Medically reversible limbal stem cell disease: clinical features and management strategies

Cell therapy in the cornea: The emerging role of microenvironment

The cornea is an ideal testing field for cell therapies. Its highly ordered structure, where specific cell populations are sequestered in different layers, together with its accessibility, has allowed the development of the first stem cell-based therapy approved by the European Medicine Agency. Today, different techniques have been proposed for autologous and allogeneic limbal and non-limbal cell transplantation. Cell replacement has also been attempted in cases of endothelial cell decompensation as it occurs in Fuchs dystrophy: injection of cultivated allogeneic endothelial cells is now in advanced phases of clinical development. Recently, stromal substitutes have been developed with excellent integration capability and transparency. Finally, cell-derived products, such as exosomes obtained from different sources, have been investigated for the treatment of severe corneal diseases with encouraging results. Optimization of the success rate of cell therapies obviously requires high-quality cultured cells/products, but the role of the surrounding microenvironment is equally important to allow engraftment of transplanted cells, to preserve their functions and, ultimately, lead to restoration of tissue integrity and transparency of the cornea.

Clinical features and management of keratoconjunctivitis associated with inadequate tear drainage

OBJECTIVE

To describe clinical features and management of toxic keratoconjunctivitis associated with punctal and (or) canaliculus stenosis (toxic soup syndrome).

DESIGN

Retrospective observational case series.

METHODS

Electronic medical record database search for the keywords "toxic soup syndrome" and retrospective chart review were performed. Thirty-five eyes of 25 patients were seen at a tertiary cornea clinic between January 2017 and December 2021. Sex, age, distance-corrected visual acuity, topical medications, symptoms, clinical signs, and outcomes after medical and surgical interventions were analyzed. The main outcome measured was improvement in ocular surface signs and symptoms after interventions.

RESULTS

Overall, 35 eyes of 25 patients with a mean age of 66.8 ± 12.8 years, of which 72% were female, were included. The primary complaint was hyperemia and epiphora in all patients. Rosacea or meibomian gland disease were present in all patients, 7 (28%) had glaucoma, and 7 (28%) developed limbal stem cell deficiency. Twenty-two patients (88%) were using topical medications on presentation. All eyes had either punctal plugs, cauterized puncta, or punctal and (or) canaliculus stenosis. Management of all patients consisted of suspension of all preserved topical medications and institution of some type of anti-inflammatory therapy. Nineteen patients (76%) improved after improvement of lacrimal drainage. One patient with severe resistance in the canaliculus required ongoing preservative-free topical steroids.

CONCLUSIONS

Chronic drug-induced or pooled inflammatory mediators causing toxic conjunctivitis may be aggravated by punctal and (or) canaliculus stenosis, leading to toxic soup syndrome. Clearance of punctal obstruction leads to improvement in most patients.

Management of corneal neovascularization: Current and emerging therapeutic approaches

Corneal neovascularization (CoNV) is a sight-threatening condition affecting an estimated 1.4 million people per year, and the incidence is expected to rise. It is a complication of corneal pathological diseases such as infective keratitis, chemical burn, corneal limbal stem cell deficiency, mechanical trauma, and immunological rejection after keratoplasties. CoNV occurs due to a disequilibrium in proangiogenic and antiangiogenic mediators, involving a complex system of molecular interactions. Treatment of CoNV is challenging, and no therapy thus far has been curative. Anti-inflammatory agents such as corticosteroids are the mainstay of treatment due to their accessibility and well-studied safety profile. However, they have limited effectiveness and are unable to regress more mature neovascularization. With the advent of advanced imaging modalities and an expanding understanding of its pathogenesis, contemporary treatments targeting a wide array of molecular mechanisms and surgical options are gaining traction. This review aims to summarize evidence regarding conventional and emerging therapeutic options for CoNV.

Cataract surgery in setting of ocular surface disease

PURPOSE OF REVIEW

The purpose of this article is to review the available strategies to successfully identify and manage ocular surface disease (OSD) pre, intra and post-cataract surgery.

RECENT FINDINGS

Cataract surgery and OSD have an intricate relationship: the surgical procedure can induce or exaggerate OSD symptoms, while OSD can negatively impact surgical refractive outcomes and increase the rate of postoperative complications.

SUMMARY

Improving the health and stability ocular surface is the key to enhance post cataract surgery refractive outcomes and avoid complications. This is pivotal for patients affected by severe OSD, but is also important for patients with minimal signs or symptoms. A correct diagnosis and a stepwise approach are the keys to improve the quality of life of such patients.

Matrix-Assisted Cell Transplantation for the Treatment of Limbal Stem Cell Deficiency in a Rabbit Model

With the development of regenerative medicine in ophthalmology, the identification of cells with high proliferative potential in the limbal area has attracted the attention of ophthalmologists and offered a new option for treatment in clinical practice. Limbal stem cell deficiency (LSCD) is an identified eye disease with a difficult and negative outcome, for which the traditional treatment is keratoplasty. This study sought to evaluate the efficacy of matrix-assisted cell transplantation consisting of in vitro-cultured autologous limbal stem cells (LSCs) and type I collagen for the treatment of LSCD in rabbits. LSCD was induced in 10 rabbits by a combination of mechanical limbectomy and alkali burns. Cells were cultured on a plate for 14 days before being transferred to a collagen-based matrix for another 7 days. Rabbits were divided into two groups as follows: the experimental group (five rabbits) received matrix-assisted cell transplantation, while the control group (five rabbits) received only conservative therapy with anti-inflammatory eye drops. During the postoperative period, all rabbits were examined using slit-lamp biomicroscopy with photo-registration and fluorescent staining, impression cytology and anterior segment optical coherence tomography (AS-OCT). Rabbits were euthanized at 30 and 120 days, and their corneas were processed for histology and immunohistochemistry. As a consequence, rabbits in the experimental group demonstrated the restoration of the corneal epithelium and transparency without epithelial defects. Moreover, goblet cells were absent in the central zone of the corneal epithelium. In conclusion, our new method of treatment enhanced the corneal surface and is an effective method of treatment for LSCD in rabbits.

Advances in Cell Transplantation Therapy for Limbal Stem Cell Deficiency

BACKGROUND

Limbal stem cells (LSCs) are essential for maintaining corneal transparency and ocular surface integrity. Many external factors or genetic diseases can lead to corneal limbal stem cell deficiency (LSCD), resulting in the loss of barrier and corneal epithelial cell renewal functions. Stem cell transplantation is one of the primary treatments for LSCD, including limbal transplantation and cultivated limbal epithelial transplantation. In addition, a variety of non-limbal stem cell lines have been experimented with for LSCD treatment. Biological scaffolds are also used to support in vitro stem cell culture and transplantation. Here, we review the mechanisms of corneal maintenance by LSCs, the clinical stage and surgical treatment of LSCD, the source of stem cells, and the biological scaffolds required for in vitro culture.

METHODS

This study is a narrative retrospective study aimed at collecting available information on various aspects of surgical treatments for LSCD. Relevant literature was searched in a range of online databases, including Web of Science, Scopus, and PubMed from 2005 to March, 2023.

RESULTS

A total of 397 relevant articles were found, and 49 articles with strong relevance to the studies in this paper were obtained and analyzed. Moreover, 11 of these articles were on the concept of LSCD and the mechanism of LESCs maintaining the corneal epithelium, 3 articles on the staging and grading of LSCD, 17 articles on cell transplantation methods and donor cell sources, and 18 articles on scaffolds for delivering stem cells. We also summarized the advantages and disadvantages of different cell transplantation methods and the benefits and limitations of scaffolds based on the above literature.

CONCLUSION

The treatment of LSCD is determined by the clinical stage and whether it involves monocular or binocular eyes. Appropriate surgical techniques should be taken for LSCD patients in order to reconstruct the ocular surface, relieve symptoms, and restore visual function. Meanwhile, biological scaffolds assist in the ex vivo culture and implantation of stem cells.

