Total Limbal Stem Cell Deficiency Research Articles

Nanohydroxyapatite Coating Attenuates Fibrotic and Immune Responses to Promote Keratoprosthesis Biointegration in Advanced Ocular Surface Disorders.

Keratoprosthesis (KPro) implantation is frequently the only recourse for patients with severe corneal disease. However, problems arise due to inadequate biointegration of the KPro, particularly the PMMA optical cylinder, such as tissue detachment, tissue melting, or eye-threatening infection in the interface. Here, using the AuroKPro as a model prosthesis, a surface functionalization approach─coating the optical cylinder with nanohydroxyapatite (nHAp)─was trialed in rabbit eyes with and without a proceeding chemical injury. In chemically injured eyes, which simulated total limbal epithelial stem cell deficiency, clear benefits were conferred by the coating. The total modified Hackett-McDonald score and area of tissue apposition differences 12 weeks after implantation were 5.0 and 22.5%, respectively. Mechanical push-in tests revealed that 31.8% greater work was required to detach the tissues. These differences were less marked in uninjured eyes, which showed total score and tissue apposition differences of 2.5 and 11.5%, respectively, and a work difference of 23.5%. The improved biointegration could be contributed by the attenuated expression of fibronectin (p = 0.036), collagen 3A1 (p = 0.033), and α-smooth muscle actin (p = 0.045)─proteins typically upregulated during nonadherent fibrous capsule envelopment of bioinert material─adjacent to the optical cylinders. The coating also appeared to induce a less immunogenic milieu in the ocular surface tissue, evidenced by the markedly lower expression of tear proteins associated with immune and stimulus responses. Collectively, the level of these tear proteins in eyes with coated prostheses was 1.1 ± 13.0% of naïve eyes: substantially lower than with noncoated KPros (246.5 ± 79.3% of naïve, p = 0.038). Together, our results indicated that nHAp coating may reduce the risk of prosthesis failure in severely injured eyes, which are representative of the cohort of KPro patients.

Outcomes of Simple Limbal Epithelial Transplantation Without Amniotic Membrane Grafting in Unilateral Limbal Stem Cell Deficiency: A Case Series of 6 Patients.

This study describes the technique of simple limbal epithelial transplantation (SLET) without amniotic membrane grafting (AMG) in limbal stem cell deficiency (LSCD). Retrospective, interventional case series of 6 patients who underwent SLET without AMG were included. The procedure followed the standard technique, involving limbal biopsy from the healthy eye, resection of symblephera, and pannus dissection in the affected eye. Following host bed preparation, limbal explants were placed on the bare cornea and secured with fibrin glue. A large-diameter bandage contact lens was applied post surgery. No amniotic membrane was used. Preoperative data, including age, gender, cause of LSCD, best-corrected visual acuity, and previous ocular surgeries, were recorded. Postoperative clinical information, such as the duration of follow-up and recurrence of LSCD, best-corrected visual acuity, and other ocular examination findings, was recorded in an excel sheet. Preoperatively, 2 patients had total LSCD (secondary to a firecracker injury and excision biopsy for ocular surface squamous neoplasia). 4 patients had partial LSCD (3 chemical injuries, 1 firecracker injury). The mean age of participants was 30.67 ± 15.91 years, with a mean follow-up duration of 9.33 ± 8.04 months. Intraoperatively, all patients exhibited a smooth corneal surface after pannus removal. Postoperatively, all limbal explants remained securely attached, with complete corneal epithelialization achieved within 2 to 3 weeks. The ocular surface remained stable throughout, and no recurrence of LSCD was observed in any patient. No loss of explants was seen. The present series suggests that AMG may not be a necessary step for performing SLET.

