ascorbic-acid and Corneal-Injuries

Topics: Animals; Antioxidants; Ascorbic Acid; Cells, Cultured; Cornea; Corneal Injuries; Eye Injuries; Fibroblasts; Filtering Surgery; Glaucoma; Humans; Wound Healing

Topics: Adrenal Cortex Hormones; Adult; Animals; Ascorbic Acid; Burns, Chemical; Citrates; Citric Acid; Clinical Trials as Topic; Conjunctiva; Corneal Injuries; Corneal Transplantation; Eye Burns; Guinea Pigs; Humans; Male; Middle Aged; Random Allocation

Ascorbic acid (AA) has a pivotal role in corneal wound healing via stimulating the biosynthesis of highly organized extracellular matrix components, but its rapid degradation and low corneal permeability limits its therapeutic effects. In this paper, we present the pharmacokinetic properties of a liposomal-based formulation of AA in terms of corneal permeation. Chemical stability, shelf-life, and drug release rate of lyophilized liposome (AA-LLipo) formulation was determined in comparison to free-form of AA solution using high-performance liquid chromatography (HPLC) and rapid equilibrium dialysis. In vitro transcorneal permeability was studied using a parallel artificial membrane permeability assay (PAMPA). Ex vivo permeation was examined on AA-LLipo-treated porcine cornea by determining the AA content on the ocular surface, in the cornea as well as in the aqueous humor using HPLC, and by Raman-mapping visualizing the AA-distribution. Our results showed that the liposomal formulation improved the chemical stability of AA, while drug release was observed with the same kinetic efficiency as from the free-form of AA solution. Both corneal-PAMPA and porcine corneal permeability studies showed that AA-LLipo markedly improved the corneal absorption kinetics of AA, thus, increasing the AA content in the cornea and aqueous humor. AA-LLipo formulation could potentially increase the bioavailability of AA in corneal tissues.

Topics: Animals; Ascorbic Acid; Cornea; Corneal Injuries; Liposomes; Permeability; Swine

The objective of this study was to develop and evaluate an effective topical formulation to promote corneal epithelial wound healing. Ascorbyl glucoside (AA-2G), a stable prodrug of AA, was formulated in solid in oil (S/O) nanodispersions by emulsifying AA-2G solutions in cyclohexane using Span 85 as an emulsifying agent and freeze-drying emulsions to produce AA-2G - surfactant complex. The complexes were then dispersed in castor oil to produce S/O nanodispersions which were evaluated in terms of their particle size, polydispersity index, encapsulation efficiency, morphology, physical stability as well as the transcorneal permeation and accumulation of AA-2G. The same preparation procedure was used to prepare S/O nanodispersions of AA. S/O nanodispersions of AA and AA-2G were formulated into oily drops that were tested for efficacy in promoting wound healing after corneal epithelial depredation. AA-2G was loaded efficiently in S/O nanodispersions (EE > 99%) in the form of spherical nanoparticles. S/O nanodispersions were physically stable and resulted in improved permeation (18x) and accumulation (7x) of AA-2G in transcorneal diffusion experiments in comparison to AA-2G solutions. Oily eye drops of AA-2G and AA showed no irritation and significant improvement in epithelial healing in vivo in comparison to AA-2G and AA solutions.

Topics: Ascorbic Acid; Castor Oil; Corneal Injuries; Cyclohexanes; Emulsifying Agents; Glucosides; Humans; Ophthalmic Solutions; Prodrugs; Surface-Active Agents; Wound Healing

