with lower coefficient of variation (BL-COV; p = 0.0002), and linear logarithmic stromal reflectivity with depth (higher R² , p = 0.0001). Compared with other corneal disorders, human donor corneas featured lower BL-COV (p = 0.012) and higher R² (p = 0.0001). Using the 95% confidence limits of the human donor cornea group, BL thickness < 6.5 μm (sensitivity, 57%; specificity, 100%), BL-COV > 18.6% (79%; 100%) and R²  < 0.94 (93%; 71%) were revealed as indictors of abnormal cornea. In CM, keratocyte density decreased with stromal depth (r = -0.56). The mean overall keratocyte density (cells/mm² ) was 205 in human donor corneas, 244 in keratoconus, 176 in other corneal disorders and 386 in normal corneas.

CONCLUSION

Full-field optical coherence microscopy (FFOCM) provides precise and reliable parameters for non-invasive assessment of human donor corneal stroma during storage, enabling detection of stromal disorders that could impair the results of keratoplasty.

Deep anterior lamellar keratoplasty of dog eyes using the big-bubble technique

This study was conducted to establish the feasibility of corneal transplantation using the big-bubble technique (BBT) to perform deep anterior lamellar keratoplasty (DALK) in three dogs. After the cornea was trephined 750 µm, 4 mL of air was injected, and the blanched stroma was removed to expose Descemet's membrane (DM). The donor corneal button, which was gently stripped off the DM, was sutured onto the bare DM of the recipient cornea. The dogs received topical antibiotics every 6 h for 7 days and 2% cyclosporine ointment every 12 h for 1 month. The eyes were examined post-operatively at 7, 14, 21, 28 and 150 days. The central portion of the transplanted cornea stayed transparent while corneal haze developed around the transplanted margin. Menace response was normal even though the transplanted cornea was edematous until 3 weeks after surgery. A marginal haze was rarely observed between the donor and recipient corneas at 150 days after the operation. A spotted haze developed in the central part of the deep stroma near the DM. Upon histopathological examination, the stroma and epithelium of the donor cornea had normal structures. Corneal transplantation using DALK with BBT can be performed in dogs preserving the healthy endothelium.

Femtosecond laser-assisted in situ keratomileusis for the correction of residual ametropia after deep anterior lamellar keratoplasty: a pilot investigation

PurposeTo evaluate the refractive and visual results of one-stage laser-assisted in situ keratomileusis with femtosecond laser (Femto-LASIK) for the correction of residual ametropia after deep anterior lamellar keratoplasty (DALK).MethodsThis retrospective study included 13 eyes of 12 patients, who underwent corneal Femto-LASIK to correct refractive errors after DALK. IntraLase FS150 was used to create a lamellar flap and excimer laser ablation for refractive correction was performed using the Star S4 IR Excimer Laser in eight cases and the Technolas 217z Excimer Laser in Tissue Saving mode in five cases. Perioperative variables of interest included uncorrected (UDVA) and corrected (CDVA) distance visual acuities, manifest refraction and corneal topography.ResultsThe mean spherical equivalent preoperatively was -4.85±2.82 (range, -9.5 to 0 D). At the last visit the mean postoperative spherical equivalent (SE) was -0.44±0.67 D (P<0.05). The mean postoperative UDVA was 0.12±0.12 logMAR. There was a statistically significant increase in CDVA 6 months after Femto-LASIK (P<0.05). Intraoperative and postoperative complications did not develop in this series of eyes.ConclusionsCorrecting the preoperative manifest refractive error with Femto-LASIK led to a significant improvement in the UDVA and CDVA without surgical complications.

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.

Refractive outcomes of penetrating keratoplasty and deep anterior lamellar keratoplasty in fellow eyes for keratoconus

PURPOSE

To compare the refractive outcomes following penetrating keratoplasty and deep anterior lamellar keratoplasty in fellow eyes in patients with keratoconus.

METHODS

This is an observational retrospective review of consecutive patients with keratoconus first managed with penetrating keratoplasty in one eye and then with lamellar keratoplasty in the fellow eye, between 2002 and 2007. Data collection was based on patients' hospital records. Information related to assessment before surgery and at 1, 3, 6, 12, 24, and 48 months after keratoplasty were retrieved and considered in the analysis. Clinical evaluations included patients' medical histories and diagnosis of keratoconus, uncorrected and best corrected visual acuity, spherical equivalent, refractive cylinder, topographic cylinder, and high-order aberrations, complications, and adverse reactions. Data on contrast sensitivity, central corneal thickness, and central residual bed thickness (only for lamellar keratoplasty) were retrieved from anterior segment optical coherence tomography observation performed at 48 months.

