Penetrating limbo-keratoplasty for granular and lattice corneal dystrophy

Classic lattice corneal dystrophy: a brief review and summary of treatment modalities

PURPOSE

To provide a brief summary and comparison of the most recent literature on available and theorized treatment modalities for classic lattice corneal dystrophy (LCD). This paper aims to support practitioners in their management of this disease.

METHODS

A search was carried out on available literature through PubMed and Google Scholar of English language articles up to January 2023 that relate to the treatment of LCD. Due to scarcity of literature regarding specific novel therapies for LCD, results from other corneal pathologies (granular corneal dystrophy, corneal scarring) are sometimes included for contrast, which is clearly denoted.

RESULTS

LCD is a slowly progressive disease that leads to recurrent epithelial corneal erosions, stromal haze, corneal opacification, substantial discomfort, and visual impairment. Due to its autosomal-dominant inheritance pattern, this disease can persist throughout ancestral lines and requires consistent treatment and follow-up. An optimal management plan is necessary to (1) prolong years of life with best achievable visual acuity; (2) treat painful recurrent corneal erosions as they occur; (3) ensure proper follow-up throughout the life of a patient, as well as monitor at-risk offspring; and (4) monitor efficacy of treatment.

CONCLUSIONS

This paper addresses (1) treatment for early disease including corneal epithelial debridement, photo therapeutic keratectomy (PTK), femtosecond laser-assisted lamellar keratectomy (FLK), and others; (2) treatment for late disease including full thickness keratoplasties and anterior lamellar keratoplasties; and (3) potential future treatment considerations including a wide variety of topical/systemic, genetic, and regenerative approaches.

Mini-Review: Clinical Features and Management of Granular Corneal Dystrophy Type 2

Granular corneal dystrophy type 2 (GCD2) is an autosomal dominant corneal stromal dystrophy that is caused by p.Arg124His mutation of transforming growth factor β induced (TGFBI) gene. It is characterized by well demarcated granular shaped opacities in central anterior stroma and as the disease progresses, extrusion of the deposits results in ocular pain due to corneal epithelial erosion. Also, diffuse corneal haze which appears late, causes decrease in visual acuity. The prevalence of GCD2 is high in East Asia including Korea. Homozygous patients show a severe phenotype from an early age, and the heterozygote phenotype varies among patients, depending on several types of compound heterozygous TGFBI mutations. In the initial stage, conservative treatments such as artificial tears, antibiotic eye drops, and bandage contact lenses are used to treat corneal erosion. Different surgical methods are used depending on the depth and extent of the stromal deposits. Phototherapeutic keratectomy removes anterior opacities and is advantageous in terms of its applicability and repeatability. For deeper lesions, deep anterior lamellar keratoplasty can be used as the endothelial layer is not always affected. Recurrence following these treatments are reported within a wide range of rates in different studies due to varying definition of recurrence and follow-up period. In patients who have undergone corneal laser vision-correction surgeries such as photorefractive keratectomy, LASEK, or LASIK including SMILE surgery, corneal opacity exacerbates rapidly with severe deterioration of visual acuity. Further investigations on new treatments of GCD2 are necessary.

Management of Stromal Corneal Dystrophies; Review of the Literature with a Focus on Phototherapeutic Keratectomy and Keratoplasty

Corneal dystrophies are a group of non-inflammatory inherited disorders of the cornea. This review considers treatment options for epithelial-stromal and stromal corneal dystrophies: namely Reis–Bücklers, Thiel–Behnke, lattice, Avellino, granular, macular and Schnyder corneal dystrophies. Where there is visual reduction, treatment options may include either phototherapeutic keratectomy (PTK) or corneal transplantation. Due to the anterior location of the deposits in Reis-Bücklers and Thiel–Behnke dystrophies, PTK is considered the treatment of choice. For lattice, Avellino, granular and macular corneal dystrophies, PTK provides temporary visual improvement; however, with recurrences, repeat PTK or a corneal transplant would be needed. For Schnyder dystrophy, should treatment be required, PTK may be the preferred option due to the potential for recurrence of the disease in corneal transplantation. This review discusses the literature and evidence base for the treatment of corneal dystrophies in terms of visual outcomes and recurrence rate.

Influence of graft vascularization on graft survival following homologous limbo-keratoplasty

PURPOSE

Limbo-keratoplasty enables visual improvement and limbal stem cell transplantation at the same. During follow-up, most grafts show vascularization of the limbus. However, it is unclear whether vascularization is harmful due to immunologic effects or helpful to nourish the limbal stem cells and is therefore necessary for a clear graft. The aim of our study is to analyze the influence of graft vascularization on graft survival following homologous limbo-keratoplasty.

