Severe corneal burn due to the accidental application of salicylic acid packed in a plastic dropper bottle. / Quemadura corneal grave debida a la aplicación accidental de ácido salicílico envasado en un frasco gotero plástico

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.

Las quemaduras oculares por aplicación accidental de sustancias farmacológicas o no farmacológicas envasadas en frascos goteros plásticos, se han descrito desde hace más de tres décadas y siguen ocurriendo. Estas quemaduras pueden causar lesiones potencialmente graves de la córnea. Se presenta el caso de un paciente que se aplicó ácido salicílico en el ojo derecho al confundir el envase con el de un lubricante ocular, lo que le causó una grave quemadura corneal. Afortunadamente, tras un manejo médico y quirúrgico agresivo (incluida oxigenoterapia e injerto de membrana amniótica) los resultados visuales fueron buenos. Se sugiere hacer campañas educativas y adoptar normas en el país para evitar el envase de sustancias corrosivas en este tipo de frascos goteros, con el fin de disminuir el riesgo de quemaduras accidentales.

The proteolytic fraction from Vasconcellea cundinamarcensis accelerates wound healing after corneal chemical burn in rabbits.

INTRODUCTION: Chemical ocular burns are among the most frequently eye-related injuries, which require immediate and intensive evaluation and care since they may lead to potential complications such as superinfection, corneal perforation, and blindness.Vasconcellea cundinamarcensis, a species from Caricaceae family, contains highly active proteolytic enzymes in its latex that show healing activity in animal models bearing lesions of different etiologies. METHODS: We evaluate the ocular toxicity of the proteolytic fraction from V. cundinamarcensis (P1G10) by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and Hen's Egg Test-Chorioallantoic Membrane test. The corneal healing property of P1G10 was studied by the ethanol-chemical burn in the rabbit's eyes. RESULTS: P1G10 is safe for ocular administration, except when administrated at 10µg/mL. P1G10 at 1µg/mL accelerates the corneal re-epithelization achieving complete wound closure after 72h of chemical burn. Also, P1G10 modulated the inflammatory response and controlled the arrangement of collagen fibers in the stroma, demonstrating its potential corneal healing properties. CONCLUSIONS: Our work was the first one to evaluate the ophthalmic application of P1G10. Here we demonstrated that P1G10 is suitable for ocular administration and it has a promising corneal healing activity which may emerge as a new pharmacological tool to the development of a new drug for ocular surface chemical injuries in the future.

Treatment for chemical burning using liquid crystalline nanoparticles as an ophthalmic delivery system for pirfenidone.

Some recent studies have shown that pirfenidone (PFD) has favorable results in the healing process of the cornea. However, PFD in solution exhibits short half-life after topical application, and in this context, a liquid crystal nanoparticle system containing PFD (PFD-LCNPs) was developed. The nanoparticles were characterized by transmission electron microscopy, atomic force microscopy, small angle X-ray diffraction and polarized light microscopy. The PFD-LCNPs had particle size and zeta potential of 247.3 nm and -33.60 mV (stores at 4 °C), respectively, and 257.5 nm and -46.00 mV (stored at 25 °C), respectively. The pH of the formulation was 6.9 and the encapsulation efficiency was 35.9%. The in vitro release profiles indicated that PFD sustained release from PFD-LCNPs for up to 12 h. In vitro study of ocular irritation (HET-CAM test) concluded that components of the formulation are well tolerated for ocular administration. Corneal re-epithelialization time after chemical burning was significantly reduced in rabbits treated with PFD-loaded LCNPs when compared to the group treated with a vehicle. In addition, the anti-inflammatory action of pirfenidone was observed by reducing myeloperoxidase activity (MPO) and inflammatory cells in the histology of the tissues of animals treated with PFD-LCNPs. These findings indicated that the PFD-LCNPs might have the potential for effective ocular drug delivery.

Molten metal-related ocular thermal burn: report on two cases.

We report two cases of severe thermal burns on the ocular surface and its adnexal appendages that developed secondary to exposure to molten heavy metal with a melting temperature of near-thousand degree Celsius. Despite aggressive intervention and strict monitoring, the profound inflammation caused significant damage to the ocular surface, ending up in an intractable infection with an unfavorable outcome. The heat of the molten metal at impact, the heat-retaining capacity of the heavy metal, the total area of the ocular surface exposed to the molten metal, and the duration of exposure determined the severity of the injury. The unfavorable outcome, despite an intensive treatment, in terms of visual acuity and cosmetic appearance, should be explicitly explained to the patient, and a psychiatrist consultation should be considered if necessary.