RESULTS

Sixteen patients (32 eyes), 7 males and 9 females, were included in the analyses. After 4 years from transplantation, at the end of follow-up, no statistically significant differences were found in visual acuity and refractive measures between the two keratoplasties. Perforating keratoplasty showed significant differences for contrast sensitivity at 6 cpd with maximum glare (p = 0.026) and without glare (p = 0.015). Deep anterior lamellar keratoplasty showed a negative correlation between central residual bed thickness and best corrected visual acuity (R = -0.414, p < 0.001).

CONCLUSIONS

The manual pre-descemetic deep anterior lamellar keratoplasty used in this study showed refractive and visual results comparable to those obtained with penetrating keratoplasty. Such results indicated that leaving healthy stroma attached to Descemet's membrane does not compromise the clinical outcome in the short and long term after surgery.

Clinical outcomes and risk factors for graft failure after deep anterior lamellar keratoplasty and penetrating keratoplasty for macular corneal dystrophy

PURPOSE

The aim of this study was to compare visual acuity, clinical outcomes, complications, and risk factors for graft failure after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) for macular corneal dystrophy.

METHODS

Retrospective comparative case series.

RESULTS

The PK group consisted of 109 eyes of 84 patients and the DALK group consisted of 21 eyes of 20 patients. The mean logarithm of the minimum angle of resolution best-corrected visual acuity at 3 and 12 months was 0.5 versus 0.5 (P = 0.285) and 0.4 versus 0.4 (P = 0.67) in the DALK and PK groups, respectively. There was no significant statistical difference in astigmatism and spherical equivalent between the 2 groups at 12 months. In the PK group, graft rejection that was the most common cause of graft failure was seen in 27 eyes (25%), of which 55% occurred within 1 year. In the DALK group, Descemet membrane microperforation occurred in 5 eyes (24%) intraoperatively, and early postoperative Descemet membrane detachment with double anterior chamber occurred in 9 eyes (43%). Kaplan-Meier estimate of graft survival in PK versus DALK groups were 93% versus 80% at 1 year and 78% versus 70% at 4 years, respectively.

CONCLUSIONS

Visual and refractive outcomes are comparable between DALK and PK groups. DALK was superior to PK in its safety against postoperative complications such as endothelial rejection and secondary glaucoma. Graft failure in DALK was mostly associated with either intraoperative or early postoperative complications. DALK is a viable surgical option in cases with macular corneal dystrophy.

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.

Keratoconus: tissue engineering and biomaterials

Keratoconus (KC) is a bilateral, asymmetric, corneal disorder that is characterized by progressive thinning, steepening, and potential scarring. The prevalence of KC is stated to be 1 in 2000 persons worldwide; however, numbers vary depending on size of the study and regions. KC appears more often in South Asian, Eastern Mediterranean, and North African populations. The cause remains unknown, although a variety of factors have been considered. Genetics, cellular, and mechanical changes have all been reported; however, most of these studies have proven inconclusive. Clearly, the major problem here, like with any other ocular disease, is quality of life and the threat of vision loss. While most KC cases progress until the third or fourth decade, it varies between individuals. Patients may experience periods of several months with significant changes followed by months or years of no change, followed by another period of rapid changes. Despite the major advancements, it is still uncertain how to treat KC at early stages and prevent vision impairment. There are currently limited tissue engineering techniques and/or "smart" biomaterials that can help arrest the progression of KC. This review will focus on current treatments and how biomaterials may hold promise for the future.

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.

Histologic findings of recipient corneas obtained via deep anterior lamellar keratoplasty

PURPOSE

We sought to investigate the histologic findings of recipient corneas obtained via deep anterior lamellar keratoplasty (DALK).

METHODS

The histology of three recipient corneas obtained from patients during DALK was investigated. In all cases, the Descemet membrane was successfully exposed without any perforation during surgery. The isolated corneal tissue was stained with hematoxylin-eosin and periodic acid-Schiff. In two cases, the tissues were examined using a transmission electron microscope.

RESULTS

In one cornea obtained via DALK, only the corneal stroma was observed, and the Descemet membrane was not confirmed. In another case, the recipient cornea was detached within the Descemet membrane. In the third cornea, the banded layer membrane was partially confirmed.

CONCLUSIONS

These findings suggest that the recipient corneas separated at different layers during the DALK procedure. With our surgical technique, the detachment of the Descemet membrane may occur at a mechanically weak segment. This separation site may not be between the Descemet membrane and the corneal stroma.

