Cornea

Severinsky B, Fadel D, Davelman J, Moulton E. Effect of Scleral Lenses on Corneal Topography in Keratoconus: A Case Series of Cross-Linked Versus Non-Cross-Linked Eyes. Cornea 2019;38(8):986-991.Abstract
PURPOSE: To evaluate the changes in anterior corneal topography induced by short-time wear of scleral contact lenses (SLs) in keratoconic subjects with and without a history of corneal cross-linking (CXL). METHODS: Nine keratoconic patients (14 eyes) were fitted with 18.5 mm SLs for optical rehabilitation. Subjects were divided into 2 groups: 7 eyes without a history of CXL (Non-CXL group) and 7 with a history of CXL (CXL group). Corneal topography was performed at baseline and after 2 and 5 hours of lens wear. The differences for simulated flat (Kflat), steep (Ksteep) and maximal (Kmax) corneal curvatures, central corneal astigmatism (CCA), and central cornea thickness were evaluated. RESULTS: No statistically significant difference was detected between Non-CXL and CXL groups in any of these measures. Statistically significant flattening was detected in Ksteep Repeated measures analysis of variance ([RM-ANOVA), F (2,24) = 11.32, P < 0.0001], CCA [RM-ANOVA, F (2,24) = 15.34, P < 0.0001], and Kmax [RM-ANOVA, F (2,24) = 19.10, P < 0.0001). From baseline to 5 hours of SL wear, Ksteep decreased on average from 53.1 to 52.4 D, Kmax decreased from 56.7 to 55.8 D, and CCA decreased from 7.2 to 6.3 D. Kmax showed a trend toward more flattening in the Non-CXL group. Central cornea thickness showed significant thickening over time from baseline (451 μm) to 5 hours (458 μm) of SL wear [RM-ANOVA, F (1,12) = 319.3, P < 0.0001]. CONCLUSIONS: Short-term scleral lens wear in keratoconic patients may cause flattening of the anterior cornea. A history of CXL treatment does not guarantee corneal shape stability after scleral lens wear. Practitioners should be aware of these changes because scleral lens wear may mask the signs of keratoconus progression.
Sharif R, Khaled ML, McKay TB, Liu Y, Karamichos D. Transcriptional profiling of corneal stromal cells derived from patients with keratoconus. Sci Rep 2019;9(1):12567.Abstract
Keratoconus (KC) is a multi-factorial corneal ectasia with unknown etiology affecting approximately 1:2000 people worldwide. Dysregulated gene expression, using RNA-Seq technology, have been reported in KC corneal tissue. However, the differential expression of genes, in KC corneal stromal cells have been widely ignored. We utilized mRNA-Seq to analyze gene expression in primary human corneal stromal cells derived from five non-Keratoconus healthy (HCF) and four Keratoconus (HKC) donors. Selected genes were further validated using real time PCR (RT-PCR). We have identified 423 differentially expressed genes with 187 down- and 236 up-regulated in KC-affected corneal stromal cells. Gene ontology analysis using WebGestalt indicates the enrichment of genes involved in cell migration, extracellular matrix, adherens junction, and MAPK signaling. Our protein-protein interaction network analysis identified several network seeds, such as EGFR, NEDD4, SNTA1, LGALS3BP, HSPB1, SDC2, MME, and HIF1A. Our work provides an otherwise unknown information on the transcriptional changes in HKCs, and reveals critical mechanisms of the cellular compartment. It also highlights the importance of human-based in vitro studies on a disease that currently lacks strong biomarkers and animal models.
Wolkow N, Habib LA, Yoon MK, Freitag SK. Corneal Neurotization: Review of a New Surgical Approach and Its Developments. Semin Ophthalmol 2019;:1-15.Abstract
Corneal neurotization is an innovative surgical approach for restoring corneal sensation, whereby the sensory functions of a normal donor nerve are rerouted to an anesthetic cornea. Many variations upon this basic surgical principal have been introduced and have proven successful in ameliorating corneal sensation in patients. It is unclear whether one surgical approach is superior to another, as each has advantages and disadvantages. Surgical approaches differ in the donor nerve selected and in whether a nerve graft is required. Surgical techniques have varied in the location, number and extent of incisions, methods of nerve coaptation, the number of surgeons required, the equipment and materials utilized and the duration of the procedure. The current review provides an overview of developments in this nascent field. A review of all peer-reviewed publications on corneal neurotization was performed. The various approaches to corneal neurotization are compared and discussed. The least morbid, simplest, most expedient and successful surgical approaches will ultimately become the most utilized.
