Oxygen therapy for acute ocular chemical or thermal burns: a pilot study

Review of evidence for treatments of acute non arteritic anterior ischemic optic neuropathy

OBJECTIVE

To review treatment modalities that have been studied in acute non arteritic anterior ischemic optic neuropathy (NAION).

METHODS

We performed a comprehensive literature search of English language publications in the last 5 years, with human species and NAION. Articles were reviewed to identify those that described original research on treatment of acute NAION. Study type, setting, duration, interventions, and results were extracted and articles were reviewed for biases and limitations.

RESULTS

We identified 22 kinds of treatment varying by compound and modality. These include topical, intravitreal, and systemic drugs as well as surgical approaches. Evidence for efficacy ranges from expert opinion to randomized control trials.

CONCLUSIONS

Although several treatments are utilized in practice, none of these have high quality evidence of efficacy to improve visual outcomes.  Continued collaborative research is necessary to complete high quality studies in order identify effective therapies for this rare and blinding disease.

Management of multi-surface ocular burns caused by molten iron

Ocular thermal burns are medical emergencies that require immediate intervention before the standard management protocol, which involves obtaining a detailed history and performing an ophthalmic examination. In this case report, we report the clinical manifestations of ocular burns caused by molten iron and the steps taken for good clinical outcomes. The patient presented with an inferior epithelial defect and limbal and lower lid ischemia at four hours post-injury. Over the course of treatment, due to non-resolving epithelial defect and increased superior lid notching, amniotic membrane transplantation (AMT) and lid repair by pentagon wedge excision were performed. Following AMT, the corneal surface completely healed with residual opacity and neovascularization. Additionally, limbal ischemia was significantly reduced with the restoration of normal lid anatomy. Corneal burns initiate a cascade of inflammatory reactions disrupting the balance between pro- and anti-angiogenic factors, leading to corneal neovascularization. The eyelid damage can lead to necrosis of tissues with eschar formation and eventually quantitative tissue loss. Therefore, timely intervention is the key to the successful management of ocular burns.

Ocular surface reconstruction of Steven Johnson syndrome / toxic epidermal necrolysis affected eye - A case report

Introduction

Toxic epidermal necrolysis (TEN), also known as Steven Johnson syndrome (SJS), is a devastating disease. Patients develop blindness and symblepharon despite multiple reconstructive surgeries. We report a case of SJS/TEN with ocular involvement where treatment with hyperbaric oxygen therapy (HBOT) resulted in a significant improvement in the visual acuity after surgery.

Case presentation

A woman with SJS/TEN with severe ocular complication (SOC) had limbal stem cell deficiency and symblepharon of the superior and inferior fornix. Pannus grew over her cornea, reducing the vision to counting finger. The symblepharon produced shortening of the fornix, causing entropion. The in-turned eyelid caused her eyelashes to rub against the cornea, causing great damage to the ocular surface. Limbal stem cell deficiency led to the loss of normal corneal morphology and invasion of the pannus onto the central visual axis, resulting in poor vision. She experienced ocular inflammation for 3 months before transfer to our hospital for admission. Ophthalmic examination showed bilateral corneal opacity with conjunctivalization, and inferior and superior fornix shortening. Symblepharon-lysis with amniotic membrane transplantation was attempted but the outcome was poor, with recurrence of superior scaring and symblepharon. She finally underwent major reconstructive surgery with allogeneic limbal stem cell transplantation with her sister as the donor, autologous minor salivary gland transplantation, and oral buccal mucosa flap transplant. HBOT was given daily post-surgery for supporting the grafts and suppressing inflammation. After 17 HBOT sessions and 3 months of autoserum drops, her left eye vision increased from the initial counting finger to 0.4 due to the successful growth of the corneal epithelium from the donor corneal limbal cell line. When a scleral contact lens which vaulted over the corneal limbal area was fitted, her vision improved to 0.8 due to redressal of high order aberration and astigmatism from the cornea scar.

Conclusion

After major reconstruction of the ocular surface with multiple cell type transplants, including limbal stem cells, minor salivary gland acinar cells, and oral mucosa cells, HBOT proved useful in supporting the graft uptake and oxygenation of the donor tissues, enabling fast recovery of the grafts and cell functioning, with eventual return of the working vision of the patient.