Corneal Epithelial Development and the Role of Induced Pluripotent Stem Cells for Regeneration

Severe corneal disorders due to infective aetiologies, trauma, chemical injuries, and chronic cicatricial inflammations, are among vision-threatening pathologies leading to permanent corneal scarring. The whole cornea or lamellar corneal transplantation is often used as a last resort to restore vision. However, limited autologous tissue sources and potential adverse post-allotransplantation sequalae urge the need for more robust and strategic alternatives. Contemporary management using cultivated corneal epithelial transplantation has paved the way for utilizing stem cells as a regenerative potential. Humaninduced pluripotent stem cells (hiPSCs) can generate ectodermal progenitors and potentially be used for ocular surface regeneration. This review summarizes the process of corneal morphogenesis and the signaling pathways underlying the development of corneal epithelium, which is key to translating the maturation and differentiation process of hiPSCs in vitro. The current state of knowledge and methodology for driving efficient corneal epithelial cell differentiation from pluripotent stem cells are highlighted.

[Experimental evaluation of the efficacy of tissue-engineered constructs in the treatment of limbal stem cell deficiency]

Limbal stem cell deficiency (LSCD) is one of the leading factors negatively affecting the success of keratoplasty, and its treatment remains an urgent problem in ophthalmology. With the development of regenerative medicine, one of the promising approaches is the transplantation of tissue-engineered constructs from cultured limbal stem cells (LSCs) in biopolymer carriers.

PURPOSE

This study was conducted to develop an experimental model of LSCD and evaluate the effectiveness of transplantation of a tissue-engineered construct consisting of cultured cells containing a population of LSCs and a collagen carrier.

MATERIAL AND METHODS

The study was performed on 12 rabbits and included several stages. At the first stage, the physiological effects of collagen matrix implantation into the limbal zone were studied. At the second stage, tissue-engineered constructs consisting of LSCs on a collagen matrix were formed and their effect on the regeneration processes in the experimental LSCD model was analyzed. The animals were divided into 2 groups: surgical treatment (transplantation of the tissue-engineered construct) was used in the experimental group, and conservative treatment was used in the control group. Slit-lamp biomicroscopy with photo-registration, fluorescein corneal staining, optical coherence tomography of the anterior segment of the eye, and impression cytology were used to assess the results.

RESULTS

No side reactions were observed after implantation of the collagen matrix into the limbal zone. One month after surgical treatment of the LSCD model in the experimental group, complete epithelization with minor manifestations of epitheliopathy was observed. In the control group, erosion of the corneal epithelium was noted. The time of corneal epithelization in the experimental and control groups was 9.2±2.95 and 46.20±12.07 days, respectively (p=0.139). According to the data of impression cytology, in the experimental group there were no goblet cells in the central part of the cornea, which indicates the restoration of corneal type epithelial cells, in contrast to the control group.

CONCLUSION

Transplantation of a tissue-engineered construct from cultured limbal cells on a collagen membrane should be considered as a promising method for the treatment of limbal stem cell deficiency.

A Review of Contact Lens-Induced Limbal Stem Cell Deficiency

Limbal stem cell deficiency (LSCD) is a pathologic condition caused by the dysfunction and destruction of stem cells, stem cell precursors and limbal cell niche in the corneal epithelium, leading to severe conjunctivalization of the cornea. Etiologies for LSCD span from congenital (aniridia), traumatic (chemical or thermal injuries), autoimmune (Stevens-Johnson syndrome) and iatrogenic disease to contact lens (CL) wear. Of these, CL wear is the least understood and is often a subclinical cause of LSCD. Even with recent advances in LSCD research, limitations persist in establishing the pathogenesis and treatment guidelines for CL-induced LSCD. A literature search was conducted to include original articles containing patients with CL-induced LSCD. This review will critically discuss the complex pathophysiology behind CL-induced LSCD, the underlying risk factors and epidemiology of the disease as well as methods to obtain a diagnosis. Various treatment options will be reviewed based on proposed treatment strategies.

Wnt activation as a potential therapeutic approach to treat partial limbal stem cell deficiency

Limbal epithelial stem/progenitor cells (LSCs) are adult stem cells located at the limbus, tightly regulated by their niche involving numerous signaling pathways, such as Wnt. Wnt proteins are secreted morphogens that play critical roles in embryonic development, stem cell proliferation, self-renewal, tissue regeneration, and remodeling in adults. It has been shown that a small molecule Wnt mimic could improve LSCs expansion ex vivo. Damage to the LSCs and/or their niche can lead to limbal stem cell deficiency (LSCD), a condition that can cause corneal blindness and is difficult to treat. This study explored if repopulating residual LSCs in partial LSCD through Wnt activation could be a novel therapeutic approach. To mimic LSCD due to a chemical injury, single cultured LSCs were exposed to various concentrations of sodium hydroxide. A progressive loss of the LSCs phenotype was observed: the percentage of p63bright cells and cytokeratin (K)14+ cells decreased while the percentage of K12+ increased. Wnt activation was attained by treating the LSCs with lithium chloride (LiCl) and a small-molecule Wnt mimic, respectively. After 18 h of treatment, LSCs proliferation was increased, and the LSCs phenotype was recovered, while the untreated cells did not proliferate and lost their phenotype. The percentage of p63bright cells was significantly higher in the Wnt mimic-treated cells compared with untreated cells, while the percentage of K12+ cells was significantly lower. These findings suggest that local Wnt activation may rescue LSCs upon alkaline injury.

The Use of Corneoscleral Grafts to Maintain Tectonic Stability in Severe Keratolysis

Severe corneal ulcerations, causing major keratolysis with large perforation of the cornea or extending to the limbal region, are an ophthalmic emergency. In these cases, a larger corneoscleral graft can be transplanted to restore tectonic integrity, alleviate pain, save vision, and prevent loss of the eye. Chart review of 34 patients with a corneoscleral graft ≥9.5 mm was conducted. Primary endpoints of the study were tectonic stability defined as no need for another keratoplasty or enucleation. In addition, visual acuity, postoperative complications, and secondary procedures were analyzed. In total, 12 patients (35%) were female. The mean age at transplantation was 65 ± 19 years. The underlying disease was a perforated infectious corneal ulcer in 30 cases (88%). Mean follow up was 675 ± 789 days. Tectonic stability at the end of the follow-up was maintained with a probability of 56% in a Kaplan-Meier analysis. Another penetrating keratoplasty was necessary in six cases (17%) and enucleation in five cases (15%). A corneoscleral transplant remains a viable treatment option to prevent enucleation in severe keratolysis. In our study, this was possible in about half of the cases. Postoperative complications, secondary surgeries, and markedly reduced visual acuity put the advantages into perspective.

Case report: Medical treatment for limbal epithelial stem cell deficiency in patients treated for glaucoma

Limbal epithelial stem cell deficiency (LSCD) is an abnormal corneal epithelial lesion with several causes. The patient was diagnosed using fluorescein staining. Bullous keratopathy, multiple surgeries, and drug-related damage can cause LSCD in glaucoma patients. We evaluated the medical treatment course for LSCD in patients with glaucoma. We retrospectively reviewed the electronic medical records of patients diagnosed with LSCD and investigated their background, course of treatment, and classification stages of LSCD before and after treatment. The global consensus classification system (stages IA-C, IIA-B, and III) proposed by Deng et al. (Cornea 2020) was used. Seven patients (two males) and eight eyes were studied. The median age of the patients was 82 years, and the mean duration of glaucoma treatment was 8 years. The patients had open-angle glaucoma (four eyes), exfoliation glaucoma (one eye), neovascular glaucoma (one eye), normal tension glaucoma (one eye), and uveitic glaucoma (one eye). Stage classifications at diagnosis were stage IA in four eyes and stages IC, IIA, IIB, and III in one eye each. All treatments were carried out with dry eye drops, steroid eye drops, and antibiotics. The mean duration of treatment was 1.4 years. The classifications at the time of the final visit were normal corneal epithelium (three eyes), stage IA (two eyes), IIA (one eye), and III (two eyes). Three eyes (37%) improved by more than one stage and one eye deteriorated by more than one stage. LSCD is long-lasting and difficult to treat in a short period; thus, it requires careful medical attention.

Outcomes of Combined Penetrating Keratoplasty and Limbal Stem Cell Transplantation: A Meta-Analysis on Simultaneous Versus Sequential Surgery

PURPOSE

The objective of this study is to perform a systematic review and meta-analysis of the published studies on limbal stem cell transplantation (LSCT) combined with penetrating keratoplasty (PK) performed either simultaneously or sequentially.

