Corneal Epithelial Disorders Research Articles

Substance P- and Insulin-like Growth Factor 1-derived Tetrapeptides for Neurotrophic Keratopathy Related to Leprosy: A Clinical Trial

PurposeNeurotrophic keratopathy is part of the leprosy sequelae and causes progressive deterioration of visual acuity. Although leprosy is bacteriologically curable, there is currently no efficient treatment. Eye drops containing tetrapeptides, Phenylalanine-Glycine-Leucine-Methionine-amide (FGLM-NH2) and Serine-Serine-Serine-Arginine (SSSR), derived from substance P and insulin-like growth factor 1 (IGF-1), are clinically efficacious in the treatment of corneal epithelial disorders caused by neurotrophic keratopathy. To further investigate the effect of this treatment on leprosy sequalae, we evaluated the clinical efficacy of FGLM-NH2+SSSR eye drops for treating neurotrophic keratopathy. DesignClinical trial: Interventional, multicenter, exploratory, single-arm, before and after comparison. ParticipantsThe eyes (12) of 11 patients, aged >60 years, were studied from two leprosy sanatoriums in Japan. MethodsPatients with neurotrophic keratopathy in leprosy sanatorium, specifically those with corneal perception of <40 mm, assessed by the Cochet-Bonnet corneal esthesiometer, and persistent corneal epithelial defects (PEDs) and/or corneal stromal thinning were included in this study. Those treated for infection in the acute phase were excluded from the study. Eye drops containing FGLM-NH2 0.05% and SSSR 5x10-6% were administered four times daily for up to 3 months. Fluorescein staining and optical corneal sections were photographed using a slit-lamp microscope at protocol-set intervals. Where possible, anterior segment optical coherence tomography was performed before and after the intervention. Main outcome measuresThe primary outcome measured was improvement in neurotrophic keratopathy. The patient was judged to have improved when one or more of the following criteria were met: 1) healing epithelial defects or 2) increased thickness in the thin area of the cornea. Secondary endpoints were visual acuity, subjective findings, and time to complete healing for a PED. ResultsNeurotrophic keratopathy on epithelial defects or stromal thickness improved in 83.3% of the patients (90% confidence interval 56.2%–97.0%, P<0.00001). The mean value of corrected visual acuity increased -0.16 by logarithm of the minimum angle of resolution. There were no adverse events reported in association with the treatment. ConclusionsWe confirmed that FGLM-NH2+SSSR eye drops are effective for neurotrophic keratopathy without any adverse reaction in leprosy. These results should be disseminated to any parties who could need this information.

Extracellular Vesicle MicroRNAs From Corneal Stromal Stem Cell Enhance Stemness of Limbal Epithelial Stem Cells by Targeting the Notch Pathway.

The limbal niche supports the self-renewal of limbal epithelial stem cells (LESCs). The corneal stromal stem cell (CSSC) is an important component in the niche that regulates the LESC phenotype. However, the intercellular communication between LESCs and CSSCs has yet to be elucidated. A traditional two-dimensional (2D) system, a direct three-dimensional (3D) system, and an indirect 3D coculture system of LESCs and CSSCs were used to elucidate the paracrine pathway effect of CSSCs on LESCs. To reveal the impact of CSSC derived extracellular vesicles (CSSC-EVs) on LESCs, GW4869 and CSSC-EVs were added separately to the LESC culture medium. The outgrowth rate, cell density, differentiation, and stemness maintenance were compared among these methods. The miRNAs in the CSSC-EVs were sequenced, and the targeted Notch pathway was further confirmed by RT‒qPCR and Western blotting. Compared with 2D culture, both the direct and indirect 3D coculture systems yielded a higher outgrowth rate and expression of stem cell markers of LESCs. The phenotypes of LESCs cultivated using the two coculture approaches were also comparable. Nevertheless, GW4869 inhibited the effect of CSSCs on LESCs, and the addition of CSSC-EVs to the 2D culture system could increase cell density, and the proportion of p63αbright cells, which indicated that CSSC-EVs were crucial in regulating LESCs. Furthermore, the EV-AlixKD with reduced miRNA partly lost its regulating function. The abundant miRNAs in CSSC-EVs, such as hsa-miR-663b, hsa-miR-16-5p, and hsa-miR-1290, target the Notch pathway. The LESCs transfected with miR-663b had higher p63 expression via downregulating of the Notch pathway. CSSC-EV played an important role in promoting LESC proliferation and stemness maintenance by targeting Notch signaling via miRNAs, which will increase our understanding of the limbal niche and provide a potential new approach for LESC culture and the treatment of corneal epithelial disorders.

