Mechanical behaviour of healthy versus alkali-lesioned corneas by a porcine organ culture model.

BACKGROUND: Cornea is a composite tissue exhibiting nonlinear and time-dependent mechanical properties. Corneal ulcers are one of the main pathologies that affect this tissue, disrupting its structural integrity and leading to impaired functions. In this study, uniaxial tensile and stress-relaxation tests are developed to evaluate stress-strain and time-dependent mechanical behaviour of porcine corneas. RESULTS: The samples are split in two groups: some corneas are analysed in an unaltered state (healthy samples), while others are injured with alkaline solution to create an experimental ulcer (lesioned samples). Furthermore, within each group, corneas are examined in two conditions: few hours after the enucleation (fresh samples) or after 7 days in a specific culture medium for the tissue (cultured samples). Finally, another condition is added: corneas from all the groups undergo or not a cross-linking treatment. In both stress-strain and stress-relaxation tests, a weakening of the tissue is observed due to the imposed conditions (lesion, culture and treatment), represented by a lower stiffness and increased stress-relaxation. CONCLUSIONS: Alkali-induced corneal stromal melting determines changes in the mechanical response that can be related to a damage at microstructural level. The results of the present study represent the basis for the investigation of traditional and innovative corneal therapies.

Streptococcus pneumoniae endophthalmitis: clinical settings, antibiotic susceptibility, and visual outcomes.

Streptococcus pneumoniae endophthalmitis is clinically more severe, more difficult to treat, and carry a higher risk of vision loss, evisceration, or enucleation. This study is to investigate the clinical settings, antibiotic susceptibility, and visual outcomes of S. pneumoniae endophthalmitis at a tertiary referral center in Taiwan. S. pneumoniae endophthalmitis was diagnosed in 38 eyes of 38 patients. The main clinical features were postcataract endophthalmitis (n = 13, 34%) and endophthalmitis associated with corneal ulcer (n = 12, 32%), trauma (n = 6, 16%), endogenous etiology (n = 4, 11%), trabeculectomy (n = 2, 5%), and pterygium excision-related scleral ulcer (n = 1, 3%). Presenting visual acuity ranged from counting fingers to no light perception. Pars plana vitrectomy with intravitreal antibiotics was performed in 17 eyes (39%) in primary or secondary treatments. S. pneumoniae isolates were susceptible to vancomycin (38/38, 100%), penicillin (37/38, 97%), ceftriaxone (37/38, 97%), cefuroxime (12/15, 80%), levofloxacin (13/15 ,87%), and moxifloxacin (15/17, 88%). Final visual acuity was better than 20/400 in 3 of 38 eyes (8%), 5/200 to hand motions in 3 eyes (8%), and light perception to no light perception in 32 eyes (84%). Ten eyes (26%) underwent evisceration or enucleation. Although S. pneumoniae isolates were susceptible to vancomycin, S. pneumoniae endophthalmitis had a very poor visual prognosis.

Epidemiology of Microbial Keratitis in Uganda: A Cohort Study.

Purpose: To describe the epidemiology of Microbial Keratitis (MK) in Uganda.Methods: We prospectively recruited patients presenting with MK at two main eye units in Southern Uganda between December 2016 and March 2018. We collected information on clinical history and presentation, microbiology and 3-month outcomes. Poor vision was defined as vision < 6/60).Results: 313 individuals were enrolled. Median age was 47 years (range 18-96) and 174 (56%) were male. Median presentation time was 17 days from onset (IQR 8-32). Trauma was reported by 29% and use of Traditional Eye Medicine by 60%. Majority presented with severe infections (median infiltrate size 5.2 mm); 47% were blind in the affected eye (vision < 3/60). Microbiology was available from 270 cases: 62% were fungal, 7% mixed (bacterial and fungal), 7% bacterial and 24% no organism detected. At 3 months, 30% of the participants were blind in the affected eye, while 9% had lost their eye from the infection. Delayed presentation (overall p = .007) and prior use of Traditional Eye Medicine (aOR 1.58 [95% CI 1.04-2.42], p = .033) were responsible for poor presentation. Predictors of poor vision at 3 months were: baseline vision (aOR 2.98 [95%CI 2.12-4.19], p < .0001), infiltrate size (aOR 1.19 [95%CI 1.03-1.36], p < .020) and perforation at presentation (aOR 9.93 [95% CI 3.70-26.6], p < .0001).Conclusion: The most important outcome predictor was the state of the eye at presentation, facilitated by prior use of Traditional Eye Medicine and delayed presentation. In order to improve outcomes, we need effective early interventions.