To offer an ideal hospitable environment for corneal keratocyte growth, the carrier materials can be functionalized with incorporation of signaling molecules to regulate cell biological events. This study reports, for the first time, the development of gelatin/ascorbic acid (AA) cryogels for keratocyte carriers in vitro and in vivo. The cryogel samples were fabricated by blending of gelatin with varying amounts of AA (0-300 mg) and carbodiimide cross-linking via cryogelation technique. Hydrophilic AA content in the carriers was found to significantly affect cross-linking degree and pore dimension of cryogels, thereby dictating their mechanical and biological stability and AA release profile. The cryogel carriers with low-to-moderate AA loadings were well tolerated by rabbit keratocyte cultures and anterior segment eye tissues, demonstrating good ocular biocompatibility. Although higher incorporated AA level contributed to enhanced metabolic activity and biosynthetic capacity of keratocytes grown on cryogel matrices, the presence of excessive amounts of AA molecules could lead to toxic effect and limit cell proliferation and matrix production. The cytoprotective activity against oxidative stress was shown to be strongly dependent on AA release, which further determined cell culture performance and tissue reconstruction efficiency. With the optimum AA content in carrier materials, intrastromally implanted cell/cryogel constructs exhibited better capability to enhance tissue matrix regeneration and transparency maintenance as well as to mitigate corneal damage in an alkali burn-induced animal model. It is concluded that understanding of antioxidant molecule-mediated structure-property-function interrelationships in gelatin/AA cryogels is critical to designing carrier materials for potential use in corneal stromal tissue engineering.. Multifunctional cryogel material can offer an ideal hospitable environment for cell-mediated tissue reconstruction. To our knowledge, this is the first report describing the use of gelatin/ascorbic acid (AA) cryogels as keratocyte carriers for corneal stromal tissue engineering. The AA loading during cryogel fabrication is found to have a significant effect on cross-linking degree and pore dimension, mechanical and biological stability, ocular biocompatibility, cell culture performance, and cytoprotective activity, giving comprehensive insight into fine-tuning the structure-property-function interrelationships of keratocyte carrier material. Using an alkali burn-induced animal model, we present evidence that with the optimum AA loading into cryogel materials, intrastromally implanted cell/carrier constructs exhibited better capability to enhance tissue matrix regeneration and transparency maintenance as well as to mitigate corneal damage.

Topics: Animals; Ascorbic Acid; Biocompatible Materials; Burns, Chemical; Cell Proliferation; Cells, Cultured; Corneal Injuries; Corneal Keratocytes; Corneal Stroma; Cryogels; Gelatin; Hydrophobic and Hydrophilic Interactions; Male; Microscopy, Electron, Scanning; Models, Animal; Oxidative Stress; Rabbits; Regeneration; Tissue Engineering

A 40-year-old woman with no known medical conditions or allergies presented with severely painful, watery eyes and blurred vision. She reported topical application of face-paint onto both upper eyelids prior to attending a Halloween party. She subsequently noticed a burning sensation, epiphora and misty vision within a few hours. On examination, bilateral large corneal epithelial defects were highlighted with fluorescein dye under cobalt-blue light. Antibiotic ointment, mydriatic and sodium ascorbate 10% eye-drops were given, and patient was advised to keep the eyelids shut to promote healing. No corneal defects were visible by day 4 and the patient was discharged with vision recovering to normal levels.

Topics: Adult; Ascorbic Acid; Chloramphenicol; Corneal Injuries; Cosmetics; Cyclopentolate; Diagnosis, Differential; Eyelids; Female; Humans; Ophthalmic Solutions; Wound Healing

To report the long-term sequelae of a case of bilateral chemical keratitis caused by airbag deployment.. Case report and review of the literature.. A 21-year-old woman presented with bilateral reduced vision, photophobia, and tearing after a car accident. Examination revealed some facial burns and severe chemical injury to the cornea and conjunctiva. Immediate irrigation with physiologic saline solution and subsequent treatment with topical antibiotics, corticosteroids, and vitamin C resulted in full restoration of vision but could not prevent permanent corneal damage.. Severe alkali injury of the cornea generally has a good prognosis but can lead to permanent damage and persistent complaints of dry eye.

Topics: Accidents, Traffic; Adult; Air Bags; Anti-Bacterial Agents; Ascorbic Acid; Burns, Chemical; Corneal Injuries; Drug Therapy, Combination; Eye Burns; Female; Follow-Up Studies; Glucocorticoids; Humans; Keratitis; Photophobia; Therapeutic Irrigation; Vision Disorders; Wounds, Nonpenetrating

Human corneal epithelial cells respond rapidly following injury to restore the integrity of the ocular surface. What stimulates and guides cells to move into the wound to heal? One candidate is the wound-induced electric field. Using vibrating probe techniques, we provide detailed temporal and spatial mapping of endogenous electric currents at rat corneal wounds. We find Cl- and Na+ are the major components of electric currents in rat corneal wounds. Na+ is the major component of ionic transport in the resting (nonwounded) rat cornea and of the wound center leakage current, whereas Cl- is a more important component of the endogenous electrical current at the wound edges. Enhancing or decreasing Cl- flow with clinically approved pharmacological agents such as aminophylline, ascorbic acid, or furosemide increased or decreased endogenous wound electric currents, respectively. These changes in wound currents correlated directly with the rate of wound healing in vivo. Thus, pharmacologically enhancing or decreasing wound-induced electric currents increased and decreased wound healing rate, respectively. This may have wide-reaching and novel therapeutic potential in the management of wound healing and may help explain some mechanistic aspects of the effects of some clinically used agents.