Cell-based Therapies for Corneal and Retinal Disorders.

Maintenance of the visual function is the desired outcome of ophthalmologic therapies. The shortcomings of the current treatment options, like partial recovery, post-operation failure, rigorous post-operative care, complications, etc., which are usually encountered with the conventional treatment options has warranted newer treatment options that may eliminate the root cause of diseases and minimize the side effects. Cell therapies, a class of regenerative medicines, have emerged as cutting-edge treatment option. The corneal and retinal dystrophies during the ocular disorders are the major cause of blindness, worldwide. Corneal disorders are mainly categorized mainly into corneal epithelial, stromal, and endothelial disorders. On the other hand, glaucoma, retinitis pigmentosa, age-related macular degeneration, diabetic retinopathy, Stargardt Disease, choroideremia, Leber congenital amaurosis are then major retinal degenerative disorders. In this manuscript, we have presented a detailed overview of the development of cell-based therapies, using embryonic stem cells, bone marrow stem cells, mesenchymal stem cells, dental pulp stem cells, induced pluripotent stem cells, limbal stem cells, corneal epithelial, stromal and endothelial, embryonic stem cell-derived differentiated cells (like retinal pigment epithelium or RPE), neural progenitor cells, photoreceptor precursors, and bone marrow-derived hematopoietic stem/progenitor cells etc. The manuscript highlights their efficiency, drawbacks and the strategies that have been explored to regain visual function in the preclinical and clinical state associated with them which can be considered for their potential application in the development of treatment.

Late-Onset Traumatic Corneal Conjunctival Epithelial Disorders due to Granular Formation After Cosmetic Suture Blepharoplasty.

The purpose of this study was to report conjunctival granular formation as one of the causative factors of a traumatic corneal conjunctival epithelial disorder after plastic suture blepharoplasty. Clinical charts of 7 patients who had visited Ohshima Eye Hospital with a symptomatic corneal epithelial disorder and history of suture blepharoplasty were reviewed. Clinical evidence of conjunctival granular formations was observed in all patients at the tarsal conjunctiva facing to corneal conjunctival traumatic epithelial disorders. The desired outcome was to alleviate the disorder. The assessment included tabulating results after the placement of a soft contact lens bandage and subsequent partial tarsal plate resection of the granular formation. Seven women (mean age 45.0±10.9 years) enrolled in this study had previously undergone suture blepharoplasty (mean 18.3±6.9 years before). Soft contact lens bandages relieved all of the patients' complaints immediately. After resecting the granular formation, the traumatic corneal conjunctival epithelial disorder disappeared, and no recurrence was observed after surgery. The conjunctival granular formation within the tarsal conjunctiva after suture blepharoplasty caused the late-onset traumatic corneal conjunctival epithelial disorder. A complete cure was obtained after resection of the granular formation at the tarsal conjunctiva. To the best of our knowledge, this is the first report to identify the removal of granular formations in 7 patients with late-onset traumatic corneal conjunctival disorders many years after blepharoplasty. The resection of these lesions is a promising procedure to treat late-onset ocular epithelial disorder after suture blepharoplasty.

Corneal Epithelial Regeneration: Old and New Perspectives.

Corneal blindness is the fifth leading cause of blindness worldwide, and therapeutic options are still often limited to corneal transplantation. The corneal epithelium has a strong barrier function, and regeneration is highly dependent on limbal stem cell proliferation and basement membrane remodeling. As a result of the lack of corneal donor tissues, regenerative medicine for corneal diseases affecting the epithelium is an area with quite advanced basic and clinical research. Surgery still plays a prominent role in the treatment of epithelial diseases; indeed, innovative surgical techniques have been developed to transplant corneal and non-corneal stem cells onto diseased corneas for epithelial regeneration applications. The main goal of applying regenerative medicine to clinical practice is to restore function by providing viable cells based on the use of a novel therapeutic approach to generate biological substitutes and improve tissue functions. Interest in corneal epithelium rehabilitation medicine is rapidly growing, given the exposure of the corneal outer layers to external insults. Here, we performed a review of basic, clinical and surgical research reports on regenerative medicine for corneal epithelial disorders, classifying therapeutic approaches according to their macro- or microscopic target, i.e., into cellular or subcellular therapies, respectively.