Corneal melt secondary to eosinophilic granulomatosis with polyangiitis.

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare antineutrophil cytoplasmic antibody-associated vasculitis that can affect any organ system. It is most often characterised by chronic airway inflammation along with prominent peripheral blood eosinophilia, although the disease can affect the cardiovascular, gastrointestinal, renal or central nervous systems. Ocular manifestations are uncommon and when they do occur, are varied in their clinical presentations. To the best of our knowledge, this is the first case of corneal melt secondary to EGPA to have been reported.

Identification and Characterization of Fusarium proliferatum, a New Species of Fungi that Cause Fungal Keratitis.

Fusarium proliferatum (F. proliferatum) is known as a pathogen of corn and other crops, but its role in fungal keratitis has not been well investigated. Among 877 Fusarium isolates, we identified 155 (17.7%) stains as F. proliferatum according to their morphological features and partial DNA sequencing of translation elongation factor-[Formula: see text] (EF-[Formula: see text]) in this study. In vitro antifungal susceptibility tests showed that the F. proliferatum strains were sensitive to natamycin and vorionazole but resistant to amphotericin B, fluconazol, ketoconazole and itaconazole. Most of the F. proliferatum-positive keratitis patients (44/155,28.4%) were aged 51-60 years old. The main cause of infection was injury by a plant (51/155, 32.9%). A combination of 1% amphotericin B and 3% ketoconazole cured 45.2% (14/31) and a combination of 0.5% natamycin and 0.5% voriconazole cured 59.1% (13/22) of F. proliferatum-positive patients. The date suggests that F. proliferatum identified through EF-1ɑ DNA sequencing is an important new species that causes fungal keratitis. Based on antifungal susceptibility, treatment with a combination of 0.5% natamycin and 0.5% voriconazole improves the therapeutic efficacy in F. prolifertum-positive patients.

Plasma rich in growth factors for the treatment of rapidly progressing refractory corneal melting due to erlotinib in nonsmall cell lung cancer.

RATIONALE: Erlotinib, an antineoplastic agent, is indicated for the treatment of patients with advanced nonsmall cell lung cancer. Most common adverse events are manageable, although more severe ones require dose reduction or discontinuation of erlotinib treatment. PATIENT CONCERNS: We present a case of severe corneal ulcer treated with autologous plasma rich in growth factors. DIAGNOSES: A 76-year-old woman with stage IVB (cT2a N0 M1c) lung cancer under erlotinib treatment presented with rapidly progressing corneal ulcer. Evolution was torpid and refractory to conventional treatment. INTERVENTIONS: Surgical options were dismissed because of the poor performance status of the patient. Despite temporary discontinuation of erlotinib treatment, the corneal ulcer continued to worsen with peripheral corneal neovascularization, stromal thinning, corneal edema, and profuse inflammation of the ocular surface. OUTCOMES: Treatment with autologous plasma rich in growth factors prevented an imminent corneal perforation and improved the corneal ulcer for over a year of follow-up. LESSONS: Considering the poor results of conventional treatment, both medical and surgical, management of the inflammation of the ocular surface together with the stimulation of the healing processes through regenerative therapy such as PRGF, can be an option worth considering in these cases.

Cytotoxic clinical isolates of Pseudomonas aeruginosa identified during the Steroids for Corneal Ulcers Trial show elevated resistance to fluoroquinolones.

