Corneal Necrosis Research Articles

Reconstruction of corneal stroma with decellularized porcine xenografts in a rabbit model

To evaluate the potential use of decellularized porcine stromal matrix (PSM) for reconstruction of corneal stroma in a rabbit model. Ten chinchilla bastard rabbit corneas were exposed to a circular half-thickness keratotomy with a 3.0 mm diameter at the central cornea. Porcine corneas were decellularized using hypotonic tris buffer, ethylene diamine tetra-acetic acid (EDTA, 0.1%), aprotinin (10 K IU/ml) and 0.3% sodium dodecyl sulphate (SDS). The 3.0 mm in diameter decellularized corneal stromal xenograft was inserted into the pocket, and the incision was closed with four 10.0 nylon sutures. Clinical photographs were taken at day 1, day 7, day 30 and on a monthly basis for up to 6 months after transplantation. Six months after surgery, the rabbits were killed and eyes were enucleated. Haematoxylin-eosin (HE) and 4,6-diamidino-2-phenylindole (DAPI) staining were performed to confirm the complete removal of the corneal cells after decellularization of porcine corneas and repopulation with rabbit cells. Alcian blue staining was performed for analysing the structure of the extracellular matrix (ECM). Efficient elimination of porcine cells was achieved by our decellularization protocol and confirmed via HE and DAPI stainings. Moreover, the major histoarchitectural ECM structure had been maintained as visualized by the alcian blue stain. Finally, the PSM was biocompatible with the host's epithelium evidenced as a regrowth covering the exposed xenograft. This novel technique of tissue engineering may provide one of many solutions to addressing anterior corneal pathological conditions in the face of a shortage of human corneal material.

The Boston Keratoprosthesis in the Management of Corneal Limbal Stem Cell Deficiency

To report the outcomes of the Boston type I keratoprosthesis (Massachusetts Eye and Ear Infirmary, Boston, MA) in the management of corneal limbal stem cell deficiency (LSCD). A retrospective review of all cases of keratoprosthesis implantation performed by a single surgeon (A.J.A.) between May 1, 2004, and March 31, 2010. Procedures performed for the management of LSCD were identified, and data were collected regarding the patients' ocular history, surgical procedure(s) performed, and postoperative outcomes, including interval visual acuities, retention, complications, and required surgical procedures. The outcome data from patients with LSCD were compared with those of individuals who underwent keratoprosthesis implantation for indications other than LSCD. Twenty-eight keratoprostheses were performed in 23 eyes of 22 patients with LSCD. The most common indications for surgery were chemical injury (7 eyes) and Stevens-Johnson syndrome (6 eyes). Preoperative corrected distance visual acuity (CDVA) was better than counting fingers in 4% of eyes with LSCD and in 9% of eyes without LSCD. Postoperative CDVA was 20/50 or better in 69%, 88%, and 67% of eyes with LSCD at 1, 2, and 3 years after keratoprosthesis implantation, respectively. Each of these percentages is higher than the percentage of eyes without LSCD obtaining CDVA of 20/50 or better at each time point. Whereas the retention failure rate in eyes with LSCD (0.148/eye-year) was higher than the rate in eyes without LSCD (0.114/eye-year), when eyes with Stevens-Johnson syndrome were excluded from the LSCD group, the non-Stevens-Johnson syndrome LSCD retention failure rate (0.056/eye-year) was half that of the non-LSCD group. The most common postoperative complications in eyes with LSCD were persistent corneal epithelial defect (PED) formation (56.5% of eyes) and sterile corneal necrosis (30%), whereas retroprosthetic membrane formation (46%) was the most common postoperative complication in eyes without LSCD, followed by PED formation (23%). The development of a PED was found to be a significant risk factor for sterile corneal stromal necrosis and infectious keratitis. Boston type I keratoprosthesis implantation results in a significant improvement in CDVA in the majority of patients with LSCD, with CDVA of 20/50 or better in more than two-thirds of eyes up to 3 years after surgery. PED formation is the most common postoperative complication in eyes with LSCD and is associated with an increased rate of sterile stromal necrosis and a lower retention rate in eyes undergoing keratoprosthesis implantation for immune-mediated LSCD. These results support the use of the Boston type I keratoprosthesis in managing bilateral, non-immune-mediated LSCD.