Perfluorodecalin-based oxygenated emulsion as a topical treatment for chemical burn to the eye

Chemical injuries to the eye are emergencies with limited acute treatment options other than prompt irrigation and can cause permanent vision loss. We developed a perfluorodecalin-based supersaturated oxygen emulsion (SSOE) to topically deliver high concentration of oxygen to the eye. SSOE is manufactured in hyperbaric conditions and stored in a ready-to-use canister. Upon dispensation, SSOE rapidly raises partial oxygen pressure 3 times over atmospheric level. SSOE is biocompatible with human corneal cells and safe on mouse eyes in vivo. A single topical application of SSOE to the eye after alkali injury significantly promotes corneal epithelial wound healing, decreases anterior chamber exudation, and reduces optical opacity and cataract formation in mice. SSOE treatment reduces intraocular hypoxia, cell death, leukocyte infiltration, production of inflammatory mediators, and hypoxia-inducible factor 1-alpha signaling, thus hastening recovery of normal tissue integrity during the wound healing process. Here, we show that SSOE is an effective topical therapeutic in the acute treatment of ocular chemical injuries.

Topical Erythropoietin for Treatment of Scleral Necrosis

PURPOSE

To investigate the safety and efficacy of topical erythropoietin for the treatment of scleral necrosis.

METHODS

This study enrolled eight consecutive patients with scleral necrosis due to previous ocular surgery, rheumatoid arthritis-associated necrotizing anterior scleritis, and thermal and chemical burns. Conventional treatments failed to heal avascular scleral lesions in all eyes. Patients were treated with topical erythropoietin (3000 IU/mL) four times a day.

RESULTS

The mean patient age was 37.6 ± 15.5 years. The interval between the development of scleral necrosis and initiation of topical erythropoietin was 25.6 ± 12.0 days. The necrotic sclera completely healed within 31.9 ± 16.9 days in all patients. The avascular lesions did not recur, and there was no evidence of side effects during the study.

CONCLUSION

Our results showed that topical erythropoietin could be safely used to manage scleral necrosis. Randomized clinical trials are needed to further explore the efficacy of this intervention in patients with avascular scleral lesions.

Effect of supersaturated oxygen emulsion treatment on chloropicrin-induced chemical injury in ex vivo rabbit cornea

With a possibility for the use of chemical weapons in battlefield or in terrorist activities, effective therapies against the devastating ocular injuries, from their exposure, are needed. Oxygen plays a vital role in ocular tissue preservation and wound repair. We tested the efficacy of supersaturated oxygen emulsion (SSOE) in reducing ex vivo corneal and keratocyte injury from chloropicrin (CP). CP, currently used as a pesticide, is a chemical threat agent like the vesicating mustard agents and causes severe corneal injury. Since our previous study in human corneal epithelial cells showed the treatment potential of SSOE (55 %), we further tested its efficacy in an ex vivo CP-induced rabbit corneal injury model. Corneas were exposed to CP (700 nmol) for 2 h, washed and cultured with or without SSOE for 24 h or 96 h. At 96 h post CP exposure, SSOE treatment presented a healing tendency of the corneal epithelial layer, and abrogated the CP-induced epithelial apoptotic cell death. SSOE treatment also reduced the CP induced DNA damage (H2A.X phosphorylation) and inflammatory markers (e.g. MMP9, IL-21, MIP-1β, TNFα). Further examination of the treatment efficacy of SSOE alone or in combination with other therapies in in vivo cornea injury models for CP and vesicants, is warranted.

A Supersaturated Oxygen Emulsion for the Topical Treatment of Ocular Trauma

INTRODUCTION

Roughly 13% of all battlefield injuries include some form of ocular trauma. Ocular tissue preservation is critical for wound healing for warfighters with ocular injuries. Our team hypothesized that oxygen plays a vital role in ocular tissue preservation and wound healing and has developed a supersaturated oxygen emulsion (SOE) for the topical treatment of ocular trauma.