BACKGROUND: To determine the relationship between type three secretion genotype and fluoroquinolone resistance for P. aeruginosa strains isolated from microbial keratitis during the Steroids for Corneal Ulcers Trial (SCUT) and for two laboratory strains, PA103 and PAO1. METHODS: Confirmed P. aeruginosa isolates from the SCUT were divided into exoU(+) or exoU(-). The exoU(+) strains contained the gene encoding ExoU, a powerful phospholipase toxin delivered into host cells by the type three secretion system. Isolates were then assessed for susceptibility to fluoroquinolone, cephalosporin, and aminoglycoside antibiotics using disk diffusion assays. Etest was used to determine the MIC of moxifloxacin and other fluoroquinolones. Laboratory isolates in which the exoU gene was added or deleted were also tested. RESULTS: A significantly higher proportion of exoU(+) strains were resistant to ciprofloxacin (p = 0.001), gatifloxacin (p = 0.003), and ofloxacin (p = 0.002) compared to exoU(-) isolates. There was no significant difference between exoU(+) or exoU(-) negative isolates with respect to susceptibility to other antibiotics except gentamicin. Infections involving resistant exoU(+) strains trended towards worse clinical outcome. Deletion or acquisition of exoU in laboratory isolates did not affect fluoroquinolone susceptibility. CONCLUSIONS: Fluoroquinolone susceptibility of P. aeruginosa isolated from the SCUT is consistent with previous studies showing elevated resistance involving exoU encoding (cytotoxic) strains, and suggest worse clinical outcome from infections involving resistant isolates. Determination of exoU expression in clinical isolates of P. aeruginosa may be helpful in directing clinical management of patients with microbial keratitis.

Comparação entre dois protocolos de tratamento de ceratoconjuntivite seca experimentalmente induzida em coelhos / Comparison of two treatment protocols of experimentally induced keratoconjunctivitis sicca in rabbits

O objetivo deste estudo foi avaliar e comparar a eficácia de dois protocolos de tratamento de ceratoconjuntivite seca (CCS) experimentalmente induzida em coelhos: uma formulação oftálmica tópica composta por álcool polivinílico 1,4%, adicionado com acetilcisteína 10% e pilocarpina 1% (AAP), e outro protocolo com o uso do óleo de semente de linhaça (OL) tópico em forma de colírio, durante 12 semanas. Foram utilizados 15 coelhos machos, adultos, da raça Nova Zelândia, alocados aleatoriamente em três grupos: grupo C (controle), grupo AAP (formulação oftálmica) e grupo L (OL tópica). Os animais foram avaliados semanalmente pelo teste lacrimal de Schirmer, teste de fluoresceína e teste de Rosa Bengala; uma vez por mês, pelo exame de citologia esfoliativa ocular; ao final do experimento, pela análise histopatológica da córnea e conjuntiva. Os resultados demonstraram que houve um aumento maior na produção lacrimal quando utilizada a formulação oftálmica, e uma resolução mais rápida das úlceras de córnea, bem como diminuição no número de células desvitalizadas quando utilizado o óleo de semente de linhaça, além de aumento no número de células caliciformes em ambos os grupos de tratamento. A associação desses dois protocolos pode ser no futuro uma alternativa no tratamento da CCS.

The objective of this study was to evaluate and compare the effectiveness of two treatment protocol of experimentally induced keratoconjunctivitis sicca (KCS) in rabbits, a topical ophthalmic formulation composed by 1.4% povinilic alcohol added with 10% acetylcysteine and 1% pilocarpine (AAP) and another protocol with the topical use of the linseed seed oil (LO) in eye drop form f or 12 weeks. Fifteen male New Zealand white rabbits were aleatory allocated in 3 groups: Group C (Control), Group AAP (ophthalmic formulation) and Group L (LO topical). The animals were evaluated weekly using the Schirmer's tear test, fluorescein test and Rose Bengal test monthly for ocular cytology, and at the end of the experiment for histopathological analysis of cornea and conjunctive. The results demonstrated that there was a larger increase in the tear production when the ophthalmic formulation was us ed and a faster rapid resolution of corneal ulcers and decrease in the number of devitalized cells when linseed seed oil was used, besides an increase in the number of caliciform cells in both treatment groups. The association of those two protocols can be a future alternative in the treatment of KCS.

Vernal keratoconjunctivitis: a severe allergic eye disease with remodeling changes.

