Cluster of Mycobacterium chelonae keratitis cases following laser in-situ keratomileusis.

PURPOSE: To describe a cluster of Mycobacterium chelonae keratitis cases involving patients who underwent laser in-situ keratomileusis (LASIK) at a single refractive surgery center. DESIGN: Descriptive case series of four patients and cohort study to identify disease associations. METHODS: Examination schedules, diagnostic tests, and therapy were based on best medical judgment. Isolates from three patients were compared by pulsed-field gel electrophoresis. Epidemiologic studies were performed to identify the source of infection. RESULTS: Seven of eight eyes developed M. chelonae keratitis following bilateral simultaneous LASIK. Each patient was thought to have diffuse lamellar keratitis initially, but all seven eyes were noted to have opacities suggestive of infectious keratitis by 13 to 21 days after surgery. All eyes had undergone hyperopic LASIK over four days in April 2001 by one surgeon in a community-based refractive surgery center. A cohort study of all patients undergoing LASIK at the same center in April 2001 revealed that M. chelonae keratitis occurred only in persons undergoing correction of hyperopia (seven of 14 eyes vs. none of 217 eyes undergoing myopic LASIK, P <.001). The only difference identified between procedures was use of masks created from a soft contact lens in hyperopic LASIK. Three isolates (three patients) were indistinguishable by pulsed-field gel electrophoresis. Eyes were treated with a combination of antimicrobial agents, including topical azithromycin in three patients, with resolution of infection in all eyes over 6 to 14 weeks. The source of infection was not identified on environmental cultures. CONCLUSION: Postoperative nontuberculous mycobacterial keratitis can occur in an epidemic fashion following LASIK. Topical amikacin, azithromycin, clarithromycin, ciprofloxacin, or a combination of these agents, appears to be effective treatment for these infections.

Experimental staphylococcal endophthalmitis.

Endophthalmitis is one of the most feared complications of ocular trauma or surgery. It is a complex pathogen- and host-mediated process that often results in significant vision loss. This review summarizes data from experimental models of staphylococcal endophthalmitis that address the host's immune response to intraocular staphylococci and those that investigate disease pathogenesis.

Acanthamoeba keratitis associated with fungal keratitis.

PURPOSE: To report fungal infection complicating Acanthamoeba keratitis. METHODS: Case report. A 45-year-old woman with contact lens-related bilateral Acanthamoeba keratitis developed corneal ulcer, corneal perforation, and mature cataract in the left eye, which was managed by penetrating keratoplasty, lensectomy, and vitrectomy. RESULTS: Histopathologic examination of the keratoplasty specimen from the left eye revealed extensive lamellar stromal necrosis with the coexistence of both empty cysts and branching hyphae. Cultures from the keratoplasty specimen grew Scedosporium apiospermum. CONCLUSION: Keratomycosis caused by S. apiospermum may complicate protracted Acanthamoeba keratitis.

Penetrating keratoplasty from a temporal approach.

PURPOSE: To describe the technique of penetrating keratoplasty using a temporal approach. METHODS: Report of two cases of phakic penetrating keratoplasty performed with the surgeon positioned at the temporal side of the head. RESULTS: The temporal approach improved the surgical exposure, which eliminated the need for a bridal suture, facilitated the placement of the first two cardinal sutures, and facilitated subsequent placement of nasal sutures. CONCLUSION: The temporal approach to penetrating keratoplasty may facilitate suture placement, decrease surgical time, and reduce suture-induced astigmatism.

Adhesion molecule expression in a rat model of Staphylococcus aureus endophthalmitis.