Outcomes with the Boston Type 1 Keratoprosthesis at Instituto de Microcirugía Ocular IMO

Purpose To report the outcomes on the Boston Type 1 Keratoprosthesis at our institution. Design Retrospective analysis case series. Participants We analyzed 54 eyes of 53 patients who previously underwent Boston Type 1 Keratoprosthesis surgery at our institution from July 2006 to March 2011. Methods Preoperative and postoperative parameters were collected and analyzed. Main outcome measures Visual acuity and keratoprosthesis stability. Results Common preoperative diagnoses were penetrating keratoplasty failure in 49 eyes (90.7%), chronic keratitis in 2 eyes (3.7%), ocular cicatricial pemphigoid in 1 eye (1.85%), Stevens Johnson syndrome in 1 eye (1.85%) and corneal vascularization in 1 eye (1.85%). Additionally, 40 eyes (74%) had preoperative glaucoma, and an Ahmed valve was implanted in 55% of them. Preoperative BCVA ranged from 20/200 to light perception. At an average follow-up of 20.15 months ± 12.7 (range, 1–56), postoperative vision improved to ⩾20/200 in 18 eyes (33.3%) and ⩾20/50 in 4 eyes (7.4%). The graft retention was 96%. Conclusions The Boston Type 1 keratoprosthesis is a valid option for high-risk patients. The design improvements in the Boston keratoprosthesis, as well as the daily implementation of the therapeutic methods, have notably diminished occurrence of the most serious complications, such as corneal necrosis and endophthalmitis. As such, glaucoma and its subsequent complications now stand as the most prevalent prognostic factor in the long term.

Pathological study of mycobacterium abscessus keratitis

To characterize the cytopathology, histopathology, immunohistochemistry and ultrastructural organization features of Mycobacterium abscessus keratitis. This retrospective case report included six cases with the lesions tissues scraped from acute phase of mycobacterium abscessus keratitis after corneal foreign body removal. Among the 6 scrapings, 4 were tested for Ziehl-Neelsen acid-fast staining and 3 were examined by transmission electron microscopy (TEM). The corneal tissues of 2 cases in chronic phase of the disease were collected during keratoplasty and were examined by pathological examination including hematoxylin-eosin (HE) staining, acid-fast staining, immunohistostaining and TEM. A single or fascicular red bacilli were observed after acid-fast staining in the four cases of corneal scrapings. The smear samples contained a large number of neutrophils and necrotic corneal epithelium and stroma tissue accompanying with a large number of mycobacteria that were positive for acid-fast staining scattered in and out of inflammatory cells. The corneal buttons obtained at keratoplasty in the 2 patients demonstrated corneal epithelial hyperplasia, stroma degeneration, necrosis and exelcosis, neutrophil and lymphocyte infiltration, neovascularization and fibrous hyperplasia, but no positive mycobacteria by Ziehl-Neelsen acid-fast staining. There were no CD4(+) or CD8(+) cells from immunohistochemistry examination. TEM of the corneal scrapings of the 3 cases showed phagocytosis of mycobacterium abscessus in mononuclear macrophage or neutrophils, inclusion compounds of small vacuoles and metachromatic granules in the thallium. TEM of corneal buttons of 2 cases showed slender rod-shaped mycobacteria with several to dozens of finely ground particles with high electron-dense, but no cell wall (L-form) or inclusion compounds. Mycobacterium abscessus keratitis presents acute purulent inflammatory changes in early stage and advances to chronic and non-specificity inflammation changes in late stage. L-formed mycobacterium abscessus make the disease protraction.