Allogenic Simple Limbal Epithelial Transplantation: An Approach to Bilateral Recurrent Pterygia and Limbal Stem Cell Deficiency

Abstract: A 44-year-old man presented with bilateral total limbal stem cell deficiency after multiple failed surgeries for recurrent pterygia in both eyes over the last 11 years. His best corrected visual acuity (BCVA) in both eyes at the time of presentation was hand movement, projection of rays accurate. Owing to bilateral involvement, allogenic simple limbal epithelial transplantation (Allo SLET) was performed in the right eye. The limbal biopsy was taken from the wife of the patient. Complete ocular surface epithelialization was achieved in 26 days. The patient has completed 15 months of postoperative follow-up with stable ocular surface and BCVA 6/12 in the RE. He is on systemic and topical immunosuppressants with no side effects to date.

Animal Models for Limbal Stem Cell Deficiency: A Critical Narrative Literature Review.

This literature review will provide a critical narrative overview of the highlights and potential pitfalls of the reported animal models for limbal stem cell deficiency (LSCD) and will identify the neglected aspects of this research area. There exists significant heterogeneity in the literature regarding the methodology used to create the model and the predefined duration after the insult when the model is supposedly fully fit for evaluations and/or for testing various therapeutic interventions. The literature is also replete with examples wherein the implementation of a specific model varies significantly across different studies. For example, the concentration of the chemical, as well as its duration and technique of exposure in a chemically induced LSCD model, has a great impact not only on the validity of the model but also on the severity of the complications. Furthermore, while some models induce a full-blown clinical picture of total LSCD, some are hindered by their ability to yield only partial LSCD. Another aspect to consider is the nature of the damage induced by a specific method. As thermal methods cause more stromal scarring, they may be better suited for assessing the anti-fibrotic properties of a particular treatment. On the other hand, since chemical burns cause more neovascularisation, they provide the opportunity to tap into the potential treatments for anti-neovascularisation. The animal species (i.e., rats, mice, rabbits, etc.) is also a crucial factor in the validity of the model and its potential for clinical translation, with each animal having its unique set of advantages and disadvantages. This review will also elaborate on other overlooked aspects, such as the anaesthetic(s) used during experiments, the gender of the animals, care after LSCD induction, and model validation. The review will conclude by providing future perspectives and suggestions for further developments in this rather important area of research.

Simultaneous simple limbal epithelial transplant and Descemet’s stripping automated endothelial keratoplasty for a case of presumed “Munchausen syndrome by proxy”: A novel surgical technique

We attempt to introduce the technique of the application of simple limbal epithelial transplantation (SLET) and Descemet stripping automated endothelial keratoplasty (DSAEK) in the same eye at the same sitting for a case of unilateral total limbal stem cell deficiency (LSCD) with endothelial decompensation and scarring. The operated eye showed significant healing within 6 months of the surgery. To our knowledge, this is the first case of unilateral total LSCD with endothelial decompensation and scarring managed by both SLET and DSAEK in the same eye.

Conjunctival Limbal Autograft Combined with Amnion-Assisted Conjunctival Epithelial Redirection for Unilateral Total Limbal Stem Cell Deficiency after Severe Chemical Burn.

(1) Background: To evaluate the efficacy of conjunctival limbal autograft (CLAU) combined with the amnion-assisted conjunctival epithelial redirection (ACER) procedure for patients with unilateral total limbal stem cell deficiency (LSCD) caused by severe chemical burn. (2) Methods: A retrospective interventional case series of unilateral total LSCD after chemical burn who underwent CLAU combined with ACER surgery between September 2021 and July 2023 was collected. Outcome measures included epithelialization of the cornea with donor limbus-derived epithelium, best corrected visual acuity (BCVA), and complications. (3) Results: Nine males and one female were included in this study. The mean age was 40.9 ± 9.63 (range, 26 to 55) years. The average duration between injury and CLAU combined with the ACER procedure was 7.67 ± 3.97 (range, 4 to 18) months. All patients achieved corneal epithelialization and improved BCVA. Postoperative complications occurred in four cases, including delayed corneal epithelial healing in one case, delayed amniotic membrane dissolution and detachment in two cases, and recurrence of symblepharon in one case. No complications were noted in the healthy donor eyes. (4) Conclusions: CLAU combined with ACER is a safe and effective treatment for unilateral total LSCD caused by severe chemical burn. This combined surgery restores visual function for patients with corneal blindness caused by chemical burn, reducing the burden on the families and society.