Treatment of an 8-mm myxoma using acellular corneal tissue

A myxoma is a benign tumor found in the heart and in various soft tissues; however, a corneal myxoma is rare. A mucinous mass of unknown etiology was observed on the left cornea of a 32-year-old male patient. We performed deep anterior lamellar keratoplasty using acellular corneal tissue and concurrent amniotic membrane transplantation. Hematoxylin and eosin staining revealed vacuolation of the parenchyma and myxoid change in the corneal tissue that occurred in the anterior half of the corneal parenchyma. We identified a myxoid stroma by Alcian blue staining and observed collagen fibers with denatured stroma by Masson trichrome staining. The patient's visual acuity improved from light perception to 20 / 200, and the intraocular pressure remained within the normal range for one year after surgery. The transplanted cornea survived successfully with well-maintained transparency, and recurrence was not observed one year after surgery.

Donor tissue selection for anterior lamellar keratoplasty

PURPOSE

To assess the influence of donor characteristics on the outcome of anterior lamellar keratoplasty (ALK) and to evaluate whether corneal donor tissue considered unsuitable for penetrating or posterior lamellar keratoplasty due to poor endothelial condition may be safely used for ALK.

METHODS

Institutional setting. One hundred sixty-six consecutive ALK (166 patients) performed for optical indication in eyes with corneal diseases not involving the corneal endothelium. The main outcome measures were graft survival, early (0-12 months postoperatively) and late (after 12 months) annual endothelial cell loss, and postoperative logarithm of the minimum angle of resolution visual acuity.

RESULTS

The average and extreme values of donor tissue characteristics were: donor age, 70.6 years (range, 28-88 years); organ culture time, 20.9 days (range, 12-35 days); graft endothelial cell density before transplantation, 2047 cells per millimeters (range, 100-3300 cells/mm2); and deswelling time, 2.0 days (range, 1-4 days). The average follow-up time of patients was 48.1 ± 24.8 months (mean ± SD). None of the donor characteristics significantly influenced graft survival or postoperative endothelial cell loss (early and late phase). Donor age >80 years was associated with lower postoperative visual acuity at all postoperative points in time (P < 0.05). At 3 years, the mean logarithm of the minimum angle of resolution visual acuity was 0.44 (20/55) for grafts from donors older than 80 years and 0.25 (20/35) for younger donors. This result was shown to be significant both in univariate and in multivariate analysis.

CONCLUSIONS

Grafts from elderly donors should be discarded before ALK. Conversely, donor tissue with poor endothelial cell density (<2000 cells/mm2) is suitable for ALK.

Outcomes of deep anterior lamellar keratoplasty for keratoconus: learning curve and advantages of the big bubble technique

PURPOSE

To evaluate retrospectively the outcomes of a case series of deep anterior lamellar keratoplasties by air dissection (DALK-AD) using the big bubble (BB) technique, in the surgical treatment of keratoconus (KC).

METHODS

Forty-four consecutive keratoplasties of 42 patients for KC were performed at the French National Reference Center for KC from January 2008 to June 2010 by the same surgeon with the aim of systematically performing DALK-AD with the BB technique. The outcomes of the DALK-AD not converted to penetrating keratoplasty were analyzed, and a learning curve was established to successfully achieve the DALK-AD using the BB technique.

RESULTS

Thirty-two DALK-AD procedures were successfully performed among 44 consecutively operated keratoplasties, with 12 being converted to penetrating keratoplasty during the surgical procedure. At 12 months, the mean best-corrected logarithm of the minimum angle of resolution visual acuity was 0.88 ± 0.14 with 93.3% seeing best-corrected visual acuity ≥ 20/30 and 100% seeing best-corrected visual acuity ≥ 20/40. The mean gain of visual acuity in logarithm of the minimum angle of resolution lines at 6 and 12 months was 6.12 ± 3.97 (P < 0.0001) and 6.94 ± 4.18 (P < 0.005), respectively. The rate for intraoperative and postoperative complications was 31.8% and 4.5%, respectively.

CONCLUSION

Despite a learning period needed to successfully perform deep lamellar anterior keratoplasty with the BB technique, this approach is safe and provides very good visual outcomes when adequate baring of Descemet membrane is achieved. The learning curve showed that complications related to this technique decrease significantly after the first 10 cases.

Long-term graft survival in deep anterior lamellar keratoplasty

PURPOSE

To determine corneal graft survival rates up to 10 years in a large consecutive series of deep anterior lamellar keratoplasties (DALKs).

