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Mechanisms of Retinal Damage after Ocular Alkali Burns.

ABSTRACT: 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-? 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.

SUBMITTER: Paschalis EI

PROVIDER: S-EPMC5455067 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Mechanisms of Retinal Damage after Ocular Alkali Burns.

Paschalis Eleftherios I EI Zhou Chengxin C Lei Fengyang F Scott Nathan N Kapoulea Vassiliki V Robert Marie-Claude MC Vavvas Demetrios D Dana Reza R Chodosh James J Dohlman Claes H CH

The American journal of pathology 20170413 6

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 ...[more]

PMID: 28412300

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Project description:BackgroundOcular surface burns can be caused by chemicals (alkalis and acids) or by direct heat. Amniotic membrane transplantation (AMT) performed in the acute phase (day 0 to day 7) of an ocular surface burn is reported to relieve pain, accelerate healing and reduce scarring and blood vessel formation. The surgery involves applying a patch of amniotic membrane (AM) over the entire ocular surface up to the eyelid margins.ObjectivesTo assess the effects of AMT on the eyes of people having suffered acute ocular surface burns.Search methodsWe searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 6), MEDLINE (January 1946 to June 2012), EMBASE (January 1980 to June 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to June 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 11 June 2012.Selection criteriaWe included randomised trials of medical therapy and AMT applied in the first seven days after an ocular surface burn compared to medical therapy alone.Data collection and analysisTwo authors independently assessed the risk of bias of included studies and extracted relevant data. We contacted trial investigators for missing information. We summarised data using risk ratios (RRs) and mean differences (MDs) as appropriate.Main resultsWe included one RCT of 100 participants with ocular burns that were randomised to treatment with AMT and medical therapy or medical therapy alone. A subset of patients (n = 68) who were treated within the first seven days of the injury met the inclusion criteria and were included in the analysis. The remaining 32 eyes were excluded. The included subset consisted of 36 moderate (Dua classification II-III) and 32 severe (Dua classification IV-VI) ocular burns from alkali, acid and thermal injuries. In the moderate category, 13/20 control eyes and 14/16 treatment eyes had complete epithelialisation by 21 days. The RR of failure of epithelialisation by day 21 was 0.18 in the treatment group (95% confidence interval (CI) 0.02 to 1.31; P = 0.09). Mean LogMAR final visual acuities were 0.06 (standard deviation (SD) 0.10) in the treatment group and 0.38 (SD 0.52) in the control group, representing a MD of -0.32 (95% CI -0.05 to -0.59). In the severe category, 1/17 treatment and 1/15 control eyes were epithelialised by day 21. The RR of failure of epithelialisation in the treatment group was 1.01 (95% CI 0.84 to 1.21; P = 0.93). Final visual acuity was 1.77 (SD 1.31) in the treated eyes and 1.64 (SD 1.48) in the control group (MD 0.13; 95% CI -0.88 to 1.14). The risks of performance and detection biases were high, because treating personnel and outcome assessors could not be masked to treatment. There was also a high risk of bias in the visual outcomes of the moderate category, since mean visual acuity was significantly worse at presentation in the control eyes. This reduced confidence in the study findings.Authors' conclusionsConclusive evidence supporting the treatment of acute ocular surface burns with AMT is lacking. Heterogeneity of disease presentation, variations in treatment, undefined criteria for treatment success and failure, and non-uniform outcome measures are some of the factors complicating the search for clear evidence regarding this treatment.

Project description:BackgroundBurn-related injury to the face involving the structures of the eyes, eyelids, eyelashes, and/or eyebrows could result in multiple reconstructive procedures to improve functional and cosmetic outcomes, and correct complications following poor acute phase management. The objective of this article was to evaluate if non-surgical or surgical interventions are best for acute management of ocular and/or peri-ocular burns.MethodsThis systematic review and meta-analysis compared 272 surgical to 535 non-surgical interventions within 1 month of patients suffering burn-related injuries to 465 eyes, 253 eyelids, 90 eyelashes, and 0 eyebrows and evaluated associated outcomes and complications. The PubMed, Embase, Cochrane Library, Web of Science, and Scopus databases were systematically and independently searched. Patient and clinical characteristics, surgical and medical interventions, outcomes, and complications were recorded.ResultsEight of the 14,927 studies queried for this study were eligible for the systematic review and meta-analysis, with results from 33 of the possible 58 outcomes and complications using Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) and Cochrane guidelines. Surgery was associated with standard mean differences (SMD) 0.44 greater visual acuity on follow-up, SMD 1.63 mm shorter epithelial defect diameters on follow-up, SMD 1.55 mm greater changes in epithelial diameters from baseline, SMD 1.17 mm2 smaller epithelial defect areas on follow-up, SMD 1.37 mm2 greater changes in epithelial defect areas from baseline, risk ratios (RR) 1.22 greater numbers of healed epithelial defects, RR 11.17 more keratitis infections, and a 2.2 greater reduction in limbal ischemia compared to no surgical intervention.ConclusionsThis systematic review and meta-analysis found that compared to non-surgical interventions, acute surgical interventions for ocular, eyelid, and/or eyelash burns were found to have greater visual acuity on follow-up, shorter epithelial defect diameters on follow-up, greater changes in epithelial diameters from baseline, smaller epithelial defect areas on follow-up, greater changes in epithelial defect areas from baseline, greater numbers of healed epithelial defects, more keratitis infections, and a greater reduction in limbal ischemia, possibility preventing the need of a future limbal stem cell transplantation.

Project description:Eye drops account for more than 90% of commercialized ophthalmic drugs. However, eye drops have certain shortcomings, such as short precorneal retention time and weak corneal penetration. The requirement of frequent instillation of eye drops also causes poor patient compliance, which may lead to further aggravation of the disease. We aimed to develop a cationic liposome formulation to increase the bioavailability of the therapeutic agent and solve the aforementioned problems. In the present study, we prepared cationic liposomal tacrolimus (FK506) with a surface potential of approximately +30 mV, which could bind to the negatively charged mucin layer of the ocular surface. Our results showed that the content of FK506 in the cornea was increased by 93.77, 120.30, 14.24, and 20.36 times at 5, 30, 60, and 90 min, respectively, in the FK506 liposome group (0.2 mg/ml) compared with the free drug group (0.2 mg/ml). Moreover, FITC-labeled FK506 liposomes significantly prolonged the ocular surface retention time to 50 min after a single dose. In addition, the results of the Cell Counting Kit-8 assay, live and dead cell assay, sodium fluorescein staining, and hematoxylin and eosin staining all indicated that FK506 liposomes had good biological compatibility in both human corneal epithelial cells and mouse eyeballs. Compared with the free drug at the same concentration, FK506 liposomes effectively inhibited vascular endothelial growth factor-induced green fluorescent protein-transduced human umbilical vein endothelial cell migration and tube formation in vitro. In a mouse corneal neovascularization model induced by alkali burns, FK506 liposomes (0.2 mg/ml) enhanced corneal epithelial recovery, inhibited corneal neovascularization, and reduced corneal inflammation, and its therapeutic effect was better than those of the commercial FK506 eye drops (1 mg/ml) and the free drug (0.2 mg/ml). Collectively, these results indicate that cationic FK506 liposomes could increase the efficacy of FK506 in the corneal neovascularization model. Therefore, cationic FK506 liposomes can be considered as a promising ocular drug delivery system.

Dataset Information

Mechanisms of Retinal Damage after Ocular Alkali Burns.

Publications

Mechanisms of Retinal Damage after Ocular Alkali Burns.

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