METHODS

In this retrospective study, we assessed all consecutive limbo-keratoplasties performed in our hospital. All eyes with suitable photo-documentation were included and divided into two groups (limbal stem cell deficiency and corneal dystrophy). We categorized the grade of vascularization (0, 1, 2, 3, 3b) and analyzed clear graft survival, recurrence of the underlying disease and the endothelial cell density (ECD) with regard to the reason for the graft. Event rates were estimated with the Kaplan-Meier method.

RESULTS

A total of 79 eyes with limbal stem cell deficiency and 15 with corneal dystrophies were analyzed. A high degree of graft vascularization had a tendency for better graft survival in limbal stem cell deficiency, whereas in corneal dystrophies, grafts with no vascularization had preferable outcomes. Recurrence-free graft survival was only seen in grade 1 and 3 vascularization in corneal dystrophies.

CONCLUSION

Vascularization of the limbus seems to have an impact on the long-term outcome of limbo-keratoplasty. The effect seems to be favorable in limbal stem cell deficiency and on recurrence rates in corneal dystrophies. However, the latter might be overshadowed by an unfavorable immunologic effect in corneal dystrophies where the baseline immunologic risk profile is commonly more favorable than in limbal stem cell deficiency.

Clinical Course of Different Types of Immune Reactions following Keratoplasty

BACKGROUND

Immune-mediated corneal graft rejection (IR) is a leading cause of corneal graft failure. The endothelium, stroma, epithelium, or a combination can be affected. Little is known about the long-term outcomes of different types of IR.

METHODS

We reviewed the medical records of all keratoplasties that had been performed at our eye centre between 2003 and 2016 (n = 3934) for any kind of IR that occurred between the surgery and 2019. All patients with a definite diagnosis of IR and sufficient clinical data were included in the analysis. IRs were grouped according to the affected part of the graft (endothelial, stromal, epithelial, and mixed). We analysed the dynamics of recovery and the clinical outcomes.

RESULTS

We identified a total of 319 patients with IR. Twenty-seven of those were lost to follow-up and were excluded from further analysis. Of the IRs, 89% affected the endothelium. Endothelial IR resulted more frequently in a considerable loss of endothelial cell density than other forms of IR. Stromal IR showed a lower relapse rate and a better visual recovery than other types of IR and resulted less often in a failure of the graft.

CONCLUSIONS

We herein report comprehensive data about the prognosis regarding functional recovery after different types of IR following keratoplasty. Our data underline that timely recognition and correct classification of IR are important because they determine the clinical course and prognosis.

A decellularized human corneal scaffold for anterior corneal surface reconstruction

Allogenic transplants of the cornea are prone to rejection, especially in repetitive transplantation and in scarred or highly vascularized recipient sites. Patients with these ailments would particularly benefit from the possibility to use non-immunogenic decellularized tissue scaffolds for transplantation, which may be repopulated by host cells in situ or in vitro. So, the aim of this study was to develop a fast and efficient decellularization method for creating a human corneal extracellular matrix scaffold suitable for repopulation with human cells from the corneal limbus. To decellularize human donor corneas, sodium deoxycholate, deoxyribonuclease I, and dextran were assessed to remove cells and nuclei and to control tissue swelling, respectively. We evaluated the decellularization effects on the ultrastructure, optical, mechanical, and biological properties of the human cornea. Scaffold recellularization was studied using primary human limbal epithelial cells, stromal cells, and melanocytes in vitro and a lamellar transplantation approach ex vivo. Our data strongly suggest that this approach allowed the effective removal of cellular and nuclear material in a very short period of time while preserving extracellular matrix proteins, glycosaminoglycans, tissue structure, and optical transmission properties. In vitro recellularization demonstrated good biocompatibility of the decellularized human cornea and ex vivo transplantation revealed complete epithelialization and stromal repopulation from the host tissue. Thus, the generated decellularized human corneal scaffold could be a promising biological material for anterior corneal reconstruction in the treatment of corneal defects.