Artificial Intelligence and Corneal Confocal Microscopy: The Start of a Beautiful Relationship.

Corneal confocal microscopy (CCM) is a rapid non-invasive in vivo ophthalmic imaging technique that images the cornea. Historically, it was utilised in the diagnosis and clinical management of corneal epithelial and stromal disorders. However, over the past 20 years, CCM has been increasingly used to image sub-basal small nerve fibres in a variety of peripheral neuropathies and central neurodegenerative diseases. CCM has been used to identify subclinical nerve damage and to predict the development of diabetic peripheral neuropathy (DPN). The complex structure of the corneal sub-basal nerve plexus can be readily analysed through nerve segmentation with manual or automated quantification of parameters such as corneal nerve fibre length (CNFL), nerve fibre density (CNFD), and nerve branch density (CNBD). Large quantities of 2D corneal nerve images lend themselves to the application of artificial intelligence (AI)-based deep learning algorithms (DLA). Indeed, DLA have demonstrated performance comparable to manual but superior to automated quantification of corneal nerve morphology. Recently, our end-to-end classification with a 3 class AI model demonstrated high sensitivity and specificity in differentiating healthy volunteers from people with and without peripheral neuropathy. We believe there is significant scope and need to apply AI to help differentiate between peripheral neuropathies and also central neurodegenerative disorders. AI has significant potential to enhance the diagnostic and prognostic utility of CCM in the management of both peripheral and central neurodegenerative diseases.

Evaluation of the postoperative course of East Asian eyelid reconstruction with free tarsoconjunctival graft transplantation: A Japanese single-centre retrospective study

SummaryAlthough eyelid reconstruction by transplanting an autologous free tarsoconjunctival graft (FTG) is a well-established technique, few studies have examined the postoperative course of FTG transplantation for East Asian eyelids, including those of Japanese patients. Therefore, this study investigated complication and reoperation rates after FTG transplantation in the reconstruction of East Asian (Japanese) eyelids.This study included 42 eyelids wherein posterior lobe reconstruction after resection of a malignant tumour of the eyelid was performed by FTG transplantation between 2007 and 2019 at Niigata University Medical and Dental Hospital. We investigated complications and need for revision surgery during the patients’ postoperative courses. The relationship between postoperative complications, tumour diameter, and eyelid defect width was statistically examined.Of 42 cases reconstructed with FTG, the upper eyelid was reconstructed in 23. Postoperative complications were observed in 12 cases (52%): entropion in eight and corneal epithelial disorder in four. Revision surgery was required in three of those cases (13%). There were 19 cases of lower eyelid reconstruction. Postoperative complications were observed in seven cases (32%): ectropion in three and corneal epithelial disorder in two and one lower eyelid ptosis. Two of these cases (11%) required revision surgery. There was no statistically significant difference in tumour diameter between cases with and without postoperative complications. There was also no significant association between the width of the eyelid defect and the presence/absence of complications. Entropion and ectropion were more likely to occur in the upper and lower eyelids, respectively.For Japanese eyelids, complication rates after FTG transplantation were approximately 50% and 30% for the upper and lower eyelids, respectively. The revision surgery rate was approximately 10% for both upper and lower eyelids. As these revision surgery rates are low, FTG transplantation may be an option for the reconstruction of Japanese eyelids.

A multicenter clinical trial of orthokeratology in school-aged children and adolescents in Japan.

This study investigated the safety and efficacy of orthokeratology in myopic children in Japan. Prospective clinical trial. This study enrolled myopic children aged 6-16years with a spherical equivalent of -1.00 D to -4.00 D and astigmatism of -1.5 D or lower, whose parents could manage contact lens use and could provide written informed consent. The children were treated with orthokeratology lenses (BREATH-O CORRECT R, Universal View Co., Ltd.) for 3years. Slit-lamp findings, visual acuity, intraocular pressure, subjective refraction, corneal topography, corneal endothelial cell density, corneal thickness, and axial length were regularly assessed. This study included 96 eyes of 48 patients (average age, 10.7 ± 2.08years). The average baseline spherical equivalent was -2.46 ± 0.97 D. The average baseline uncorrected visual acuity was 0.74 ± 0.32 logMAR, with significant improvement to -0.08 ± 0.18 logMAR at 4weeks and 0.02 ± 0.21 logMAR at 3years (both p < 0.001, Dunnett's test). The average baseline corneal endothelial cell density was 3053 ± 181 cells/mm2 and 3028 ± 213 cells/mm2 at postoperative 3years (p = 0.9933, Dunnett's test). The average axial length was 24.70 ± 0.78mm at baseline, 24.77 ± 0.80mm at 12weeks, and 25.32 ± 0.85mm at 36months. Although mild corneal epithelial disorders occurred in 18% of eyes, they were successfully treated with eye drops, enabling resumption of lens usage. No serious adverse events were observed. Orthokeratology lens (BREATH-O CORRECT R) use in children demonstrated good efficacy and safety during 3years of follow-up.

