Dexamethasone and MicroRNA-204 Inhibit Corneal Neovascularization

INTRODUCTION

This was an in vivo animal study designed to investigate the interaction between dexamethasone (Dex) and microRNA-204 (miR-204) in a mouse alkali burn-induced corneal neovascularization (CNV) model. The function of miR-204 was then investigated in human mammary epithelial cells (HMECs) in vitro.

MATERIALS AND METHODS

The CNV model was induced by corneal alkali burn in BLAB/c mice. The mice were randomly divided into five groups: normal control (Ctrl), alkali burn-induced corneal injury (Alkali), alkali burn + Dex (Dex), alkali burn + negative control (NTC), and alkali burn + miR-204 agomir (miR-204). Subconjunctival injection of NTC, Dex, or miR-204 agomir was conducted at 0, 3, and 6 days, respectively, after alkali burn. The corneas were collected at day 7 after injury, and the CNV area was observed using immunofluorescence staining. The expression of miR-204 was analyzed with quantitative real time (qRT)-PCR. In HMECs, exogenous miR-204 agomir or antagomir was used to strengthen or inhibit the expression of miR-204. Migration assays and tube formation studies were conducted to evaluate the function of miR-204 on HMECs.

RESULTS

At 7 days post-alkali burn, CNV grew aggressively into the cornea. MicroRNA-204 expression was reduced in the Alkali group in contrast with the Ctrl group (P = .003). However, miR-204 was upregulated in the Dex group (vs. alkali group, P = .008). The CNV areas in the NTC and miR-204 groups were 59.30 ± 8.32% and 25.60 ± 2.30%, respectively (P = .002). In vitro, miR-204 agomir showed obvious inhibition on HMEC migration in contrast with NTC (P = .033) and miR-204 antagomir (P = .017). Compared with NTC, miR-204 agomir attenuated tube formation, while miR-204 antagomir accelerated HMEC tube formation (P < .05).

CONCLUSION

The role of Dex in attenuating CNV may be partly attributed to miR-204. MiR-204 may be a potential therapeutic target in alkali burn-induced CNV.

URP20 improves corneal injury caused by alkali burns combined with pathogenic bacterial infection in rats

Corneal alkali burns often occur in industrial production and daily life, combined with infection, and may cause severe eye disease. Oxidative stress and neovascularization (NV) are important factors leading to a poor prognosis. URP20 is an antimicrobial peptide that has been proven to treat bacterial keratitis in rats through antibacterial and anti-NV effects. Therefore, in this study, the protective effect and influence mechanism of URP20 were explored in a rat model of alkali burn together with pathogenic bacteria (Staphylococcus aureus and Escherichia coli) infection. In addition, human umbilical vein endothelial cells (HUVECs) and human corneal epithelial cells (HCECs) were selected to verify the effects of URP20 on vascularization and oxidative stress. The results showed that URP20 treatment could protect corneal tissue, reduce corneal turbidity, and reduce the NV pathological score. Furthermore, URP20 significantly inhibited the expression of the vascularization marker proteins VEGFR2 and CD31. URP20 also reduced the migration ability of HUVECs. In terms of oxidative stress, URP20 significantly upregulated SOD and GSH contents in corneal tissue and HCECs (treated with 200 μM H2O2) and promoted the expression of the antioxidant protein Nrf2/HO-1. At the same time, MDA and ROS levels were also inhibited. In conclusion, URP20 could improve corneal injury combined with bacterial infection in rats caused by alkali burns through antibacterial, anti-NV, and antioxidant activities.

Development of dual-functional core-shell electrospun mats with controlled release of anti-inflammatory and anti-bacterial agents for the treatment of corneal alkali burn injuries

In this study, a novel dual-drug carrier for the co-administration of an anti-inflammatory and antibiotic agent consisting of core-shell nanofibers for the treatment of cornea alkali burns was designed. The core-shell nanofibers were prepared via coaxial electrospinning of curcumin-loaded silk fibroin as the core and vancomycin-loaded chitosan/polyvinyl alcohol (PVA) as the shell. Electron microscopy (SEM and TEM) images confirmed the preparation of smooth, bead-free, and continuous fibers that formed clear core-shell structures. For further studies, nanofiber mats were cross-linked by heat treatment to avoid rapid disintegration in water and improve both mechanical properties and drug release. The release profile of curcumin and vancomycin indicated an initial burst release, continued by the extended release of both drugs within 72 hours. Rabbit corneal cells demonstrated high rates of proliferation when evaluated using a cell metabolism assay. Finally, the therapeutic efficiency of core/shell nanofibers in healing cornea alkali burn was studied by microscopic and macroscopic observation, fluorescence staining, and hematoxylin-eosin assay on rabbit eyes. The anti-inflammatory activity of fabricated fibers was evaluated by enzyme-linked immunosorbent assay and Immunofluorescence analysis. In conclusion, using a robust array of in vitro and in vivo experiments this study demonstrated the ability of the dual-drug carriers to promote corneal re-epithelialization, minimize inflammation, and inhibit corneal neovascularization. Since these parameters are critical to the healing of corneal wounds from alkali burns, we suggest that this discovery represents a promising future therapeutic agent that warrants further study in humans.

Disulfiram Ophthalmic Solution Inhibited Macrophage Infiltration by Suppressing Macrophage Pseudopodia Formation in a Rat Corneal Alkali Burn Model

FROUNT is an intracellular protein that promotes pseudopodia formation by binding to the chemokine receptors CCR2 and CCR5 on macrophages. Recently, disulfiram (DSF), a drug treatment for alcoholism, was found to have FROUNT inhibitory activity. In this study, we investigated the effect of DSF eye drops in a rat corneal alkali burn model. After alkali burn, 0.5% DSF eye drops (DSF group) and vehicle eye drops (Vehicle group) were administered twice daily. Immunohistochemical observations and real-time reverse transcription-polymerase chain reaction (RT-PCR) analyses were performed at 6 h and 1, 4, and 7 days after alkali burn. Results showed a significant decrease in macrophage accumulation in the cornea in the DSF group, but no difference in neutrophils. RT-PCR showed decreased expression of macrophage-associated cytokines in the DSF group. Corneal scarring and neovascularization were also suppressed in the DSF group. Low-vacuum scanning electron microscopy imaging showed that macrophage length was significantly shorter in the DSF group, reflecting the reduced extension of pseudopodia. These results suggest that DSF inhibited macrophage infiltration by suppressing macrophage pseudopodia formation.

CXCR3 deletion aggravates corneal neovascularization in a corneal alkali-burn model

Corneal neovascularization can cause devastating consequences including vision impairment and even blindness. Corneal inflammation is a crucial factor for the induction of corneal neovascularization. Current anti-inflammatory approaches are of limited value with poor therapeutic effects. Therefore, there is an urgent need to develop new therapies that specifically modulate inflammatory pathways and inhibit neovascularization in the cornea. The interaction of chemokines and their receptors plays a key role in regulating leukocyte migration during inflammatory response. CXCR3 is essential for mediating the recruitment of activated T cells and microglia/macrophages, but the role of CXCR3 in the initiation and promotion of corneal neovascularization remains unclear. Here, we showed that the expression of CXCL10 and CXCR3 was significantly increased in the cornea after alkali burn. Compared with WT mice, CXCR3-/- mice exhibited significantly increased corneal hemangiogenesis and lymphangiogenesis after alkali burn. In addition, exaggerated leukocyte infiltration and leukostasis, and elevated expression of inflammatory cytokines and angiogenic factor were also found in the corneas of CXCR3-/- mice subjected to alkali burn. With bone marrow (BM) transplantation, we further demonstrated that the deletion of CXCR3 in BM-derived leukocytes plays a key role in the acceleration of alkali burn-induced corneal neovascularization. Taken together, our results suggest that upregulation of CXCR3 does not exhibit its conventional action as a proinflammatory cytokine but instead serves as a self-protective mechanism for the modulation of inflammation and maintenance of corneal avascularity after corneal alkali burn.