Sustained and Widespread Gene Delivery to the Corneal Epithelium via In Situ Transduction of Limbal Epithelial Stem Cells, Using Lentiviral and Adeno-Associated Viral Vectors

Corneal epithelial dystrophies are typically characterized by symptoms such as pain, light sensitivity, and corneal opacification leading to impaired vision. The development of gene therapy for such conditions has been hindered by an inability to achieve sustained and extensive gene transfer, as the epithelium is highly replicative and has evolved to exclude foreign material. We undertook a comprehensive study in mice aiming to overcome these impediments. Direct injection of lentiviral vector within the stem cell niche resulted in centripetal streaks of epithelial transgene expression sustained for >1 year, indicating limbal epithelial stem cell transduction in situ. The extent of transgene expression varied markedly but at maximum covered 26% of the corneal surface. After intrastromal injection, adeno-associated viral (AAV) vectors were found to penetrate Bowman's membrane and mediate widespread, but transient (12-16 days), epithelial transgene expression. This was sufficient, when applied within a Cre/lox system, to result in recombined epithelium covering up to approximately 80% of the corneal surface. Lastly, systemic delivery of AAV2/9 in neonatal mice resulted in extensive corneal transduction, despite the relative avascularity of the tissue. These findings provide the foundations of a gene therapy toolkit for the corneal epithelium, which might be applied to correction of inherited epithelial dystrophies.

Long-term results of allogenic penetrating limbo-keratoplasty: 20 years of experience

AimThe objective of the study was to evaluate the long-term results of allogenic penetrating limbo-keratoplasy. This method allows simultaneous transplantation of a corneal graft and limbal stem cells of the donor by means of eccentric trephination of the donor button.MethodThe data of 192 consecutive cases of allogenic penetrating limbo-keratoplasty from 1995 to 2015 were reviewed. These had been performed exclusively in eyes with complete failure of the limbal stem cells, in combination with deep corneal scarring. Indications were predominantly eye burns, inflammatory conditions, and congenital aniridia. Graft survival and rejection rates were assessed using Kaplan-Meier analysis.ResultsFollow-up averaged 2.1±2.2 years. Median graft survival was 3.4 years in eye burns, 3.9 years in inflammatory disease, and 3.2 years in congenital aniridia. Median survival was 3.9 years in the heterogenous group of other indications.ConclusionAllogenic limbo-keratoplasty is a suitable option used to treat patients with bilateral complete failure of the limbal stem cells and deep opacification of the central cornea. The main reasons for graft failure are the loss of graft-limbal stem cell functioning and endothelial graft rejection.

New histopathologic and ultrastructural findings in Reis-Bücklers corneal dystrophy caused by the Arg124Leu mutation of TGFBI gene

Background

Reis-Bücklers corneal dystrophy (RBCD) was consistently reported as a corneal dystrophy only affected Bowman’s layer and superficial corneal stroma, and superficial keratectomy was a recommendation surgery for treatment in literatures. The study reported new histopathological and ultrastructural findings in RBCD caused by the Arg124Leu mutation of transforming growth factor induced (TGFBI) gene in a four-generation Chinese pedigree.

Methods

Subjects including eight patients and seven unaffected family members received slit-lamp biomicroscopy and photography. DNA was obtained from all subjects, and exons 4 and 11 to 14 of TGFBI gene were analyzed by polymerase chain reaction and the products were sequenced. Anterior segment optical coherence tomography (AS OCT) and in vivo confocal microscopy were conducted for ten eyes of five patients. Based on the results of AS OCT and in vivo confocal microscopy, deep anterior lamellar keratoplasty (DLKP) using cryopreserved donor cornea was applied for four eyes of four patients. Four lamellar dystrophic corneal buttons were studied by light and transmission electron microscopy, and TGFBI immunohistochemistry.

Results

Eight patients had typical clinical manifestations of RBCD presenting recurrent painful corneal erosion starting in their early first decades, along with age-dependent progressive geographic corneal opacities. TGFBI sequencing revealed a heterozygous mutation, Arg124Leu in all eight patients. Anterior segment optical coherence tomography and in vivo confocal microscopy showed the dystrophic deposits involved not only in subepithelial and superficial stroma, but also in mid- or posterior stroma in four examined advanced eyes. Light microscopy showed Bowman’s layer was absent, replaced by abnormal deposits stain bright red with Masson’s trichrome. In superficial cornea, the deposits stacked and produced three to five continuous bands parallel to the corneal collagen lamellae. In mid- to posterior stroma, numerous granular or dot- like aggregates were heavily scattered, and most of them presented around the nuclei of stromal keratocytes. Transmission electron microscopy revealed the multiple electron-dense rod-shaped deposits aggregated and formed a characteristic pattern of three to five continuous bands in superficial cornea, which were similar to those seen under light microscopy. In mid- to posterior stroma, clusters of rod-shaped bodies were scattered extracellular or intracellular of the stromal keratocytes between the stromal lamellae suggesting the close relationship between mutated proteins and keratocyte.

Conclusions

The study offer evidences indicating DLKP is a viable treatment option for advanced RBCD to avoid recurrence, and the mutated TGFBIp in dystrophic corneas are of keratocytes origin.