A case of intractable infectious keratitis and subsequent flap necrosis after laser in situ keratomileusis

We report on a patient in whom intractable infectious keratitis and subsequent lamellar flap necrosis necessitating flap amputation after laser in situ keratomileusis (LASIK). A 34-year-old woman undergoing LASIK complained of blurred vision and pain in the left eye. The best spectacle-corrected visual acuity was 0.01, and slit-lamp examination showed a marked presence of stromal infiltrates involving the flap and the underlying stroma in that eye. The patient was treated topically with hourly instillation of micronomicin, levofloxacin, and cefmenoxime, together with systemic administration of imipenem, but the left eye developed corneal flap necrosis. We performed surgical debridement of the diseased stroma and excised the lamellar flap. Since nontuberculous mycobacterium was detected on the surgical instruments, we then added oral clarithromycin, and substituted systemic administration of amikacin with that of imipenem. At one month after the flap removal, the visual acuity gradually improved to 0.7, but the stromal opacity of the central cornea and hyperopic shift of +3.0 diopters remained. LASIK can cause intractable keratitis, resulting in significant visual disturbance that presumably results from insufficient antisepsis of the medical instruments used for this surgery, supporting the importance of strict sterilization of these instruments.

Infectious Keratitis Caused by Aspergillus tubingensis

To report 2 cases of keratomycosis caused by Aspergillus tubingensis. The therapeutic courses were recorded for 2 male patients, 52 and 78 years old, with fungal keratitis caused by black Aspergillus strains. Morphological examination of the isolates was carried out on malt extract agar plates. A segment of the beta-tubulin gene was used for molecular identification. Antifungal susceptibilities were determined by the E test method for molds and the broth microdilution technique National Committee for Clinical Laboratory Standards M38-A. A 52-year-old man presented with complaints of pain and redness in the right eye. The patient was successfully treated with natamycin and econazole eyedrops, itraconazole eye ointment, and oral ketoconazole. A 78-year-old man presented with total corneal necrosis in the right eye. A therapeutic keratoplasty was performed, and topical natamycin and econazole were applied. At the postoperative visit after 3 weeks, almost the full corneal graft was clear with formed anterior chamber. Black Aspergillus strains were isolated from the corneal scrapings of both cases and initially identified as Aspergillus niger based on culture characteristics. Sequence analysis of a segment of the beta-tubulin gene revealed that the isolates are representatives of A. tubingensis. Aspergillus tubingensis is closely related with A. niger, the differentiation of these 2 species is difficult by classical morphological criteria. To our knowledge, the presented cases of fungal keratitis are the first reports on ocular infection caused by A. tubingensis.

Modulation of Integrin α4β1 (VLA-4) in Dry Eye Disease

To study the effect of topical application of very late antigen 4 (VLA-4) small-molecule antagonist (anti-VLA-4 sm) in a mouse model of dry eye disease. Anti-VLA-4 sm (or control vehicle) was applied topically to mice placed in a controlled-environment chamber. Corneal fluorescein staining and conjunctival T-cell enumeration were performed in the different treatment groups. Real-time polymerase chain reaction was used to quantify expression of inflammatory cytokines in the cornea and conjunctiva. Dry eye syndrome induced increased corneal fluorescein staining, corneal and conjunctival tumor necrosis factor alpha messenger RNA expression, and T-cell infiltration into the conjunctiva. Very late antigen 4 blockade significantly decreased corneal fluorescein staining compared with the untreated dry eye disease and control vehicle-treated groups (P < .001 and P = .02, respectively). In addition, VLA-4 blockade was associated with a significant decrease in conjunctival T-cell numbers (P < .001 vs control vehicle-treated group) and tumor necrosis factor-alpha transcript levels in the cornea (P = .04 vs control vehicle-treated group) and conjunctiva (P = .048 vs control vehicle-treated group). Application of topical anti-VLA-4 sm led to a significant decrease in dry eye signs and suppression of inflammatory changes at the cellular and molecular levels. Topical blockade of VLA-4 may be a novel therapeutic approach to treat the clinical signs and inflammatory changes accompanying dry eye disease.