PURPOSE: To determine whether Staphylococcus aureus and its components induce expression of E-selectin and intercellular adhesion molecule (ICAM)-1 in rat ocular tissues and on human endothelial cells in culture. METHODS: Experimental and control rat eyes were injected with 80 colony-forming units of viable S. aureus and lipopolysaccharide-free sterile saline (NS), respectively. Eyes were enucleated and immediately frozen. E-selectin and ICAM-1 expression were evaluated on frozen sections by using standard immunohistochemical techniques. Using an enzyme-linked immunoassay, in vitro expression of E-selectin and ICAM-1 was evaluated on macrovascular endothelial cells after stimulation with S. aureus and selected purified components. RESULTS: In S. aureus-injected eyes, E-selectin and ICAM-1 expression peaked at six to 24 hours, decreased slightly at 24 and 48 hours, and further declined by 72 hours. However, in NS-injected eyes, peak levels of E-selectin and ICAM-1 were seen at 6 hours, after which expression declined in the areas in which an increase was previously observed. In in vitro assays, peptidoglycan (0.01 microg/ml) induced a fourfold increase in E-selectin (P < 0.0001) and a twofold increase in ICAM-1 (P < 0.002) expression. Ribitol teichoic acid (RTA) (1 microg/ml) induced a twofold increase in E-selectin (P < 0.0001) and a threefold increase in ICAM-1 (P < 0.0001) expression. CONCLUSIONS: Eyes injected with S. aureus demonstrated a more intense and prolonged expression of both E-selectin and ICAM-1 than did eyes injected with NS. In addition, S. aureus components induced the in vitro expression of these adhesion molecules on macrovascular endothelial cells. The relevance of these findings to microvascular endothelial cells is yet to be determined.

Systemic disorders associated with peripheral corneal ulceration.

Peripheral ulcerative keratitis may be associated with a variety of autoimmune diseases. In some diseases, corneal involvement occurs after the systemic disease has been present for many years, whereas in others, it may be the first manifestation. Regardless of the time of presentation, the development of corneal ulceration in the setting of systemic autoimmune disease may represent progression of a potentially life threatening disease. The relatively rare incidence of these diseases has limited publications over the past year to a few case series that have further characterized the natural history of the diseases associated with peripheral ulcerative keratitis. Current laboratory research has been directed at describing the antigenic targets within the cornea of the abnormal immune response in these patients and also the mechanism of keratolysis that results in ulceration.

A comparison of the early inflammatory effects of an agr-/sar- versus a wild type strain of Staphylococcus aureus in a rat model of endophthalmitis.

PURPOSE: We examined the ability of a wild type and an isogenic mutant strain of Staphylococcus aureus, deficient in the production of hemolysins and lipase (agr (-)/sar (-)), to induce endophthalmitis and inflammatory cell infiltration into the eye at 6, 24 and 48 hours after injection in a rat model of endophthalmitis. METHODS: Rat eyes were injected with 25 microl of viable S. aureus or sterile saline. Eyes were graded for clinical signs of inflammation daily, removed and processed for standard histologic analysis 6, 24 and 48 hours after injections. Comparisons of clinical scores and mean inflammatory cell numbers were made between S. aureus and control injected eyes. RESULTS: Both experimental groups developed clinical signs of endophthalmitis and demonstrated infiltration of inflammatory cells at 24 and 48 hours. Clinical inflammation in the Mutant I group was less than the wild type group at these times and significantly less at 48 hours (p<0.05). No statistically significant difference in the number of inflammatory cells was detected between the wild type and Mutant I injected eyes at 24 hours. At 48 hours, inflammatory cells increased by 75.0% in the wild type group and decreased by 19.0% in the Mutant I group and a statistically significant difference was seen between these two groups (p<0.05). At all times, the majority of inflammatory cells were neutrophils. By 48 hours, an increase in monocytes-macrophages was noted. CONCLUSION: Both strains of S. aureus induced clinical signs of inflammation and inflammatory cell infiltration. Clinical inflammation and inflammatory cell numbers were less in rats injected with the Mutant I strain. These results suggest that hemolysins and lipase may be important in the early induction phase of the inflammatory response.

Cytokine expression in a rat model of Staphylococcus aureus endophthalmitis.