Ocular Surface Regeneration by Limbal Stem Cells Therapies: State of the Art, Challenges, and Perspectives.

Limbal stem cells (LSCs) are adult stem cells located at the limbus ensuring the continuous renewal of the corneal epithelium, critical to maintain an optimal visual function. Damages to the LSCs or their niche microenvironment lead to limbal stem cell deficiency (LSCD), a potentially blinding disease. Transplantation of LSCs as a treatment for severe to total LSCD has gained popularity since 1980s, owing to the clinical success of the first direct limbal autograft transplantation. Recent advances in the understanding of the LSCs' molecular identity and regulation have enabled preclinical and clinical advancements of promising LSCs therapies. However, lack of standardization of the diagnostic methods, staging of the disease severity, manufacturing process, and clinical outcome measures have hindered the advancement of the therapy. To move these therapies to the clinic, optimization and standardization of the diagnostic strategy, cell product manufacturing, and assessment of clinical efficacy with potency assays are key points to the development of customized therapies. Recent findings suggest that residual LSCs exist in eyes presenting with clinical signs of total LSCD, which opens new therapeutic strategies for eyes with partial LSCD. Prospective, randomized, multicentric controlled clinical trials are necessary to determine the efficacy of different LSCs therapies for different stages of LSCD using a set of standardized outcome measures.

Case Report: Simultaneous penetrating keratoplasty with autologous simple limbal epithelial transplantation as an alternative to keratoprosthesis

Introduction and importance: This case report highlights the multidisciplinary approach required to achieve successful anatomical and functional outcomes, in an eye with total limbal stem cell deficiency (LSCD) associated with underlying corneal scarring and thinning. Presentation of case: A 59-year-old gentleman had poor visual recovery in the right eye (RE) following accidental carbide blast, 1-year before presenting to us. The visual acuity was counting fingers and clinical examination revealed cicatricial entropion involving the upper eyelid, total LSCD, corneal scarring with a central descemetocele and cataract in the RE. Prior to ocular surface reconstruction, entropion correction was performed. Three months later, penetrating keratoplasty combined with cataract surgery and intraocular lens implantation (penetrating keratoplasty (PK) triple), with autologous simple limbal epithelial transplantation (SLET) was performed. The visual acuity was 20/100, 18 months after the surgery, with a clear well-epithelized corneal graft and stable ocular surface. Discussion: LSCD is caused by a decrease in the population and /or function of the limbal epithelial stem cells. Limbal stem cell transplantation (LSCT) is warranted in eyes with total LSCD. In eyes with coexisting corneal scarring, LSCT alone may be inadequate to restore the vision. These eyes require simultaneous or sequential lamellar or full-thickness corneal transplantation for visual rehabilitation. Though, the existing literature favors a sequential approach, where LSCT is performed first followed by corneal transplantation, under certain circumstances such as a thin underlying cornea like in our case, corneal transplantation may have to be combined with LSCT to achieve optimal outcomes. Conclusion: Combining autologous SLET with PK can be performed for visual rehabilitation in eyes with unilateral total LSCD and underlying corneal thinning. Corneal and limbal graft survival is prolonged if existing adnexal comorbidities are addressed before any surgical intervention is planned and adequate time interval is allowed for the surface inflammation to subside.

Comparison between Cultivated Oral Mucosa and Ocular Surface Epithelia for COMET Patients Follow-Up.

Total bilateral Limbal Stem Cell Deficiency is a pathologic condition of the ocular surface due to the loss of corneal stem cells. Cultivated oral mucosa epithelial transplantation (COMET) is the only autologous successful treatment for this pathology in clinical application, although abnormal peripheric corneal vascularization often occurs. Properly characterizing the regenerated ocular surface is needed for a reliable follow-up. So far, the univocal identification of transplanted oral mucosa has been challenging. Previously proposed markers were shown to be co-expressed by different ocular surface epithelia in a homeostatic or perturbated environment. In this study, we compared the transcriptome profile of human oral mucosa, limbal and conjunctival cultured holoclones, identifying Paired Like Homeodomain 2 (PITX2) as a new marker that univocally distinguishes the transplanted oral tissue from the other epithelia. We validated PITX2 at RNA and protein levels to investigate 10-year follow-up corneal samples derived from a COMET-treated aniridic patient. Moreover, we found novel angiogenesis-related factors that were differentially expressed in the three epithelia and instrumental in explaining the neovascularization in COMET-treated patients. These results will support the follow-up analysis of patients transplanted with oral mucosa and provide new tools to understand the regeneration mechanism of transplanted corneas.