Vernal keratoconjunctivitis (VKC) is an unusually severe sight-threatening allergic eye disease, occurring mainly in children. Conventional therapy for allergic conjunctivitis is generally not adequate for VKC. Pediatricians and allergists are often not familiar with the severe clinical symptoms and signs of VKC. As untreated VKC can lead to permanent visual loss, pediatric allergists should be aware of the management and therapeutic options for this disease to allow patients to enter clinical remission with the least side effects and sequelae. Children with VKC present with severe ocular symptoms, that is, severe eye itching and irritation, constant tearing, red eye, eye discharge, and photophobia. On examination, giant papillae are frequently observed on the upper tarsal conjunctiva (cobblestoning appearance), with some developing gelatinous infiltrations around the limbus surrounding the cornea (Horner-Trantas dot). Conjunctival injections are mostly severe with thick mucus ropy discharge. Eosinophils are the predominant cells found in the tears and eye discharge. Common therapies include topical antihistamines and dual-acting agents, such as lodoxamide and olopatadine. These are infrequently sufficient and topical corticosteroids are often required for the treatment of flare ups. Ocular surface remodeling leads to severe suffering and complications, such as corneal ulcers/scars. Other complications include side effects from chronic topical steroids use, such as increased intraocular pressure, glaucoma, cataract and infections. Alternative therapies for VKC include immunomodulators, such as cyclosporine A and tacrolimus. Surgery is reserved for those with complications and should be handled by ophthalmologists with special expertise. Newer research on the pathogenesis of VKC is reviewed in this article. Vernal keratoconjunctivitis is a very important allergic eye disease in children. Complications and remodeling changes are unique and can lead to blindness. Understanding of pathogenesis of VKC may lead to better therapy for these unfortunate patients.

Comparison of besifloxacin, gatifloxacin, and moxifloxacin against strains of pseudomonas aeruginosa with different quinolone susceptibility patterns in a rabbit model of keratitis.

PURPOSE: Determine the effectiveness of topical besifloxacin, gatifloxacin, and moxifloxacin in treating keratitis caused by 2 strains of Pseudomonas aeruginosa with different quinolone susceptibility profiles. METHODS: Minimal inhibitory concentrations (MICs) were determined for each fluoroquinolone. Sequence analysis was performed on the quinolone resistance determining regions of the ciprofloxacin/levofloxacin-resistant strain. Rabbit corneas were injected with 10 colony-forming units (CFU). After 16 hours, phosphate-buffered saline, besifloxacin (6 mg/mL), gatifloxacin (3 mg/mL), or moxifloxacin (5 mg/mL) was applied topically every 15 minutes for 5 doses, then every 30 minutes for 14 doses. Eyes were examined pre- and posttreatment. Corneas were harvested for bacterial quantitation. RESULTS: MICs against the fully susceptible strain were 0.5, 0.25, and 0.5 µg/mL for besifloxacin, gatifloxacin, and moxifloxacin, respectively. The MICs against the ciprofloxacin/levofloxacin-resistant strain were 2, 16, and 32 µg/mL for besifloxacin, gatifloxacin, and moxifloxacin, respectively. Sequence analysis revealed amino acid mutations in all 4 fluoroquinolone target genes. None of the treatments had an effect on clinical severity of eyes infected with the fully susceptible strain (P > 0.05); however, all were effective at significantly reducing the bacterial CFU in the corneas (P < 0.05). For the ciprofloxacin/levofloxacin-resistant strain, clinical scores of besifloxacin-treated eyes were significantly lower than moxifloxacin-treated eyes (P < 0.037). The quantities of ciprofloxacin/levofloxacin-resistant bacteria recovered from corneas of all treatment groups were significantly lower than those recovered from phosphate-buffered saline-treated corneas (P < 0.05). Besifloxacin-treated eyes had significantly lower CFU recovered as compared with that of gatifloxacin- and moxifloxacin-treated eyes (P < 0.05). CONCLUSIONS: These results support clinical investigation of the effectiveness of besifloxacin in treating Pseudomonas keratitis.

Nona-D-arginine therapy for Pseudomonas aeruginosa keratitis.

PURPOSE: Nona-D-arginine amide (D9R) was evaluated as treatment for Pseudomonas aeruginosa keratitis when administered alone and with ciprofloxacin. METHODS: Mouse corneas were infected with P. aeruginosa. Immediately after infection and hourly for 5 hours, eyes received 5 microL of either Dulbecco phosphate-buffered saline (D-PBS), 10 microM D9R, or 100 microM D9R. At 16 hours postinfection (PI) and then hourly for 5 hours, eyes treated with D9R or D-PBS then received 5 microL ciprofloxacin (0.08%) or deionized water. On days 1, 7, and 14 PI, eyes were scored on a scale of 0 (normal eye) to +4 (corneal perforation). On day 1 PI, mice were euthanatized and eyes were harvested for histopathology or colony-forming unit (CFU) determination. At 6, 12, and 24 hours PI, corneas treated with 100 microM D9R or D-PBS alone were harvested for the determination of IL-1beta cytokine concentrations. RESULTS: Eyes treated with 10 or 100 microM D9R and ciprofloxacin had significantly less disease than eyes treated with D-PBS and ciprofloxacin. Fewer than 30 CFUs were recovered from any eye treated with ciprofloxacin. Eyes treated with D9R alone had significantly less disease and lower IL-1beta cytokine concentrations than D-PBS-treated eyes; however, there were no significant differences in CFU (> or = 4 log(10)) between these groups. CONCLUSIONS: Administration of 10 or 100 microM D9R effectively reduced the abnormality associated with P. aeruginosa keratitis. Treatment with D9R and ciprofloxacin was superior to treatment with antibiotic alone by reducing ocular disease through suppression of the proinflammatory cytokine IL-1beta and eradicating viable bacteria from the eye.