Clostridium perfringens Keratitis Leading to Blinding Panophthalmitis

The purpose of this study was to report a case of Clostridium perfringens keratitis, which led rapidly to panophthalmitis, with loss of the eye in a healthy patient. Clinicopathologic case report, with a brief review of the literature. An otherwise healthy 50-year-old man without known risk factors developed a corneal ulcer, and within 48 hours, he lost all vision, with corneal perforation and panophthalmitis. The eye was enucleated, and the globe was examined histopathologically. The cornea was sampled for Gram staining and cultures, which revealed gram-positive rods and the growth of C. perfringens in the anaerobic culture. The globe revealed corneal necrosis and perforation, with acute inflammation in all layers of the eye. Gram-positive bacilli, consistent with C. perfringens, were identified in the vitreous cavity abscess. C. perfringens endophthalmitis cases from penetrating injuries are fulminant infections, with near universal loss of the eye, whereas C. perfringens keratitis cases are relatively indolent infections. To the best of our knowledge, this is the first report of a C. perfringens keratitis, which led rapidly to panophthalmitis. This aggressive behavior of C. perfringens has not been described previously in human subjects.

The clinical and pathogenic characteristics of keratitis caused by Alternaria alternata

To study the clinical and pathogenic characteristics of keratitis caused by Alternaria alternata and to provide evidence for the diagnose and treatment of mycotic keratitis. The patients with keratitis were examined by lamp microscope; the direct smears of corneal scrapings were stained using 10% potassium hydroxide and Giemsa's staining and the results were observed under microscope. After hypha was found, the samples from corneal were taken for fungal culture and fungal susceptibility test in vitro according to the National Community of Clinical Laboratory Standard (NCCLS) document M38-A at the same time. Ketoconazole, Amphotericin B and Fluconazole eye drops were applied into eyes frequently and alternately. The affectivity of the treatment were also observed. The isolates of Alternaria alternata from patients were used to induce keratitis in rabbits. The rabbits were sacrificed by air after 5 days and 14 days and their corneas were taken for pathology and inoculating for fungi. All the patients have only one eye with Alternaria alternata's keratitis and their average age was 50 years old. The lesions of corneal necrosis in the patients and Alternaria alternata's keratitis in the rabbits were appeared as light grey, shallow and a diffused edge. Alternaria alternata showed as thick transparent hypha and a great of spherical chlamydospores on the top of hypha or cluster one and the other in corneal scraping under microscope. The hypha and spores of Alternaria alternata in the culture medium were all brown and the spores were separated into cells like wall brick and grew on the top of spores linking like chains. Anti-microbial susceptibility testing in vitro showed that Alternaria alternata was susceptible to Voriconazole, Amphotericin B, Ketoconazole, Miconazole, Econazole, Terbinafine and Fluconazole but it was resistant to Clotrimazole, Flucytosine ang Itraconazole. 22 of the patients were cured by dropping Amphotericin B, Ketoconazole and Fluconazole frequently and alternately but surgery was performed in one case. The mean cured time was 34 day. The lesion of rabbits keratitis caused by Alternaria alternata was thin and localized only in the region of lacking epicytes. The isolate from the rabbit's keratitis model was Alternaria alternata. The keratitis caused by Alternaria alternata has its distinct clinical and laboratory characteristics. The virulence of Alternaria alternata is relatively low to cornea and the combination of anti-fungal agents could cure Alternaria alternata keratitis.

Delay in diagnosis and outcome of Acanthamoeba keratitis.