Case Report: Simultaneous penetrating keratoplasty with autologous simple limbal epithelial transplantation as an alternative to keratoprosthesis

Introduction and importance: This case report highlights the multidisciplinary approach required to achieve successful anatomical and functional outcomes, in an eye with total limbal stem cell deficiency (LSCD) associated with underlying corneal scarring and thinning. Presentation of case: A 59-year-old gentleman had poor visual recovery in the right eye (RE) following accidental carbide blast, 1-year before presenting to us. The visual acuity was counting fingers and clinical examination revealed cicatricial entropion involving the upper eyelid, total LSCD, corneal scarring with a central descemetocele and cataract in the RE. Prior to ocular surface reconstruction, entropion correction was performed. Three months later, penetrating keratoplasty combined with cataract surgery and intraocular lens implantation (penetrating keratoplasty (PK) triple), with autologous simple limbal epithelial transplantation (SLET) was performed. The visual acuity was 20/100, 18 months after the surgery, with a clear well-epithelized corneal graft and stable ocular surface. Discussion: LSCD is caused by a decrease in the population and /or function of the limbal epithelial stem cells. Limbal stem cell transplantation (LSCT) is warranted in eyes with total LSCD. In eyes with coexisting corneal scarring, LSCT alone may be inadequate to restore the vision. These eyes require simultaneous or sequential lamellar or full-thickness corneal transplantation for visual rehabilitation. Though, the existing literature favors a sequential approach, where LSCT is performed first followed by corneal transplantation, under certain circumstances such as a thin underlying cornea like in our case, corneal transplantation may have to be combined with LSCT to achieve optimal outcomes. Conclusion: Combining autologous SLET with PK can be performed for visual rehabilitation in eyes with unilateral total LSCD and underlying corneal thinning. Corneal and limbal graft survival is prolonged if existing adnexal comorbidities are addressed before any surgical intervention is planned and adequate time interval is allowed for the surface inflammation to subside.

Keratoprosthesis in dry eye disease.

Bilateral corneal blindness with severe dry eye disease (DED), total limbal stem cell deficiency with underlying corneal stromal scarring and vascularization, combined with adnexal complications secondary to chronic cicatrizing conjunctivitis is a highly complex situation to treat. In such eyes, procedures such as penetrating keratoplasty alone or combined with limbal stem cell transplantation are doomed to fail. In these eyes, keratoprosthesis (Kpro) or an artificial cornea is the most viable option, eliminating corneal blindness even in eyes with autoimmune disorders such as Stevens-Johnson syndrome, ocular mucous membrane pemphigoid, Sjogren's syndrome, and nonautoimmune disorders such as chemical/thermal ocular burns, all of which are complex pathologies. Performing a Kpro in these eyes also eliminates the need for systemic immunosuppression and may provide relatively early visual recovery. In such eyes, the donor cornea around the central cylinder of the Kpro needs to be covered with a second layer of protection to avoid desiccation and progressive stromal melt of the underlying cornea, which is a common complication in eyes with severe DED. In this review, we will focus on Kpro designs that have been developed to survive in eyes with the hostile environment of severe DED. Their outcomes in such eyes will be discussed.