Effect of the vehicle on the topical itraconazole efficacy for treating corneal ulcers caused by Aspergillus fumigatus.

BACKGROUND: The clinical behaviour of mycotic keratitis is aggressive, and the options for treating it are limited. This poses a need to explore new options for efficacious, low-cost treatment. Recent evidence suggests that topical itraconazole may be useful for treating this entity and that it may be possible to improve its efficacy using a suitable vehicle. METHODS: We included 12 New Zealand white (NZW) rabbits (24 eyes). The rabbits were infected with pathogenic strains of Aspergillus fumigatus and subsequently randomized to receive every 2 h for 5 weeks two different preparations of topical itraconazole 1%. In group 1 (12 eyes), ricinus oil and in group 2 (12 eyes), Systane were used as vehicle. Rabbits were evaluated every week by a masked ophthalmologist to determine the treatment response. RESULTS: The size of the ulcers was similar in the two groups at the baseline: group 1: 12.7 +/- 2.7 mm (median 12.8, range 9.8-15.5 mm); and group 2: 12.3 +/- 3.1 mm (median 12.1, range 9.8-20.8; P = 0.67). Although both groups responded well to the treatment, the response was better in the group 2, especially in weeks 2 and 3: week 1: 12.7 +/- 2.7 vs. 9.3 +/- 4.61 mm (P = 0.1); week 2: 9.4 +/- 3.4 vs. 4.1 +/- 2.9 mm (P = 0.004); week 3: 5.0 +/- 3.4 vs. 1.7 +/- 1.0 mm (P = 0.004); week 4: 1.9 +/- 1.9 vs. 1.0 +/- 1.2 mm (P = 0.1); and week 5: 0.68 +/- 1.2 vs. 0.0 +/- 0.0 mm (P = 0.3). CONCLUSION: Topical itraconazole may be useful for treating corneal ulcers caused by Aspergillus fumigatus, and its efficacy seems to be related with the vehicle solubility.

Severe corneal toxicity after topical fluoroquinolone therapy: report of two cases.

PURPOSE: To describe 2 cases of sterile corneal ulcers that persisted after several weeks of therapy with topical moxifloxacin 0.5% but that resolved when antibiotic therapy was changed. METHODS: Small case series. RESULTS: Both cases presented here describe corneal ulcers that persisted and showed signs of worsening during weeks of frequent topical dosing with moxifloxacin. Descemet folds and an atypically large amount of stromal edema were present in both cases, and there appeared to be possible endothelial dysfunction as well. There was no sign of bacterial, viral, or fungal infection in either case. In both cases, healing began a few days after moxifloxacin was discontinued, and topical gatifloxacin and corticosteroids were initiated. CONCLUSION: These cases suggest that moxifloxacin may interfere with the healing of corneal ulcers.

Ocular complications in a child with acute graft-versus-host disease following cord blood stem cell transplantation: therapeutic challenges.

We present the first child case of pseudomembranous conjunctivitis accompanied by an extensive corneal ulcer with acute graft-versus-host disease (GVHD) after cord blood stem cell transplantation (CBSCT). The histopathology of the pseudomembrane and the ocular changes following its excision were investigated specifically. One week after the excision of pseudomembrane, the extensive corneal epithelial defects had totally disappeared. Pseudomembrane excision may be an effective method of treatment in corneal epithelial defects observed after GVHD.

[Corneal precipitation of fluoroquinolones with magnesium]. / Cristallisation cornéenne de fluoroquinolones en présence de magnésium.