Rico-Sánchez L, Garzón I, González-Andrades M, Ruíz-García A, Punzano M, Lizana-Moreno A, Muñoz-Ávila JI, Sánchez-Quevedo MDC, Martínez-Atienza J, Lopez-Navas L, Sanchez-Pernaute R, Oruezabal RI, Medialdea S, Gonzalez-Gallardo MDC, Carmona G, Sanbonmatsu-Gámez S, Perez M, Jimenez P, Cuende N, Campos A, Alaminos M. Successful development and clinical translation of a novel anterior lamellar artificial cornea. J Tissue Eng Regen Med 2019;13(12):2142-2154.Abstract
Blindness due to corneal diseases is a common pathology affecting up to 23 million individuals worldwide. The tissue-engineered anterior human cornea, which is currently being tested in a Phase I/II clinical trial to treat severe corneal trophic ulcers with preliminary good feasibility and safety results. This bioartificial cornea is based on a nanostructured fibrin-agarose biomaterial containing human allogeneic stromal keratocytes and cornea epithelial cells, mimicking the human native anterior cornea in terms of optical, mechanical, and biological behavior. This product is manufactured as a clinical-grade tissue engineering product, fulfilling European requirements and regulations. The clinical translation process included several phases: an initial in vitro and in vivo preclinical research plan, including preclinical advice from the Spanish Medicines Agency followed by additional preclinical development, the adaptation of the biofabrication protocols to a good manufacturing practice manufacturing process, including all quality controls required, and the design of an advanced therapy clinical trial. The experimental development and successful translation of advanced therapy medicinal products for clinical application has to overcome many obstacles, especially when undertaken by academia or SMEs. We expect that our experience and research strategy may help future researchers to efficiently transfer their preclinical results into the clinical settings.
Yong JJ, Hatch KM. Corneal Cross-Linking: An Effective Treatment Option for Pellucid Marginal Degeneration. Semin Ophthalmol 2019;:1-6.Abstract
: This is the first review article examining literature specific to the use of corneal cross-linking (CXL) to treat pellucid marginal degeneration (PMD). : CXL appears to be an effective treatment that may halt the progression of PMD to stabilize vision. This could postpone or eliminate the need for corneal transplantation in the management of these patients. Furthermore, combining CXL with keratorefractive surgery in a single procedure has been shown to be safe and successful in improving vision in PMD patients. : The data reported in literature is limited at this time, consisting mostly of retrospective studies with short term follow up. Further research is needed to evaluate refractive effects of combined CXL and excimer laser procedures.
Islam MM, Sharifi R, Mamodaly S, Islam R, Nahra D, AbuSamra DB, Hui PC, Adibnia Y, Goulamaly M, Paschalis EI, Cruzat A, Kong J, Nilsson PH, Argüeso P, Mollnes TE, Chodosh J, Dohlman CH, Gonzalez-Andrades M. Effects of gamma radiation sterilization on the structural and biological properties of decellularized corneal xenografts. Acta Biomater 2019;96:330-344.Abstract
To address the shortcomings associated with corneal transplants, substantial efforts have been focused on developing new modalities such as xenotransplantion. Xenogeneic corneas are anatomically and biomechanically similar to the human cornea, yet their applications require prior decellularization to remove the antigenic components to avoid rejection. In the context of bringing decellularized corneas into clinical use, sterilization is a crucial step that determines the success of the transplantation. Well-standardized sterilization methods, such as gamma irradiation (GI), have been applied to decellularized porcine corneas (DPC) to avoid graft-associated infections in human recipients. However, little is known about the effect of GI on decellularized corneal xenografts. Here, we evaluated the radiation effect on the ultrastructure, optical, mechanical and biological properties of DPC. Transmission electron microscopy revealed that gamma irradiated decellularized porcine cornea (G-DPC) preserved its structural integrity. Moreover, the radiation did not reduce the optical properties of the tissue. Neither DPC nor G-DPC led to further activation of complement system compared to native porcine cornea when exposed to plasma. Although, DPC were mechanically comparable to the native tissue, GI increased the mechanical strength, tissue hydrophobicity and resistance to enzymatic degradation. Despite these changes, human corneal epithelial, stromal, endothelial and hybrid neuroblastoma cells grew and differentiated on DPC and G-DPC. Thus, GI may achieve effective tissue sterilization without affecting critical properties that are essential for corneal transplant survival.