Prophylactic Instillation of Hydrogen-Rich Water Decreases Corneal Inflammation and Promotes Wound Healing by Activating Antioxidant Activity in a Rat Alkali Burn Model

Many studies have demonstrated the therapeutic effects of hydrogen in pathological conditions such as inflammation; however, little is known about its prophylactic effects. The purpose of this study is to investigate the prophylactic effects of hydrogen-rich water instillation in a rat corneal alkali burn model. Hydrogen-rich water (hydrogen group) or physiological saline (vehicle group) was instilled continuously to the normal rat cornea for 5 min. At 6 h after instillation, the cornea was exposed to alkali. The area of corneal epithelial defect (CED) was measured every 6 h until 24 h after alkali exposure. In addition, at 6 and 24 h after injury, histological and immunohistochemical observations were made and real-time reverse transcription polymerase chain reaction (RT-PCR) was performed to investigate superoxide dismutase enzyme (SOD)1, SOD2, and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) mRNA expression. CED at 12 h and the number of inflammatory infiltrating cells at 6 h after injury were significantly smaller in the hydrogen group than the vehicle group. Furthermore, SOD1 expression was significantly higher in the hydrogen group than the vehicle group at both 6 and 24 h, and the number of PGC-1α-positive cells was significantly larger in the hydrogen group than the vehicle group at 6 h after injury. In this model, prophylactic instillation of hydrogen-rich water suppressed alkali burn-induced inflammation, likely by upregulating expression of antioxidants such as SOD1 and PGC-1α. Hydrogen has not only therapeutic potential but also prophylactic effects that may suppress corneal scarring following injury and promote wound healing.

Investigating the Anti-Inflammatory Effects of RCI001 for Treating Ocular Surface Diseases: Insight Into the Mechanism of Action

The ocular surface is continuously exposed to various environmental factors, and innate and adaptive immunity play crucial roles in ocular surface diseases (OSDs). Previously, we have reported that the topical application of RCI001 affords excellent anti-inflammatory and antioxidant effects in dry eye disease and ocular chemical burn models. In this study, we examined the inhibitory effects of RCI001 on the Rac1 and NLRP3 inflammasomes in vitro and in vivo. Following RCI001 application to RAW264.7 and Swiss 3T3 cells, we measured Rac1 activity using a glutathione-S-transferase (GST) pull-down assay and G-protein activation assay kit. In addition, we quantified the expression of inflammatory cytokines (interleukin [IL]-1β, IL-6, and tumor necrosis factor [TNF]-α) in lipopolysaccharide (LPS)-stimulated RAW264.7 cells using ELISA and real-time PCR. In the mouse ocular alkali burn model, RCI001 was administered via eye drops (10 mg/mL, twice daily) for 5 days, and 1% prednisolone acetate (PDE) ophthalmic suspension was used as a positive control. Corneal epithelial integrity (on days 0-5) and histological examinations were performed, and transcript and protein levels of Rac1, NLRP3, caspase-1, and IL-1β were quantified using real-time PCR and western blotting in corneal tissues collected on days 3 and 5. We observed that RCI001 dose-dependently inhibited Rac1 activity and various inflammatory cytokines in LPS-stimulated murine macrophages. Furthermore, RCI001 restored corneal epithelial integrity more rapidly than corticosteroid treatment in chemically injured corneas. Compared to the saline group, activation of Rac1 and the NLRP3 inflammasome/IL-1β axis was suppressed in the RCI001 group, especially during the early phase of the ocular alkali burn model. Topical RCI001 suppressed the expression of activated Rac1 and inflammatory cytokines in vitro and rapidly restored the injured cornea by inhibiting activation of Rac1 and the NLRP inflammasome/IL-1β axis in vivo. Accordingly, RCI001 could be a promising therapeutic agent for treating OSDs.

Study of the Effectiveness of Drug No. 1 on the Model of Alkaline Eye Burn in Rabbits

Studies have shown that 0.05 mL/kg of drug No. 1 as 1:15 dilution with sterile saline solution has anti-inflammatory, wound-healing, and angioprotective effects if instilled in both eyes of rabbits twice a day for 30 days after an alkaline burn. A stimulation of reparative processes in the cornea was observed with the test dose of drug No. 1. This was manifested by accelerating the recovery of defects in the anterior epithelium and stroma, reducing the frequency of formation of deep defects and the severity of inflammatory reaction and vascularization, and inhibiting the formation of turbidity of its lower intensity and area. A tendency to restore laminarity of the stroma was determined by the action of drug No. 1 throughout the observation period. This contributed to a decrease in the degree of vascularization and prevented ulceration and perforation of the cornea. By the end of experiment, a restoration of strong epithelial-stromal relationships in the experimental group, compared to the control group, was observed due to formation of normal architectonics of fibrous components of intercellular substance. A more pronounced proliferative activity, with an increase in the layering of limbal epithelial cells, was noted in the limbal zone of the cornea in the experimental group rabbits compared to the control group.

Topical Effects of N-Acetyl Cysteine and Doxycycline on Inflammatory and Angiogenic Factors in the Rat Model of Alkali-Burned Cornea

The aim of this study was to analyze the single and combined effects of N-acetyl cysteine (NAC) and doxycycline (Dox) on the inflammatory and angiogenic factors in the rat model of alkali-burned cornea. Rats were treated with a single and combined 0.5% NAC and 12.5 μg/mL Dox eye drops and evaluated on days 3, 7, and 28. In the corneas of various groups, the activity of Catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) enzymes was assessed. The expression of inflammatory factors (TNF-α, Rel-a, and CXCL-1) and angiogenic factors (VEGF-a, MMP2, and MMP9) was measured using real-time polymerase chain reaction. The antioxidant enzyme activities decreased substantially 3 days after injury with sodium hydroxide (NaOH). NAC and combined NAC+ Dox topical treatments increased the SOD enzyme activity on day 28 (P < 0.05). The expression of TNF-α and Rel-a genes following single and combined treatment of NAC and Dox decreased significantly on days 7 and 28 (P < 0.05). The mRNA level of angiogenic factors and corneal neovascularization (CNV) level declined in NaOH-injured rats treated with Dox (P < 0.05). The topical treatment of Dox could attenuate inflammation and CNV complications. However, NAC treatment may not reduce the expression of angiogenic genes.

Canonical NF-κB signaling maintains corneal epithelial integrity and prevents corneal aging via retinoic acid

Disorders of the transparent cornea affect millions of people worldwide. However, how to maintain and/or regenerate this organ remains unclear. Here, we show that Rela (encoding a canonical NF-κB subunit) ablation in K14+ corneal epithelial stem cells not only disrupts corneal regeneration but also results in age-dependent epithelial deterioration, which triggers aberrant wound-healing processes including stromal remodeling, neovascularization, epithelial metaplasia, and plaque formation at the central cornea. These anomalies are largely recapitulated in normal mice that age naturally. Mechanistically, Rela deletion suppresses expression of Aldh1a1, an enzyme required for retinoic acid synthesis from vitamin A. Retinoic acid administration blocks development of ocular anomalies in Krt14-Cre; Relaf/f mice and naturally aged mice. Moreover, epithelial metaplasia and plaque formation are preventable by inhibition of angiogenesis. This study thus uncovers the major mechanisms governing corneal maintenance, regeneration, and aging and identifies the NF-κB-retinoic acid pathway as a therapeutic target for corneal disorders.

Efficacy of systemic administration of riboflavin on a rabbit model of corneal alkali burn

Changes in the barrier mechanisms in the eye should determine the rational route for the administration and dosage of each drug in the treatment of traumatic injuries and other pathologies. The aim of this study was to examine the efficacy of intra-arterial delivery of 14C-riboflavin (as an "indicator") and compare it with intravenous and intramuscular administration in an animal model of chemical eye burn. 14C-riboflavin (14C-I) was administered by intra-arterial (carotid artery), intravenous (femoral vein) and intramuscular (femoral muscle) routes. The total radioactivity was determined over 2 h in the plasma and structures of the rabbit's eyes using a scintillation counter. The results of the study show that intravascular administration of 14C-I gives significantly higher concentrations of total radioactivity in the blood and is accompanied by a significant increase in the permeability of the blood-barrier and barrier in eyes suffering from burns. The highest concentration in the plasma and aqueous humour of the anterior chamber of the eye was observed during the first hour with the intra-arterial route of administration of 14C-I in either burnt and unburnt eyes. The distribution of total radioactivity in the structures of the eye over the 2 h of the experiment showed a higher level of the drug under intra-arterial administered in the uveal regions, namely: the iris, ciliary body, choroid, retina and also the sclera and cornea. This experimental model shows that intra-arterial administration can increase the bioavailability of a drug to the structures of the eye within a short period of time.

Cytoprotective effect of crocin and trans-resveratrol on photodamaged primary human retinal pigment epithelial cells

PURPOSE

Light-induced damage to retinal pigment epithelium during pars plana vitrectomy remains a hot topic in ophthalmology. Improvements in technology led to a change of light sources, selective filters, and shorter light exposure time. Currently, there is no satisfying solution to the problem. The aim of the study was to investigate the cytoprotective effects of crocin and resveratrol on light-induced damage to primary human retinal pigment epithelial cells in vitro.