MATERIALS AND METHODS

The partial pressure of oxygen (PO2) was measured in the SOE. Safety and efficacy studies were carried out in primary human corneal epithelial (HCE) cells, as the outermost layer is the first barrier to chemical and mechanical injury. Western blot, scratch assay, and MTT assays were conducted to determine the effect of the SOE on various molecular markers, the rate of scratch closure, and cellular viability, respectively.

RESULTS

Data indicate that the SOE releases oxygen in a time-dependent manner, reaching a partial pressure within the emulsion over four times atmospheric levels. Studies in HCE cells indicate that application of the SOE does not lead to DNA damage, promote cell death, or hinder the rate of scratch closure and enhances cellular viability. Preliminary studies were carried out with chloropicrin (CP; developed as a chemical warfare agent and now a commonly used pesticide) as a chemical agent to induce ocular injury in HCE cells. CP exposures showed that SOE treatment reverses CP-induced DNA damage, apoptotic cell death, and oxidative stress markers.

CONCLUSIONS

Maintaining adequate tissue oxygenation is critical for tissue preservation and wound repair, especially in avascular tissues like the cornea. Further studies examining the application of the SOE in corneal injury models are warranted.

Management Strategies of Ocular Chemical Burns: Current Perspectives

Ocular chemical burns are absolute ophthalmic emergencies and require immediate management to minimize devastating sequelae. Management of alkali and acid burns is started at the scene of the accident by copious irrigation. Treatment is directed at improving epithelial integrity and stromal stability, reduction of undue inflammation, and prevention or timely management of complications. To ascertain the best possible outcome, numerous biological medications and surgical interventions have been merged into conventional therapeutic regimens. These include autologous and umbilical cord serum preparations, platelet-rich plasma, amniotic membrane transplantation, limbal stem-cell transplantation, and anti-angiogenic agents.

Severe corneal burn due to the accidental application of salicylic acid packed in a plastic dropper bottle

Eye burns due to the accidental application of pharmacological or nonpharmacological substances packaged in plastic dropper bottles have been described for more than three decades and continue to occur. These burns can cause potentially serious corneal injuries. We report the case of a patient who mistakenly applied salicylic acid to the right eye after confusing it with an eye lubricant, which caused him a severe corneal burn. Fortunately, after aggressive medical and surgical management (including oxygen therapy and amniotic membrane grafting), the visual results were good. We suggest conducting educational campaigns and taking legislative measures in our country to avoid packaging corrosive substances in this type of dropper bottle to reduce the risk of accidental burns.

Correlation analysis of the clinical features and prognosis of acute ocular burns-exploration of a new classification scheme

PURPOSE

To explore a new classification scheme for acute ocular burns.

METHODS

Medical records of 345 patients (450 eyes) with acute ocular burns treated at Shandong Eye Institute between January 2013 and January 2018 with a 12-month minimum follow-up were retrospectively reviewed. A total of 8 parameters in the acute phase were evaluated and graded on a scale from 0 to 3 according to their severity.

RESULTS

The key factors affecting the prognosis of acute ocular burns were conjunctival involvement (386 eyes, 85.8%), corneal epithelial defect (349 eyes, 77.6%), and limbal ischemia (244 eyes, 54.2%). Visual acuity in 181/450 eyes (40.2%) was worse than 6/60. The injury severity of the cornea, limbus, bulbar conjunctiva, eyelid, and fornix and intraocular signs in the acute phase was significantly correlated with the logarithm of the minimum angle of resolution (logMAR) visual acuity (correlation coefficient [R] 0.481-0.933, P < 0.0001) and corneal opacification, neovascularization, and symblepharon scores in the stable phase (R 0.513-0.855, P < 0.0001). The mean total score for the 8 parameters in the acute phase was 5.34 ± 4.04 (range 0-14); higher scores indicated worse visual acuity (R = 0.899, P < 0.0001). The total score for acute-phase parameters was significantly correlated with that for the stable-phase parameters (R = 0.872, P < 0.0001).

CONCLUSIONS

The severity of acute-phase parameters is significantly correlated with the final visual outcome and prognosis. The new grading scheme can help clinicians more accurately analyze the degree of ocular burns, determine a reasonable treatment protocol, and rationally evaluate the prognosis.