METHODS

A retrospective, consecutive, noncomparative cases series of DALK procedures in a total of 806 eyes of 711 patients with stromal diseases and healthy endothelium performed between 2000 and 2009. Inclusion criterion was surgery performed by a single surgeon (660 eyes), with at least 6 months of follow-up. Graft survival was analyzed using the Kaplan-Meier method. Endothelial loss was analyzed with the Gaussian distribution and the χ methods. Follow-up time, and preoperative and postoperative endothelial cell density (ECD) were considered in the analyses.

RESULTS

Six hundred sixty eyes of 502 patients met the entry criteria. Mean length of follow-up was 4.5 years (range, 0.5-10 years). We report an average graft survival rate of 99.3% (range, 98.5%-100%); 3 eyes (0.45%) experienced graft failure and 1 eye (0.15%) developed late endothelial failure because of an intraoperative complication. Predominant indications for DALK in this series were keratoconus (74%), postherpetic keratitis scarring (15%), and corneal stromal opacities of different etiology (11%). Endothelial loss from preoperative levels averaged 11% (range, 10%-13%) at 6 months through 10 years after DALK. ECD was unchanged between 6 months postoperatively and the last follow-up visits.

CONCLUSIONS

DALK is a successful form of transplantation in stromal corneal disorders with healthy endothelium, with higher long-term graft survival rates and stable ECD 6 months postoperatively. DALK survival rates do not vary significantly over time.

Femtosecond laser and big-bubble deep anterior lamellar keratoplasty: a new chance

Purpose. To report the 12-month follow-up after big-bubble deep anterior lamellar keratoplasty (DALK) assisted by femtosecond laser that we have called IntraBubble. Methods. A 60 kHz IntraLase femtosecond laser (Abbott Medical Optics) firstly created a 30° angled intrastromal channel to insert the air injection cannula, 50 μ above the thinnest corneal site measured by Sirius Scheimpflug camera (CSO, Firenze, Italy), then performed a full lamellar cut 100 μ above the thinnest corneal point, and from the same corneal depth, created a mushroom incision. The lamella was removed, and the smooth cannula of Fogla was inserted into the stromal channel and air was injected to achieve a big bubble. The follow up is 12 months, and sutures were removed by the 10th postoperative month in all patients. Best Corrected Visual Acuity (BCVA), spherical equivalent and, by Sirius Scheimpflug camera (CSO, Firenze, Italy) keratometric astigmatism were evaluated. Results. All procedures were completed as DALK except 2 converted to PK because an inadvertent intraoperative macroperforation occurred. Mean postoperative BCVA was 0.8, mean spherical equivalent was -3.5 ± 1.7 D, and mean keratometric astigmatism was 4.8 ± 3.1 D. Conclusion. The femtosecond laser could standardize the big-bubble technique in DALK, reducing the risk of intraoperative complications and allowing good refractive outcomes.

Survival of mushroom keratoplasty performed in corneas with postinfectious vascularized scars

PURPOSE

To report the visual outcomes and graft survival rates of mushroom keratoplasty for the treatment of postinfectious corneal scars.

DESIGN

Prospective, noncomparative, interventional case series.

METHODS

A microkeratome-assisted mushroom-shaped keratoplasty was performed in 31 eyes of 31 patients with a central vascularized full-thickness leukoma, resulting from infectious keratitis of various origin (herpes simplex virus, n = 16; bacteria, n = 10; Acanthamoeba, n = 5), with healthy endothelium. The donor graft consisted of a large anterior stromal lamella (9.0 mm in diameter and ± 250 μm in thickness) and a small posterior button (5 to 6 mm in diameter). Visual acuity, refraction, and endothelial cell density were evaluated before surgery, as well as at 12, 24, and 36 months after surgery, and the postoperative graft survival rate was evaluated.

RESULTS

Three years after surgery, in 26 (83.8%) of 31 patients, best spectacle-corrected visual acuity was 20/40 or better with a refractive astigmatism of 4.5 diopters or less. The endothelial cell count at the last follow-up examination averaged 1584 ± 381 cells/mm(2), with an average cell loss of 40.7% from the preoperative value. The survival rate at 3 years was 90.3%, improving to 96.7% when excluding nonimmunologic causes for graft failure.

CONCLUSIONS

Similarly to penetrating keratoplasty, microkeratome-assisted mushroom keratoplasty restores vision in eyes with postinfectious, full-thickness, central corneal scars. For these vascularized corneas at high risk for immunologic rejection, mushroom keratoplasty combines the visual and refractive advantages of large penetrating keratoplasty grafts with the high survival rate of small penetrating keratoplasty grafts.