METHODS

An extensive search was conducted in the MEDLINE and Google Scholar databases. Prospective and retrospective trials and case series reporting on the outcomes of LSCT with PK were included. Primary outcomes were the stability of the ocular surface and the rejection and/or failure of the corneal graft.

RESULTS

A total of 209 eyes from 13 studies were included in the simultaneous group and 489 eyes from 33 studies in the sequential group. Ocular surface stability was 88% [95% confidence interval (CI), 79%-96%] for sequential cases and 64% (95% CI, 43%-82%) for simultaneous cases ( P = 0.001). The graft failure rate was 15% (95% CI, 6%-26%) for sequential cases and 44% (95% CI, 31%-58%) for simultaneous cases ( P < 0.001). For cases performed sequentially, subgroup analysis revealed a stable ocular surface in 97% (95% CI, 91%-100%) of autograft cases and 63% (95% CI, 45%-80%) of allograft cases ( P < 0.001). The graft failure rate in sequential cases was 7% (95% CI, 0%-18%) for autografts and 34% (95% CI, 18%-52%) for allografts ( P < 0.001).

CONCLUSIONS

Sequential LSCT followed by PK demonstrated superior results in terms of ocular surface stability and graft retention compared with simultaneous LSCT and PK. Limbal stem cells of autologous origin fare better than allogeneic ones in sequential cases.

Single-cell RNA sequencing in cornea research: Insights into limbal stem cells and their niche regulation

The corneal epithelium is composed of stratified squamous epithelial cells on the outer surface of the eye, which acts as a protective barrier and is critical for clear and stable vision. Its continuous renewal or wound healing depends on the proliferation and differentiation of limbal stem cells (LSCs), a cell population that resides at the limbus in a highly regulated niche. Dysfunction of LSCs or their niche can cause limbal stem cell deficiency, a disease that is manifested by failed epithelial wound healing or even blindness. Nevertheless, compared to stem cells in other tissues, little is known about the LSCs and their niche. With the advent of single-cell RNA sequencing, our understanding of LSC characteristics and their microenvironment has grown considerably. In this review, we summarized the current findings from single-cell studies in the field of cornea research and focused on important advancements driven by this technology, including the heterogeneity of the LSC population, novel LSC markers and regulation of the LSC niche, which will provide a reference for clinical issues such as corneal epithelial wound healing, ocular surface reconstruction and interventions for related diseases.

A systematic review on the effects of ROCK inhibitors on proliferation and/or differentiation in human somatic stem cells: A hypothesis that ROCK inhibitors support corneal endothelial healing via acting on the limbal stem cell niche

Rho kinase inhibitors (ROCKi) have attracted growing multidisciplinary interest, particularly in Ophthalmology where the question as to how they promote corneal endothelial healing remains unresolved. Concurrently, stem cell biology has rapidly progressed in unravelling drivers of stem cell (SC) proliferation and differentiation, where mechanical niche factors and the actin cytoskeleton are increasingly recognized as key players. There is mounting evidence from the study of the peripheral corneal endothelium that supports the likelihood of an internal limbal stem cell niche. The possibility that ROCKi stimulate the endothelial SC niche has not been addressed. Furthermore, there is currently a paucity of data that directly evaluates whether ROCKi promotes corneal endothelial healing by acting on this limbal SC niche located near the transition zone. Therefore, we performed a systematic review examining the effects ROCKi on the proliferation and differentiation of human somatic SC, to provide insight into its effects on various human SC populations. An appraisal of electronic searches of four databases identified 1 in vivo and 58 in vitro studies (36 evaluated proliferation while 53 examined differentiation). Types of SC studied included mesenchymal (n = 32), epithelial (n = 11), epidermal (n = 8), hematopoietic and other (n = 8). The ROCK 1/2 selective inhibitor Y-27632 was used in almost all studies (n = 58), while several studies evaluated ≥2 ROCKi (n = 4) including fasudil, H-1152, and KD025. ROCKi significantly influenced human somatic SC proliferation in 81% of studies (29/36) and SC differentiation in 94% of studies (50/53). The present systemic review highlights that ROCKi are influential in regulating human SC proliferation and differentiation, and provides evidence to support the hypothesis that ROCKi promotes corneal endothelial division and maintenance via acting on the inner limbal SC niche.

Outcomes of keratolimbal allograft from ABO compatible donors for severe bilateral limbal stem cell deficiency

PURPOSE

To report outcomes of keratolimbal allograft (KLAL) compatible for both human leukocyte (HLA) and/or blood type using oral prednisone, mycophenolate, and tacrolimus, with basiliximab if panel reactive antibodies (PRA) are present. Intravenous immunoglobulin (IVIG) was used post-operatively if donor-specific anti-HLA antibodies (DSA) were present.

METHODS

Retrospective interventional series of consecutive patients with KLAL for limbal stem cell deficiency (LSCD) from HLA and/or blood type compatible deceased donors with a minimum follow-up time of 12 months. Main outcome measures were ocular surface stability, visual acuity and systemic immunosuppression (SI) adverse events.

RESULTS

Eight eyes of eight patients with mean age of 48.6 ± 10.1 years (range 34-65 years) were included. Mean follow-up time was 37.3 ± 22.7 months (range 12-71 months) following KLAL; four (50%) had combined LR-CLAL surgery. The etiologies of LSCD were Stevens-Johnson Syndrome (n = 4/8), aniridia (n = 2/8), chemical injury (n = 1/8) and atopic eye disease (n = 1/8). All patients had PRA present and received basiliximab infusions. 5/8 patients received IVIG based on DSA identified pre-operatively. At last follow-up, 7 eyes (87.5%) had a stable ocular surface; 1 eye (12.5%) developed failure and had keratoprosthesis implantation. There was a significant improvement in visual acuity from 1.65 ± 0.48 to 0.68 ± 0.34 logMAR (p = 0.01). SI was tolerated well with minimal adverse events.

CONCLUSIONS

Preliminary outcomes of KLAL with ABO compatible tissue using the Cincinnati protocol, preoperative basiliximab (when PRA present) and post-operative IVIG (when DSA present) are encouraging. This protocol may allow for utilization of deceased donor tissue with results approximating those of living donor tissue transplanted for severe bilateral LSCD.

Autologous Serum Eye Drops in the Management of Limbal Stem Cell Deficiency Associated With Glaucoma Surgery

PURPOSE

To evaluate safety and efficacy of autologous serum eye drops (AS) in the treatment of limbal stem cell deficiency (LSCD) associated with glaucoma surgery.

METHODS

Retrospective case series of eyes with glaucoma surgery-induced LSCD treated with AS. Diagnosis of LSCD was confirmed by anterior segment optical coherence tomography, in vivo confocal microscopy, and/or impression cytology. Limbal stem cell deficiency severity was staged using a clinical scoring system (2-10 points). Outcome measures were changes (≥2 points) of the LSCD score and best-corrected visual acuity (BCVA) from the baseline to the last follow-up.

RESULTS

Thirteen eyes of 12 consecutive patients treated with 50% AS for at least 3 months were included. The mean age was 78.9±7.5 years and the mean duration of AS use was 20.9±16.8 months. Indications of AS included LSCD progression in eight eyes (61.5%) and visual axis threatening in five eyes (38.5%). The mean LSCD score at baseline (6.7±1.6) was similar to that at last follow-up (6.5±2.2, P =0.625). Two eyes (15.4%) showed improvement, nine eyes (69.2%) were stable, and two eyes (15.4%) worsened. The mean baseline BCVA (0.89±0.64 logMAR) was similar to the mean final BCVA (1.05±0.63 logMAR, P =0.173). There were no serious adverse complications related to AS.

CONCLUSION

AS appears to be well tolerated and may stabilize the progression of LSCD with limited effects. A larger study is necessary to confirm the findings.