Identification of two novel mutations in the cornea-specific TGFBI gene causing unique phenotypes in patients with corneal dystrophies

The purpose of this study was to report on two novel missense mutations of the cornea-specific TGFBI gene in one single patient and in two generations of a family diagnosed with unique corneal dystrophy (CD) phenotypes. Ophthalmologic examination, in several cases ocular coherence tomography of the anterior segment (AS-OCT), was performed in 21 affected patients and in two unaffected members of one affected family. Coding regions of the TGFBI gene were direct sequenced in all 23 individuals. The two novel mutations were verified by RFLP analysis. A novel mutation c.1640T > G (p.Phe574Cys) in exon 12 of the TGFBI gene was detected in one single patient with recurrent granular intrastromal deposits comparable to a type of granular dystrophy. In AS-OCT, the deposit pattern reached up to the Descemet's layer. A further novel mutation c.393G > T(p.Glu131Asp) in exon 4 of the TGFBI gene was detected in all three affected members of one family with superficial cloud- and honeycomb-like opacifications, comparable to a Schnyder corneal dystrophy. Two unaffected members did not carry this alteration. The two identified novel mutations add other two phenotypes in patients suffering from TGFBI-linked CD to those reported so far. In one case, clinical finding indicates a Schnyder corneal dystrophy-like phenotype due to its superficial crystalline shape, and in the second one, granular deposits who reach Descemet's layer indicate a granular CD subtype. Molecular genetic analysis may help to distinguish those subtypes and to decide for specific treatment in time of a wide variation of corneal surgical techniques.

Pathogenesis and treatments of TGFBI corneal dystrophies

Transforming growth factor beta-induced (TGFBI) corneal dystrophies are a group of inherited progressive corneal diseases. Accumulation of transforming growth factor beta-induced protein (TGFBIp) is involved in the pathogenesis of TGFBI corneal dystrophies; however, the exact molecular mechanisms are not fully elucidated. In this review article, we summarize the current knowledge of TGFBI corneal dystrophies including clinical manifestations, epidemiology, most common and recently reported associated mutations for each disease, and treatment modalities. We review our current understanding of the molecular mechanisms of granular corneal dystrophy type 2 (GCD2) and studies of other TGFBI corneal dystrophies. In GCD2 corneal fibroblasts, alterations of morphological characteristics of corneal fibroblasts, increased susceptibility to intracellular oxidative stress, dysfunctional and fragmented mitochondria, defective autophagy, and alterations of cell cycle were observed. Other studies of mutated TGFBIp show changes in conformational structure, stability and proteolytic properties in lattice and granular corneal dystrophies. Future research should be directed toward elucidation of the biochemical mechanism of deposit formation, the relationship between the mutated TGFBIp and the other materials in the extracellular matrix, and the development of gene therapy and pharmaceutical agents.

Simultaneous transplantation of limbal stem cells may reduce recurrences of granular dystrophy after corneal transplantation: 2 long-term case reports

To present 2 cases with long-term relapse-free intervals only after limbo-keratoplasty but not after conventional penetrating keratoplasty in granular dystrophy.Retrospective review of the patient charts and photographs taken during long-term follow-up of 2 cases with granular dystrophy, in which 1 eye received penetrating keratoplasty and the fellow eye received penetrating limbo-keratoplasty.In the first patient, 1 eye showed extensive recurrence of granular deposits 17 years after penetrating keratoplasty was performed while in the second eye two-thirds of the corneal transplant adjacent to the transplanted limbal area remained clear 12 years after the limbo-corneal transplant. In the second patient, 1 eye showed no signs of recurrence 5 years after limbo-keratoplasty, whereas a recurrence of granular corneal deposits occurred 18 months after surgery in the fellow eye.These cases show that the simultaneous transplantation of healthy donor limbus when performing penetrating keratoplasty may prolong recurrence in granular corneal dystrophy. Although we were unable to prove it on the molecular level, these clinical courses may support the hypothesis that a limbal transplant helps prevent a recurrence.

Granular corneal dystrophy: a novel approach to classification and treatment

PURPOSE

The purpose of this case report is to review granular corneal dystrophy (GCD) and examine the new paradigm in its classification and treatment.

CASE REPORT

A 49-year-old white male patient reported yearly for monitoring of GCD. He had an ocular surgical history in the left eye for penetrating keratoplasty in 1989 and phototherapeutic keratectomy with mitomycin C for graft recurrence of stromal bread-crumb opacities 17+ years later in 2002. At his last examination, the patient's vision and comfort was stable in each eye, with minimal recurrence of granular opacities in the left surgical eye, stable granular opacities in the right eye, no recurrent corneal erosion symptoms in either eye, and best spectacle-corrected vision of 20/40 OD and 20/30 OS.