Treatment of acute ocular chemical burns

Ocular chemical burns are an ophthalmic emergency and are responsible for 11.5%-22.1% of ocular injuries. Immediate copious irrigation is universally recommended in acute ocular burns to remove the offending agent and minimize damage. Conventional medical therapy consists of the use of agents that promote epithelialization, minimize inflammation, and prevent cicatricial complications. Biological fluids such as autologous serum, umbilical cord blood serum, platelet-rich plasma, and amniotic membrane suspension are a rich source of growth factors and promote healing when used as adjuncts to conventional therapy. Surgical treatment of acute ocular burns includes the debridement of the necrotic tissue, application of tissue adhesives, tenoplasty, and tectonic keratoplasty. Amniotic membrane transplantation is a novel surgical treatment that is increasingly being used as an adjunct to conventional treatment to promote epithelial healing, minimize pain, and restore visual acuity. Various experimental treatments that aim to promote wound healing and minimize inflammation are being evaluated such as human mesenchymal and adipose stem cells, beta-1,3 glucan, angiotensin-converting enzyme inhibitors, cultivated fibroblasts, zinc desferrioxamine, antifibrinolytic agents, antioxidants, collagen cross-linking, and inhibitors of corneal neovascularization.

The effect of high-dose steroids, and normobaric oxygen therapy, on recent onset non-arteritic anterior ischemic optic neuropathy: a randomized clinical trial

BACKGROUND

To evaluate the effect of high-dose intravenous steroids, as well as normobaric oxygen therapy, in the management of recent onset non-arteritic anterior ischemic optic neuropathy (NAION).

METHOD

Ninety eyes of 90 patients diagnosed with NAION within 14 days of onset were included in this single masked randomized clinical trial. Thirty patients were randomized into each set as group 1 (control), group 2 (steroids), and group 3 (oxygen). Controls received placebo; group 2 received methylprednisolone 500 mg twice a day for 3 days followed by 2 weeks of oral prednisolone 1 mg/kg/day; group 3 received 100 % normobaric oxygen with mask, at a flow rate of 5 liters per minute for 1 hour twice a day for two weeks. Functional and structural outcomes were analyzed at 1 and 6 months following treatment. Best corrected visual acuity (BCVA) was the main outcome measure, and mean deviation (MD) of visual field (VF) test and peripaillary retinal nerve fiber layer thickness (PRNFLT) were secondary outcome measures.

RESULTS

The mean BCVA at the time of presentation was 1.02 ± 0.63, 1.05 ± 0.7, and 0.76 ± 0.5 LogMAR in groups 1, 2, and 3, respectively (p = 0.293); corresponding values were 0.8 ± 0.45, 0.84 ± 0.45, and 0.58 ± 0.4 at month 1 (p = 0.127, 0.19, and 0.168, respectively). BCVA improved to 0.71 ± 0.46, 0.73 ± 0.36, and 0.59 ± 0.41 LogMAR at the 6-month follow-up point (p = 0.039, 0.048, and 0.195, respectively). The mean deviation (MD) at the time of presentation was 19.26 ± 7.02, 20.51 ± 4.68, and 19.3 ± 7.17 in the control, steroid, and oxygen groups, respectively (p = 0.65). Corresponding values at month 1 were 20.26 ± 8.52, 19.52 ± 7.08, and 18.3 ± 7.45, (p = 0.656); and at month 6 were 18.42 ± 8.17, 17.66 ± 6.44 and 16.53 ± 6.32, respectively (p = 0.635). PRNFLT at presentation was 166 ± 57, 184 ± 57, and 193 ± 65 micrometer in the control, steroid, and oxygen groups, respectively (p = 0.265); which decreased to 73 ± 11, 87 ± 26, and 79 ± 19 at the final foll-w up (all p < 0.001). There were no statistically significant differences between the three groups in terms of final visual function and structure.

CONCLUSION

The lack of demonstrable improvement in the structural and functional outcomes of NAION with high-dose IV steroids, or normobaric oxygen, in this randomized controlled trial calls into question the administering of systemic steroid or normobaric oxygen in this condition.