Shanbhag SS, Rashad R, Chodosh J, Saeed HN. Long-Term Effect of a Treatment Protocol for Acute Ocular Involvement in Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis. Am J Ophthalmol 2019;208:331-341.Abstract
PURPOSE: To describe the long-term effect of a treatment protocol for ocular involvement in acute Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), including focused ocular examination and pathology-appropriate use of lubrication, topical corticosteroids, topical antibiotics, and amniotic membrane transplantation (AMT). DESIGN: Retrospective, comparative case series. METHODS: A total of 48 patients (96 eyes) were included in this study. Nine of 48 patients (18 eyes) had acute SJS/TEN from 2000 to 2007 and did not receive protocol care (Group I). Thirty-nine of 48 patients (78 eyes) had acute SJS/TEN from 2008 to 2017 and received protocol care (Group II). The main outcome measures were best-corrected visual acuity (BCVA) at final follow-up visit and incidence of complications in the chronic phase. RESULTS: No eyes in Group I received AMT for SJS/TEN, compared to 87% of qualifying eyes in Group II (P < .0001) There was a significant difference in the proportion of eyes with BCVA ≥20/40 at last follow-up between Group I and Group II (33% vs 92%, P < .001). The proportion of eyes with vision-threatening complications in the chronic phase was significantly higher in Group I versus Group II (67% vs 17%, P = .002), with most complications occurring in the first 2 years after disease onset in both groups. CONCLUSIONS: A specific protocol for acute ocular care in SJS/TEN, including aggressive use of AMT, was highly successful in reducing corneal blindness and severe vision-threatening complications of the disorder.
Kheirkhah A, Coco G, Satitpitakul V, Pham TT, Dana R. Limbal and Conjunctival Epithelial Thickness in Ocular Graft-Versus-Host Disease. Cornea 2019;38(10):1286-1290.Abstract
PURPOSE: To compare the thickness of the limbal epithelium (LE) and the bulbar conjunctival epithelium (BCE) between patients with dry eye disease (DED) with and without ocular graft-versus-host disease (GVHD). METHODS: This cross-sectional study enrolled 40 patients with moderate to severe DED including 20 with and 20 without chronic ocular GVHD. All patients had a comprehensive clinical ophthalmic assessment. Moreover, the thickness of the LE and BCE in both nasal and temporal regions of both eyes was measured using spectral domain optical coherence tomography. RESULTS: The average LE thickness in all patients with dry eye (GVHD and non-GVHD) was 65.8 ± 11.9 μm temporally and 69.7 ± 11.1 μm nasally (P = 0.02). The average BCE thickness was 55.8 ± 11.4 μm temporally and 60.1 ± 11.0 μm nasally (P = 0.03). There were no statistically significant differences between GVHD and non-GVHD groups in LE thickness (69.6 ± 11.7 vs. 66.1 ± 6.2 μm, respectively, P = 0.31) or BCE thickness (58.9 ± 9.6 vs. 57.3 ± 9.8 μm, respectively, P = 0.82). There was a significant correlation between LE thickness and BCE thickness (P = 0.01, Rs = 0.41). A statistically significant negative correlation was also observed between LE thickness and age (P = 0.002, Rs = -0.35). There were no significant correlations between the thickness of the LE or BCE and other clinical parameters. CONCLUSIONS: No difference exists in the thickness of the ocular surface epithelia between dry eyes with and without ocular GVHD, which would suggest that these epithelial changes may be independent of the underlying etiology and possibly only reflect the disease severity. Furthermore, there are regional variations in the thickness of the ocular surface epithelia in patients with DED.