Fenofibrate suppresses corneal neovascularization by regulating lipid metabolism through PPARα signaling pathway

Purpose: The purpose of this study was to explore the potential underlying mechanism of anti-vascular effects of peroxisome proliferator-activated receptor α (PPARα) agonist fenofibrate against corneal neovascularization (CNV) through the changes of lipid metabolism during CNV. Methods: A suture-induced CNV model was established and the clinical indications were evaluated from day 1 to day 7. Treatments of vehicle and fenofibrate were performed for 5 days after suture and the CNV areas were compared among the groups. The eyeballs were collected for histological analysis, malondialdehyde (MDA) measurement, terminal deoxynucleotidyl transferase 2'-deoxyuridine 5'-triphosphate nick end labeling (TUNEL) staining, western blot, quantitative real-time PCR (qRT-PCR) assays and immunohistochemical (IHC) staining to elucidate pathological changes and the underlying mechanism. Results: Lipi-Green staining and MDA measurement showed that lipid deposition and peroxidation were increased in the CNV cornea while the expression of long-chain acyl-coenzyme A synthetase 1 (ACSL1), carnitine palmitoyltransterase 1A(CPT1A) and medium-chain acyl-coenzyme A dehydrogenase (ACADM), which are key enzymes of fatty acid β-oxidation (FAO) and targeted genes of peroxisome proliferator-activated receptor alpha (PPARα) pathway, were decreased in CNV cornea. Fenofibrate suppressed lipid accumulation and peroxidation damage in the CNV cornea. Fenofibrate upregulated the expression levels of PPARα, ACSL1, CPT1A, and ACADM compared with vehicle group. IHC staining indicated that fenofibrate also decreased the expression of VEGFa, VEGFc, TNFα, IL1β and CD68. Conclusion: Disorder of lipid metabolism may be involved in the formation of suture-induced CNV and fenofibrate played anti-neovascularization and anti-inflammatory roles on cornea by regulating the key enzymes of lipid metabolism and ameliorating lipid peroxidation damage of cornea through PPARα signaling pathway.

Prosthetic Replacement of the Ocular Surface Ecosystem for Limbal Stem Cell Deficiency: A Case Series

OBJECTIVES

To assess outcomes of limbal stem cell deficiency (LSCD) in patients treated with Prosthetic Replacement of the Ocular Surface Ecosystem (PROSE).

METHODS

Retrospective case series. Patients with LSCD who received PROSE treatment were included. Data including best-corrected visual acuity (BCVA) and LSCD staging before and after PROSE dispensing were collected to characterize each case.

RESULTS

Five eyes of four patients were included. All patients were female, with an age range of 21 to 80 years. Each patient received a PROSE device with diameters ranging from 16 to 18.5 mm. Follow-up ranged from 11 to 29 months. Tolerated wear times ranged from 3.5 to 10 hr daily. Four eyes showed improved BCVA and unchanged LSCD staging as per the global consensus after PROSE treatment. Three of these eyes had stage 3 and one had stage 1C LSCD at diagnosis. The fifth eye had worse BCVA and recurrence of stage 3 LSCD post-living-related conjunctival limbal allograft transplant despite PROSE treatment.

CONCLUSIONS

Prosthetic Replacement of the Ocular Surface Ecosystem may be a viable treatment for LSCD, including severe cases, because it can provide symptom relief and improve vision. Its customizability, as demonstrated in this study, is beneficial for troubleshooting issues with fitting. Future studies are needed to further assess PROSE as treatment for LSCD.

Unilateral vortex keratopathy of unknown etiology

A 54-year-old man with noncontributory medical history presented to an ophthalmologist in January 2022 after 10 days of irritation in his right eye. The patient recounts having felt something get into his eye and under his contact lens (CL) while he was climbing into his car, but he was unsure what the foreign body may have been. Initial examination by the clinician found uncorrected distance visual acuity of 20/100-2 with a corneal abrasion, 4+ corneal edema, and 3+ conjunctival injection, for which he was placed on topical antibiotics (ocuflox and tobradex) with a bandage CL. 1 week later, visual acuity was 20/80, corneal edema had improved, and he was noted to have corneal scarring and an epithelial defect. Tobradex was continued while prednisolone drops and preservative-free artificial tears were started. 1 week later, the patient had worsening visual acuity to 20/250 and was referred to our tertiary center. On initial consultation, the patient had an uncorrected distance visual acuity of 20/500 and an uncorrected near visual acuity of >J10 in the right eye. Slitlamp examination of the right eye was significant for vortex keratopathy and mild corneal pannus with 360-degree subtle conjunctivalization of the limbus ( Figure 1JOURNAL/jcrs/04.03/02158034-202210000-00022/figure1/v/2022-10-03T121249Z/r/image-tiff ). The corneal topograph was obtained showing significant surface irregularity on the Placido image ( Figure 2JOURNAL/jcrs/04.03/02158034-202210000-00022/figure2/v/2022-10-03T121249Z/r/image-tiff ). Examination of the left eye was unremarkable. The ocular history is significant for myopia of -4.0 diopters and CL use for 20 years. The patient admits to regularly wearing soft CLs for several days straight and only removing them for a few hours. Antibiotics were discontinued, corticosteroid drops were reduced in frequency, and the patient was continued on preservative-free artificial tears. What imaging might you consider? What is your differential diagnosis at this point? What would be the most appropriate surgical and/or medical interventions? What would you counsel in prognosis for this patient?

Importance of Corneal Angiography in Subclinical Limbitis in a Case of Atopic Keratoconjunctivitis

PURPOSE

The aim of this study was to report corneal angiography features in subclinical limbitis in a patient with atopic keratoconjunctivitis.

METHODS

This is a case report.

RESULTS

A 22-year-old woman with a medical history of atopic keratoconjunctivitis was referred for bilateral corneal neovascularization with scarring. On examination, no signs of active disease were noticed at the slit lamp. Ocular surface angiography detected active corneal limbitis, showing as limbal leakage at fluorescein angiography in the early phase and leakage after indocyanine green angiography in the late phase. The patient was treated with topical corticosteroid. At follow-up, the fluorescein angiography and indocyanine green angiography no longer showed limbal leakage, whereas the slit lamp examination was unchanged.

CONCLUSIONS

Active allergic corneal limbitis may present as subclinical inflammation, with no signs of activity at the slit lamp examination. Therefore, its diagnosis can be challenging without the use of corneal angiography.

Advancing wavelike epitheliopathy after conjunctival intraepithelial neoplasia. Atipical case report

An atypical Advancing Wavelike Epitheliopathy case, consecutive to topical treatment for a 360º Conjunctival Intraepithelial Neoplasia, is presented. Mitomycin (0.2 mg/mL) and interferon (1 MUI/mL) drops were used. An atypical presentation, with migrating limbal focus, non clearly delimited in its hourly site through its evolution. Treated with flurometholone drops plus artificial tears, working to complete resolution.

Finite Element Analysis of Cornea and Lid Wiper during Blink, with and without Contact Lens

Ocular surface disorders such as Lid Wiper Epitheliopathy (LWE), Superior Epithelial Arcuate Lesion (SEAL), and contact lens-induced Limbal Stem Cell Deficiency (LSCD) as well as Superior Limbic Keratoconjunctivitis (SLK) affect one’s quality of life. Hence, it is imperative to investigate the underlying causes of these ocular surface disorders. During blink, the undersurface of the eyelid tends to interact with the cornea and the conjunctiva. The presence of a contact lens can add to the biomechanical frictional changes on these surfaces. To estimate these changes with and without a contact lens, a finite element model (FEM) of the eyelid wiper, eyeball, and contact lens was developed using COMSOL Multiphysics. Biomechanical properties such as von Mises stress (VMS) and displacement were calculated. Our study concluded that (a) maximum VMS was observed in the lid wiper in the absence of contact lens in the eye and (b) maximum VMS was observed in the superior 1.3 mm of the cornea in the presence of the contact lens in the eye. Thus, the development of friction-induced ocular surface disorders such as LWE, SLK, SEAL, and LSCD could be attributed to increased VMS. FEA is a useful simulation tool that helps us to understand the effect of blink on a normal eye with and without CL.