METHODS

Primary human retinal pigment epithelial cells were exposed to light analogous to the illumination during pars plana vitrectomy. To evaluate the cytoprotective effects and potential toxicity of resveratrol and crocin, human retinal pigment epithelial cells were incubated with varying concentrations of both before 3-[4,5-dimethylthiazol-2-yl] tetrazolium bromide (MTT) viability assay. Furthermore, glutathione levels were measured to investigate synergistic antioxidant potential. Apoptosis of human retinal pigment epithelial cells was determined by a nucleosome detection enzyme-linked immunosorbent assay.

RESULTS

Crocin and resveratrol improved cell viability in photodamaged human retinal pigment epithelial cells significantly from 40.65 ± 21.99% in illuminated human retinal pigment epithelial cells and reached a peak viability of 85.64 ± 11.37% in crocin and resveratrol pretreated cells (for all: p < 0.001). In line, the combination of the supplements increased glutathione levels significantly from 39.35 ± 21.96% to 80.74 ± 10.32% (p = 0.017). No toxic effects were detected (p > 0.99). However, no change in apoptosis rates could be observed following pretreatment with crocin and resveratrol (p > 0.99).

CONCLUSION

Crocin and trans-resveratrol revealed cytoprotective effects on human retinal pigment epithelial cells supporting both supplement's development as potential perioperative treatments in light-induced retinal pigment epithelial damage.

Leukotriene Antagonist S 872419 A for Early-Phase Treatment of Chemical Burn in the Rabbit Eye

S 872419 A, a specific receptor antagonist of peptide leukotrienes, was tested in the early-phase treatment of chemically burned eye (0.25 mol/l sodium hydroxide) of the rabbit. The drug was topically applied 5 times a day in a 1% solution, controls were the untreated opposite eye. Gross and microscopic investigations indicated that S 872419 A inhibits the inflammatory response of the chemically burned anterior eye segment. The parameters of healing considered (epithelial regeneration, corneal clouding and swelling, infiltration with polymorphonuclear leukocytes) suggest inhibition of lipoxygenase-mediated reactions in the tissue. PGF2 alpha levels were the same in aqueous humour of treated and untreated eyes. Further experiments with S 872419 A and other nonsteroidal drugs should improve the anti-inflammatory therapy of the chemically burned eye.

Chemical burns: Diphoterine untangled

OBJECTIVE

Diphoterine is a hypertonic, amphoteric, polyvalent and chelating decontamination solution used in the treatment of cutaneous and ocular chemical burns. Due to infrequent use by emergency physicians along with the small number of available studies, its debate in the literature as to its efficacy and safety remains inconclusive.

METHODS

A structured literature search was performed in MEDLINE, EMBASE BIOLOGICAL ABSTRACTS and TOXNET to June 2016 for original English-language studies reporting on the safety and effectiveness of Diphoterine. Methodological and reporting quality of pre-clinical animal studies was assessed using the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) risk of bias tool and Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines. Clinical studies were assessed using Chambers' criteria.

RESULTS

13 studies (seven in the pre-clinical, five in the clinical setting and one mixed) met the study inclusion criteria. Pre-clinical studies showed a faster resolution of pH and reduced tissue necrosis with Diphoterine. Clinical studies showed reduced tissue necrosis/severity of symptoms, faster pH resolution and a reduction in pain when using Diphoterine. No adverse events were attributable to Diphoterine. Reporting and methodology of the studies was poor or showed a high risk of bias.

CONCLUSIONS

Diphoterine appears to be safe to use and is probably superior to other rinsing solutions. However, immediate decontamination is imperative and if Diphoterine is not available a different rinsing solution should be used. The methodology of the published literature for Diphoterine is generally poor and future publications should use the frameworks given as templates.

Effects of nicotine on corneal wound healing following acute alkali burn

Epidemiological studies have indicated that smoking is a pivotal risk factor for the progression of several chronic diseases. Nicotine, the addictive component of cigarettes, has powerful pathophysiological properties in the body. Although the effects of cigarette smoking on corneal re-epithelialization have been studied, the effects of nicotine on corneal wound healing-related neovascularization and fibrosis have not been fully demonstrated. The aim of this study was to evaluate the effects of chronic administration of nicotine on corneal wound healing following acute insult induced by an alkali burn. BALB/C female mice randomly received either vehicle (2% saccharin) or nicotine (100 or 200 μg/ml in 2% saccharin) in drinking water ad libitum. After 1 week, animals were re-randomized and the experimental group was subjected to a corneal alkali burn, and then nicotine was administered until day 14 after the alkali burn. A corneal alkali burn model was generated by placing a piece of 2 mm-diameter filter paper soaked in 1N NaOH on the right eye. Histopathological analysis and the expression level of the pro-angiogenic genes vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP9) revealed that chronic nicotine administration enhanced alkali burn-induced corneal neovascularization. Furthermore, the mRNA expression of the pro-fibrogenic factors α-smooth muscle actin (αSMA), transforming growth factor-β (TGF-β), and collagen α1 (Col1) was enhanced in the high-concentration nicotine-treated group compared with the vehicle group after corneal injury. Immunohistochemical analysis also showed that the αSMA-positive area was increased in chronic nicotine-treated mice after corneal alkali burn. An in vitro assay found that expression of the α3, α7, and β1 nicotinic acetylcholine receptor (nAChR) subunits was significantly increased by chemical injury in human corneal fibroblast cells. Moreover, alkali-induced fibrogenic gene expression and proliferation of fibroblast cells were further increased by treatment with nicotine and cotinine. The proliferation of such cells induced by treatment of nicotine and cotinine was reduced by inhibition of the PI3K and PKC pathways using specific inhibitors. In conclusion, chronic administration of nicotine accelerated the angiogenic and fibrogenic healing processes in alkali-burned corneal tissue.

Mechanisms of Retinal Damage after Ocular Alkali Burns

Alkali burns to the eye constitute a leading cause of worldwide blindness. In recent case series, corneal transplantation revealed unexpected damage to the retina and optic nerve in chemically burned eyes. We investigated the physical, biochemical, and immunological components of retinal injury after alkali burn and explored a novel neuroprotective regimen suitable for prompt administration in emergency departments. Thus, in vivo pH, oxygen, and oxidation reduction measurements were performed in the anterior and posterior segment of mouse and rabbit eyes using implantable microsensors. Tissue inflammation was assessed by immunohistochemistry and flow cytometry. The experiments confirmed that the retinal damage is not mediated by direct effect of the alkali, which is effectively buffered by the anterior segment. Rather, pH, oxygen, and oxidation reduction changes were restricted to the cornea and the anterior chamber, where they caused profound uveal inflammation and release of proinflammatory cytokines. The latter rapidly diffuse to the posterior segment, triggering retinal damage. Tumor necrosis factor-α was identified as a key proinflammatory mediator of retinal ganglion cell death. Blockade, by either monoclonal antibody or tumor necrosis factor receptor gene knockout, reduced inflammation and retinal ganglion cell loss. Intraocular pressure elevation was not observed in experimental alkali burns. These findings illuminate the mechanism by which alkali burns cause retinal damage and may have importance in designing therapies for retinal protection.

Therapeutic effects of topical netrin-4 inhibits corneal neovascularization in alkali-burn rats

Netrins are secreted molecules involved in axon guidance and angiogenesis. However, the role of netrins in the vasculature remains unclear. Netrin-4 and netrin-1 have been found to be either pro- or antiangiogenic factors. Previously, we found that netrin-1 acts as an anti-angiogenic factor in rats by inhibiting alkali burn-induced corneal neovascularization. Here, we further investigate the effects of netrin-4, another member of the same netrin family, on neovascularization in vitro and in vivo. We found that netrin-4 functions similarly as netrin-1 in angiogenesis. In vitro angiogenesis assay shows that netrin-4 affected human umbilical vein endothelial cell (HUVEC) tube formation, viability and proliferation, apoptosis, migration, and invasion in a dose-dependent manner. Netrin-4 was topically applied in vivo to alkali-burned rat corneas on day 0 (immediately after injury) and/or day 10 post-injury. Netrin-4 subsequently suppressed and reversed corneal neovascularization. Netrin-4 inhibited corneal epithelial and stromal cell apoptosis, inhibited vascular endothelial growth factor (VEGF), but promoted pigment epithelium-derived factor (PEDF) expression, decreased NK-KB p65 expression, and inhibits neutrophil and macrophage infiltration. These results indicate that netrin-4 shed new light on its potential roles in treatmenting for angiogenic diseases that affect the ocular surface, as well as other tissues.