Shukla S, Mittal SK, Foulsham W, Elbasiony E, Singhania D, Sahu SK, Chauhan SK. Therapeutic efficacy of different routes of mesenchymal stem cell administration in corneal injury. Ocul Surf 2019;Abstract
PURPOSE: Corneal injuries are associated with significant impairment in vision. Mesenchymal stem cells (MSCs) have been shown to limit inflammation and promote tissue repair at the ocular surface. Here, we evaluate the efficacies of different modes of MSC delivery (topical, subconjunctival, intraperitoneal [IP] and intravenous [IV]) to promote tissue repair and restore corneal transparency in a murine model of corneal injury. METHODS: MSCs were purified from the bone marrow of C57BL/6 J mice and expanded using plastic adherence in vitro. Corneal injury was created using an Algerbrush, and 0.5 × 10 MSCs/mouse were administered via topical, subconjunctival, IP or IV routes. Qdot-labeled MSCs were employed to determine the effect of route of administration on corneal and conjunctival MSC frequencies. Corneal opacity scores were calculated using ImageJ. Expression of inflammatory cytokines was quantified by qPCR, and infiltration of CD45 cells was evaluated by flow cytometry. RESULTS: Subconjunctival or IV administration results in increased frequencies of MSCs in ocular surface tissues following corneal injury, relative to topical or intraperitoneal delivery. Subconjunctival or IV administration reduces: (i) corneal opacity, (ii) tissue fibrosis as quantified by α-Sma expression, (iii) the expression of inflammatory cytokines (Il-1β and Tnf-α) and (iv) CD45 inflammatory cell infiltration relative to untreated injured control animals. Administration via subconjunctival or IV routes was observed to accelerate corneal repair by restoring tissue architecture and epithelial integrity. CONCLUSIONS: Our data suggest that subconjunctival or IV delivery of MSCs have superior therapeutic efficacy compared to topical or IP delivery following corneal injury.
AbuSamra DB, Mauris J, Argüeso P. Galectin-3 initiates epithelial-stromal paracrine signaling to shape the proteolytic microenvironment during corneal repair. Sci Signal 2019;12(590)Abstract
Paracrine interactions between epithelial cells and stromal fibroblasts occur during tissue repair, development, and cancer. Crucial to these processes is the production of matrix metalloproteinases (MMPs) that modify the microenvironment. Here, we demonstrated that the carbohydrate-binding protein galectin-3 stimulated microenvironment remodeling in the cornea by promoting the paracrine action of secreted interleukin-1β (IL-1β). Through live cell imaging in vitro, we observed rapid activation of the promoter in clusters of cultured human epithelial cells after direct heterotypic contact with single primary human fibroblasts. Soluble recombinant galectin-3 and endogenous galectin-3 of epithelial origin both stimulated MMP9 activity through the induction of IL-1β secretion by fibroblasts. In vivo, mechanical disruption of the basement membrane in wounded corneas prompted an increase in the abundance of IL-1β in the stroma and increased the amount of gelatinase activity in the epithelium. Moreover, corneas of galectin-3-deficient mice failed to stimulate IL-1β after wounding. This mechanism of paracrine control has broad importance for our understanding of how the proteolytic microenvironment is modified in epithelial-stromal interactions.
Chen X, Sullivan BD, Rahimi Darabad R, Liu S, Kam WR, Sullivan DA. Are BALB/c Mice Relevant Models for Understanding Sex-Related Differences in Gene Expression in the Human Meibomian Gland?. Cornea 2019;38(12):1554-1562.Abstract
BACKGROUND: A compelling feature of dry eye disease is that it occurs predominantly in women. We hypothesize that this female prevalence is linked to sex-related differences in the meibomian gland (MG). This gland plays a critical role in maintaining the tear film, and its dysfunction is a major cause of dry eye disease. To understand the factors that underlie MG sexual dimorphism and promote dry eye in women, we seek to identify an optimal model for the human MG. Our goal was to determine whether a murine MG is such a model. Toward that end, we examined whether sex differences in MG gene expression are the same in BALB/c mice and humans. METHODS: Eyelid tissues were collected from humans (n = 5-7/sex) and BALB/c mice (n = 9/sex). MGs were isolated and processed for the evaluation of gene expression by using microarrays and bioinformatics software. RESULTS: Our analysis of the 500 most highly expressed genes from human and mouse MGs showed that only 24.4% were the same. Our comparison of 100 genes with the greatest sex-associated differences in human and mouse MGs demonstrated that none were the same. Sex also exerted a significant impact on numerous ontologies, Kyoto Encyclopedia of Genes and Genomes pathways, and chromosomes, but these effects were primarily species-specific. CONCLUSIONS: Our results indicate that BALB/c mice are not optimal models for understanding sex-related differences in gene expression of the human MG.