Treatment of Non-Infectious Corneal Injury: Review of Diagnostic Agents, Therapeutic Medications, and Future Targets

Corneal injuries can occur secondary to traumatic, chemical, inflammatory, metabolic, autoimmune, and iatrogenic causes. Ocular infection may frequently occur concurrent to corneal injury; however, antimicrobial agents are excluded from this present review. While practitioners may primarily rely on clinical examination techniques to assess these injuries, several pharmacological agents, such as fluorescein, lissamine green, and rose bengal, can be used to formulate a diagnosis and develop effective treatment strategies. Practitioners may choose from several analgesic medications to help with patient comfort without risking further injury or delaying ocular healing. Atropine, cyclopentolate, scopolamine, and homatropine are among the most frequently used medications for this purpose. Additional topical analgesic agents may be used judiciously to augment patient comfort to facilitate diagnosis. Steroidal anti-inflammatory agents are frequently used as part of the therapeutic regimen. A variety of commonly used agents, including prednisolone acetate, loteprednol, difluprednate, dexamethasone, fluorometholone, and methylprednisolone are discussed. While these medications are effective for controlling ocular inflammation, side effects, such as elevated intraocular pressure and cataract formation, must be monitored by clinicians. Non-steroidal medications, such as ketorolac, bromfenac, nepafenac, and diclofenac, are additionally used for their efficacy in controlling ocular inflammation without incurring side effects seen with steroids. However, these agents have their own respective side effects, warranting close monitoring by clinicians. Additionally, ophthalmologists routinely employ several agents in an off-label manner for supplementary control of inflammation and treatment of corneal injuries. Patients with corneal injuries not infrequently have significant ocular surface disease, either as a concurrent pathology or as an exacerbation of previously existing disease. Several agents used in the management of ocular surface disease have also been found to be useful as part of the therapeutic armamentarium for treatment of corneal injuries. For example, several antibiotics, such as doxycycline and macrolides, have been used for their anti-inflammatory effects on specific cytokines that are upregulated during acute injuries. There has been a recent wave of interest in amniotic membrane therapies (AMTs), including topical, cryopreserved and dehydrated variants. AMT is particularly effective in ocular injuries with violation of corneal surface integrity due to its ability to promote re-epithelialization of the corneal epithelium. Blood-based therapies, including autologous serum tears, plasma-enriched growth factor eyedrops and autologous blood drops, have additionally been explored in small case series for effectiveness in challenging and recalcitrant cases. Protection of the ocular surface is also a vital component in the treatment of corneal injuries. Temporary protective methods, such as bandage contact lenses and mechanical closure of the eyelids (tarsorrhaphy) can be particularly helpful in selective cases. Glue therapies, including biologic and non-biologic variants, can also be used in cases of severe injury and risk of corneal perforation. Finally, there are a variety of recently introduced and in-development agents that may be used as adjuvant therapies in challenging patient populations. Neurotrophic corneal disease may occur as a result of severe or chronic injury. In such cases, recombinant human nerve growth factor (cenegermin), topical insulin, and several other novel agents may be an alternate and effective option for clinicians to consider.

Effects of corneal epithelial superficial keratectomy in patients with focal limbal stem cell disease

Purpose

Irregular corneal epithelium in limbal stem cell disease can cause visual acuity to deteriorate substantially when it reaches the pupil. In this case series, we assessed the effectiveness of simple corneal epithelial superficial keratectomy in improving visual acuity in patients with irregular corneal epithelium in focal limbal stem cell disease covering the visual axis.

Observations

We performed simple corneal epithelial superficial keratectomy in four patients (five eyes) with irregular corneal epithelium covering the visual axis. The main outcome measures were best-corrected visual acuity, slit lamp findings with fluorescein staining, anterior segment optical coherence tomography and histopathology. In all five eyes, slit lamp findings showed uneven fluorescein staining in a spiral pattern, with impaired corneal epithelial smoothness and visual disturbance. We removed the irregular epithelium in all five eyes. Visual acuity in all the eyes was improved immediately after surgery, and good visual acuity and stable epithelium were maintained for the duration of the observation periods. Hematoxylin and eosin staining showed, normal squamous and columnar epithelial cells. Goblet cells were not detected.

Conclusionsand Importance

Corneal epithelial superficial keratectomy can lead to a pathological diagnosis by examining the removed epithelial tissues, and result in excellent therapeutic outcomes in focal limbal stem cell disease reaching the pupil.

Limbal Stem Cell Deficiency: Demographics and Clinical Characteristics of a Large Retrospective Series at a Single Tertiary Referral Center

PURPOSE

The aim of this study was to characterize a large cohort of patients presenting to a single referral center for limbal stem cell deficiency (LSCD).

METHODS

A retrospective chart review of all patients with a clinical diagnosis of LSCD from 2002 to 2015 was performed. Demographics, etiology, previous ocular surgeries, visual acuity, and treatment were assessed.

RESULTS

Seven hundred thirty-eight eyes of 434 patients (51.4% male subjects) were diagnosed with LSCD. The mean presenting age was 42.9 years, 70% presented with bilateral disease, and overall vision was poor. The most common etiologies were congenital aniridia (30.9%), chemical or thermal injuries (20.6%), contact lens (16.8%), Stevens-Johnson syndrome (SJS, 10.4%), and iatrogenic (7.3%). Congenital aniridia had a significantly increased association with glaucoma or ocular hypertension (P < 0.0001). Chemical or thermal injuries (P = 0.0007), SJS (P < 0.0001), and mucous membrane pemphigoid (P < 0.0001) had a significantly increased association with eyelid pathology. The mean logMAR best corrected visual acuity (analysis excluded eyes with light perception and no light perception) at presentation was 1.145 (∼20/280). Keratoplasty performed (before presentation at our center) without first addressing the LSCD was seen in 80 eyes; all keratoplasties failed due to recurrence of the LSCD.

CONCLUSIONS

Patients presenting with LSCD were on average middle aged without sex predominance. LSCD was most commonly bilateral, comprised a wide range of etiologies, and decreased vision substantially. Ocular comorbidities may need to be treated before treating the LSCD surgically. Finally, not addressing the LSCD (primary issue) first can result in keratoplasty failure.

The Limbal Niche and Regenerative Strategies

The protective function and transparency provided by the corneal epithelium are dependent on and maintained by the regenerative capacity of limbal epithelial stem cells (LESCs). These LESCs are supported by the limbal niche, a specialized microenvironment consisting of cellular and non-cellular components. Disruption of the limbal niche, primarily from injuries or inflammatory processes, can negatively impact the regenerative ability of LESCs. Limbal stem cell deficiency (LSCD) directly hampers the regenerative ability of the corneal epithelium and allows the conjunctival epithelium to invade the cornea, which results in severe visual impairment. Treatment involves restoring the LESC population and functionality; however, few clinically practiced therapies currently exist. This review outlines the current understanding of the limbal niche, its pathology and the emerging approaches targeted at restoring the limbal niche. Most emerging approaches are in developmental phases but show promise for treating LSCD and accelerating corneal regeneration. Specifically, we examine cell-based therapies, bio-active extracellular matrices and soluble factor therapies in considerable depth.

Outcomes of Ipsilateral Simple Limbal Epithelial Transplantation, Tenonectomy, Mitomycin and Amniotic Membrane Transplantation for Treatment of Recurrent Pterygium

PURPOSE

To report on the outcomes of recurrent pterygium treated by ipsilateral simple limbal epithelial transplantation (SLET), mitomycin, tenonectomy, and amniotic membrane transplantation.

METHODS

A retrospective, interventional study was conducted including all patients with recurrent pterygium who underwent SLET surgery under a single surgeon using ipsilateral donor tissue with a minimum 6-month follow-up at Toronto Western Hospital, Canada. Outcome measures included the following: recurrence rates, best spectacle-corrected visual acuity, and postoperative complications.

RESULTS

Ten eyes of 10 patients, aged 60.7 ± 18.5 years (range 23-79) with a mean follow-up time of 15.2 ± 10.0 months of which 50% (n = 5) were men, were included. Eight eyes (80%) had a history of 2 or less pterygium operations. Two patients had 3 and 5 previous pterygium operations, respectively. Concurrent limbal stem cell disease was noted in 6 eyes (60%). Average number of pterygium recurrences per eye was 1.9 ± 1.3 (range 1-5). Mean pre-op best-corrected visual acuity was 0.5 LogMAR (Snellen equivalent 20/60, range 20/20 to counting fingers). Best-corrected visual acuity remained the same or improved in 6 eyes (60%). Recurrence was noted in 1 eye (10%) with a history of 5 previous pterygium excisions and remained stable at the last follow-up. No patients required a second operation.

CONCLUSIONS

Ipsilateral SLET with mitomycin, tenonectomy, and amniotic membrane transplantation is a novel technique to address recurrent pterygium. Concurrent limbal stem cell diseases are often present. Initial results demonstrate low recurrence. Visual improvement is modest. Stabilization of the ocular surface to improve vision is possible.