Comparison of Amniotic Membrane Transplantation and Umbilical Cord Serum in Acute Ocular Chemical Burns: A Randomized Controlled Trial

PURPOSE

To compare the efficacy of topical umbilical cord serum drops (UCS) and amniotic membrane transplantation (AMT) in acute ocular chemical burns.

DESIGN

Randomized controlled trial.

METHODS

setting: Tertiary care hospital.

STUDY POPULATION

Forty-five eyes with acute chemical burns of grade III, IV, and V (Dua's classification) presenting within the first week of injury were randomized into 3 groups (15 each). Patients with perforation/impending corneal perforation were excluded from the study.

INTERVENTION

Groups 1, 2, and 3 received UCS with medical therapy (MT), AMT with MT, and MT alone, respectively.

MAIN OUTCOME MEASURE

Time to complete epithelialization.

RESULTS

The mean time to complete epithelialization was 56.7 ± 14.9, 22.0 ± 10.2, and 22.9 ± 10.1 days in MT, AMT, and UCS groups, respectively, with a significant difference between MT and AMT (P = .001) and between MT and UCS (P = .001), but not between UCS and AMT (P = .9). Improvement in pain score was better with UCS than AMT (P value: .012, .002, and .012 on days 7, 14, and 21, respectively). Corneal clarity was better in the UCS group at 21 (P = .008) and 30 days (P = .002), but not at 3 months (P = .9). By month 3, visual outcome, symblepharon, tear film status, and lid abnormalities were comparable between the 3 groups.

CONCLUSIONS

UCS and AMT, as an adjuvant to standard medical therapy in acute chemical injury, are equally efficacious. UCS has the advantage of faster improvement in corneal clarity, better pain control, and avoidance of surgery in an inflamed eye.

In vivo oximetry of human bulbar conjunctival and episcleral microvasculature using snapshot multispectral imaging

Multispectral imaging (MSI) is a well-established technique for non-invasive oximetry of retinal blood vessels, which has contributed to the understanding of a variety of retinal conditions, including glaucoma, diabetes, vessel occlusion, and retinal auto-regulation. We report the first study to use snapshot multi-spectral imaging (SMSI) for oximetry of the bulbar conjunctival and episcleral microvasculature in the anterior segment of the eye. We report the oxygen dynamics of the bulbar conjunctival and episcleral microvasculature at normoxia and at acute mild hypoxia conditions. A retinal-fundus camera fitted with a custom Image-Replicating Imaging Spectrometer was used to image the bulbar conjunctival and episcleral microvasculature in ten healthy human subjects at normoxia (21% Fraction of Inspired Oxygen [FiO2]) and acute mild hypoxia (15% FiO2) conditions. Eyelid closure was used to control oxygen diffusion between ambient air and the sclera surface. Four subjects were imaged for 30 seconds immediately following eyelid opening. Vessel diameter and Optical Density Ratio (ODR: a direct proxy for oxygen saturation) of vessels was computed automatically. Oximetry capability was validated using a simple phantom that mimicked the scleral vasculature. Acute mild hypoxia resulted in a decrease in blood oxygen saturation (SO2) (i.e. an increase in ODR) when compared with normoxia in both bulbar conjunctival (p < 0.001) and episcleral vessels (p = 0.03). Average episcleral diameter increased from 78.9 ± 8.7 μm (mean ± standard deviation) at normoxia to 97.6 ± 14.3 μm at hypoxia (p = 0.02). Diameters of bulbar conjunctival vessels showed no significant change from 80.1 ± 7.6 μm at normoxia to 80.6 ± 7.0 μm at hypoxia (p = 0.89). When exposed to ambient air, hypoxic bulbar conjunctival vessels rapidly reoxygenated due to oxygen diffusion from ambient air. Reoxygenation occured in an exponential manner, and SO2 reached normoxia baseline levels. The average ½ time to full reoxygenation was 3.4 ± 1.4 s. As a consequence of oxygen diffusion, bulbar conjunctival vessels will be highly oxygenated (i.e. close to 100% SO2) when exposed to ambient air. Episcleral vessels were not observed to undergo any significant oxygen diffusion, instead behaving similarly to pulse oximetry measurements. This is the first study to the image oxygen dynamics of bulbar conjunctival and episcleral microvasculature, and consequently, the first study to directly observe the rapid reoxygenation of hypoxic bulbar conjunctival vessels when exposed to ambient air. Oximetry of bulbar conjunctival vessels could potentially provide insight into conditions where oxygen dynamics of the microvasculature are not fully understood, such as diabetes, sickle-cell diseases, and dry-eye syndrome. Oximetry in the bulbar conjunctival and episcleral microvasculature could be complimentary or alternative to retinal oximetry.