CONCLUSIONS

GCD is a Category 1, Stromal, TGFBI-associated corneal dystrophy. Although it is classified as a stromal dystrophy, research suggests the possibility that the granular opacities have an origination to the corneal epithelium with a migratory effect to the corneal stroma. Patients with Groenouw I, like the one in this report, usually do not have severely compromised vision. When vision is significantly affected or recurrent corneal erosion occurs, despite first- and second-line treatments, viable management options thereafter include photokeratectomy and other new surgical treatments such as femtosecond deep anterior lamellar keratoplasty and femtosecond laser-assisted keratoplasty. Future advancements in diagnostic technology, immunohistologic and genetic testing, medications, and surgery will allow for advancements in treating and managing patients with GCD.

Limbal epithelial cell therapy: past, present, and future

The cornea, the clear window at the front of the eye, transmits light to the retina to enable vision. The corneal surface is renewed by stem cells located at the peripheral limbal region. These cells can be destroyed by a number of factors, including chemical burns, infections, and autoimmune diseases, which result in limbal stem cell deficiency (LSCD), a condition that can lead to blindness. Established therapy for LSCD based on ex vivo expanded limbal epithelial cells is currently at a stage of refinement. Therapy for LSCD is also rapidly evolving to include alternative cell types and clinical approaches as treatment modalities. In the present perspectives chapter, strategies to treat LSCD are discussed and advances in this important field of regenerative medicine are highlighted.

[Ocular surface reconstruction in limbal stem cell insufficiency: transplantation of limbal tissue]

Reconstruction of the ocular surface in patients with limbal stem cell insufficiency (LSI) remains one of the most challenging tasks in ophthalmology. The transplantation of lamellar limbal tissue in total LSI represents an established therapeutic concept, while an abrasion of the conjunctival pannus allowing normal limbal epithelium to recolonize the cornea is the treatment of choice in partial LSI. Surgery must be postponed until an inflammation-free period is reached and lid abnormalities have been corrected. In unilateral total LSI autologous limbal tissue from the healthy eye is transplanted in order to circumvent immunological adverse events. In bilateral total LSI cadaveric or living related allogenic limbal tissue is used for transplantation, in which case systemic immunosuppression and HLA matching are mandatory. The combination with amniotic membrane transplantation and mitomycin C treatment can further improve long-term outcome of limbal stem cell transplantation.

Adverse effects of systemic immunosuppression in keratolimbal allograft

Purpose. Keratolimbal allograft (KLAL) is a treatment for limbal stem cell deficiency. One disadvantage is systemic immunosuppression to avoid rejection. Our purpose was to examine the adverse effects of systemic immunosuppression in KLAL. Methods. A retrospective case review of 16 patients with KLAL who received systemic immunosuppression consisting of a corticosteroid, an antimetabolite, and/or a calcineurin inhibitor was performed. Patients were monitored for signs, symptoms, or laboratory evidence of toxicity. Results. Eleven of 16 patients (68%) experienced an adverse effect. The average age of those with adverse effects was 43.5 years and without was 31.4 years. Ten of 11 patients (91%) had resolution during mean followup of 16.4 months. No serious adverse effects occurred. The most common included anemia, hyperglycemia, elevated creatinine, and elevated liver function tests. Prednisone and tacrolimus were responsible for the most adverse effects. Patients with comorbidities were more likely to experience an adverse effect (82% versus 20%, P = 0.036). Conclusions. KLAL requires prolonged systemic immunosuppression. Our data demonstrated that systemic immunosuppression did not result in serious adverse effects in our population and is relatively safe with monitoring for toxicity. In addition, we demonstrated that adverse effects are more likely in older patients with comorbidities.

Allogenic limbo-keratoplasty with conjunctivoplasty, mitomycin C, and amniotic membrane for bilateral limbal stem cell deficiency

OBJECTIVE

To present the technique and report the results of up to 36 months after allogenic central penetrating limbo-keratoplasty in conjunction with conjunctivoplasty, mitomycin C (MMC), and amniotic membrane (AM) transplantation in patients with bilateral limbal stem cell deficiency (LSCD).

DESIGN

Retrospective, consecutive subject cohort study.

PARTICIPANTS

Case records of 20 eyes from 20 patients who presented with bilateral LSCD due to aniridia, chemical/thermal burn, cicatrizing pemphigoid, and chronic ocular surface inflammation and who were treated at the University Eye Hospital, Freiburg.