Molten metal-related ocular thermal burn: report on two cases / Queimadura térmica ocular por metal derretido: relato de dois casos

ABSTRACT We report two cases of severe thermal burns on the ocular surface and its adnexal appendages that developed secondary to exposure to molten heavy metal with a melting temperature of near-thousand degree Celsius. Despite aggressive intervention and strict monitoring, the profound inflammation caused significant damage to the ocular surface, ending up in an intractable infection with an unfavorable outcome. The heat of the molten metal at impact, the heat-retaining capacity of the heavy metal, the total area of the ocular surface exposed to the molten metal, and the duration of exposure determined the severity of the injury. The unfavorable outcome, despite an intensive treatment, in terms of visual acuity and cosmetic appearance, should be explicitly explained to the patient, and a psychiatrist consultation should be considered if necessary.

RESUMO Relatamos dois casos de queimaduras graves da superfície ocular e seus anexos causadas por exposição à metais pesados derretidos com temperatura de fusão de quase mil graus Celsius. Embora rigorosamente acompanhados, a inflamação intensa causou danos significativos para a superfície ocular, que acabou em uma infecção intratável com um resultado desfavorável. O calor do metal fundido no momento do impacto, a capacidade de retenção de calor do metal pesado, a área total da superfície ocular exposta ao metal fundido e a duração da exposição determinaram a gravidade da lesão que vai ocorrer. O resultado desfavorável, apesar do tratamento intensivo, em relação à acuidade visual e à aparência estética, devem ser claramente explicados ao paciente e uma consulta ao psiquiatra deve ser considerada, se necessário.

Comparative study of conjunctival limbal transplantation not associated with the use of amniotic membrane transplantation for treatment of total limbal deficiency secondary to chemical injury.

PURPOSE: The aim of this study was to compare the outcome of conjunctival limbal transplantation with and without the use of amniotic membrane (AM) transplantation for the treatment of limbal deficiency after chemical burns to the eyes. METHODS: This is a retrospective, comparative, interventional case series that included 34 eyes (34 patients) with total limbal deficiency after chemical burns, who were submitted to conjunctival limbal transplantation. Two groups were formed: group 1 (15 eyes) limbal transplantation associated with AM transplantation and group 2 (19 eyes) only limbal transplantation. Success and failure rates, epithelialization time, and visual acuity were compared between the 2 groups. RESULTS: The mean follow-up period was 19.71 ± 5.6 months in group 1 and 18.26 ± 7.78 months in group 2. The proportion of conjunctival limbal autograft and living-related conjunctival limbal allograft was similar in both groups (P = 0.914). Time until complete epithelialization of the corneal surface was significantly longer in group 1 (P = 0.007). Graft survival was similar in both groups (P = 0.581). Failure rate was also similar in both groups (P = 0.232). The most common cause of failure was transplanted stem cell depletion in group 1 (20% of cases) and rejection in group 2 (10.5%). The visual acuity improved postoperatively in 12 eyes (80%) in group 1 and 16 (84.2%) in group 2 (P = 0.430). CONCLUSIONS: Results with the use of AM associated with conjunctival limbal transplantation in ocular surface reconstruction were similar to those obtained with limbal transplantation alone. Both techniques were found to be satisfactory for ocular surface reconstruction in patients with total limbal deficiency after chemical burns.

Clinical and histopathological outcomes of subconjunctival triamcinolone injection for the treatment of acute ocular alkali burn in rabbits.