[Efficacy of epigallocatechin gallate in treatment of alkali burn injury of murine cornea]

OBJECTIVE

To evaluate the efficacy of epigallocatechin gallate (EGCG) in treatment of corneal alkali burn injury in mice.

METHODS

Corneal alkali burn injury was induced by sodium hydroxide method in C57BL/6J mice. The mice with cornea burns were treated intraperitoneally with EGCG solution or phosphate buffer solution (PBS) respectively. The healing of corneal epithelium, the formation of corneal neovascularization (CNV) and the inflammation reaction were assessed by slit -lamp microscopy and histological examination. Expression of vascular endothelial growth factor (VEGF) mRNA and protein in cornea was evaluated by real -time reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry, respectively. Myeloperoxidase (MPO) assay was used to quantitatively evaluate the polymorphonuclear neutrophils (PMNs) infiltration in the corneas.

RESULTS

The healing rate of corneal epithelium in EGCG group was significantly higher than that of PBS group at d1, d3 and d7 after treatment (d1: 41.0%±13.0% vs 23.8%±7.6%; d3: 76.6%±7.5% vs 61.2%±6.8%; d7: 87.8%±8.5% vs 74.0%±9.1%; all P <0.05). The CNV scores and the number of CNV in the corneal sections of EGCG group were significantly lower than those of PBS group at d3, d7 and d14 after treatment (CNV score: d3: 1.1±0.5 vs 6.6±1.0; d7: 1.3±0. 3 vs 8.1±1.0; d14: 0.9±0.2 vs 9.2±1.1; CNV number: d3: 1.68±0.61 vs 2.92±0.95; d7: 4.80±1.36 vs 7.92±1.28; d14: 3.64±0.71 vs 5.88±0.76; all P<0.05) . The expression of VEGF protein at d3 (0.19±0.05 vs 0.45±0.08) and d7 (0.42±0.07 vs 0.84±0.09), the expression of VEGF mRNA at d1, d3 and d7 in EGCG group were significantly lower than those in PBS group (all P <0.05). Compared to PBS group, the inflammatory index at d3 (3.2±0.4 vs 3.7±0.5) and d7 (2.3±0.5 vs 4.0±0.0), the number of PMNs in the corneal sections and the MPO values at d3, d7 and d14 in EGCG group were significantly decreased (PMNs: d3: 34.5±15.7 vs 90.0±28.8; d7: 17.1±11.4 vs 54.9±25.9; d14: 12. 8±4.6 vs 39.0±17.9; all P <0.05).

CONCLUSION

In the murine corneal alkali burn model, intraperitoneal injection of EGCG solution can promote the healing of corneal epithelium, inhibit the formation of CNV and reduce the inflammatory cell infiltration in the corneas.

Pirfenidone nanoparticles improve corneal wound healing and prevent scarring following alkali burn

Purpose

To evaluate the effects of pirfenidone nanoparticles on corneal re-epithelialization and scarring, major clinical challenges after alkali burn.

Methods

Effect of pirfenidone on collagen I and α-smooth muscle actin (α-SMA) synthesis by TGFβ induced primary corneal fibroblast cells was evaluated by immunoblotting and immunocytochemistry. Pirfenidone loaded poly (lactide-co-glycolide) (PLGA) nanoparticles were prepared, characterized and their cellular entry was examined in primary corneal fibroblast cells by fluorescence microscopy. Alkali burn was induced in one eye of Sprague Dawley rats followed by daily topical treatment with free pirfenidone, pirfenidone nanoparticles or vehicle. Corneal re-epithelialization was assessed daily by flourescein dye test; absence of stained area indicated complete re-epithelialization and the time for complete re-epithelialization was determined. Corneal haze was assessed daily for 7 days under slit lamp microscope and graded using a standard method. After 7 days, collagen I deposition in the superficial layer of cornea was examined by immunohistochemistry.

Results

Pirfenidone prevented (P<0.05) increase in TGF β induced collagen I and α-SMA synthesis by corneal fibroblasts in a dose dependent manner. Pirfenidone could be loaded successfully within PLGA nanoparticles, which entered the corneal fibroblasts within 5 minutes. Pirfenidone nanoparticles but not free pirfenidone significantly (P<0.05) reduced collagen I level, corneal haze and the time for corneal re-epithelialization following alkali burn.

Conclusion

Pirfenidone decreases collagen synthesis and prevents myofibroblast formation. Pirfenidone nanoparticles improve corneal wound healing and prevent fibrosis. Pirfenidone nanoparticles are of potential value in treating corneal chemical burns and other corneal fibrotic diseases.

[An experimental study on inhibition effects of KH902 on rat corneal neovascularization]

OBJECTIVE

To observe the inhibition effect of subconjunctival injection of KH902 on rat corneal neovascularization (CNV)induced by alkaline burn.

METHODS

Alkaline burn was adopted to make rat corneal neovascularization models. The rats were randomly divided into four groups: (1) Experimental group, subconjunctival injection of KH902 (30 mg/mL); (2) Masculine comparison group, subconjunctival injection of dexamethasone (1 mg/mL); (3) Comparison group I, subconjunctival injection of solvent of KH902; (4) Comparison group II, subconjunctival injection of saline. At the 28th day after the treatments, the maximal length, area of corneal neovascularization, and the average optical density value of vascular endothelial cell growth factor (VEGF) immunohistochemical staining in the four groups were measured.

RESULTS

On the 28th day after molding, the corneal neovascularization area of KH902 experimental group was distinctly smaller than that of dexamethasone group, solvent group and saline group (P < 0.05 or P < 0.01). The expression of VEGF in the experimental group was distinctly lower than that of other groups (P < 0.01).

CONCLUSION

Subconjunctival injection of KH902 (30 mg/mL) may inhibit rat corneal neovascularization.

Diagnosis and management of red eye in primary care

Red eye is the cardinal sign of ocular inflammation. The condition is usually benign and can be managed by primary care physicians. Conjunctivitis is the most common cause of red eye. Other common causes include blepharitis, corneal abrasion, foreign body, subconjunctival hemorrhage, keratitis, iritis, glaucoma, chemical burn, and scleritis. Signs and symptoms of red eye include eye discharge, redness, pain, photophobia, itching, and visual changes. Generally, viral and bacterial conjunctivitis are self-limiting conditions, and serious complications are rare. Because there is no specific diagnostic test to differentiate viral from bacterial conjunctivitis, most cases are treated using broad-spectrum antibiotics. Allergies or irritants also may cause conjunctivitis. The cause of red eye can be diagnosed through a detailed patient history and careful eye examination, and treatment is based on the underlying etiology. Recognizing the need for emergent referral to an ophthalmologist is key in the primary care management of red eye. Referral is necessary when severe pain is not relieved with topical anesthetics; topical steroids are needed; or the patient has vision loss, copious purulent discharge, corneal involvement, traumatic eye injury, recent ocular surgery, distorted pupil, herpes infection, or recurrent infections.

[Experimental rationale for local use of angiotensin-converting enzyme inhibitors for the treatment of ocular tissue ischemia on a model of postburn conjunctival ischemia]

The authors have evaluated the local renin-angiotensin system on a model of experimental postburn conjunctival ischemia from the tear activity of angiotensin-converting enzyme (ACE) and studied whether impaired microcirculation might be restored by locally applying the ACE inhibitor captopril. It has been found that in conjunctival ischemia, there is a considerable increase in the activity of ACE, the key enzyme of the renin-angiotensin system, the activity of which largely determines the microcirculation in eye tissues. Instillations of the ACE inhibitor to rabbits within 2 weeks after alkaline burn of the eye result in a reduction in ACE activity and an earlier recovery of microcirculation in the area of conjunctival ischemia. Instillations of the ACE inhibitor captopril in ocular burn facilitate the maintenance of the tear antioxidant potential at the high level, which also suggests that the ACE inhibitor has a positive effect on the course of reparative processes after ocular burn injury. The findings suggest that it is promising to locally use ACE inhibitors for the treatment of ischemic processes in the eye.

[Effect of TGF-beta1 on expression of integrin beta1 following corneal alkali burns in rabbits]

PURPOSE

To observe the effect of TGF-beta1 applied topically to the alkali-injured rabbit eye on corneal epithelial wound healing and expression of integrin beta1 and its therapeutic action on corneal alkali burns.