To evaluate the outcome of Acanthamoeba keratitis with respect to the delay in diagnosis. A retrospective review of the records of 14 patients treated for Acanthamoeba keratitis was carried out. Delay in diagnosis was correlated with risk factors, clinical presentation, method of diagnosis, final visual acuity and need for penetrating keratoplasty. Based on the time interval between the first symptoms and the diagnosis of Acanthamoeba keratitis, it appeared that patients could be divided into two groups: an early treatment group (group I), consisting of six patients treated within 18 days of onset of symptoms, and a late treatment group (group II), composed of eight patients treated beyond that time. There were no statistically significant differences between the two groups as far as risk factors, clinical presentation, accuracy of diagnosis and method of diagnosis were concerned, although more extensive and deeper corneal involvement was noted in group II. Improvement in visual acuity following medical therapy was seen in all six patients in the early group and in three (37%) of the eight patients in the late group. One patient in group I needed urgent penetrating keratoplasty for corneal necrosis. In group II, two patients underwent penetrating keratoplasty à chaud to prevent corneal perforation and three patients needed penetrating keratoplasty to restore functional visual acuity. A diagnostic delay of less than 18 days between onset of symptoms and start of anti-amoebic treatment results in a better final VA after medical treatment and obviates the need for urgent and elective penetrating keratoplasty.

Intraoperative wavefront monitoring during laser thermal keratoplasty.

Low energy laser thermal keratoplasty (LTK) is being proposed as an alternative to conventional holmium LTK in an effort to minimize corneal tissue necrosis, regression, and induced astigmatism. Real-time wavefront monitoring during surgery is also being proposed as a method for regulating induced aberrations and the treatment end point. We evaluated the feasibility of intraoperative wavefront monitoring during low energy LTK. An investigational prototype system combining a Sunrise Hyperion laser with a Shack-Hartmann wavefront sensor (Wavefront Sciences COAS) was used to treat 20 hyperopic eyes with a low energy application of eight spots of 18mJ/shot (144mJ/pulse) at 5 Hz in two rings of 6 mm and 7-mm diameter, while monitoring the treatment with real-time dynamic wavefront sensing up to 10 captures/second of 4th order Zernike data. The integrated wavefront-monitored LTK unit showed good stability in measuring dynamic intraoperative wavefront refractions before, during, and after the low energy LTK treatment. The readings did not interfere with the application of holmium laser pulses, nor did the LTK treatment distort the captured wavefront readings. A steady improvement of the wavefront-derived spherical equivalent refraction followed the laser treatment pattern, with a mean attempted spherical equivalent refractive change of 1.66 D and mean achieved change of 1.71 D. Intraoperative wavefront monitoring was feasible during low energy LTK. With future adaptation, it might be possible to dynamically relay the captured wavefront information to the laser during ongoing treatment, to intraoperatively control the surgical endpoint for multiple aberration terms.

Custom-designed plaque radiotherapy for nonresectable iris melanoma in 38 patients: tumor control and ocular complications

PurposeTo evaluate plaque radiotherapy for iris melanoma. DesignProspective noncomparative interventional case series. MethodsFor 38 patients, custom-designed plaque radiotherapy using iodine 125 isotope was applied overlying the cornea with a tumor apex dose of 80 Gy. The main outcome measures were tumor control and ocular complications using Kaplan-Meier estimates and Cox proportional hazards regression analysis. ResultsIn all cases, the melanoma was nonresectable owing to large or discohesive tumor. The tumor configuration was nodular in 24 cases (63%) and flat (diffuse) in 14 (37%). The mean tumor basal diameter was 9 mm (range 4 to 13 mm). Solid tumor extended into the anterior chamber angle in 36 eyes (95%). Tumor seeds were noted on the iris stroma for a mean of 7 clock hours and in the anterior chamber angle for a mean of 4 clock hours. Five-year follow up revealed tumor metastasis in 0% and tumor recurrence in 8% of patients. Visual acuity of 20/200 or worse was found in 16% at 5 years. Radiation-related complications at 5 years included corneal epitheliopathy (9%), cataract (70%), and neovascular glaucoma (8%). No patients developed corneal necrosis, scleral necrosis, retinopathy, or papillopathy. After treatment, the combined incidence of tumor-related and radiation-related elevated intraocular pressure at 5 years was 33%. Enucleation was necessary in 13% at 5 years, for tumor recurrence (n = 3) and patient preference (n = 1). ConclusionsPlaque radiotherapy is a useful alternative to enucleation for eyes with nonresectable iris melanoma. Tumor control is 92% at 5 years, but related complications, especially cataract and elevated intraocular pressure, should be anticipated.