A Case of Pulmonary Adenocarcinoma with Repeated Corneal Epithelial Disorder and Herpes Simplex due to Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors

A Case of Pulmonary Adenocarcinoma with Repeated Corneal Epithelial Disorder and Herpes Simplex due to Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors

Effects of Benzalkonium Chloride in Ophthalmic Eyedrop Medications on Corneal Epithelium

Eyedrops often contain additives other than active pharmaceutical ingredients, such as preservatives. The most frequently used preservative is benzalkonium chloride (BAC). When the ocular surface is exposed to eyedrops, the active pharmaceutical ingredients and additives can cause corneal epithelial disorder. Particularly in clinical settings, there is great interest in corneal epithelial disorders resulting from the use of glaucoma eyedrops, which is inevitable when instilled for a long period of time after the onset of disease. At the authors' institute, glaucoma is treated with consideration of reducing corneal epithelial disorder while ensuring the effect of lowering intraocular pressure by the appropriate choice of eyedrops. In this review, we show the examples of the retrospective studies. Sodium hyaluronate eyedrops are prescribed for corneal epithelial disorders such as superficial punctate keratitis associated with dry eye. Prescribable concentrations of sodium hyaluronate in Japan are 0.1% or 0.3%, and the 0.3% formulation does not contain BAC. The authors' study showed that 0.3% sodium hyaluronate pretreatment reduced the cytotoxicity of BAC in cultured corneal epithelial cells, whereas an in vivo study in mice showed that a 0.3% sodium hyaluronate instillation was suggested and that the drug may enhance the cytotoxicity of separately administered BAC. It is suggested that sodium hyaluronate prolonged the retention of BAC on the ocular surface. However, there have been no reports of this problem in the clinical setting. It is important for ophthalmologists to understand the properties of additives other than the active pharmaceutical ingredients in eyedrops.

Assessment of clinical signs associated with adenoviral epidemic keratoconjunctivitis cases in southern Japan between 2011 and 2014

Adenoviral epidemic keratoconjunctivitis (EKC) is a major cause of ocular morbidity worldwide and specific antiviral therapies are not available. EKC is primarily caused by Human adenovirus D (HAdV-D) types 8, 37, 53, 54, 56 and 64. Considering the genomic variation in HAdV-D, we hypothesized that clinical signs could be differentiated by virus type. The hypothesis was retrospectively tested with clinical signs recorded from 250 patients with ocular infections visiting an ophthalmological clinic in southern Japan between 2011 and 2014. The results showed that conjunctival opacity, corneal epithelial disorders and pre-auricular lymphadenopathy, were more frequently associated with EKC than other ocular infections. Furthermore, HAdV types 8, 37 and 54, caused corneal complications and longer infections significantly more frequently than infections by types 53 and 56 (P < 0.05). Our descriptive results supported that symptoms severity vary with the infecting type, however, further research is needed to improve diagnosis of EKC.

Use of topical bromfenac for treating ocular pain and inflammation beyond cataract surgery: a review of published studies.