Topics: Aminophylline; Animals; Ascorbic Acid; Biological Transport; Chlorides; Corneal Injuries; Cyclic AMP; Electric Conductivity; Epithelium, Corneal; Female; Furosemide; Kinetics; Male; Phosphodiesterase Inhibitors; Potassium; Rats; Rats, Sprague-Dawley; Sodium; Wound Healing

Topics: Administration, Topical; Adult; Alkalies; Amnion; Ascorbic Acid; Burns, Chemical; Conjunctiva; Corneal Injuries; Drug Therapy, Combination; Eye Burns; Humans; Male; Tetracyclines; Treatment Outcome

To investigate the effect of artificial tear (AT) solution and epidermal growth factor (EGF) treatment on the cornea and aqueous humour ascorbic acid (AA) levels of full-thickness corneal wounded eyes.. The effect of EGF on the AA levels of aqueous humour and corneal wound tissue was determined in full-thickness corneal wounded rabbit eyes on the seventh post-operative day. There were three groups: untreated controls, AT-treated controls and an EGF+AT-treated experimental group (n = 6 in each group). Corneal wounded eyes were topically treated with 5 microl AT or 5 microl EGF in AT (1 mg/l EGF in AT prepaaration which contained 3.0% carbopol 940) twice daily for 6 days after operation. The wound strengths were also measured on the seventh post-operative day as a measure of wound healing. Statistical analysis was carried out using the Mann-Whitney U-test by Statview program.. The wound strengths of corneas, and AA levels of wound tissues and aqueous humour, increased significantly following AT and EGF treatment (p < 0.05).. In the corneal wounded eye, aqueous humour serves as a source of vitamin C and there may be a relation between EGF treatment in AT and AA levels of corneal wounded eye tissues.

Topics: Animals; Aqueous Humor; Ascorbic Acid; Cornea; Corneal Injuries; Epidermal Growth Factor; Female; Male; Ophthalmic Solutions; Rabbits; Tensile Strength; Wound Healing

We examined the effect of L-ascorbic acid 2-phosphate (P-Asc) on the healing of alkali-burned corneas in rabbits. Round filter paper containing 1 N NaOH was applied to the central cornea for 60 or 120 s to produce the alkali burn. Animals were treated with topical saline, 10% ascorbate, or 6.5% P-Asc applied on the cornea. The corneas were then examined histologically. Burned stroma showed no toluidine blue staining, indicating a loss of glycosaminoglycan. In the 60-s burn group, P-Asc reduced the size of the unstained area as compared with the control. Transmission electron microscopy showed basal lamina under new epithelia in the corneas treated with ascorbate or P-Asc, but not in controls. These observations support the theory that P-Asc may have a therapeutic role in the repair of corneal alkali burns.

Topics: Administration, Topical; Animals; Ascorbic Acid; Basement Membrane; Burns, Chemical; Cornea; Corneal Injuries; Corneal Stroma; Eye Burns; Female; Male; Ophthalmic Solutions; Rabbits; Sodium Hydroxide; Wound Healing

Topics: Alkalies; Animals; Aqueous Humor; Ascorbic Acid; Burns, Chemical; Carbon Dioxide; Conjunctiva; Corneal Injuries; Hydrogen-Ion Concentration; Oxygen Consumption; Rabbits

Topics: Ascorbic Acid; Burns, Chemical; Chemical Phenomena; Chemistry; Conjunctiva; Corneal Injuries; Eye Burns; Female; Humans; Infant, Newborn; Potassium Permanganate

Rabbits receiving subcutaneous ascorbate after corneal wounding showed significant elevation of aqueous humor ascorbate levels but no enhancement of wound breaking strength when compared to controls. In a second group of rabbits, perilimbal alkali burning reduced aqueous humor ascorbate levels one-half to one-third normal. In these perilimbally burned eyes with wounds in clear cornea, subcutaneous ascorbate significantly raised the aqueous humor ascorbate level and enhanced breaking wound strength compared to controls. We conclude that parenterally administered ascorbate has no salutory effect on the breaking strength of corneal wounds in the normal rabbit eye. In contrast, subcutaneous ascorbate has a very favorable effect on the breaking strengths of corneal wounds in those eye with depressed aqueous humor ascorbate.