METHODS

Alkali burn was produced in 60 corneas from 30 rabbits. Two groups were randomly divided. One group was treated with TGF-beta1 solution (200 ng/ml) topically 3 times one day within the first 7 days, the other group was treated with phosphate-buffered saline (PBS) solution. The injured eyes were photographed after the fluorescence staining with a digital camera and the pictures were analyzed with computer-aided picture analysis system to calculate the rate of corneal epithelial healing. The expression of integrin beta1 was investigated in the point 6 h, 1 d, 3 d, 7 d, 14 d after the injury by means of immunohistochemical analysis.

RESULTS

On the 4th, 10th, 11th, 12th and 14th days after the burning,the rate of corneal epithelial healing of TGF-beta1 groups was markedly higher than that of the PBS group (P < 0.05). The expression of integrin beta1 in the cornea epithelial cells gradually increased during the wound healing. On the 7th and 14th days after the burning, the expression of integrin beta1 in the cornea epithelial cells of TGF-beta1 group was remarkably higher than that of the PBS group (P < 0.05).

CONCLUSIONS

TGF-beta1 could up-regulate integrin beta1 in vivo corneal alkali burn model, which could stimulate the cornea epithelial cells to migrate and adhere to the cornea stroma, that can reduce the cases of the epithelial cells'detachment from the cornea stroma and sustain the corneal reepithelization.

[Mental rationale for local use of angiotensin-converting enzyme in the treatment of inflammatory processes in the eye]

A rabbit model of deep alkaline-induced corneal burn was used to study the involvement of the local renin-angiotensin system of the eye in the development of an inflammatory process and wound healing. Corneal burn injury was shown to cause a significant increase in the activity of angiotensin-converting enzyme (ACE) in the tear and internal ocular tissue structures, promoting their microcirculatory disorders and inflammation development. The local use of ACE inhibitors as instillations substantially reduces an inflammatory reaction and the incidence of deep and extensive corneal ulcers. The study performed provides experimental rationale for the local use of ACE inhibitors for the treatment of inflammatory processes in the eye.

[Subconjunctival application of plasma platelet concentrate in the treatment of ocular burns. Preliminary results]

PURPOSE

The efficiency of the subconjunctival application of autologous platelet concentrate in patients with ocular burns was assessed.

METHODS

This was carried out by analysing the effect of treatment in the eyes of 10 patients suffering from ocular burns as a result of work-related accidents. Two types of treatment were evaluated: the first group only received conventional topical medical treatment; and the second group, in addition, had subconjunctival injection of plasma platelet concentrate. The clinical condition of the patient and the period in which the disease prevented the patient from working were studied; monitoring was carried out until the burns had fully healed.

RESULTS

Statistically significant differences were found between the group treated with subconjunctival autologous platelet concentrate and the group treated with conventional topical medications, with a shorter period of time in corneal and conjunctival healing, time on sick leave and time needed for full healing.

CONCLUSIONS

Subconjunctival infiltration of autologous platelet concentrate should be considered as a straightforward, economical and possibly effective form of treatment for traumatic accidents (burns) of the ocular surface.

Keratinocyte growth factor-2 on the proliferation of corneal epithelial stem cells in rabbit alkali burned cornea

PURPOSE

To determine whether the topical application of keratinocyte growth factor-2 (KGF-2) can enhance corneal epithelial healing in rabbit alkali burned cornea. In addition, the distribution and proliferation of corneal epithelial stem cells in KGF-2-treated and control corneas were investigated to explain their mechanisms of effects on the epithelium.

METHODS

Twenty-four New Zealand eyes were divided into four groups, treated with KGF-2 solution (1, 50, 100 microg/ml) and PBS solution. Eighth millimeter filter paper discs, produced by standard paper punch, were soaked for 15 sec in 0.5N NaOH solution. The alkali-soaked discs were applied to the central cornea, centered on the pupil and held gently in position with forceps for 1 min. The cornea was finally irrigated over 1 mm with 100 ml balanced salt solution (BSS). Keratinocyte growth factor-2 was then applied topically three times a day. The phosphate-buffered saline (PBS) group was served as a control. Each corneal epithelial defect was subsequently photographed every 24 hours with a slit lamp and was measured by computer-assisted digitizer. In each group, two rabbits were sacrificed for light microscopic examination after the interval of 7, 14 and 21 days. Meanwhile, the cornea epithelium was examined hy immunohistochemistry for P63, AE5, EGFR.

RESULTS

Topical application of 10 microg/ml to 100 microg/ml KGF-2 significantly accelerated corneal epithelial wound healing when compared with controls. After 24 hours, epithelial healing rate of the 100 microg/ml KGF-2 group and the PBS treated group was (74 +/- 6)% and (40 +/- 8)% (P < 0.05). After 48 hours, the rate of the C group was (94 +/- 6)%, whereas in the control group it was (73 +/- 12)% (P < 0.05). Epithelial defects were often recurrent, which happened only two times in the 100 microg/ml KGF-2-treated group, but many times in the control group. In the corneal epithelial stem cell analysis, the number of the P63 positive cells was higher in the KGF-2-treated

Effects of Vitamin E, Pentoxifylline and Aprotinin on Light-Induced Retinal Injury

PURPOSE

A considerable amount of clinical and experimental evidence exists suggesting the involvement of reactive oxygen species (ROS) in the etiology of light-induced retinal injury. The aim of this study was to investigate the protective role of vitamin E, pentoxifylline (PTX) and aprotinin against light-induced retinal injury in guinea pigs.

METHODS

Thirty adult male guinea pigs were divided into 5 groups of 6 animals each. The first group was used as control. The guinea pigs were kept in cyclic light for 2 weeks before the experiments. The animals were maintained in 12-hour light-dark cycles, before and after exposure to intense white fluorescent light, for as long as 12 h and then returned to cyclic light. Groups 3-5 received intraperitoneal injections of vitamin E, PTX and aprotinin, respectively. One eye of each animal was selected for histopathological evaluation and the other for biochemical assay. Retinal malondialdehyde (MDA) levels and the thickness of the outer nuclear layers were measured.

RESULTS

The compounds had the following relationships: vitamin E more than PTX more than aprotinin in preventing light-induced retinal damage. All 3 gave significant protection against the formation of MDA. Retinas of all 3 treatment groups had been protected from light-induced injury.

CONCLUSION

The intraperitoneal vitamin E, PTX and aprotinin supplementations may strengthen the antioxidant defense system because of decreased ROS, and these agents may play a role in treating light-induced retinal injury.

Camphor-related self-inflicted keratoconjunctivitis complicating delusions of parasitosis

PURPOSE

To report a case of camphor-related self-inflicted keratoconjunctivitis secondary to delusions of parasitosis.

METHODS

A 61-year-old man with delusions of parasitosis suffered from camphor-related self-inflicted ocular trauma that manifested with corneal epithelial defects and secondary anterior chamber reaction. Two episodes of exacerbation of the ocular conditions related to the use of camphor occurred. The left eye had secondary infection with Sternotrophomonas maltophilia and Staphylococcus aureus in the second episode of exacerbation.

RESULTS

The right eye recovered well with the treatment of topical lubricants and corticosteroids and had best-corrected visual acuity (BCVA) of 20/25. The infection of the left eye led to corneal perforation, necessitating penetrating keratoplasty; BCVA was hand motions because of a mature cataract. Olanzapine therapy for 1 month to decrease the delusions of parasitosis and 24-hour watch to prevent the use of camphor led to the resolution of self-inflicted keratoconjunctivitis in the patient.

CONCLUSIONS

Delusions of parasitosis may lead to vision-threatening self-inflicted ocular trauma. This may be the first case report of pure camphor-related self-inflicted toxic keratoconjunctivitis.

Ocular indigo dye injury

PURPOSE

To describe the clinical course, management, and final outcome in a case of ocular injury caused by accidental fall of indigo dye in both eyes.

METHODS

Review of patient's record and relevant literature.

RESULTS

A 32-year-old man sustained ocular injury caused by inadvertent indigo dye in both eyes. He presented with bluish staining of the entire ocular surface, subtotal corneal epithelial breakdown in both eyes, and entry of dye into the anterior chamber in the left eye. This was treated as acute alkali burns with lubricants and steroids. Over a period of 3 to 4 months, the ocular surface staining resolved completely, and visual acuity improved remarkably.

CONCLUSION

Although the clinical presentation was initially a cause for concern, the condition resolved completely with the same conservative management as applicable for other chemical injuries.

Ocular and facial injuries associated with the use of immersion heaters in an inmate population

PURPOSE

To report ocular and facial injuries caused by the use of electric immersion heaters in an inmate population.

DESIGN

Prospective observational case series.