Topical ophthalmic nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used to treat postoperative inflammation and pain following cataract surgery and for treatment and prophylaxis of pseudophakic cystoid macular edema (CME). Bromfenac is a brominated NSAID with strong in vitro anti-inflammatory potency. Like other ophthalmic NSAIDs, bromfenac is often used outside of the cataract surgery setting. This paper provides an overview of bromfenac’s preclinical ocular pharmacology and pharmacokinetics, followed by a review of 23 published clinical studies in which various marketed bromfenac formulations were used for conditions other than cataract surgery or pseudophakic CME. These include: post-refractive eye surgery; macular edema associated with diabetes, uveitis, or retinal vein occlusion; inflammation associated with age-related macular degeneration; pain related to intravitreal injections; and other ocular anterior segment and surface disorders with an inflammatory component. The published evidence reviewed supports the safety and effectiveness of bromfenac in these additional ophthalmic indications. Bromfenac was well tolerated when given alone or in combination with intravitreal anti-vascular endothelial growth factor agents, topical corticosteroids, or topical mast-cell stabilizers. The most common adverse event reported was ocular irritation. No serious adverse events (ie, corneal epithelial disorders) were reported, although the majority of studies did not systematically evaluate potential side effects. Corneal complications, such as melts reported with diclofenac and ketorolac, were not observed with bromfenac in the studies. In summary, published study data support the clinical utility of bromfenac in various ocular disorders beyond post-cataract surgery. Additional studies are warranted to further define the potential role of bromfenac ophthalmic solution in clinical practice.

Therapeutic Proteins for Treatment of Corneal Epithelial Defects.

Corneal epithelial disorders take pride of place in modern ophthalmology. Defects of corneal epithelium are commonly accompanied by blurry vision, photophobia and tearing. Since cornea is the most densely innervated tissue of organisms, its disruption leads to development of a severe pain syndrome. Mild corneal erosions commonly undergo quick spontaneous recovery. Suppression of corneal wound healing due to various pathological causes results in development of severe recurrent erosions and persistent corneal defects. These pathological events can in turn lead to corneal scarring, opacification, and ulceration of cornea, and ultimately to the permanent vision impairment. The etiology of the underlying corneal diseases that commonly involves inflammatory, neurotrophic and systemic factors, should be considered for treating such defects. Therefore, the research focus has been shifted to establish therapeutics based on proteins and peptides. Due to varied mechanisms of action, proteinbased pharmaceuticals can be involved in the protection of corneal surface, mimicking tear components, stimulation of corneal wound healing, regeneration of corneal innervation, suppressing oxidative stress, inflammation and neovascularization. The active components can be naturally occurring (blood- or tear-derived) or be created de novo and optimized in order to achieve the level of activity required. Such pharmaceuticals are characterized by low toxicity and absence of systemic side-effects due to their low absorption into the bloodstream, if administrated topically. This review summarizes existing data on protein-based drugs for treatment of corneal epithelial defects that are currently under preclinical development or testing in clinical trials, or approved for medical use.

The corneal epitheliotrophic abilities of lyophilized powder form human platelet lysates.

PurposeTo evaluate whether lyophilized human platelet lysate (HPL) powder can preserve the growth factor concentrations and epitheliotrophic properties of liquid HPL, and potentially be used as a clinically-friendly treatment option.MethodsTwo commercialized liquid HPLs, UltraGRO TM (Helios, Atlanta, GA) and PLTMax (Mill Creek, Rochester, MI), were obtained and converted to lyophilized powder. After redissolution, lyophilized powder HPLs were compared with liquid HPLs, as well as human peripheral serum (HPS) and fetal bovine serum (FBS) in liquid or redissolved lyophilized powder forms. Concentrations of epidermal growth factor (EGF), transforming growth factor-β1 (TGF-β1), platelet-derived growth factor-AB (PDGF-AB) and platelet-derived growth factor-BB (PDGF-BB) were evaluated by enzyme-linked immunosorbent assay (ELISA). Human corneal epithelial cell line was incubated with the blood derivatives and evaluated for cell migration with scratch-induced directional wounding and proliferation with MTS assays. Cell differentiation was examined by transepithelial electrical resistance (TEER). Fluorescein staining and in vivo confocal microscopy were used to evaluate in vivo corneal epithelial wound healing in Sprague-Dawley rats that underwent corneal debridement and topical application of liquid and redissolved powder HPLs.ResultsLiquid form and redissolved lyophilized powder form HPLs had similar concentrations of EGF, TGF-β1, PDGF-AB and PDGF-BB. In vitro experiments on cell migration, proliferation and differentiation and rat models on wound healing demonstrated no significant difference between the liquid and redissolved lyophilized powder forms for HPLs, HPS and FBS. In vivo confocal microscopy revealed similar wound healing process at different layers of cornea after corneal epithelial debridement between liquid form and redissolved lyophilized power form of HPLs.ConclusionsThe redissolved lyophilized powder form of both commercialized HPLs showed similar growth factor concentrations and corneal epitheliotrophic abilities compared to the liquid form. Results suggest that the properties of liquid HPLs can be retained despite lyophilization and that lyophilized HPLs can be a treatment option for corneal epithelial disorders.