Long-term results of deep anterior lamellar versus penetrating keratoplasty

OBJECTIVE

To compare deep anterior lamellar keratoplasty (DALK) with penetrating keratoplasty (PK) in eyes with corneal diseases not involving the corneal endothelium (keratoconus, scars after infectious keratitis, stromal dystrophies, and trauma).

DESIGN

Retrospective, comparative case series.

PARTICIPANTS

One hundred forty-two consecutive DALK (DALK group; big-bubble technique or manual lamellar dissection using a slitlamp) and 142 matched PK (PK group).

METHODS

Three models were used to describe the postoperative outcomes of the endothelial cell density. A joint regression model was used to predict long-term graft survival. Visual acuity, ultrasound pachymetry, specular microscopy, and optical coherence tomography (OCT) findings were recorded.

MAIN OUTCOME MEASURES

Postoperative endothelial cell loss and long-term predicted graft survival.

RESULTS

The average 5-year postoperative endothelial cell loss was -22.3% in the DALK group and -50.1% in the PK group (P<0.0001). The early- and late-phase annual rates of endothelial cell loss were -8.3% and -3.9% per year, respectively, in the DALK group and -15.2% and -7.8% per year in the PK group (P<0.001; biphasic linear model). The median predicted graft survival was 49.0 years in the DALK group and 17.3 years in the PK group (P<0.0001). The average visual acuity was lower in the manual dissection subgroup compared with the PK group (average difference, 1.0 to 1.8 line) and with the big-bubble subgroup (average difference, 2.2 to 2.5 lines). The average central corneal thickness at 12 months was 536 μm in the PK group, 523 μm in the big-bubble subgroup, and 562 μm in the manual dissection subgroup (P<0.001). The average thickness of the residual recipient stroma measured by OCT was 87±26 μm in the manual dissection subgroup. No correlation was found between this figure and logarithm of the minimal angle of resolution at any postoperative time point (P>0.05).

CONCLUSIONS

Long-term, model-predicted graft survival and endothelial densities are higher after DALK than after PK. The big-bubble technique gives better results than manual dissection and PK. Compared with PK, manual dissection provides higher survival of both the corneal endothelium and graft, but lower visual acuity.

Deep anterior lamellar keratoplasty: indications, surgical techniques and complications

The concept of lamellar keratoplasty (LK) is not new. However, it had been abandoned and largely replaced by the time-honored technique of penetrating keratoplasty (PK) because LK is technically demanding, time consuming and gives suboptimal visual outcomes due to interface irregularity arising from manual lamellar dissection. Recent improvements in surgical instruments and introduction of new techniques of maximum depth of corneal dissection as well as inherent advantages such as preservation of globe integrity and elimination of endothelial graft rejection have resulted in a re-introduction of LK as an acceptable alternative to conventional PK. This review article describes the indications, different techniques, clinical outcomes and complications of deep anterior LK.

Graft rejection and graft failure after anterior lamellar versus penetrating keratoplasty

PURPOSE

To compare anterior lamellar keratoplasty (ALK) with the reference surgical technique (penetrating keratoplasty [PK]) for risk of rejection.

DESIGN

Retrospective, comparative case series.

METHODS

setting: Institutional. patients: One hundred forty-nine consecutive ALK procedures (ALK group) and 149 matched PK procedures (PK group) performed for optical indication in eyes with corneal diseases not involving the corneal endothelium (ie, keratoconus, scars after infectious keratitis, stromal dystrophies, and trauma). main outcome measures: Three-year graft survival and cumulative incidence of rejection episodes.

RESULTS

The 3-year overall graft survival was 98.3% in the ALK group and 94.3% in the PK group (P = .03). The 3-year cumulative incidence of irreversible rejection was 0.0% in the ALK group and 5.2% in the PK group (P = .02). The 3-year cumulative incidence of rejection episodes was 10.0% in the ALK group and 23.2% in the PK group (P = .01). The average graft-to-rejection episode time was 21.6 ± 22.0 months in the PK group and 19.4 ± 12.7 months in the ALK group (P = .76).

CONCLUSIONS

ALK techniques dramatically decrease the risk of irreversible endothelial and stromal rejection after corneal transplantation. Immune-mediated rejection episodes are observed after ALK, but its lower graft failure rate compared with PK is at least partly the result of the absence of endothelial rejection. In addition, the incidence of rejection episodes after ALK was 50% less than that observed after PK.