Genetic analysis of allogenic donor cells after successful allo-limbal epithelial transplantation in simple and cultivated limbal epithelial transplantation procedures

This non-comparative cohort study investigated long-term donor cell survival after allogenic simple/cultivated limbal epithelial transplantations (allo-SLET/allo-CLET, respectively) by genetic analysis. Transplanted corneal epithelial cells, which underwent impression cytology and/or corneal-button biopsy, were examined for personal identities of autosomal short-tandem repeats; the percentages of donor cells were calculated based on matching recipient or donor buccal-DNA references. Twelve patients were included; 4 underwent allo-CLET, 8 underwent allo-SLET. Eight patients (67%) had total limbal stem cell deficiency (LSCD). Genetic analysis was performed postoperatively (mean, 55.3 months). Donor cells were detected in 4 of 12 patients (25%), all of whom underwent allo-SLET; 1 patient had a donor genotype and 3 patients had a mixed donor/recipient genotype. The longest time of donor cell detection was 30 months. Seven patients (58%) used systemic immunosuppressives at the time of genetic analysis (mean use, 22.5 months). Allogenic donor cells survived in both procedures for the long term postoperatively, which encourages the long-term use of systemic immunosuppressives. Donor cells may not be the only factor in graft survival, in that most successful cases had a recipient profile. Their presence for a specific time may promote niches for the patients’ own cells to repopulate, especially for partial LSCD.

Understanding Ocular Surface Inflammation in Tears Before and After Autologous Cultivated Limbal Epithelial Stem Cell Transplantation.

We aimed to determine the expression of inflammatory cytokines in the tears of patients with unilateral total limbal stem cell deficiency (TLSCD) caused by chemical burns before and after autologous cultivated limbal epithelial stem cell transplantation (CLET). Tear samples were collected from both eyes of 23 patients with unilateral TLSCD and 11 healthy controls, at fixed timepoints before and after CLET. Dissolved molecules were extracted from Schirmer's strips using a standardised method and analysed on an array plate of ten inflammatory cytokines (V-Plex Proinflammatory Panel 1 Human Kit, MSD). IL1β expression was significantly elevated in the TLSCD eye compared with the unaffected eye at baseline (p < 0.0001) but decreased to normal 3months post-CLET (p = 0.22). IL6 and IL8 were unaffected at baseline but significantly elevated in the TLSCD eyes at 1month post-CLET (p = 0.001 and p < 0.0001, respectively). IL6 returned to normal at 3months and IL8 at 6months post-CLET. There was a significant renewed increase in IL1β, IL6 and IL8 expression at 12months post-CLET (p < 0.0001, p = 0.0001 and p = 0.0003, respectively). IFNγ, IL10 and IL12p70 expression were significantly reduced in both eyes of patients with unilateral TLSCD at all timepoints. IL1β is a specific marker of inflammation in TLSCD eyes that could be therapeutically targeted pre-CLET to improve stem cell engraftment. At 12months post-CLET the spike in levels of IL1β, IL6 and IL8 coincides with cessation of topical steroids, suggesting ongoing subclinical inflammation. We therefore recommend not discontinuing topical steroid treatment in cases where penetrating keratoplasty is indicated; however, further investigation is needed to ascertain this. European Union Drug Regulating Authorities Clinical Trials Database (EuDRACT 2011-000608-16); ISRCTN (International Standard Randomised Controlled Trial Number (isrctn51772481).

Safety and Efficacy of Contact Lenses in Eyes After Simple Limbal Epithelial Transplantation.

The aim of this study was to evaluate the safety and efficacy of contact lenses (CLs) in eyes after simple limbal epithelial transplantation (SLET) for limbal stem cell deficiency (LSCD). This retrospective study included 61 eyes with partial or total LSCD which underwent SLET and were fitted with corneal or scleral rigid gas-permeable CLs. The primary outcome measure was best-corrected visual acuity (BCVA) with CLs. The median age at presentation was 22 years. The most common cause of LSCD was chemical injury [47/61 eyes (77%)]. Twenty-seven eyes (44%) were fitted with corneal rigid gas-permeable lenses, while 34 eyes (56%) were prescribed scleral lenses. The median duration of interval between SLET and CL trial was 10 months (interquartile range: 4-17). The median preoperative BCVA was logarithm of minimal angle of resolution (logMAR) 1.8. This improved to logMAR 1 (P < 0.001) after SLET and to logMAR 0.6 (P < 0.001) with CLs. Eyes with chemical injury (logMAR 1 vs. 0.6, P = 0.0001), grade 1 (logMAR 0.8 vs. 0.4, P < 0.0001), and grade 2 (logMAR 0.9 vs. 0.6, P = 0.004) corneal scarring had better improvement in BCVA with CLs. No complications were noted until the last follow-up visit. CLs, both corneal and scleral lenses, provide significant visual improvement in eyes after SLET with residual corneal scarring. These can be safely prescribed in such eyes without any adverse effects. This option can be considered before offering keratoplasty in these eyes.