Topics: Alkalies; Animals; Aqueous Humor; Ascorbic Acid; Burns, Chemical; Corneal Injuries; Eye Burns; Injections, Subcutaneous; Rabbits; Wound Healing

Severe ocular alkali burns in rabbits result in a decrease in aqueous humor ascorbate levels to one-third normal levels. If this deficiency is reversed by immediate treatment with parenteral or topical ascorbate, there is a significantly decreased incidence of subsequent corneal ulceration and perforation. The morphologic changes in these ulcerating corneas are typical of those noted in scorbutus (scurvy). It is concluded that alkali injury to the ciliary epithelial transport processes or ciliary body vasculature results in localized deficiency of ascorbic acid in the aqueous humor and cornea. The development of corneal ulceration is thought to be based on this deficiency which results in the failure of fibroblasts to produce sufficient collagen for repair. A randomized clinical trial of ascorbic acid in the treatment of human alkali burned eyes is now underway.

Topics: Alkalies; Animals; Aqueous Humor; Ascorbic Acid; Burns, Chemical; Cornea; Corneal Injuries; Corneal Ulcer; Disease Models, Animal; Eye Burns; Rabbits; Scurvy

Topics: Animals; Ascorbic Acid; Burns, Chemical; Cornea; Corneal Injuries; Corneal Ulcer; Eye Burns; Humans; Rabbits; Wound Healing

The corneas of albino rabbits were subjected to 45 sec, 12 mm, 2.3N hydrochloric acid burns. Of 18 eyes in nine rabbits receiving no treatment (controls), 11 (61%) developed ulceration sometimes progressing to descemetoceles and perforation. Of 17 eyes in nine rabbits receiving a daily subcutaneous injection of ascorbic acid (0.5 gm/kg), only one eye (5.9%) developed an anterior stromal ulcer. The difference in incidence of ulceration between the control and ascorbate-treated eyes was statistically significant (p less than 0.01). The aqueous humor level of ascorbate in untreated animals was 6.0 +/- 0.6 mg/dl compared to 33.0 +/- 2.7 in the treated group. This study therefore demonstrates that subcutaneous administration of ascorbic acid significantly raises the aqueous humor level of ascorbic acid in severely acid-burned eyes, thereby largely preventing the characteristic development of corneal ulceration. The mechanism of this effect is presumably the same as previously described for alkali-burned eyes.

Topics: Animals; Aqueous Humor; Ascorbic Acid; Burns, Chemical; Corneal Injuries; Corneal Ulcer; Eye Burns; Female; Hydrochloric Acid; Injections, Subcutaneous; Male; Rabbits

Topics: Adenosine Monophosphate; Adenosine Triphosphate; Animals; Ascorbic Acid; Cornea; Corneal Injuries; Cysteine; Male; Phospholipids; Rabbits

Topics: Adult; Ascorbic Acid; Corneal Injuries; Epithelium; Foreign-Body Reaction; Glyoxylates; Humans; Hydrogen-Ion Concentration; Male; Melanins; Metabolic Diseases; Oxalates; Retinal Detachment; Retinal Diseases; Uveitis; X-Ray Diffraction

Topics: Argyria; Ascorbic Acid; Cornea; Corneal Injuries; Humans; Iatrogenic Disease; Male; Middle Aged; Silver Nitrate; Spectrum Analysis

Topics: Acute Disease; Adrenal Cortex Hormones; Ascorbic Acid; Burns, Chemical; Chronic Disease; Contact Lenses; Cornea; Corneal Injuries; Edema; Eye Diseases; Glaucoma; Glucose; Glycerol; Humans; Hypertonic Solutions; Idoxuridine; Intraocular Pressure; Keratitis, Dendritic; Keratoconus; Ophthalmic Solutions; Povidone; Silicones; Sodium Chloride; Surface-Active Agents; Tears

Topics: Alkalies; Ascorbic Acid; Burns; Cornea; Corneal Injuries; Eye Burns; Humans