Potential New Modes of Treatment of Neurotrophic Keratopathy.

The cornea focuses external light onto the retina, a function for which it must be transparent and possess a smooth surface. Homeostasis of the corneal epithelium is regulated by various humoral factors present in the tear fluid and by neural factors derived from the trigeminal nerve. Neurotrophic keratopathy (NK) is characterized by corneal epithelial disorders that result from impairment of trigeminal nerve function and a consequent deficiency of neural factors. The ideal mode of treatment for this condition is the regeneration of damaged trigeminal nerve fibers, but such therapy is not currently available. In this review, we describe established and potential new treatments of NK. Our research demonstrated that a combination of the neurotransmitter substance P and insulin-like growth factor 1 (IGF-1) has a synergistic stimulatory effect on corneal epithelial migration in vitro and on corneal wound closure in vivo. Furthermore, we identified the minimal amino acid sequences of substance P and IGF-1 required for this synergistic action based on the assumption that the clinical application of peptides corresponding to these sequences would have fewer side effects compared with the full-length molecules. Combination of the substance P-derived peptide FGLM-amide and the IGF-1-derived peptide SSSR promoted corneal epithelial wound healing in patients with NK.Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01756456.

Wide-Angle Viewing System versus Conventional Indirect Ophthalmoscopy for Scleral Buckling

Wide-angle viewing systems (WAVSs) were originally established for pars plana vitrectomy. However, their application to scleral buckling surgery was recently reported. In this study, we compared the outcomes of scleral buckling using a noncontact WAVS with that of scleral buckling using conventional indirect ophthalmoscopy for rhegmatogenous retinal detachment. The clinical records of 39 eyes (39 patients) with rhegmatogenous retinal detachment primarily treated between November 2012 and June 2014 at the Vitreo-Retina Surgical Division Clinic at the Department of Ophthalmology, Keio University Hospital were retrospectively reviewed. Scleral bucking was performed using WAVS with surgical placement of an endoilluminator in 16 eyes and indirect ophthalmoscopy in 23 eyes. The patients in these groups were consecutive over different intervals. The preoperative demographics, success rate of retinal reattachment, intraoperative findings, and postoperative complications were evaluated. There were no significant differences in pre- or postoperative conditions between groups, and similar surgical outcomes were achieved with the WAVS and conventional procedures. However, compared with the conventional procedure, the WAVS procedure resulted in fewer intraoperative corneal epithelial disorders (p = 0.049) and decreased the surgical duration of segmental buckling (p = 0.02); therefore, it may be suggested as an effective alternative procedure.

Changes in Matrix Metalloproteinases in Diabetes Patients' Tears After Vitrectomy and the Relationship With Corneal Epithelial Disorder.

Previous studies indicate involvement of matrix metalloproteinases (MMPs) in the pathogenesis of diabetic keratopathy. To evaluate MMP levels in the tears of patients with diabetes, we investigated changes in MMP levels during perioperative periods and clarify the relationship with corneal epithelial disorders following vitrectomy. Matrix metalloproteinase levels in tears were measured by multiplex bead array in patients with or without diabetes who were scheduled for vitrectomy. Twenty-two patients with diabetes and proliferative diabetic retinopathy, and 20 patients with epiretinal membrane or macular hole (control group), were recruited. Changes in MMP levels during perioperative periods and the relationship with corneal epithelial disorders after vitrectomy were analyzed. The levels of MMP-2, -9, and -10 at 1 day after surgery in the diabetic group were significantly higher than in the control group. At 1 week after surgery, MMP-10 levels in the diabetic group were significantly higher than in the control group. After vitrectomy, corneal epithelial disorders occurred in six patients in the diabetic group but not in the control group. In the diabetic group, MMP-10 levels in tears of patients with corneal epithelial disorders were significantly higher than those in patients without corneal epithelial disorders. The MMP concentration in tears of patients with diabetes was higher than in nondiabetic patients after vitrectomy. High MMP-10 levels were observed in patients with diabetes and corneal epithelial disorders after vitrectomy. Aberrant levels of MMP-10 may cause corneal epithelial disorder after vitrectomy.