Stem Cell Niche Microenvironment: Review

The cornea comprises a pool of self-regenerating epithelial cells that are crucial to preserving clarity and visibility. Limbal epithelial stem cells (LESCs), which live in a specialized stem cell niche (SCN), are crucial for the survival of the human corneal epithelium. They live at the bottom of the limbal crypts, in a physically enclosed microenvironment with a number of neighboring niche cells. Scientists also simplified features of these diverse microenvironments for more analysis in situ by designing and recreating features of different SCNs. Recent methods for regenerating the corneal epithelium after serious trauma, including burns and allergic assaults, focus mainly on regenerating the LESCs. Mesenchymal stem cells, which can transform into self-renewing and skeletal tissues, hold immense interest for tissue engineering and innovative medicinal exploration. This review summarizes all types of LESCs, identity and location of the human epithelial stem cells (HESCs), reconstruction of LSCN and artificial stem cells for self-renewal.

Global Consensus on the Management of Limbal Stem Cell Deficiency

PURPOSE

In recent decades, the medical and surgical treatment of limbal stem cell deficiency (LSCD) has evolved significantly through the incorporation of innovative pharmacological strategies, surgical techniques, bioengineering, and cell therapy. With such a wide variety of options, there is a need to establish a global consensus on the preferred approaches for the medical and surgical treatment of LSCD.

METHODS

An international LSCD Working Group was established by the Cornea Society in 2012 and divided into subcommittees. Four face-to-face meetings, frequent email discussions, and teleconferences were conducted since then to reach agreement on a strategic plan and methods after a comprehensive literature search. A writing group drafted the current study.

RESULTS

A consensus in the medical and surgical management of LSCD was reached by the Working Group. Optimization of the ocular surface by eyelid and conjunctival reconstruction, antiinflammatory therapy, dry eye and meibomian gland dysfunction treatment, minimization of ocular surface toxicity from medications, topical medications that promote epithelialization, and use of a scleral lens is considered essential before surgical treatment of LSCD. Depending on the laterality, cause, and stage of LSCD, surgical strategies including conjunctival epitheliectomy, amniotic membrane transplantation, transplantation of limbal stem cells using different techniques and sources (allogeneic vs. autologous vs. ex vivo-cultivated), transplantation of oral mucosal epithelium, and keratoprosthesis can be performed as treatment. A stepwise flowchart for use in treatment decision-making was established.

CONCLUSIONS

This global consensus provides an up-to-date and comprehensive framework for the management of LSCD.

Spectral-domain optical coherence tomography for evaluating palisades of Vogt in ocular surface disorders with limbal involvement

Spectral-domain optical coherence tomography (SD-OCT) has been used to observe the morphology of the palisades of Vogt (POV) with satisfactory resolutions. In this study, we used SD-OCT to examine the microstructure of the POV in ocular surface disorders with limbal involvement. We detect subclinical limbal pathologies based on five parameters, including (1) decreased epithelial thickness, (2) loss of the sharp stromal tip, (3) loss of the smooth epithelial-stromal interface, (4) dilated stromal vessels, and (5) decreased POV density. Eighteen eyes of 10 patients with advancing wavelike epitheliopathy (AWE) and 15 eyes of 9 patients with phlyctenular keratitis/ocular rosacea were recruited. SD-OCT could detect abnormal changes in the POV in 100% of the lesion sites. In presumed-healthy areas of the diseased eyes diagnosed by slit-lamp biomicroscopy, SD-OCT detected abnormal changes in the POV in 100% of the eyes in both groups. In patients with unilateral disease, abnormal changes in the POV were detected by SD-OCT in 50% and 100% of presumed-healthy eyes diagnosed by slit-lamp biomicroscopy in the AWE group and phlyctenular keratitis/ocular rosacea group, respectively. SD-OCT is powerful in detecting POV changes in ocular surface disorders and can provide useful information that cannot be provided by slit-lamp biomicroscopy.

Molecular identity of human limbal heterogeneity involved in corneal homeostasis and privilege

PURPOSE

The corneal limbus maintains the homeostasis, immune and angiogenic privilege of cornea. This study aimed to depict the landscape of human limbal tissues by single-cell RNA sequencing (scRNA-seq).

METHODS

Single cells of human limbus collected from donor corneas were subjected to 10x scRNA-seq, followed by clustering cell types through the t-distributed stochastic neighbor embedding (t-SNE) and unbiased computational informatic analysis. Immunofluorescent staining was performed using human corneas to validate the analysis results.

RESULTS

47,627 cells acquired from six human limbal tissues were collected and subjected to scRNA-seq. 14 distinct clusters were identified and 8 cell types were annotated with representative markers. In-depth dissection revealed three limbal epithelial cell subtypes and refined the X-Y-Z hypothesis of corneal epithelial maintenance. We further unveiled two cell states with higher stemness (TP63⁺ and CCL20⁺ cells), and two other differentiated cell states (GPHA2⁺ and KRT6B ⁺ cells) in homeostatic limbal stem/progenitor cells (LSPCs) that differ in transcriptional profiles. Cell-cell communication analysis revealed the central role of LSPCs and their bidirectional regulation with various niche cells. Moreover, comparative analysis between limbus and skin deciphered the pivotal contribution of limbal immune cells, vascular and lymphatic endothelial cells to corneal immune and angiogenic privilege.

CONCLUSIONS

The human limbus atlas provided valuable resources and foundations for understanding corneal biology, disease and potential interventions.

Limbal stem cell diseases

The function of limbal stem/progenitor cells (LSCs) is critical to maintain corneal epithelial homeostasis. Many external insults and intrinsic defects can be deleterious to LSCs and their niche microenvironment, resulting in limbal stem cell dysfunction or deficiency (LSCD). Ocular comorbidities, frequent in eyes with LSCD, can exacerbate the dysfunction of residual LSCs, and limit the survival of transplanted LSCs. Clinical presentation and disease evolution vary among different etiologies of LSCD. New ocular imaging modalities and molecular markers are now available to standardize the diagnosis criteria and stage the severity of the disease. Medical therapies may be sufficient to reverse the disease if residual LSCs are present. A stepwise approach should be followed to optimize the ocular surface, eliminate the causative factors and treat comorbid conditions, before considering surgical interventions. Furthermore, surgical options are selected depending on the severity and laterality of the disease. The standardized diagnostic criteria to stage the disease is necessary to objectively evaluate and compare the efficacy of the emerging customized therapies.

The Use of Autologous Serum to Reverse Severe Contact Lens-induced Limbal Stem Cell Deficiency

PURPOSE

To describe the efficacy of autologous serum (AS) eye drops to reverse severe contact lens (CL)-induced limbal stem cell (LSC) deficiency (LSCD).

METHODS

This is a prospective, uncontrolled, interventional case series that enrolled 20 eyes of 14 consecutive patients diagnosed with severe CL-induced LSCD at presentation, based on clinical examination, at a tertiary referral center for the period December 2016 to December 2018. All eyes underwent AS treatment for at least 2 weeks with a follow-up for at least 2 months. Demographic data and treatment outcomes were collected and analyzed.

RESULTS

The mean patient age at presentation was 30.5 years (range, 19-49 years). The mean duration of soft contact lens wear was 15.6 years (SD, 7.58 years; range, 5-31 years). All study eyes had pain and blurred vision at presentation. All eyes had recurrent or persistent corneal epithelial defect, stromal scarring and opacity, and superficial vascularization and peripheral pannus at presentation. Aggressive treatment with AS succeeded in all eyes. Signs and symptoms of LSCD stabilized in all eyes within 2 weeks and resolved in 6 eyes (30.0%) in 2 weeks, 9 eyes (45.0%) in 4 weeks, and 5 eyes (25.0%) in 8 weeks. The mean follow-up time was 9.45 ± 1.79 weeks (range, 8-24 weeks).

CONCLUSIONS

Early identification and aggressive treatment of the ocular surface disease with AS can medically reverse severe CL-induced LSCD and prevent the need for surgical intervention.

Reversible HER2 antibody-drug conjugate-induced ocular toxicity

PURPOSE

To report 3 cases of reversible epitheliopathy induced by A166-a human epidermal growth factor receptor (HER2)-targeted antibody-drug conjugate (ADC) therapy for resistant HER2 tumours.