PURPOSE: To evaluate the efficacy and safety of subconjunctival injection of triamcinolone in the treatment of acute ocular alkali burn in rabbits. METHODS: Two groups of 5 rabbits were subjected to alkali burn (1 N NaOH). One group was treated with 1 subconjunctival injection of 0.3 mL of triamcinolone and the other with 1 subconjunctival injection of 0.3 mL of 0.9% saline. The affected corneas were observed for vascularization and opacity approximately 10 minutes after the burn and also after 7, 14, and 21 days. Photographs were taken for observation and statistical analyses. At all time intervals, the corneas were classified according to predetermined scores. Twenty-one days after the treatment, the animals were anesthetized, and their eyes were enucleated and processed for histopathology. RESULTS: Greater vascularization and opacity appeared in the animals that were treated with saline than in those treated with subconjunctival triamcinolone (vascularization: 7 days, P = 0.0107; 14 days, P = 0.0099; and 21 days, P = 0.0088; opacity: 7 days, P = 0.0079; 14 days, P = 0.0112; and 21 days, P = 0.0255). These results were also compatible with the morphological and statistical analyses, which revealed a more intense inflammatory process in the group treated with saline (P = 0.0317). No complications, such as corneal melting, perforation, or infection, were observed. CONCLUSIONS: Subconjunctival injection of triamcinolone may be a therapeutic option for the treatment of acute ocular burn because it reduced the corneal inflammatory process, opacity, and vascularization, with no apparent clinical changes in the general state of the animal.

Corneal reconstruction with tissue-engineered cell sheets composed of human immature dental pulp stem cells.

PURPOSE: To determine the outcome of the use of a tissue-engineered cell sheet composed of human undifferentiated immature dental pulp stem cells (hIDPSC) for ocular surface reconstruction in an animal model of total limbal stem cell deficiency (LSCD). METHODS: LSCD was induced by the application of 0.5 M NaOH to the right eye of rabbits for 25 seconds (mild chemical burn [MCB]) and for 45 seconds (severe chemical burn [SCB]). After 1 month, a superficial keratectomy was performed to remove the fibrovascular pannus that covered the animals' burned corneas. A tissue-engineered hIDPSC sheet was transplanted onto the corneal bed and then covered with deepithelialized human amniotic membrane (AM). In the respective control groups, the denuded cornea was covered with AM only. After 3 months, a detailed analysis of the rabbit eyes was performed with regard to clinical aspect, histology, electron microscopy, and immunohistochemistry. RESULTS: Corneal transparency of the rabbit eyes that underwent hIDPSC transplantation was improved throughout the follow-up, while the control corneas developed total conjunctivalization and opacification. Rabbits from the MCB group showed clearer corneas with less neovascularization. The clinical data were confirmed by histologic analysis that showed healthy uniform corneal epithelium, especially in the MCB group. The presence of hIDPSC was detected using an anti-hIDPSC antibody. The corneal tissue also showed positive immunostaining with anti-human antibodies. In the control corneas, none of these antigens were detected. CONCLUSIONS: Overall, these data showed that transplantation of a tissue-engineered hIDPSC sheet was successful for the reconstruction of corneal epithelium in an animal model of LSCD.

Human immature dental pulp stem cells share key characteristic features with limbal stem cells.

OBJECTIVES: Limbal stem cells (LSC) are self-renewing, highly proliferative cells in vitro, which express a set of specific markers and in vivo have the capacity to reconstruct the entire corneal epithelium in cases of ocular surface injury. Currently, LSC transplantation is a commonly used procedure in patients with either uni- or bilateral total limbal stem cells deficiency (TLSCD). Although LSC transplantation holds great promise for patients, several problems need to be overcome. In order to find an alternative source of cells that can partially substitute LSC in cornea epithelium reconstruction, we aimed at investigating whether human immature dental pulp stem cells (hIDPSC) would present similar key characteristics as LSC and whether they could be used for corneal surface reconstruction in a rabbit TLSCD model. MATERIALS: We used hIDPSC, which co-express mesenchymal and embryonic stem cell markers and present the capacity to differentiate into derivative cells of the three germinal layers. TLSCD was induced by chemical burn in one eye of rabbits. After 30 days, the opaque tissue formed was removed by superficial keratectomy. Experimental group received undifferentiated hIDPSC, while control group only received amniotic membrane (AM). Both groups were sacrificed after 3 months. RESULTS AND CONCLUSIONS: We have demonstrated, using immunohistochemistry and reverse transcription-polymerase chain reaction, that hIDPSCs express markers in common with LSC, such as ABCG2, integrin beta1, vimentin, p63, connexin 43 and cytokeratins 3/12. They were also capable of reconstructing the eye surface after induction of unilateral TLSCD in rabbits, as shown by morphological and immunohistochemical analysis using human-specific antibodies against limbal and corneal epithelium. Our data suggest that hIDPSCs share similar characteristics with LSC and might be used as a potential alternative source of cells for corneal reconstruction.

Does amniotic membrane transplantation improve the outcome of autologous limbal transplantation?