Peptide therapies for ocular surface disturbances based on fibronectin-integrin interactions.

The condition of the corneal epithelium is a critical determinant of corneal transparency and clear vision. The corneal epithelium serves as a barrier to protect the eye from external insults, with its smooth surface being essential for its optical properties. Disorders of the corneal epithelium include superficial punctate keratopathy, corneal erosion, and persistent epithelial defects (PEDs). The prompt resolution of these disorders is important for minimization of further damage to the cornea. Currently available treatment modalities for corneal epithelial disorders are based on protection of the ocular surface in order to allow natural healing to proceed. PEDs remain among the most difficult corneal conditions to treat, however. On the basis of characterization of the pathobiology of PEDs at the cell and molecular biological levels, we have strived to develop new modes of treatment for these defects. These treatments rely on two key concepts: provision of a substrate, such as the adhesive glycoprotein fibronectin, for the attachment and migration of corneal epithelial cells, and activation of these cells by biological agents such as the combination of substance P and insulin-like growth factor-1 (IGF-1). Central to both approaches is the role of the fibronectin-integrin system in corneal epithelial wound healing. Determination of the minimum amino acid sequences required for the promotion of corneal epithelial wound closure by fibronectin (PHSRN) and by substance P (FGLM-amide) plus IGF-1 (SSSR) has led to the development of peptide eyedrops for the treatment of PEDs that are free of adverse effects of the parent molecules.

Landolt ring-shaped epithelial keratopathy: a novel clinical entity of the cornea.

Landolt ring-shaped epithelial keratopathy is a newly identified disease with vesicular changes of unknown origin in the epithelial cells. Eleven Japanese patients with specific epithelial lesions that resembled a Landolt ring in the corneal epithelium were assessed. The main symptoms of Landolt ring-shaped epithelial keratopathy are foreign-body sensation and photophobia. Slitlamp examination indicates that Landolt ring-shaped lesions located only in the corneal epithelium are randomly distributed and occur unilaterally, bilaterally, or asymmetrically. Small lesions are sometimes connected to each other to form a large Landolt ring in a fractal pattern. Confocal microscopy reveals that the Landolt ring lesions are vesicular changes in the epithelial cells from the basal cell layer to the superficial cell layer without inflammation. The lesions form for weeks to months with sporadic exacerbations and natural remissions with or without treatments. The outcomes do not include epithelial disorders in the affected corneas or visual disruptions. We describe a new disease entity of unknown origin referred to as Landolt ring-shaped epithelial keratopathy, which is usually bilateral and characterized by specific Landolt ring-shaped focal epithelial lesions with vesicular changes only in the epithelial cells. The disorder has an insidious onset and self-limiting nature despite treatment and should be included in the differential diagnosis of corneal epithelial disorders.

Conjunctival expression of the P2Y2 receptor and the effects of 3% diquafosol ophthalmic solution in dogs

Conjunctival epithelial and goblet cell P2Y2 nucleotide receptors regulate ion transport and secretory function. Diquafosol is a P2Y2 purinergic receptor agonist that stimulates secretion of aqueous tear components from conjunctival epithelial cells and secretion of mucin from conjunctival goblet cells. In humans suffering from keratoconjunctivitis sicca (dry eye), topical administration of diquafosol improves corneal epithelial integrity and stabilises the tear film. The aim of the present study was to investigate P2Y2 receptor expression and to determine the effect of topical administration of diquafosol on mucin and aqueous tear production in dogs.Canine conjunctival P2Y2 receptor expression was evaluated by Western blotting and immunohistochemical analysis. The effect of diquafosol on mucin secretion was evaluated by examining mucin-5 subtype AC (MUC5AC) concentration in tears. The effect of diquafosol on aqueous secretions was evaluated by performing the Schirmer tear test (STT) and phenol red thread test. Expression of the P2Y2 receptor was confirmed in canine bulbar and palpebral conjunctivae and receptors were identified at the conjunctival epithelial and goblet cell surface. Tear MUC5AC concentration significantly increased after administration of 3% diquafosol ophthalmic solution, although neither STT nor phenol red thread test values showed any significant change after diquafosol instillation. Topical ocular administration of 3% diquafosol might improve corneal epithelial disorders in dogs through stabilisation of the tear film, by virtue of an increase in MUC5AC secretion.