Severe chemical eye injuries - clinical outcomes and associated socio-economic factors.

To describe clinical outcomes, management, and socio-economic impact of severe acute chemical eye injuries in a tertiary hospital. 37 patients required emergency admission to the Royal Victoria Infirmary eye ward between April 2013 and September 2015. Demographics, best corrected distance visual acuity (BCDVA), causative agent, degree of limbal stem cell deficiency (LSCD), management and socio-economic data were evaluated. Mean age on admission was 34.5 years (SD 16.3; range 16-82); 30 males (81.1%); 22 bilateral (59.5%). Causative agent: alkali in 30 cases (81.1%); acid in three cases (8.1%); and unknown in four cases (10.8%). Fifteen cases (40.5%) were assaults, 12 (32.5%) work-related accidents, nine (24.3%) domestic accidents and one (2.7%) undetermined. Eleven patients (29.7%) were unemployed, 18 (48.6%) were labourers, three (8.1%) were students, three (8.1%) were retired and two (5.4%) were professionals. Mean admission time was five days (SD 3.2; range 1-12). Mean follow-up time was 170.5 days (range 1-946). Mean cost of admission was £2478 (range £274-5785). Five patients (13%; seven eyes) developed total or partial limbal stem cell deficiency, all being assaults. Main causative agent in our study was alkali, with young men in the working age being most frequently involved. Many patients required prolonged hospital admission and costly follow-up. The majority of cases were assaults, mostly occurring in unemployed patients. All the limbal stem cell deficiency cases were due to assaults. We believe that socio-economic factors play an important role in the cause, severity and cost of chemical eye injuries. Acute chemical eye injuries have a significant and extensive impact on patients' visual function outcomes and vision-related quality of life, with consequent enormous burden to affected individuals, their families and society. We believe that by understanding the socio-economic environment, we may not only be able to enforce safety measures to tackle the increasing rate of severe chemical eye injuries in our community, but also to develop collaborative programmes with the community, educating the population on the seriousness of chemical eye injuries, and with the local authorities, trying to understand the clustering of assaults in areas and tackling the associated socio-economic risk factors, such as unemployment. Given the increasing rate of assaults using chemicals in recent times, it is also important to assess availability of adequate victim support programmes and develop good interaction with relevant local, regional and national authorities to ensure all aspects of community security service are in place to be able to address any potential deficiencies in line with police and home office guidelines. Keeping in mind that the best action plan is always prevention. However, when an ocular injury does occur it is evident that significant morbidity and visual sequelae can result and affect the socio-economic status of the victims despite our best current medical and surgical care.

En Bloc Keratolimbal Allograft and Central Penetrating Keratoplasty: A Novel Surgical Technique in Severe Limbal Stem Cell Deficiency.