METHODS

Advanced HER2 tumour patients were enrolled in A166 phase I/II clinical trial using Bayesian logistic regression model dose escalation. Key exclusion criteria were ≥grade 2 (G2) corneal pathology, severe organ disease, and other cancer therapy within 4 weeks. Eye exams were performed at baseline, regularly scheduled intervals, and additionally upon A166-induced ocular symptoms. Topical therapy with autologous serum tears (ASTs) was implemented based on visual acuity, symptoms, and slit lamp exam. A166 was withheld if ≥G2 ocular toxicity developed; if status improved to ≤G1, A166 therapy was resumed. Visual acuity, corneal exam, and subjective comfort were recorded.

RESULTS

After ≥2 cycles of A166, 6 eyes of 3/23 enrolled patients developed whorl pattern epitheliopathy suggestive of limbal stem cell (LSC) dysfunction requiring cessation of A166 despite positive tumour response. Patients 1 and 3 received 3.6 mg/kg A166 dose, and patient 2 received 3.0 mg/kg. Topical steroids (2/4 eyes) failed to improve epitheliopathy. Adding ASTs improved vision, ocular comfort, and whorl pattern epitheliopathy in 6/6 eyes within 3 weeks. Patient 1 continues to improve on ASTs; patient 2 withdrew from the study; and patient 3 resumed A166 therapy.

CONCLUSION

A166 precipitates LSC dysfunction-like epitheliopathy. Combination therapy including aggressive lubrication, withholding drug, and ASTs help reverse toxicity. Recognizing that ADC-induced epitheliopathy can respond to ocular management may enable cancer patients to continue lifesaving therapy.

Limbal Stem Cell Deficiency After Glaucoma Surgery

PURPOSE

To characterize the clinical presentation of limbal stem cell deficiency (LSCD) associated with glaucoma surgeries.

METHODS

This is a retrospective cross-sectional study of patients with LSCD and glaucoma who presented to the Stein Eye Institute at the University of California, Los Angeles, between 2009 and 2018. Patients who underwent trabeculectomy and/or aqueous shunt surgery were included. The severity of LSCD was staged using global consensus guidelines and a clinical scoring system, and basal epithelial cell density was measured by in vivo confocal microscopy. Anatomic locations of glaucoma and non-glaucoma surgeries, locations of LSCD, and severity of LSCD were compared.

RESULTS

Fifty-one eyes of 41 patients with LSCD associated with glaucoma surgery were included in this study. LSCD in these patients uniquely featured sectoral replacement of corneal epithelium by conjunctival epithelium, without corneal neovascularization or pannus. The sites of glaucoma surgery strongly correlated with the locations of LSCD (P = 0.002). There was a trend toward increased severity of LSCD in eyes with 2 or more glaucoma surgeries as compared to eyes with 1 glaucoma surgery, although the difference did not reach statistical significance (P = 0.3). Use of topical glaucoma medications correlated with LSCD severity, while the impact of antimetabolites did not reach statistical significance. The location of glaucoma drainage surgery is correlated with the location of LSCD.

CONCLUSIONS

LSCD associated with glaucoma surgery has clinical features distinct from LSCD resulting from other etiologies. Further study is required to delineate the full impact of glaucoma surgery on limbal stem cell function and survival.

Medical management and visual rehabilitation of limbal niche dysfunction

Limbal niche dysfunction (LND) has been described as a medically reversible form of limbal stem cell deficiency. The current literature is sparse regarding therapeutic options to improve visual function after stabilization of the disease. A 61-year-old monocular woman with an extensive medical and ocular history presented with long-standing recalcitrant epitheliopathy in both eyes. History and examination findings on presentation led to a diagnosis of LND, and medical therapy was initiated. After 8 months, her ocular surface had improved and corrected distance visual acuity (CDVA) was 20/40. She was fit with a scleral contact lens because of its ability to promote ocular surface healing and improve visual acuity. She maintained symptom resolution and her CDVA improved to 20/20. LND is a distinctive and reversible epitheliopathy that responds favorably to appropriate medical therapy. To the authors' knowledge, this is the first reported case of using the scleral contact lens as an adjunctive visual rehabilitation therapy to complement medical treatment for LND.

Outcomes of Limbal Stem Cell Transplant: A Meta-analysis

Importance

Limbal stem cell transplant (LSCT) can be categorized as direct autologous limbal transplant (AULT), direct allogenic limbal transplant (ALLT), cultivated autologous limbal stem cells transplant (cAULT), and cultivated allogenic limbal stem cells transplant (cALLT). To our knowledge, there is no study directly comparing the outcomes and complications of these procedures.

Objective

To evaluate the outcomes of different LSCT procedures.

Data Source

We searched PubMed, EMBASE, Web of Science, and Cochrane without language filter for peer-reviewed articles about LSCT. The latest search was performed on June 30, 2019.

Study Selection

Clinical studies with the outcome of at least 20 eyes after LSCT were included. Animal studies and studies of other surgical interventions were excluded.

Data Extraction and Synthesis

Two reviewers independently abstracted the data from each study. Heterogeneity was evaluated with the I2 statistic, and a meta-analysis was performed using the random-effects model.

Main Outcomes and Measures

Outcome measures included the improvement of ocular surface, visual acuity (VA), and adverse events of recipient eyes and donor eyes.

Results

Forty studies (2202 eyes) with a mean (SD) follow-up of 31.3 (20.9) months met the inclusion criteria. The mean (SD) age of study participants was 38.4 (13.1) years, and men accounted for 74%. The number of eyes that underwent AULT, ALLT, cAULT, and cALLT were 505, 742, 771, and 184, respectively. Improvement of the ocular surface was achieved in 74.5% of all eyes, 85.7% of eyes after AULT (95% CI, 79.5%-90.3%), 84.7% after cAULT (95% CI, 77.2%-90.0%), 57.8% after ALLT (95% CI, 49.0%-66.1%), and 63.2% after cALLT (95% CI, 49.3%-75.2%). Autologous limbal transplantation resulted in a greater VA improvement rate (76%) than did the other 3 procedures (cAULT: 56.4%; ALLT: 52.3%; cALLT: 43.3%; all P < .001). The most common adverse events in all recipient eyes were recurrent/persistent epithelial erosion (10.5%; 95% CI, 7.2%-23.3%) and elevated intraocular pressure (intraocular pressure, 1.7%; 95% CI, 0.5%-7.8%). Patients who underwent ALLT had the highest rate of recurrent epithelial erosion (27.8%; 95% CI, 17.1%-41.9%) and intraocular pressure elevation (6.3%; 95% CI, 1.8%-19.4%).

Conclusions and Relevance

These findings suggest LSCT can improve or stabilize the corneal surface with a low rate of severe ocular complications and that autologous LSCT may have a higher success rate and fewer complications than allogenic LSCT.

Topical preservative-free ophthalmic treatments: an unmet clinical need

Introduction: The main role of preservatives in eyedrops is to ensure sterility and microbiological integrity of the drug, and to facilitate the penetration of active compounds into the eye. However, several studies documented significant toxic effects induced by preservatives, especially on the ocular surface. Consequently, most of the ophthalmic medications became progressively available in preservative-free (PF) formulations.Areas covered: We analyzed pre-clinical and clinical studies on PF eyedrops with particular attention to common chronic diseases such as dry eye and glaucoma. We discussed about the pros and cons of using PF eyedrops, in terms of efficacy, safety, and social-economic aspects.Expert opinion: There are still unresolved issues that make hard for PF medications to definitively conquer the drug market. Despite robust pre-clinical evidences of less toxicity, the low number of randomized clinical trials does not permit to state that PF eyedrops have, in clinical practice, a similar efficacy or a higher safety compared to preserved forms. These aspects limit their use to chronic diseases requiring long-term therapies with multiple daily instillations, especially in the presence of concomitant ophthalmic diseases that expose to a risk of ocular surface worsening.