Infrared spectrophotometric analysis (FTIR) was performed on a crystalline deposit developed in a corneal ulcer by an old woman who received ciprofloxacine ophthalmic drops. We collected the data of the literature on the subject. After in vitro crystallization experiments, we conclude that ciprofloxacin and norfloxacin corneal precipitates occur at physiological lachrymal pH with magnesium.

[Multilayer amniotic membrane transplantation for corneal ulcers not treatable by conventional therapy - a prospective study of the status of cornea and graft during follow-up]. / Mehrlagige Amnionmembran-Transplantation bei therapieresistentem Hornhautulkus - eine prospektive Studie des Zustandes von Hornhaut und Amnionmembran im Verlauf 123.

PURPOSE: The purpose of this prospective clinical study was to evaluate the condition of the cornea (epithelium and vascularization) and the membrane presence and retraction during follow-up after amniotic membrane transplantation in patients with persistent corneal ulcers. PATIENTS AND METHODS: Between June 1999 and November 2000 AM transplantation was performed in 30 consecutive patients (average age 59 +/- 17 years) with corneal ulcers refractory to clinical treatment. We evaluated the clinical diagnosis, localisation, size and depth of the ulcers, condition of the ocular surface and visual acuity before and after surgery. After complete removal of the epithelium and pannus, one (n=11), two (n=17) or three (n=2) layers of amniotic membrane were fixed with multiple interrupted sutures, depending on the depth of the lesion. A therapeutic contact lens was applied in most eyes and removed after one month. The most frequent diagnoses were chemical burn (5 x lime, 1 x lye and 1 x liquid aluminium), 7 x herpes, 3 x polyarthritis and 3 x blepharo-keratoconjunctivitis in neurodermitis. The ulcers had a medium length of 4.9 +/- 3.2 mm, a width of 3.5 +/- 3.0 mm and a depth ranging between 30 % and 95 % (68 +/- 21 %). RESULTS: Complete epithelial closure was achieved in 27 of 30 eyes (90 %). In 4 eyes a recurrent epithelial defect occurred after initial closure. At the 1-, 3- and 6 month follow-up the amniotic membrane was present in 93 %, 73 % or 30 %, respectively, but was more or less retractet in 52 %, 58 % or 67 %, respectively. A complete corneal epithelium was noted in 79 %, 89 % or 90 % of eyes, respectively. However, corneal neovascularization was observed in 24 %, 58 % or 60 % of eyes. Visual acuity was

[Analysis of corneal pathologic changes and laboratory parameters in herpes simplex karatitis patients with ganhuo-shangyanzheng or ganshengyinxuzheng].

In order to investigate the relationship between Ganhuo shangyanzheng and Can-shengyin xuzheng in herpes simplex karatitis patients, we observed corneal pathologic changes and examined blood levels of prostaglandin F2 (PGF2), prostaglandin E2 (PGF2), tumor necrosis factor (TNF), arginine vasopressin (AVP), norepinephrine (NR), epinephrine (E) in sixty herpes simplex karatitis patients with Ganhou shangyanzheng or Gan-shengyinxuzheng. The results showed that the corneal pathologic changes were corneal ulcer infiltrating to stroma of cornea in Ganhuo shangyanzheng patients, and refractary corneal ulcer with large amount of corneal neovascularizaton and infiltration of corneal stroma in Gan-shengyinxuzheng patients, the blood levels of PGF2, PGE2, TNF, AVP, NE, E in Ganhuo shangyanzheng patients were higher than those in Gan-shengyinxuzheng patients or healthy persons. The results suggest that these parameters may be objective parameters for differential diagnosis of traditional Chinese medicine Zheng types in patients with herpes simplex karatitis.

The effectiveness of a topical antibiotic irrigating solution in a model of staphylococcal keratitis after lamellar keratectomy.