The purpose of this study was to present a novel surgical technique combining 360-degree keratolimbal allograft (KLAL) and simultaneous central keratoplasty termed en bloc KLAL with the central penetrating keratoplasty (PKP) performed in those cases with total limbal stem cell deficiency (LSCD) and corneal scars. Nine eyes of 9 patients underwent en bloc KLAL and central PKP between 2014 and 2016. All patients had bilateral total LSCD with total corneal opacity due to different etiologies. The exclusion criteria were previous limbal stem cell transplantation and the presence of active and uncontrolled ocular surface inflammation. The same donor globe was used for harvesting 360-degree KLAL and central PKP. The 1-piece integrity of the KLAL and PKP graft was preserved during the described technique. All patients received modified immunosuppressive regimens compatible with the Cincinnati solid organ transplantation protocol. The average age of patients was 58.6 ± 18.6 years. The diagnosis was mustard gas keratopathy in 6, herpes simplex keratitis in 1, and severe acid chemical burn in 2 patients. Seven patients were male. An integrated ocular surface without epitheliopathy and a clear cornea was achieved in 8 patients (88.8%) with an average of 6.5 years in follow-up. The average best-corrected visual acuity was 1.89 ± 0.18 (20/1600) preoperatively which improved to 1.02 ± 0.64 (20/200) logMAR in the postoperative period. Endothelial immune rejection episodes were observed in 3 patients. KLAL rejection was not observed in any patient. One patient required repeat PKP due to corneal graft failure. En bloc 360-degree KLAL and central PKP could simultaneously be performed in patients with total LSCD and corneal opacification.

Outcome of keratolimbal allograft transplantation with deep anterior lamellar keratoplasty for bilateral limbal stem cell deficiency.

To evaluate and compare the outcome of keratolimbal allograft (KLAL) transplantation with or without deep anterior lamellar keratoplasty (DALK) for bilateral severe limbal stem cell deficiency (LSCD). This retrospective review included 49 eyes of 46 patients who underwent KLAL transplantation at the Department of Ophthalmology of Chinese PLA general hospital, 2009-2020, for bilateral severe LSCD were examined for corneal clarity and corneal scarring to determine whether to combine DALK with KLAL transplantation. Preoperative information, surgical decision tree, surgical procedures, and postoperative data were collected for each eye. All patients had preoperative severe or total LSCD. Twenty-four eyes underwent KLAL transplantation only, 25 KLAL transplantation plus DALK. The mean follow-up was 46.80 ± 31.22 months (18-158 months). Overall KLAL survival (with or without DALK) was 71.43% at the final follow-up (KLAL-only 66.67%, KLAL-DALK 76%). Kaplan-Meier survival analysis showed that the 3-year survival probability of all grafts was 70.53 ± 10.89% (KLAL-only 64.86 ± 10.11%, KLAL-DALK 75.79 ± 8.62%). The proportion of BCVA ≥ 20/200 eyes among all KLAL transplantations increased from 11 eyes (22.45%) preoperatively to 25 eyes (51.02%) after 1 year and 24 eyes (48.98%) at the last follow-up (P = 0.01). The proportion of BCVA ≥ 20/200 eyes in the KLAL-DALK group increased significantly (P = 0.04), from 16.0% at baseline to 48.0% after 1 year to 44.0% at the last follow-up. Seventeen eyes (34.69%) had postoperative complications. KLAL-DALK is an effective option to restore a stable ocular surface and visual acuity rapidly in patients with bilateral, late-stage, severe LSCD.

Mini-Conjunctival Limbal Autograft (Mini-CLAU) Using Platelet-Rich Plasma Eye Drops (E-PRP): A Case Series.

The purpose of this study was to introduce a new method of limbal stem cell transplantation using autologous platelet-rich plasma (E-PRP) eye drops for unilateral total limbal stem cell deficiency. Patients with total unilateral limbal stem cell deficiency due to chemical burn underwent mini-conjunctival limbal autograft using autologous E-PRP drops. One small limbal block, measuring 2 × 2 mm, was harvested from the patients' contralateral healthy eye and transplanted to the diseased eye. All patients received E-PRP drops until achieving complete corneal epithelialization. Subsequent corneal transplantation was performed in eyes with significant stromal opacification. Corneal buttons obtained during corneal transplantation underwent immunohistochemistry for the evaluation of limbal stem cell markers (ABCG2 and P63). Visual acuity, epithelial healing, corneal clarity, and regression of corneal conjunctivalization/vascularization were evaluated after surgery. Ten patients with acid (n = 7) or alkali (n = 3) burn were included. The mean follow-up period was 21.7 ± 5.8 months (range, 12-32 months). Corneas were completely reepithelialized within 14.9 ± 3.5 days (range, 11-21 days). Corneal conjunctivalization/vascularization dramatically regressed 1 to 2 months after surgery in all cases, and corneal clarity considerably improved in 7 patients. In the 3 eyes with significant stromal opacification, subsequent optical penetrating keratoplasty was performed. The ocular surface was stable throughout the follow-up period in all eyes. BSCVA improved to 0.60 ± 0.0.32 and 0.46 ± 0.0.25 logMAR in eyes with and without corneal transplantation, respectively, at the final follow-up visit. ABCG2 and P63 markers were detected on corneal buttons after keratoplasty. Based on our clinical and laboratory findings, mini-conjunctival limbal autograft using E-PRP can be considered as a promising alternative to ocular surface reconstruction.