METHODS

All eyes were treated with central limbo-keratoplasty in conjunction with conjunctivoplasty, MMC, and AM. There were 20 human leukocyte antigen-typed allolimbal transplants from cadaveric donors. All patients received systemic immunosuppression with mycophenolate mofetil or cyclosporine A.

MAIN OUTCOME MEASURES

Surgical success was measured by the duration for which a healthy corneal epithelium was maintained. Visual success was measured by an improvement in visual acuity (VA) in the eye during follow-up and directly correlated with central clear graft survival.

RESULTS

The follow-up period was up to 34 months (mean, 20 months; median, 22.4 months). Mean VA, measured in decimal fractions, increased from 0.029 (∼20/400; median, 0.005; first quartile 0.005; third quartile 0.005) before surgery to 0.281 (20/70; median, 0.2; first quartile 0.04; third quartile 0.55) after surgery. Healthy corneal epithelium showing survival of limbal stem cells was observed in 14 eyes (70%) during complete follow-up.

CONCLUSIONS

Penetrating limbo-keratoplasty with conjunctivoplasty, MMC, and AM transplantation is a promising new surgical technique for improving vision and conjunctivalization in patients with severe bilateral LSCD necessitating allogenic transplants.

Efficacy of postoperative immunosuppression after keratoplasty in herpetic keratitis

PURPOSE

Recurrence of herpetic keratitis and immune reactions is the major cause of graft failures after penetrating keratoplasty as a consequence of herpes simplex keratitis. No treatment regimen is yet considered a standard of care. This retrospective study analyzes the effectiveness of combined systemic acyclovir and immunosuppressive therapy with cyclosporine A (CSA) or mycophenolate mofetil (MMF) after high-risk keratoplasty in herpetic keratitis.

METHODS

A total of 87 high-risk keratoplasties treated with postoperative combined systemic acyclovir and immunosuppressive therapy with CSA or MMF were analyzed retrospectively according to the therapeutic regimen, the degree of preoperative corneal vascularization, and tissue matching of the graft. Endpoints included immunological graft rejection, recurrence of the herpetic keratitis, graft failure, and visual acuity.

RESULTS

There was an overall trend toward an improvement of visual acuity. Graft failure occurred in 13.1%, in all cases after termination of immunosuppression with MMF or CSA. In 4 of 11 cases, immune reactions caused graft failure. Patients with 3 to 4 quadrants of corneal vascularization showed significantly higher rates of graft rejection than patients with 1 to 2 quadrants vascularized or avascular corneas. Herpetic recurrence occurred in 31.8% and caused 18.2% of graft failure. In 7 of 23 cases, graft rejection was induced by herpetic recurrence.

CONCLUSIONS

Graft survival rate and functional outcome after postoperative antiviral and immunosuppressive treatment in cases of penetrating keratoplasties after herpetic keratitis are comparable with results of normal-risk keratoplasties, despite existing high risks for immune rejections or herpetic recurrences.

Analysis of deposit depth and morphology in granular corneal dystrophy type 2 using fourier domain optical coherence tomography

PURPOSE

Granular corneal dystrophy type 2 (GCD2) causes the formation of corneal deposits having 3 different morphological types. We used Fourier domain optical coherence tomography to assess the depths of each type according to the morphology.

METHODS

A prospective study was performed in 54 eyes of 54 heterozygous patients with GCD2. Corneal deposits of 54 patients with GCD2 were classified into 3 morphological types: type 1, diffuse haze; type 2, granular shape (2 subgroups: type 2a, round granulated and type 2b, round spiculated); and type 3, linear shape (2 subgroups: type 3a, short side branched and type 3b, long side branched). Using Fourier domain optical coherence tomography, we measured the distances from the Bowman layer to the upper surface of the deposits (USBL), to the lower surface of the deposits (LSBL), and the thickness of the deposits (TD). The deposits formed along the flap interface were also examined among 19 patients who had LASIK.

RESULTS

Types 1 and 2 deposits were always adjacent to the Bowman layer; thus the USBLs for each were 0.0 ± 0.0 μm, whereas that of type 3 deposits was 65.4 ± 48.0 μm (P < 0.0001). The LSBL and TD of linear deposits with long side branches (type 3) (313.3 ± 71.4 and 246.2 ± 71.9 μm) were greater than those of type 1 (47.7 ± 10.2 and 47.7 ± 10.2 μm) and type 2 (91.3 ± 39.5 and 91.3 ± 39.5 μm) (P < 0.0001). There were no differences in the measurements between the subgroups type 2a and type 2b or between types 3a and 3b. USBL of the laser in situ keratomileusis group was 54.5 ± 29.8 μm.