Corneal perforation due to late radiation therapy-induced corneal necrosis ? Clinicopathological correlation

Corneal perforation due to late radiation therapy-induced corneal necrosis ? Clinicopathological correlation

Corneal perforation due to late radiation therapy-induced corneal necrosis – Clinicopathological correlation

A clinicopathological correlation is made between corneal perforation and late radiation therapy-induced corneal necrosis in a male adolescent treated for orbital rhabdomyosarcoma.

Acute corneal necrosis after excimer laser keratectomy for hyperopia

ObjectiveTo describe a new, rare clinical complication after routine excimer laser photorefractive keratectomy to correct hyperopia. DesignCase report with clinicopathologic correlation. Main outcome measuresFour weeks after treatment with excimer laser, a perforating keratoplasty was performed for persistent corneal opacities. The corneal button was examined using light and electron microscopy. Special immunohistochemical stains were used to detect apoptosis. ResultsThe patient developed corneal opacities, endothelial precipitates, and a fibrinous exudate in the anterior chamber after the laser treatment. The changes did not respond to therapy directed against bacteria, fungi, and Acanthamoeba. All examinations and special stains were negative for micro-organisms. By light microscopy, an anterior zone of corneal necrosis was present with a moderate amount of acute inflammatory cells. At the interface between necrotic and viable corneal stroma, keratocytes with typical features of apoptosis were detected by immunohistochemistry and electron microscopy. ConclusionThis is the first full histopathologic report of a case of acute corneal necrosis with signs of apoptosis after excimer laser therapy of the cornea. Surgeons should be aware of this rare but potentially severe complication.

Subconjunctival injection of low-dose Mitomycin-C for treatment of failing human trabeculectomies.

To evaluate the safety and efficacy of a low-dose Mitomycin C injected subconjunctivally after a guarded filtration operation in humans. Fourteen patients with failing filters received an injection of 0.01 mg Mitomycin C (0.25 ml of 0.04 mg/ml solution) into the filtering bleb. Eyes with end stage glaucoma of patients with healthy or successfully operated fellow eye were selected for the treatment. In 6 of the cases 2 to 5 days later a needle revision of the bleb was performed. In 12 of the treated eyes (86%) we found a lowering of the IOP with a mean of 8.08 mmHg (range 4 to 13 mmHg) and a development of a typical wide, pale, avascular filtering bleb. Complications, such as conjunctival, scleral or corneal necrosis, wound dehiscence, bleb leaks, hypotony or any clinically detectable signs of toxic damage of the anterior segment of the eye were not observed. Subconjunctival injection of low-dose Mitomycin C in the early postoperative period may offer a useful option for improving the outcome in some cases of failing trabeculectomies. This alternative method of application seems to enhance the effect of a subsequent needle revision. With the concentration used we did not find any undesirable complications after a follow-up of 1 to 9 months.

Xerophthalmia, keratomalacia and nutritional blindness

Vitamin A deficiency remains a major cause of pediatric ocular morbidity. Over five million children develop xerophthalmia annually, a quarter million or more becoming blind. It is also a major pathway for measles-associated blindness, particularly in Africa. Treatment is practical and inexpensive, based upon the oral administration of 200,000 IU vitamin A on two successive days, at a cost of 10 cents U.S. Given the potential rapidity of corneal necrosis (keratomalacia) and the relative inaccessibility of health services to those at greatest risk, prevention is probably more important than treatment. Oral administration of high dose supplements (2000,000 IU every 3 to 6 months), vitamin A fortification of commonly consumed items, or best of all, increased dietary intake of natural sources of vitamin A will reduce the number of needlessly blind young children. Given recent evidence that vitamin A deficiency greatly increases overall mortality, even among children without evidence of xerophthalmia, the same prophylactic regimen may improve child survival by 35% or more.