PURPOSE: To evaluate the additional benefits of amniotic membrane transplantation (AMT) when combined with conjunctival limbal autograft (CLAU) in the treatment of chronic chemical burns. METHODS: Thirty eyes of 30 rabbits underwent a chemical burn to create limbal deficiency. Forty-five days later, the animals were randomized into three groups of 10 rabbits each. Eyes from group 1 were treated with CLAU, group 2 underwent CLAU and AMT, and group 3 served as control without surgery. Corneal vascularization and opacity were documented with external photographs at postoperative days 30, 60, and 90. The rabbits were killed 3 months after surgery, and their corneas divided into two halves. One half was prepared for hematoxylin-eosin and periodic acid-Schiff staining and the other for frozen sections and immunostaining with AM3 (to MUC 5AC mucin) and AE5 (to K3 keratin). Final clinical outcome was also scored using external photographs at the last follow-up examination. RESULTS: After chemical burn, all groups showed similar degrees of conjunctivalization. After transplantation, corneal vascularization was worse in controls at 60 and 90 days (p < 0.001). At 30 days, eyes from group 1 had less corneal opacity (p < 0.05). At 90 days, corneal opacity was worse in controls but the same in groups 1 and 2 (p < 0.05). At the same time, limbal deficiency was significantly worse in controls (p < 0.05) but similar between groups 1 and 2. Corneal phenotype was present in 70% of the eyes in group 1, 50% in group 2, but in 10% of the controls. Clinical success with clear corneas was significantly more common in groups 1 and 2 when compared with controls (p < 0.001). CONCLUSIONS: CLAU is effective in treating limbal deficiency. The concurrent AMT does not add benefits in this rabbit model of chemical burns.

Amniotic membrane transplantation for partial and total limbal stem cell deficiency secondary to chemical burn.

PURPOSE: To evaluate the surgical outcome of preserved amniotic membrane transplantation (AMT) for ocular surface reconstruction in chemical burn with limbal stem cell deficiency. DESIGN: Prospective, noncomparative, interventional case series. PARTICIPANTS: Twenty eyes of 20 consecutive patients with limbal stem cell deficiency secondary to ocular chemical injury. INTERVENTION: AMT with or without adjunctive limbal transplantation using limbal tissue from either the healthy contralateral eye (CLAU) or a living related donor (lr-CLAL). MAIN OUTCOME MEASURES: Reconstruction of corneal epithelium (clear appearance without epithelial defect, normal fluorescein permeability and the absence of conjunctiva-derived goblet cells on impression cytology), decrease in corneal vascularization and improvement in visual acuity. RESULTS: With a mean follow-up time of 19 months (range, 8-27 months), satisfactory ocular surface reconstruction was obtained in 15 eyes (75%), with reduced inflammation and vascularization of the ocular surface and a mean epithelialization time of 3.3 weeks. Success was observed in all cases of partial limbal stem cell deficiency (PLD) and in 68.75% (11 eyes) of cases of total limbal stem cell deficiency (TLD). Surgical failure was observed in five severe cases (31.25%). A significant visual improvement was observed in all cases after surgery, except for 2 eyes that maintained preoperative visual acuity. CONCLUSIONS: AMT seems to be an efficient adjunct for ocular surface reconstruction in chemical burns with PLD. When performed in conjunction with limbal stem cell transplantation, it is also effective in most cases of TLD.

Quantitative CW Nd:YAG pars plana transscleral photocoagulation in postmortem eyes.

The effect of different types of burns and numbers of lesions on, and the role of initial pressure head in, the rate of aqueous outflow was studied in enucleated human and porcine eyes. Noncontact and contact CW Nd:YAG laser applied to human eyes 3 mm posterior to the limbus produced a 34% and 51% increase, respectively, in outflow as compared with controls (P = .01). In porcine eyes, outflow increased directly with the number of noncontact burns as well as with the amount of perfusion pressure. Our results suggest that intraocular pressure and outflow are functions of both the intensity of irradiation and the surface area treated, and that each individual pressure head may require an optimal pars plana area of treatment of therapeutic degree to lower pressure and yet prevent overfiltration and phthisis. Our results also suggest that there may be a passive transneuroepithelial and transscleral outflow component in clinical laser cycloablation and, therefore, a need to grade laser treatments in order to prevent visual loss through unnecessary injury.