METHODS

Data were recorded over a six-month period on age, gender, mechanism of injury, examination, and treatment of Dallas County inmates who experienced ophthalmic injuries from immersion heaters and were referred to a tertiary-care center.

RESULTS

Eight male inmates were treated for thermal ocular injuries, which occurred within jail cells as a result of cooking explosions from electric immersion heaters, known by inmates as "stingers." All patients had thermal eyelid burns, either first- or second-degree facial burns, and corneal abrasions with corneal edema. Corneal metallic foreign bodies were removed in one patient, and three patients underwent debridement for corneal sloughing.

CONCLUSIONS

Immersion heater-related accidents may cause thermal injuries within the inmate population. Physicians evaluating incarcerated patients with ocular trauma should be aware of immersion heaters as a common cause.

Effects of the matrix metalloproteinase inhibitor GM6001 on the destruction and alteration of epithelial basement membrane during the healing of post-alkali burn in rabbit cornea

PURPOSE

To examine the alteration in structure and matrix composition of epithelial basement membrane (BM) during the healing of alkali-burned rabbit cornea, and the roles of matrix metalloproteinases (MMPs) in these alterations.

METHODS

The central cornea of one eye of 78 albino rabbits was exposed to 1 N NaOH for 180 s under general and topical anesthesia and allowed to heal with or without subconjunctival injection of GM6001 (an MMP inhibitor). Cryosections of affected corneas were observed by H&E staining, immunohistochemistry for type IV collagen subtypes, or in situ zymography for detection of localization of MMP activity.

RESULTS

Uninjured corneal epithelial BM exhibited alpha5 (IV)-immunoreactivity, but lacked the alpha1/alpha2-immunoreactivity of collagen IV. Epithelial BM in healing burned cornea transiently exhibited alpha1/alpha2-immunoreactivity. Examination by in situ zymography showed an upregulation of MMP activity in the regenerated central epithelium and anterior stroma of the burned corneas at days 7 and 14. GM6001 suppressed degradation of alpha5-containing epithelial BM in vivo and also in organ culture.

CONCLUSIONS

Epithelial BM was degraded by endogenous MMPs during healing following an alkali burn in rabbit cornea. GM6001 had an inhibitory effect on the degradation of the epithelial basement membrane in burned cornea in vivo.

Alkali-induced corneal stromal melting prevention by a novel platelet-activating factor receptor antagonist

OBJECTIVE

To evaluate the effect of LAU0901 (2,4,6-trimethyl-1,4-dihydropyridine-3,5-dicarboxylic acid ester), a novel platelet-activating factor (PAF) receptor antagonist, on a rabbit model of severe corneal alkali injury.

METHODS

Adult New Zealand albino rabbits were anesthetized and the right eyes were injured with 2N sodium hydroxide for 60 seconds using a 12-mm plastic well, then rinsed. After the injury, 10 rabbits were treated topically with LAU0901 every 2 hours 4 times per day and received a subconjunctival injection of 200 microL of LAU0901 once per week and 10 rabbits were treated with vehicle the same way. Over the course of 4 weeks, the corneas were examined daily by slitlamp microscopy and corneal ulcers were graded with a clinical scoring system. Ten additional rabbits were treated as described but 1 rabbit from each group was killed at 1, 3, 7, 14, or 21 days after injury. The corneas were processed for histopathologic and immunofluorescence examination.

RESULTS

Persistent epithelial defects were present in both groups from day 5 postinjury, but from day 9 through day 25, the average clinical scores of both epithelial defects and stromal ulcerations in the vehicle-treated eyes were significantly higher than those in the LAU0901-treated eyes (P<.01). By day 28, 90% of the eyes in the vehicle-treated group perforated, while only 20% of the eyes in the LAU0901-treated group developed deep ulceration and none were perforated. Histologic examination showed that the corneas treated with LAU0901 for 4 weeks were completely reepithelialized, with fewer inflammatory polymorphonuclear leukocytes and more repair fibroblasts (myofibroblasts) in the stroma as compared with those treated with vehicle.

CONCLUSIONS

LAU0901 inhibits corneal ulceration and perforation in a severe alkali-burn model in the rabbit. In the cornea, PAF is a strong inflammatory mediator, a chemotactic to inflammatory polymorphonuclear leukocytes, and an inducer of several proteases that degrade the extracellular matrix. Clinical Relevance The inhibition of PAF action by LAU0901 could be important in the immediate and intermediate treatment of chemical injuries to preserve the integrity of the cornea.

Corneal injury by anti-misting agent in swim goggles: a case report

PURPOSE

To report a case of corneal injury by swim goggle anti-misting agent.

METHODS

Case report.

RESULTS

A 47-year-old man presented with ocular injury caused by swim goggle anti-misting agent. Two weeks previously, the patient felt sudden ocular pain and grit after pool water flooded his goggles while swimming. Before the patient's swim, a copious amount of anti-misting agent was sprayed inside his goggles. On examination, severe corneal epithelial defect and stroma edema of the right eye were noted. Best-corrected visual acuity (BCVA) was 20/40. Right eye corneal thickness was 625 microm. Topical corticosteroids, antibiotic eye drops, and oral tetracycline were started. After 1 week of treatment, the epithelial defect of his right cornea improved slightly. Stromal edema decreased mildly. Epithelial defect persisted at 1 month follow-up. Right eye BCVA remained 20/40. Three months after treatment, the right eye epithelial defect healed completely. Mild diffuse superficial stromal opacity was noted. BCVA improved to 20/20. At 1-year follow-up, right eye corneal thickness was 547 microm, which was thinner than the left eye. Right eye corneal endothelial cell density measured approximately 1500 cells/mm2, which was less than the left eye at 2300 cells/mm2. The faint, diffuse stromal opacity disappeared; however, white subepithelial plaques were noted in the cornea centers. After 1 month of treatment with topical corticosteroids, the plaques subsided completely. The corneas remained clear at 2-year follow-up.

CONCLUSION

Anti-misting agent can cause severe corneal injuries, including persistent epithelial defects, stromal edema and opacity, endothelial cell loss, and subepithelial plaque.

Studies on Corneal Wound Healing

Corneal wound healing often leads to the development of scar tissue with loss of transparency. Reconstitution of transparent corneal stroma depends on the regulation of the biosynthetic activities of postlesional keratocytes and also to a large extent on the limitation of matrix degradation, attributed essentially to the upregulation of matrix metalloproteases and especially MMP-9. Using a standardized method for the production of reproducible corneal lesions by burning with iodine vapors, we could show that the local application of 0.5 mg/ml L-fucose reduced significantly MMP-9 upregulation and accelerated the recovery of the epithelial layer of the cornea. The iodine vapor used in the experiments produces a rapid loss of epithelium with no or slight effect below the basement membrane. A relatively rapid regrowth of epithelium was observed. The speed of this reepithelialization was stimulated by the local application of fucose. At 48 h after burn, there was a difference between fucose-treated and control corneas (epithelial thickness was about 50 mum for fucose-treated corneas and 37 microm for control corneas). Culture media of in vivo fucose-treated corneas showed an important decrease of MMP-9 activity (-51%, n = 6, p < 0.01). It appears that the in vivo fucose treatment reduced the MMP-9 activity released in the media. This effect is significant 24 h after iodine vapor burn. In order to study the effect of fucose on normal corneas, it was added to rabbit as well as human cornea explant cultures, and the production and release of MMP-9 was determined by zymography. Fucose at a concentration of 0.5 mg/ml produced a 70% decrease of MMP-9 activity released in the medium by corneal explant cultures. Other mono- and oligosaccharides were also tested. Besides lactose, fucose-rich oligosaccharides also produced significant inhibition. Galactose, melibiose, mannose and glucose were inactive. These results justify the use of fucose for the local treatment of corneal wounds.

[Examination of the local antioxidative system of the eye in experimental corneal burn injury and the prospects for pharmacological correction of its parameters]

The present paper deals with the study of the efficiency of oral use of the antioxidative drug Immugen (a complex of alpha-tocopherol, oubichinone, selenium aspartate, methionine, and soyabean phospholipids) on a rabbit model of severe alkaline-induced corneal burn. The investigations have indicated that addition of Immugen to the rabbit feed exerts a significant positive effect on the parameters of the local antioxidative system of the eye and causes an increase in the activity of superoxide dismutase and catalase, and, on day 14, in antioxidative activity. The early experimental periods were marked by a slight rise in the frequency of deep corneal ulcerations. Moreover, the long-term clinical effect of use of Immugen appears as a significant increase in the area of the transparency-preserving affected cornea. The findings suggest that the antioxidants can show their optimal effect in the complex therapy for burn processes, including the use of proteinase inhibitors.