Foulsham W, Dohlman TH, Mittal SK, Taketani Y, Singh RB, Masli S, Dana R. Thrombospondin-1 in ocular surface health and disease. Ocul Surf 2019;Abstract
Thrombospondin 1 (TSP-1) is an extracellular matrix protein that interacts with a wide array of ligands including cell receptors, growth factors, cytokines and proteases to regulate various physiological and pathological processes. Constitutively expressed by certain ocular surface tissues (e.g. corneal and conjunctival epithelium), TSP-1 expression is modulated during ocular surface inflammation. TSP-1 is an important activator of latent TGF-β, serving to promote the immunomodulatory and wound healing functions of TGF-β. Mounting research has deepened our understanding of how TSP-1 expression (and lack thereof) contributes to ocular surface homeostasis and disease. Here, we review current knowledge of the function of TSP-1 in dry eye disease, ocular allergy, angiogenesis/lymphangiogenesis, corneal transplantation, corneal wound healing and infectious keratitis.
Wirta DL, Torkildsen GL, Moreira HR, Lonsdale JD, Ciolino JB, Jentsch G, Beckert M, Ousler GW, Steven P, Krösser S. A Clinical Phase II Study to Assess Efficacy, Safety, and Tolerability of Waterfree Cyclosporine Formulation for Treatment of Dry Eye Disease. Ophthalmology 2019;126(6):792-800.Abstract
PURPOSE: To compare the efficacy, safety, and tolerability of waterfree cyclosporine formulation (CyclASol) at 2 concentrations (0.1% and 0.05% of cyclosporine [CsA]) to vehicle when applied twice daily for 16 weeks in patients with dry eye disease (DED). An open-label Restasis (Allergan, Irvine, CA) arm was included to allow a direct comparison with an approved therapy. DESIGN: An exploratory phase II, multicenter, randomized, vehicle-controlled clinical trial, double-masked between CyclASol and vehicle with an open-label comparator. PARTICIPANTS: Two hundred and seven eligible patients with a history of dry eye disease were randomized 1:1:1:1 to 1 of 4 treatment arms (CyclASol 0.05%, n = 51; CyclASol 0.1%, n = 51; vehicle, n = 52, and Restasis, n = 53). METHODS: After a 2-week run-in period with twice-daily dosing of Systane Balance (Alcon, Fort Worth, TX), patients were randomized to the respective treatment arm and dosed twice daily for 16 weeks. MAIN OUTCOME MEASURES: The study was set up to explore efficacy on a number of sign and symptom end points including total and subregion corneal fluorescein staining, conjunctival staining, visual analog scale (VAS) for dry eye symptoms VAS severity, and Ocular Surface Disease Index (OSDI) questionnaire. RESULTS: CyclASol showed a consistent reduction in corneal and conjunctival staining compared with both vehicle and Restasis over the 16-week treatment period, with an early onset of effect (at day 14). A mixed-effects model-based approach demonstrated that the CyclASol drug effect was statistically significant over vehicle (total corneal staining P < 0.1, central corneal staining P < 0.001, conjunctival staining P < 0.01). This model-based analysis suggests a significant CyclASol effect for OSDI as symptom parameter (P < 0.01). The numbers of ocular adverse events were low in all treatment groups. CONCLUSIONS: CyclASol showed efficacy, safety, and tolerability at 2 concentrations in moderate-to-severe DED. In a direct head-to-head against open-label Restasis, CyclASol was found to have an earlier onset of action, as early as after 2 weeks of treatment, in relieving the signs of DED, as measured by corneal and conjunctival staining. The central region of the cornea, an important area for visual function in dry eye sufferers, was shown to have the most benefit from treatment. Excellent safety, tolerability, and comfort profile supports this new CsA formulation as having a positive benefit-to-risk ratio.

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