Vitamin A Deficiency and Xerophthalmia

Vitamin A deficiency and xerophthalmia are widely considered to be problems of developing countries. Indeed, more than 60 such countries are recognized by the World Health Organization as suffering from an aggregate 5 million new cases of xerophthalmia, one quarter million resulting in blindness, every year. 1 The true number may be twice as large: recent data suggest that a significant proportion of measles-associated blindness, the major cause of pediatric blindness in Africa, is secondary to acute decompensation of borderline vitamin A status. 2 The mechanism(s) by which vitamin A deficiency results in corneal ulceration and necrosis remains uncertain, but local sepsis appears to be a late and variable complication. 3,4 See also pp 350 and 354. Recent data suggest that vitamin A deficiency also has a profound impact on general morbidity, 5 mortality, 6-8 growth, 8,9 and hematopoiesis. 8,10 Even subclinical deficiency may have important implications for survival. 11

6 Final Report on the Safety Assessment of Morpholine

Morpholine is used in cosmetic products as a surfactant and emulsifier at concentrations up to 5%.Morpholine is metabolized in guinea pigs but was not significantly metabolized in rats, dogs, or rabbits. Dermal LD50s in rabbits ranged between 0.3 and 1.2 g/kg. The oral LD50s in rats were between 1.1 and 1.6 g/kg; in guinea pigs the oral LD50was 0.9 g/kg.In studies of acute and short-term dermal toxicity Morpholine as an undiluted and unneutralized solution or as a diluted and unneutralized solution applied daily to the skin of guinea pigs and rabbits, respectively, caused the deaths of the test animals within 2 weeks. In both cases, the skin was necrotic.Unneutralized solutions of Morpholine caused severe corneal necrosis, but upon neutralization Morpholine was not injurious to rabbit eyes.In short-term inhalation studies (in rats) with varying concentrations of Morpholine, the effects observed included irritation of the mucous membranes and an increased respiratory rate. Chronic inhalation studies of Morpholine in rats and guinea pigs reported changes in the nervous system activity and arterial and peripheral blood pressure. At high concentrations Morpholine produced swelling of the alveolar cells and atrophy of lymphoid elements in the spleen. At lower concentrations a decrease in the size of the lymph nodules in the spleen was noted.Morpholine was a weak positive mutagen in L5178 mouse lymphoma assay, in BALB/3T3 malignant cell transformation and fibroblast transformation assays, and in sister chromatid exchange assays, but was negative in the Ames test with and without metabolic activation. At nontoxic doses Morpholine did not increase the rate of DNA repair in rat hepatocytes. Results of other mutagenic assays varied according to the system used.Nitrosation of Morpholine produces N-nitrosomorpholine, which has been mutagenic in a variety of test systems. Simultaneous exposure of laboratory animals to Morpholine and nitrites has caused a number of different cancers. A carcinogenic response was produced in rats in a long-term feeding study of Morpholine in which nitrites were present in the diet.In humans, Morpholine is absorbed and is considered to be a skin and eye irritant, as well as a skin sensitizer. A formulation containing 1% Morpholine indicated that the ingredient was neither an irritant nor sensitizer.Morpholine is not considered to be an animal carcinogen. It reacts easily with nitrosating agents, resulting in the formation of N-nitrosomorpholine. Under conditions of use, it is highly unlikely that Morpholine is totally free of carcinogenic nitrosoamines. Without quantitative data regarding the formation of N-nitrosomorpholine under conditions of use, it cannot be concluded that Morpholine is safe for use in cosmetic products.

Corneal necrosis and sequestration in the cat: a review and record of 100 cases

ABSTRACTA distinct type of ulcerative keratitis, apparently specific to the cat, and of unknown aetiology, has been noted by many authors. This condition is described and a review of the literature is provided. Clinical signs presented are analysed, together with breed, sex and age incidence, and a record of 100 cases noted over a 12 year period is provided. Earlier observations of possible causation are discussed and a note made of further investigations needed to establish the aetiology of this corneal disorder.