Therapeutic effect of topical administration of SN50, an inhibitor of nuclear factor-kappaB, in treatment of corneal alkali burns in mice

We evaluated the therapeutic efficacy of topical administration of SN50, an inhibitor of nuclear factor-kappaB, in a corneal alkali burn model in mice. An alkali burn was produced with 1 N NaOH in the cornea of C57BL/6 mice under general anesthesia. SN50 (10 microg/microl) or vehicle was topically administered daily for up to 12 days. The eyes were processed for histological or immunohistochemical examination after bromodeoxyuridine labeling or for semi-quantification of cytokine mRNA. Topical SN50 suppressed nuclear factor-kappaB activation in local cells and reduced the incidence of epithelial defects/ulceration in healing corneas. Myofibroblast generation, macrophage invasion, activity of matrix metalloproteinases, basement membrane destruction, and expression of cytokines were all decreased in treated corneas compared with controls. To elucidate the role of tumor necrosis factor (TNF)-alpha in epithelial cell proliferation, we performed organ culture of mouse eyes with TNF-alpha, SN50, or an inhibitor of c-Jun N-terminal kinase (JNK) and examined cell proliferation in healing corneal epithelium in TNF-alpha-/- mice treated with SN50. An acceleration of epithelial cell proliferation by SN50 treatment was found to depend on TNF-alpha/JNK signaling. In conclusion, topical application of SN50 is effective in treating corneal alkali burns in mice.

[Mechanism of keratinocyte growth factor-2 accelerating corneal epithelial wound healing on rabbit alkali burned cornea]

OBJECTIVE

To evaluate the curative effect of KGF-2 on the alkali-injured rabbit eye and to investigate the mechanism of KGF-2 accelerating corneal epithelial wound healing.

METHODS

Alkali burn was produced in 24 corneas from 24 New Zealand rabbits. Four groups were randomly divided. Three groups (A, B, and C groups) were treated with KGF-2 solution (1, 50, 100 microg/ml, respectively), and one group (D group) was treated with phosphate-buffered saline (PBS) solution. The injured eyes were photographed after the fluorescence staining with a slit lamp and the pictures were analyzed with computer-aided picture analysis system to calculate the rate of corneal epithelial healing. Morphologic and immunohistological examinations (using P63, AE5 and EGFR antibodies) of the cornea were performed.

RESULTS

KGF-2 at dosages ranging from 1 microg/ml to 100 microg/ml could enhance the cornea wound healing process. After 24 hours, epithelial healing rate of the 100 microg/ml KGF-2 group and the PBS treated group was 74% and 40%, respectively (P < 0.05). The corneal epithelial healing rate of each group was variable after four days and achieved complete healing after ten days. The P63 positive cells in KGF-2 groups appeared not only in the limbal area but also in the central area. For example, on the seventh day, in the limbal area, the P63 positive cells in the 100 microg/ml KGF-2 group, the PBS treated group and the normal group were 53.8 +/- 2.6, 29.5 +/- 2.2 and 17.0 +/- 2.1, respectively (P = 0.000). At the same time, the P63 positive cells in the non-limbal area in the 100 microg/ml KGF-2 group, the PBS treated group and the normal group were 69.5 +/- 2.8, 19.5 +/- 2.8 and 0, respectively (P = 0.000).

CONCLUSIONS

These results suggested KGF-2 can stimulate the limbal epithelial stem cells to migrate to the central cornea. KGF-2 can accelerate the healing of alkali burned cornea.

Relationship of eye burns with calcifications of the cornea?

INTRODUCTION

The clinical pattern of corneal calcification has been considered to be a part of chronic eye diseases, such as uveitis, severe glaucoma, keratitis and eye burns. Since, in some cases of eye burns, we have found corneal calcifications to be related to the initial calciferous caustic agents and to the use of phosphate-buffer-containing fluids, we have reviewed our files of clinical eye burns for the incidence and appearance of corneal calcification.

METHODS

A total of 176 burnt eyes of 98 patients suffering from severe eye burns were retrospectively reviewed. The following data set was acquired: the type of caustic agent, the time of the burns, the delay and type of immediate treatment and the time and type of first aid, the subsequent medication, the clinical grading and the later results.

RESULTS

Calciferous burning agents and corneal calcification are correlated (P<0.01). Initial single rinsing with phosphate does not produce corneal calcification (P=0.134). There is evidence that corneal calcifications are correlated with chronically administered phosphate-buffered eye drops (P<0.005).

DISCUSSION

Eye burns followed by calcifications follow two different major patterns: the corrosive substance contained calcium or the continued therapy was applied with phosphate-buffered eye drops. We present case reports of three different types of eye burns and later therapy resulting in corneal calcification. Corneal calcifications are presumably related to longer-lasting phosphate application. One suspicious mechanism is the low content of calcium ion stabilizing proteins such as hyaluronate or fetuin in treatments for severe eye burns. The exceeding of the solubility product of Ca(2+) and PO(4) (-) results in the precipitation of calcium phosphates. In cases of chronic corneal disturbance, we recommend the elimination of phosphate-buffered medications to prevent corneal calcification.

Alkali ocular burns in Martinique (French West Indies)

PRECIS

During the 4 years of this study, we noted 66 cases of alkali ocular burns, or approximately 16 cases per year, nearly half (45.5%) of which are due to an assault. For grade 1 and 2 burns the time elapsed to reepithelialization appears to be shorter when rinsed with Diphoterine* versus physiological solution.

PURPOSE

Comparison of the effectiveness of two rinsing solutions for emergency use: a physiological solution and an amphoteric solution (Diphoterine*, Laboratories Prevor, Valmondois, France). Description of the clinical and progressive characteristics of alkali burns treated at the University Hospital Center of Fort de France in Martinique (French West Indies).

DESIGN

Prospective consecutive observational case series and nonrandomized comparative study.

PARTICIPANTS

Sixty-six patients were included. The total number of burned eyes is 104. Forty-eight eyes (46%) were rinsed with physiological solution and 56 eyes (54%) with Diphoterine*.

METHODS

All patients benefited from an ocular rinse with 500ml of physiological solution or Diphoterine*, followed by a complete ophthalmologic exam. The ocular injuries were classified according to the Roper-Hall modification of the Hughes classification system. The same standardized therapeutic protocol was applied and adapted to the seriousness of the burn.

MAIN OUTCOME MEASURES

Demographic data, time to corneal reepithelialization, final best corrected visual acuity and complications were analysed.

RESULTS

Twenty-eight (42.4%) patients have a unilateral burn and 38 (57.6%) patients have bilateral burns. In decreasing order of frequency, the circumstances surrounding the injury are: assaults in 45.5% of cases (n=30), work-related accidents in 32% of cases (n=31), and domestic accidents in 23% of cases (n=15). For grade 1 and 2 burns the time elapsed to reepithelialization appears to be shorter when rinsed with Diphoterine* versus physiological solution (respectively): 1.9+/-1 days versus 11.1+/-1.4 days (p=10(-7)) and 5.6+/-4.9 days versus 10+/-9.2 days (p=0.02). For grade 3 and 4 burns, there are complications in 11 cases (11.6%): 8 corneal opacities and 3 perforations.

CONCLUSIONS

This study is the first conducted in humans that takes into account the type of ocular rinse product used in the progressive follow-up study of injuries. The time elapsed to reepithelialization is shorter with Diphoterine* for grade 1 and 2 burns. There are not enough cases of grade 3 and 4 burns to make a conclusion. Diphoterine* seems very effective in terms of its mechanism of action and the experimental and clinical results.

[A comparative evaluation of the oxidant and antioxidant blood systems in rabbits with caustic burns of the eyes in their treatment by synthetic and natural antioxidants]

A method of provoking a caustic burn was described on the basis of experiments made in 36 rabbits (72 eyes) who were shared between 2 groups. Effects from histochrom, a natural antioxidant, and from emoxipin, a synthetic antioxidant, produced on the lipid-peroxidation parameters at early stages of ocular burn disease were studied. A higher clinical efficiency of histochrom versus emoxipin was demonstrated.

Descemet Membrane Detachment Caused by Hydrogen Peroxide Injury

OBJECTIVE

To describe a patient who developed a Descemet membrane detachment after hydrogen peroxide injury with successful reattachment by intracameral injection of sulfur hexafluoride gas.

METHODS

Case report.