Concise review: transplantation of cultured oral mucosal epithelial cells for treating limbal stem cell deficiency-current status and future perspectives

A number of diseases and external factors can deplete limbal stem cells, causing pain and visual loss. Ten years have passed since the first transplantation of cultured oral mucosal epithelial cells in humans, representing the first autologous cell-based therapy for severe bilateral limbal stem cell deficiency. Its steady increase in popularity since then can be attributed to the accumulating evidence of its efficacy in reverting limbal stem cell deficiency. In this review, the focus is on clinical, and to a lesser degree laboratory, features of cultured oral mucosal epithelial transplants over the past 10 years. Comparisons with other available technologies are made. Avenues for research to stimulate further improvements in clinical results and allow worldwide distribution of limbal stem cell therapy based on oral mucosal cells are discussed. These include storage and transportation of cultured oral mucosal epithelial sheets and in vivo culture of oral mucosal epithelial cells.

Effects of topical chondrocyte-derived extracellular matrix treatment on corneal wound healing, following an alkali burn injury

Numerous treatments have been used in the management of corneal chemical burns; however, no optimal treatment for corneal chemical burns currently exists. The present study investigated the effects of topical chondrocyte-derived extracellular matrix (CD-ECM) treatment on corneal wound healing, using an alkali burn mouse model. Topical treatment with CD-ECM was shown to reduce corneal opacity following an alkali burn. A histological examination observed the presence of regenerated epithelial cells and a small number of inflammatory cells in the corneas of CD-ECM-treated mice. The majority of the inflammatory cells present in the corneas of the phosphate-buffered saline (PBS)-treated mice were neutrophils that expressed matrix metalloproteinase (MMP)-9. The amount of neutrophils was significantly reduced in the corneas of the CD-ECM-treated mice. Furthermore, the expression levels of interleukin (IL)-8 were significantly reduced in the CD-ECM treatment group, but not in the mice that received the PBS treatment. The results of the present study indicate that CD-ECM treatment may accelerate wound healing in a model of alkali burn-induced corneal injury. The therapeutic mechanism may be associated with accelerated reepithelialization and reduced recruitment of MMP-9-expressing neutrophils, through inhibiting the production of IL-8.

The ocular surface chemical burns

Ocular chemical burns are common and serious ocular emergencies that require immediate and intensive evaluation and care. The victims of such incidents are usually young, and therefore loss of vision and disfigurement could dramatically affect their lives. The clinical course can be divided into immediate, acute, early, and late reparative phases. The degree of limbal, corneal, and conjunctival involvement at the time of injury is critically associated with prognosis. The treatment starts with simple but vision saving steps and is continued with complicated surgical procedures later in the course of the disease. The goal of treatment is to restore the normal ocular surface anatomy and function. Limbal stem cell transplantation, amniotic membrane transplantation, and ultimately keratoprosthesis may be indicated depending on the patients' needs.

Limbal epithelial cell therapy: past, present, and future

The cornea, the clear window at the front of the eye, transmits light to the retina to enable vision. The corneal surface is renewed by stem cells located at the peripheral limbal region. These cells can be destroyed by a number of factors, including chemical burns, infections, and autoimmune diseases, which result in limbal stem cell deficiency (LSCD), a condition that can lead to blindness. Established therapy for LSCD based on ex vivo expanded limbal epithelial cells is currently at a stage of refinement. Therapy for LSCD is also rapidly evolving to include alternative cell types and clinical approaches as treatment modalities. In the present perspectives chapter, strategies to treat LSCD are discussed and advances in this important field of regenerative medicine are highlighted.