CONCLUSIONS

The depths of corneal deposits in patients with GCD2 were associated with the morphology of the deposits. The linear deposits were located most deeply in the cornea, followed by granular deposits and diffuse haze moving anteriorly. Several deposits have distinct depths according to the morphological types.

Assessment of limbus and central cornea in patients with keratolimbal allograft transplantation using in vivo laser scanning confocal microscopy: an observational study

BACKGROUND

Keratolimbal allograft (KLAL) transplantation has been proved to be a useful surgical procedure for limbal stem cell deficiency patients. However, information about in vivo ocular surface changes in those patients is limited, due to the lack of a reliable and non-invasive technique for closely monitoring the changes of KLAL grafts. The aim of this study is to characterize the cellular changes in the limbus and central cornea after KLAL in patients with severe ocular chemical injury, using in vivo laser scanning confocal microscopy (LSCM).

METHODS

This is a prospective, noncomparative, observational case series. Twenty-three patients (23 eyes) with total limbal stem cell deficiency due to ocular chemical injury were recruited. KLAL with or without other concurrent surgery were performed. LSCM and slit-lamp examination were performed on the limbus and the central cornea before surgery and at 6 and 12 months postoperatively. Presence of palisades of Vogt, limbal basal epithelial cell density within the palisades of Vogt (LEC), limbal dendritic cells (DC) density, and central corneal basal epithelial cell (CEC) density were assessed by LSCM.

RESULTS

All patients completed 12 months of follow-up. Twenty-one patients were male and two were female, with a mean age of 39.5 ± 12.5 years. Six cases were due to acid burns, and the others were alkali burns. Palisades of Vogt were observed in all surviving grafts but were absent in graft failure. The epithelial cells in the central cornea of the failed graft had lost the classic polygonal morphology of the normal corneal basal epithelial cells. The cell density of LEC and CEC decreased significantly, whereas DC density increased in the failed grafts over time.

CONCLUSIONS

In vivo LSCM is a useful tool for monitoring the cellular changes in KLAL grafts, and has the potential to diagnose the failure of KLAL grafts at the cellular level.

Deep anterior lamellar keratoplasty with melles technique for granular corneal dystrophy

PURPOSE

The purpose of this study was to evaluate the clinical results of deep anterior lamellar keratoplasty (DALK) using the Melles technique in granular corneal dystrophy.

METHODS

Seven eyes from 5 patients who underwent DALK using Melles technique for granular corneal dystrophy were included in this study. The parameters evaluated included patients' demographics, preoperative and postoperative best spectacle-corrected visual acuities (BSCVAs), and timing and pattern of recurrence.

RESULTS

The mean age of the patients was 37 +/- 9.4 years (range 29-46 years) at the time of surgery. The mean length of follow-up (DALK to last visit) was 38.4 +/- 18.6 months (range 10-63 months). The procedure was performed without any major complication in all eyes. Mean preoperative BSCVA was 20/220 (range 20/400 to 20/100), which improved to 20/27 (range 20/30 to 20/25) at 6 months after DALK. Mean BSCVA was 20/50 (range 20/400-20/20) at last follow-up. Simple recurrence occurred in 5 (71%) of 7 eyes. The mean time from surgery to recurrence was 15.6 +/- 1.8 months (range 13-16 months). Clinically significant recurrences occurred 34 +/- 2 months after the procedures in 3 (43%) of 7 eyes. Two (30%) of 7 eyes had no recurrence at all.

CONCLUSIONS

Although granular corneal dystrophy is likely to recur after DALK, this technique can restore and preserve useful visual function for a significant period in these patients.

Transplantation of ex vivo cultured limbal epithelial stem cells: a review of techniques and clinical results

Ex vivo cultured limbal epithelial stem cells have been used successfully to treat corneal limbal stem cell deficiency. We identified 17 reports of the application of this novel cell-based therapy in humans. In addition we identified four reports of the use of culture oral mucosal epithelial cells to treat limbal stem cell deficiency. We examined these reports to discern the success rate, complication rate, visual outcome, whether there is an optimal technique and which patients are the most likely to benefit. We also discuss the different culture methods employed and the regulations governing cell banks that are providing this service. We found that the techniques used to cultivate and transplant cells varied, but that no individual method was clearly superior. The reported success rate is similar across all studies for both allografts and autografts. The clinical indications for this treatment are not clearly defined as indicated by the variety of disorders treated. Follow-up is limited and the long-term success rate is yet to be established. Nonetheless, we conclude that there is sufficient evidence to support the continued use and refinement of this procedure as a treatment for corneal stem cell deficiency.