RESULTS

The right eye of a 40-year-old man was exposed to 35% hydrogen peroxide. This resulted in a central corneal epithelial defect, corneal edema, a localized detachment of Descemet membrane, and a gas bubble between the posterior corneal stroma and Descemet membrane. The Descemet membrane detachment persisted after reabsorption of the gas bubble. Successful reattachment of Descemet membrane was achieved with injection of 0.15 mL of 20% sulfur hexafluoride gas into the anterior chamber.

CONCLUSION

Hydrogen peroxide ocular injury may cause Descemet membrane detachment, and successful reattachment may be achieved with intracameral injection of 20% sulfur hexafluoride gas.

[Local express auto-cytokine therapy (a complex of cytokines) in the treatment of viral and nonviral eye lesions]

The method of local express-autocytocinetherapy (LEACCT) consists in using an experimentally tested autologous complex of cytokines (alpha- beta- gamma-interferons, interleukins 2.8, tumor necrosis factor gamma etc.), which is produced by joining the autoblood of patients with immune-modulator poludan (complex poly A:poly U). The external LEACCT and the intrachamber LEACCT are distinguished. The former presupposes the administration (subconjunctivally and in installations) of the autoblood-poludan mixture. This method is used in herpes- and adenovirus keratoconjunctivitis, slow re-epithelization after laser keratectomy and in eye burns (178 patients). The latter comprises, apart from the external LEACCT procedures, a 1-4-time introduction of the mentioned mixture into patient's anterior chamber. It was used in endothelial herpetic keratoiridocyclitis, initial bullous keratopathy, severe keratoconus and in injuries of the anterior lens capsule (117 patients). The clinical-study results (main group--295 patients) show that the designed method based on poludan has pronounced anti-inflammatory and regenerative effects in different viral and virus-free lesions of the eye tissues; it is simple and can be applied in clinical settings. An increased visual acuity ranging from 0.05 to 1.0 was registered in 85% of cases. The action of the complex of cytokines is as close as possible to the physiological mechanism, which provides for avoiding the side-effects and for applying the treatment scheme in situations when the administration of other drugs is limited or their efficiency is not sufficient.

Ascorbate for alkali burns to the eye

A short cut review was carried out to establish whether ascobate drops are useful in the management of alkalis burns to the eyes. Altogether 33 papers were found using the reported search, of which one presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of this best paper are tabulated. A clinical bottom line is stated.

Ver�tzungen des Auges

PURPOSE

Eye irrigation is a widely accepted therapeutic must in first aid treatment. The burning agent is removed, diluted, and if possible neutralized. Usually water, NaCl 0.9%, Ringer's lactate or phosphate buffer are the most accepted rinsing solutions. We present a relatively new substance called Previn (Diphoterine in countries other than Germany). It is a hypertonic, polyvalent, and amphoteric substance. Its binding energy for acids, bases, reducers, and oxidation is stronger than the binding energy of biological compounds for these burning agents. Concerning its compatibility with the eye and its efficacy, we compare Previn to the rinsing solutions in general use.

MATERIAL AND METHODS

The first experiment (I) shows the effects of ocular rinsing with 500 ml Previn in ten healthy human subjects compared with phosphate buffer rinsing. Evaluation is done by slit lamp examination and confocal microscopy. An experimental study (II) compares in vitro buffering capacity (a) of Previn to other rinsing solutions and shows (b) in vivo efficacy of rinsing with Previn versus other rinsing solutions by pH measurements on the corneal surface and anterior chamber of rabbits after a 30-s burn with 1 N sodium hydroxide.

RESULTS

(I) No harmful effect of irrigation with Previn could be found. Its compatibility with the eye is comparable to phosphate buffer rinsing. (II a) Buffering capacity was found to be stronger for Previn in acids and bases compared to phosphate buffer or Ringer's lactate. (II b) The in vivo study on rabbits proved Previn effect onaqueous pH comparable to phosphate buffer in buffering 1 N NaOH, whereas NaCl showed no buffering effect at all.

CONCLUSION

The above studies have shown that Previn (Diphoterine) is comparable to other rinsing solutions concerning its compatibility with the human eye. Its buffering capacity is comparable to phosphate buffer. Previn and phosphate buffer should only be used in first aid treatment and not for continued rinsing therapy.

[Necrolytic properties of alkaline protease in the treatment of severe eye burns]

Both eyes of 62 rabbits (124 eyes) were experimentally studied. Necrolytic properties of alkaline protease were examined on a model of an isolated alkaline retinal burn by 10% NaOH with a 10 sec exposure; the protease optimal concentration and an optimal exposure were determined. It was established that a necrolytic effect correlating with that of lecozyme can be achieved when a protease solution with an activity of 25-27 PE is used. An increased activity of protease in the solution results not only in hydrolysis of the turbid corneal part, but it also melts the perifocal area entailing a danger of perforation. Alkaline protease can be used as an ointment to ensure the necrolytic effect, however, its dosage in such medication form must be above 30-35 PE. The administration of a preliminary enzymatic necrectomy produced a positive effect on the postoperative cause and the results of keratoplasty as compared with surgical necrectomy, which can be explained by a better quality necrectomy involving the use of alkaline protease.

[Study of two immunosuppresive strategies after limbal allograft transplantation]

PURPOSE

Comparison of two immunosuppressive strategies after limbal allograft transplantation in an experimental model of ocular surface chemical burn.

METHODS

Twenty albino rabbits underwent corneal and limbal chemical burn with NaOH. One week later limbal transplantation was performed. Clinical assessments included measurements of epithelial defect, stromal opacity and neovascularization areas, using a computerized planimetry system 0, 7, 15, 30, 60 and 90 days after the chemical burn. Histologic examination was performed at 3 months, after sacrifice of the animals. Two immunosuppressive strategies were evaluated: topical cyclosporin A on constant dosage (group 1), and a combination of topical cyclosporin A and dexamethasone followed by a tapered dosage of topical cyclosporin A (group 2).

RESULTS

No statistical differences were observed between both groups regarding all of the variables 3 months after the chemical burn. Differences in the stromal opacity area were detected on day 7 (43.33 D.E. 4.84 vs 36.67 D.E. 3.88; p<0.01), day 15 (41.68 3 D.E.95 vs 33.6 D.E. 1.99; p<0.01), and day 30 (40.1 D.E. 5.45 vs 32.52 D.E. 7.33; p<0.05). As for the neovascularization area, differences were detected on day 7 (1.92 D.E. 0.48 vs 3.73 D.E. 1.18; p<0.01), day 15 (7.08 D.E. 1.54 vs 4.42 D.E. 1.68; p<0.01), and day 60 (4.9 D.E. 2.58 vs 9.65 D.E. 5.55; p<0.05).

CONCLUSIONS

There are no long-term differences between both immunosuppressive strategies regarding all the studied variables (Arch Soc Esp Oftalmol 2003; 78: 29-34).

Use of an amphoteric lavage solution for emergency treatment of eye burns. First animal type experimental clinical considerations

PURPOSE

Severe eye burns occur rarely, but are related to a poor prognosis in rehabilitation. As emergency treatment has been identified as decisive factor for the prognosis of eye burns, new first aid rinsing solutions should be considered carefully in their clinical action. In a first approach, the new drug Diphoterine was subjected to a comparison with saline solution to evaluate the effects in a model of severe eye burns.

METHODS

In a double-masked experiment 16 rabbits underwent a severe eye burn of one cornea followed by immediate rinsing with 0.9% sodium-chlorine solution (n=8) or Diphoterine (n=8). During 16 days after burn, an irrigation therapy with 0.9% saline solution three times daily 160 ml was applied in both groups following the recommendation of prolonged irrigation therapy performed in our clinic. In a similar setup, 16 eyes were subjected alkali burns with measurements of aqueous humor pH within 30s after burn and after a period of 5 min rinsing with 500 ml saline 0.9% or Diphoterine, respectively.

RESULTS

The result of the severe eye burn with an opaque cornea was similar in both groups. During rinsing no fibrin precipitates occurred in the Diphoterine rinsed group whereas this was detectable in all eyes rinsed with saline solution. After 16 days there was no difference between both groups indicating no harmful effect of Diphoterine as emergency treatment compared to saline 0.9%. After 30s of burn with 1N NaOH and rinsing with 500 ml of the specified solutions the anterior chamber pH was 10+/-0 in the saline group and 9.35+/-0.3 in the Diphoterine group showing efficacy of the buffering capacity of Diphoterine.

CONCLUSION

Diphoterine proves to be efficient in the primary treatment of burns. The anterior chamber pH could be lowered by 5min of rinsing. No harmful effects of Diphoterine could be observed compared to rinsing with saline solution in the course of an severe alkali burn of the cornea.