Recent Advances in Stem Cell Therapy for Limbal Stem Cell Deficiency: A Narrative Review

Destruction of the limbus and depletion of limbal stem cells (LSCs), the adult progenitors of the corneal epithelium, leads to limbal stem cell deficiency (LSCD). LSCD is a rare, progressive ocular surface disorder which results in conjunctivalisation and neovascularisation of the corneal surface. Many strategies have been used in the treatment of LSCD, the common goal of which is to regenerate a self-renewing, transparent, and uniform epithelium on the corneal surface. The development of these techniques has frequently resulted from collaboration between stem cell translational scientists and ophthalmologists. Direct transplantation of autologous or allogeneic limbal tissue from a healthy donor eye is regarded by many as the technique of choice. Expansion of harvested LSCs in vitro allows smaller biopsies to be taken from the donor eye and is considered safer and more acceptable to patients. This technique may be utilised in unilateral cases (autologous) or bilateral cases (living related donor). Recently developed, simple limbal epithelial transplant (SLET) can be performed with equally small biopsies but does not require in vitro cell culture facilities. In the case of bilateral LSCD, where autologous limbal tissue is not available, autologous oral mucosa epithelium can be expanded in vitro and transplanted to the diseased eye. Data on long-term outcomes (over 5 years of follow-up) for many of these procedures is needed, and it remains unclear how they produce a self-renewing epithelium without recreating the vital stem cell niche. Bioengineering techniques offer the ability to re-create the physical characteristics of the stem cell niche, while induced pluripotent stem cells offer an unlimited supply of autologous LSCs. In vivo confocal microscopy and anterior segment OCT will complement impression cytology in the diagnosis, staging, and follow-up of LSCD. In this review we analyse recent advances in the pathology, diagnosis, and treatment of LSCD.

Corneal Epithelial Findings in Patients with Multiple Myeloma Treated with Antibody-Drug Conjugate Belantamab Mafodotin in the Pivotal, Randomized, DREAMM-2 Study

INTRODUCTION

Patients with relapsed or refractory multiple myeloma (RRMM) represent an unmet clinical need. Belantamab mafodotin (belamaf; GSK2857916) is a first-in-class antibody-drug conjugate (ADC; or immunoconjugate) that delivers a cytotoxic payload, monomethyl auristatin F (MMAF), to myeloma cells. In the phase II DREAMM-2 study (NCT03525678), single-agent belamaf (2.5 mg/kg) demonstrated clinically meaningful anti-myeloma activity (overall response rate 32%) in patients with heavily pretreated disease. Microcyst-like epithelial changes (MECs) were common, consistent with reports from other MMAF-containing ADCs.

METHODS

Corneal examination findings from patients in DREAMM-2 were reviewed, and the clinical descriptions and accompanying images (slit lamp microscopy and in vivo confocal microscopy [IVCM]) of representative events were selected. A literature review on corneal events reported with other ADCs was performed.

RESULTS

In most patients receiving single-agent belamaf (72%; 68/95), MECs were observed by slit lamp microscopy early in treatment (69% had their first event by dose 4). However, IVCM revealed hyperreflective material. Blurred vision (25%) and dry eye (15%) were commonly reported symptoms. Management of MECs included dose delays (47%)/reductions (25%), with few patients discontinuing due to MECs (1%). The first event resolved in most patients (grade ≥2 MECs and visual acuity [each 77%], blurred vision [67%], and dry eye [86%]), with no reports of permanent vision loss to date. A literature review confirmed that similar MECs were reported with other ADCs; however, event management strategies varied. The pathophysiology of MECs is unclear, though the ADC cytotoxic payload may contribute to on- or off-target effects on corneal epithelial cells.

CONCLUSION

Single-agent belamaf represents a new treatment option for patients with RRMM. As with other ADCs, MECs were observed and additional research is warranted to determine their pathophysiology. A multidisciplinary approach, involving close collaboration between eye care professionals and hematologist/oncologists, is needed to determine appropriate diagnosis and management of these patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier, NCT03525678.

Contact Lens Induced Limbal Stem Cell Deficiency: Clinical Features in Korean Patients

Purpose

To describe the clinical features of Korean patients with contact lens-induced limbal stem cell deficiency (CL-LSCD).

Methods

Medical records of 22 patients who were diagnosed with CL-LSCD between 2014 and 2019 were reviewed retrospectively. Outcome measures included demographics, clinical presentation, treatment, clinical course, and pattern of contact lens (CL) wear.

Results

Forty-two eyes of 22 patients were found to have typical changes associated with CL-LSCD. Twenty (91%) patients were women and mean age was 36 ± 12 years. All patients had myopia with mean spherical equivalent of −7.52 ± 3.2 diopter. Twenty (91%) patients had bilateral disease and the location of limbal involvement was diffuse in 20 eyes (47.6%) and partial in 22 eyes (52.4%, superior in 20 eyes and inferior in 2 eyes). Fourteen (63.6%) patients complained of decreased visual acuity. Average period of CL wear was 14 ± 9 years. Four patients used cosmetic colored CLs and four patients had a history of overnight CL wear. All 12 patients who completed follow-up (28 ± 42 weeks) showed improvement in visual acuity and ocular surface condition after cessation of CL wear and medical treatment. Of them, five (42%) patients showed full recovery while seven (58%) showed partial recovery.

Conclusions

If a patient with a history of CL wear for an extended period of time presents with decreased visual acuity, practitioners should perform detailed examinations with suspicion of CL-LSCD, including fluorescein staining. CL-LSCD is usually reversible and close follow-up with conservative treatment is recommended as the initial treatment option.

Insulin-like growth factor binding protein-7: A marker of conjunctivalization in an animal model of limbal stem cell deficiency

PURPOSE

Limbal stem cell deficiency (LSCD) is characterized by the loss of limbal epithelial stem cells, resulting in a pathological process termed 'conjunctivalization' which compromises corneal transparency, leading to blindness. Current diagnosis for LSCD is limited because reliable conjunctiva-specific biomarkers are lacking. This study sought to address this shortcoming through the serendipitous discovery of insulin-like growth factor binding protein (IGFBP)-7.

METHODS

IGFBP-7 expression was determined in normal (n=83) and conjunctivalized (n=52) mouse corneas with experimentally-induced LSCD, and in cadaveric normal human corneas (n=7) and human pterygia (n=15); a disease characterized by the invasion of a conjunctivalized, fibrovascular pannus. Clinical assessments including slit-lamp microscopy, fluorescein staining and impression cytology, and biochemical, molecular and immunological assays were also conducted.

RESULTS

Mass spectrometry of conditioned media from mouse limbal explant-derived cells revealed the presence of IGFBP-7. This factor was expressed in normal limbal and conjunctival epithelium and conjunctivalized corneas from mice with LSCD, and in human pterygium epithelium but not in normal mouse or human corneal epithelium. Four weeks after inducing LSCD, IGFBP-7 staining was increased by 2.9-fold in mouse corneas compared to steady-state, and by 1.6-fold in impression cytology specimens derived from the same mice. Notably, IGFBP-7 was detected approximately 2-weeks earlier than Muc5AC.

CONCLUSIONS

This study provides novel insights into the specificity of IGFBP-7 for the mammalian conjunctival epithelium in health and disease. A point-of-care test for IGFBP-7 could be developed to assist clinicians in early diagnosis, and in monitoring disease progression, severity and therapeutic outcomes in patients with LSCD.

Global Consensus on Definition, Classification, Diagnosis, and Staging of Limbal Stem Cell Deficiency

PURPOSE

Despite extensive knowledge gained over the last 3 decades regarding limbal stem cell deficiency (LSCD), the disease is not clearly defined, and there is lack of agreement on the diagnostic criteria, staging, and classification system among treating physicians and research scientists working on this field. There is therefore an unmet need to obtain global consensus on the definition, classification, diagnosis, and staging of LSCD.

METHODS

A Limbal Stem Cell Working Group was first established by The Cornea Society in 2012. The Working Group was divided into subcommittees. Four face-to-face meetings, frequent email discussions, and teleconferences were conducted since then to obtain agreement on a strategic plan and methodology from all participants after a comprehensive literature search, and final agreement was reached on the definition, classification, diagnosis, and staging of LSCD. A writing group was formed to draft the current manuscript, which has been extensively revised to reflect the consensus of the Working Group.

RESULTS

A consensus was reached on the definition, classification, diagnosis, and staging of LSCD. The clinical presentation and diagnostic criteria of LSCD were clarified, and a staging system of LSCD based on clinical presentation was established.

CONCLUSIONS

This global consensus provides a comprehensive framework for the definition, classification, diagnosis, and staging of LSCD. The newly established criteria will aid in the correct diagnosis and formulation of an appropriate treatment for different stages of LSCD, which will facilitate a better understanding of the condition and help with clinical management, research, and clinical trials in this area.