PURPOSE: To create a model of Staphylococcus aureus keratitis after lamellar keratectomy; to assess the toxicity of an antibiotic irrigating solution on the corneal stromal bed; and to test the chemotherapeutic effectiveness of a topical antibiotic, both alone and with an antibiotic-containing irrigating solution in preventing S. aureus keratitis after lamellar keratectomy. METHODS: The right eye of each of 38 rabbits were used in this study. In 18 eyes, a lamellar flap was created with a microkeratome, and an inoculum of S. aureus (either 1,000, 5,000, or 50,000 CFUs) was instilled under each flap; the eyes were examined for signs of infection and inflammation at 24 and 48 hours. In another five eyes, a lamellar flap was created in the same manner and the stromal bed was irrigated with 0.3% ofloxacin; the eyes were assessed for ocular inflammatory changes and evidence of crystalline deposits. Finally, in each of 15 additional eyes, 1,000 CFUs of S. aureus were instilled under a lamellar flap to create experimental infectious keratitis. The keratitis was treated according to three regimens: irrigation of the stromal bed with sterile balanced salt solution; irrigation of the stromal bed with 0.3% ofloxacin, followed by application of topical ofloxacin four times a day; application of topical ofloxacin only, four times a day. Eyes were examined for infection and ocular inflammatory changes at 24 and 48 hours. RESULTS: Staphylococcus aureus keratitis can consistently be produced under the stromal flap by inoculation of relatively few organisms. Irrigation of the stromal bed with commercial-strength topical ofloxacin does not appear to be toxic to the stromal bed, with no evidence of crystalline precipitates of the antibiotic. In our model of infectious keratitis after lamellar keratectomy, both topical ofloxacin alone and the combination of topical ofloxacin and irrigation of the stromal bed with 0.3% ofloxacin were effective at preventing S. aureus keratitis. However, the combined treatment of antibiotic irrigation plus topical antibiotic was more effective at preventing inflammation than topical ofloxacin alone. CONCLUSIONS: In this model of S. aureus keratitis after lamellar keratectomy, irrigation of the stromal bed with antibiotic plus topical antibiotic appears to be both safe and effective for preventing infection.

Effect of vitamin A deficiency on the early response to experimental Pseudomonas keratitis.

PURPOSE: Vitamin A-deficient humans and animals are more susceptible to infections than are healthy humans and animals. This study compares the early corneal response (within 24 hours) to an experimental Pseudomonas aeruginosa infection between vitamin A deficient and control rats. METHODS: Male WAG/Rij/MCW rats were fed either a vitamin A- deficient diet (A-) or the same diet with retinyl palmitate added back in a nonrestricted manner (N) or under pair-fed conditions (A+) to yield weight-matched rats. Some A-rats were repleted wih retinyl palmitate 16 days before being killed and then given free access to the retinyl palmitate-supplemented diet (R). Twenty-four hours before being killed, the corneas of anesthetized rats were scratched and P. aeruginosa organisms were applied to the corneal surface. The rats were killed using an overdose of sodium pentobarbital. Corneas were either processed for light and electron microscopic examination or extracted for proteinase and myeloperoxidase determination. Corneal myeloperoxidase concentrations relative to neutrophil myeloperoxidase concentrations were used to determine the number of neutrophils in the cornea. Zymography was used to study caseinases, gelatinases, and plasminogen activators. Reverse zymography was used to detect proteinase inhibitors. Similar results were noted at early, mid, and late weight plateau stages of vitamin A deficiency. RESULTS: Ulceration occurred within 24 hours when low numbers of P. aeruginosa (10(4) cpu) were applied topically onto scratched A- corneas, whereas no ulceration was observed in the A+, R, and N corneas. When higher numbers of P. aeruginosa (10(7)-10(8)) were applied to the scratched corneas, all corneas became ulcerated within 24 hours. The extent of ulceration in the control corneas was greater than that in A- corneas by a factor of two. Only the A- corneas contained inflammatory cells with unusual striated deposits in phagolysosomes. The total number of neutrophils in the cornea and the concentrations of caseinases, plasminogen activators, and gelatinases in the infected corneal extracts were similar; however, the concentrations of cysteine proteinase inhibitors were elevated under A- conditions. CONCLUSIONS: Vitamin A deficiency alters the response of the cornea to a P. aeruginosa infection during the first 24 hours. The alterations observed are probably due to multiple factors: an insufficient tear film for bacterial clearance and migration of neutrophils, epithelial keratinization, alterations in corneal wound healing, and changes in polymorphonuclear function.

Peripheral corneal ulcers associated with use of African traditional eye medicines.

The most common cause of monocular blindness in Africa is corneal opacification. Traditional eye medicines (TEM) are widely used in Africa and their use has been associated with corneal ulceration, however, no controlled studies of the effects of TEM on the cornea have been published. We conducted a case-control study of 39 patients with corneal ulcers matched to controls with severe conjunctivitis. Microbiological investigations were conducted on 20 cases. There was a significant association between corneal ulceration and TEM use and, in particular, peripheral corneal ulcerations were significantly associated with TEM use.