Ophthalmic Complications and Managements of Sulfur Mustard Exposure: A Narrative Review.

Sulfur mustard (SM) is a lethal chemical agent that affects many organs, particularly the eyes, respiratory system and skin. Even asymptomatic patients with documented SM vapor exposure may develop organ disorder many years later. Patients with even minor signs in the acute stage may experience late complications that necessitate surgery. Early decontamination and conservative measures could help the patients and decrease the complications. Despite decades of research, there is still no effective treatment for either acute or long-term SM-induced ocular complications. Even after multiple medications and surgical procedures, the majority of patients continue to have symptoms. For dry eye, punctual occlusion, autologous eye drops, and aggressive lubrication are used; for persistent epithelial defects (PED), tarsorrhaphy, amniotic membrane transplant, and stem cell transplantation are used; for total limbal stem cell deficiency (LSCD), living-related conjunctivolimbal allograft and keratolimbal allograft are used; for corneal vascularization, steroids, non-steroidal anti-inflammatory drugs, and anti-vascular endothelial growth factor prescribed; and for corneal opacities, corneal transplantation is done. Platelet rich plasma and topical drops containing stem cell transplantation for LSCD, photodynamic therapy paired with subconjunctival or topical anti-vascular endothelial growth factors for corneal vascularization, topical curcumin and topical ciclosporin-A for dry eye, and orbital fat-derived stem cells for PED are all alternative treatments that can be suggested. Despite the experimental and clinical research on the complications of SM exposure over the past decades, there is still no effective treatment for eye complications. However, supportive medical and surgical management has been applied with relatively good outcome.

Labial Mucosa Stem Cells: Isolation, Characterization, and Their Potential for Corneal Epithelial Reconstruction.

PurposeThe purpose of this study was to characterize labial mucosa stem cells (LMSCs) and to investigate their potential for corneal epithelial reconstruction in a rabbit model of total limbal stem cell deficiency (LSCD).MethodsRabbit LMSCs (rLMSCs) and human (hLMSCs) LMSCs were derived from labial mucosa and characterized in terms of their proliferation activity by the evaluation of proliferation index (PI) and colony forming efficiency (CFE), cell senescence, and differentiation abilities. The expression of various limbus-specific, stem cell-specific, and epithelial markers was assessed via immunocytochemistry. Flow cytometry was used to evaluate mesenchymal and hematopoietic cell surface markers expression. Chromosomal stability of the derived cells was examined using the conventional GTG-banding technique. To assess the impact of LMSCs on corneal epithelial reconstruction, rLMSCs were seeded onto a decellularized human amniotic membrane (dHAM), thereafter their regeneration potential was examined in the rabbit model of total LSCD.ResultsBoth rLMSCs and hLMSCs showed high proliferation and differentiation abilities, entered senescence at later passages, and expressed different stem cell-specific (ABCB5, ALDH3A1, ABCG2, and p63α), mesenchymal (vimentin), and epithelial (CK3/12, CK15) markers. Cell surface antigen expression was similar to other described mesenchymal stem cells. No clonal structural chromosome abnormalities (CSCAs) and the low percentage of non-clonal structural chromosome abnormalities (NSCAs) were observed. Transplantation of rLMSCs promoted corneal epithelial reconstruction and enhanced corneal transparency.ConclusionsLMSCs have significant proliferation and differentiation abilities, display no detrimental chromosome aberrations, and demonstrate considerable potential for corneal repair.