Recurrence of lattice corneal dystrophy caused by incomplete removal of stroma after deep lamellar keratoplasty

PURPOSE

To report clinical and histopathological characteristics of postoperative amyloidosis recurrence in a patient with lattice corneal dystrophy (LCD) type I.

METHODS

The clinical manifestation of recurrent amyloidosis in the residual stroma was delineated in a patient with LCD type I after deep lamellar keratoplasty (DLKP) for 6.5 years. Complete removal of the residual recipient stroma and regrafting of a new cryopreserved donor button were accomplished by a secondary DLKP. The primary DLKP donor graft and the underlying residual stroma of the recipient obtained by the secondary DLKP were examined for analysis of histopathologic and ultrastructural changes.

RESULTS

A tongue-shaped retained stroma with linear opacity was observed underneath the primary DLKP donor graft. The retained stromal layer was thoroughly detached from Descemet membrane, removed, and followed by grafting a new cryopreserved button. The primary donor button exhibited a normal epithelium, fewer keratocytes, an intact Descemet membrane, and mild positive Congo red staining in the middle layer of the stroma. The total retained recipient stroma removed by the secondary DLKP measured approximately 20 mum in thickness, showing thick and massive amyloid accumulation. The surface of the removed residual stroma toward Descemet membrane showed collagen fibers in an interwoven fashion without bundle structure under a scanning electron microscope.

CONCLUSION

Incomplete removal of the recipient stroma by DLKP can lead to the recurrence of amyloidosis in the residual stroma in patients with LCD. Clinical and histologic findings in the primary graft and in the residual recipient stroma implicate stromal genesis of recurrence of LCD after DLKP.

[Satisfaction with penetrating keratoplasty. Results of a questionnaire census]

BACKGROUND

Penetrating keratoplasty (PKP) is commonly referred to as the most successful transplantation procedure in medicine. This appraisal, however, is currently poorly supported by evidence. The aim of our study was to collect data on patient satisfaction with PKP as well as to analyze factors predisposing to dissatisfaction.

PATIENTS AND METHODS

In the years 1988-2002 a total of 3,219 PKPs were performed on 2,981 patients. These patients were sent a questionnaire. The items pertained to subjective assessment of visual quality as compared to the situation before PKP and about regretting the PKP.

RESULTS

The questionnaire was answered by 1,142 patients (59% of the traceable persons). The mean follow-up was 3.3+/-2.9 years. Indications for PKP were Fuchs' endothelial dystrophy (26%), keratoconus (23%), bullous keratopathy (15%), and further indications (36%). For these groups, best corrected visual acuity improved by more than two lines in 51, 80, 42, and 50%, respectively. The percentage of subjective improvement of vision was 73, 78, 47, and 63%. The percentage of regretting the PKP was 12, 4, 27, and 10%, respectively. All differences were highly statistically significant. Significant influencing factors on regretting the PKP were (inversely sorted for relevance): repeat graft failure, bullous keratopathy, contact lens wear, paresthesia, removal of running sutures, and patient age.

CONCLUSIONS

General satisfaction with PKP is high. An important exception is bullous keratopathy, most likely due to accompanying morbidity (e.g., cystoid macular edema).

Localization of candidate stem and progenitor cell markers within the human cornea, limbus, and bulbar conjunctiva in vivo and in cell culture

Corneal diseases are some of the most prevalent causes of blindness worldwide. While the most common treatment for corneal blindness is the transplantation of cadaver corneas, expanded limbal stem cells are finding recent application. Unknown, however, is the identity of the actual repopulating stem cell fraction utilized in both treatments and the critical factors governing successful engraftment and repopulation. In order to localize potential stem cell populations in vivo, we have immunohistochemically mapped a battery of candidate stem and progenitor cell markers including c-Kit and other growth factor receptors, nuclear markers including DeltaNp63, as well as adhesion factors across the cornea and distal sclera. Cell populations that differentially and specifically stained for some of these markers include the basal and superficial limbal/conjunctival epithelium and scattered cells within the substantia propria of the bulbar conjunctiva. We have also determined that the culture of differentiated cornea epithelial cells as dissociated and explant cultures induces the expression of several markers previously characterized as candidate limbal stem cell markers. This study provides a foundation to explore candidate corneal stem cell populations. As well, we show that expression of traditional stem cell markers may not be reliable indicator of stem cell content during limbal stem cell expansion in vitro and could contribute to the variable success rates of corneal stem cell transplantation.