PURPOSE: To examine the ability of viable Staphylococcus aureus to induce the production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, cytokine-induced neutrophil chemoattractant (CINC), and interferon (IFN)-gamma after intravitreal injection. METHODS: Experimental rat eyes were injected with a 25-microl volume of approximately 80 colony-forming units of viable S. aureus; control eyes received sterile saline. Eyes were graded daily for signs of clinical inflammation and were removed 6, 24, 48, and 72 hours after injection. One group was prepared for histologic analysis, and vitreous was removed from the other group for cytokine analysis, using standard enzyme-linked immunosorbent assay procedures. RESULTS: TNF-alpha, IL-1beta, CINC, and IFN-gamma were detected in experimental vitreous samples at increased levels that peaked at 24 hours. TNF-alpha, IL-1beta, and CINC declined at 48 hours, but IFN-gamma remained elevated. At 72 hours, levels returned to baseline. Statistically significant elevations of TNF-alpha, IL-1beta, and CINC were detected in experimental samples at 24, but not at 6 and 48 hours compared with levels in saline control samples (P < 0.03). A statistically significant increase in IFN-gamma was detected at 24 and 48 hours compared with control levels (P < 0.03). In experimental animals, clinical inflammation and inflammatory cells peaked at 24 hours, persisted at 48 hours, and began to decline thereafter. Neutrophils were the predominant inflammatory cell detected at 24 (72.3% of cells) and 48 (60.1%) hours. By 72 hours, the total number of inflammatory cells had decreased by 75.0%, and the cellular infiltrate had changed so that neutrophils equaled monocytes-macrophages. CONCLUSIONS: S. aureus induced the expression of TNF-alpha, IL-1beta, CINC, and IFN-gamma. The time course of these cytokine levels could account for the clinical inflammatory responses and the entry and decline of vitreous cells in this model of bacterial endophthalmitis.

Timing of dexamethasone treatment in experimental Staphylococcus aureus endophthalmitis.

PURPOSE: This study sought to determine whether intravitreal dexamethasone with vancomycin preserves retinal function in eyes with experimental Staphylococcus aureus endophthalmitis better than intravitreal vancomycin alone. METHODS: Twenty-four rabbits received intravitreal injections in both eyes with S. aureus. Right eyes were treated with intravitreal dexamethasone plus vancomycin and left eyes were treated with vancomycin alone at 24, 36, 48, or 72 hours after inoculation. Evaluation was performed by slit-lamp biomicroscopy, indirect ophthalmoscopy, and electroretinogram. Vitreous humor cultures and histopathologic examinations were performed on the eyes after the rabbits were killed. RESULTS: The combination of intravitreal dexamethasone and vancomycin resulted in significantly less inflammation than vancomycin alone at 24 and 36 hours after inoculation, but electroretinograms showed significantly better preservation only at 36 hours after bacterial inoculation. Viable bacteria were cultured from eyes treated 48 and 72 hours after inoculation. CONCLUSION: Intravitreal dexamethasone was found to be beneficial by electroretinography when administered 36 hours after infection. In the authors' model, a single intravitreal injection of vancomycin with or without the addition of dexamethasone was insufficient to sterilize eyes 48 and 72 hours after bacterial inoculation.

Determinations of serum tumor necrosis factor alpha in corneal allografts.

Corneal allograft rejection culminates in a series of interactions between different classes of antigen presenting cells, cytokines and leukocytes. Tumor necrosis factor-alpha (TNF-alpha) was recently reported to be elevated in acute rejection of solid organ transplants. This cytokine is released early in immune activation and may be detected in the peripheral circulation. Serial determinations of TNF-alpha serum levels were performed following experimental corneal allografts. Lewis rats received 3.5 mm orthotopic corneal grafts of MHC-incompatible Wistar-Furth donors. TNF-alpha concentrations were measured in serum samples collected pre- and postoperatively and measured by micro ELISA. Clinical observations revealed graft rejection in 65.5% of corneal transplants 14 +/- 4 days following grafting. The mean serum level of TNF-alpha in control animals without corneal graft (group I) was 41 +/- 12 pg/ml. Animals following keratoplasty without allograft rejection (group II) showed a mean TNF-alpha level of 54 +/- 16 pg/ml that did not differ from group I. The rejection group III displayed significantly higher TNF-alpha levels (98 +/- 16 pg/ml, p < 0.05). These significantly elevated levels were found even before the diagnosis of rejection was established by clinical criteria. These data suggest systemic immunoreactivity to corneal allografts. Elevated levels of cytokines may provide valuable information in recipients undergoing rejection and may also provide a rationale for systemic immunotherapy in some instances.

Immunopathologic features of Staphylococcus epidermidis-induced endophthalmitis in the rat.

PURPOSE: To investigate the clinical, histopathologic and immunologic responses to Staphylococcus epidermidis endophthalmitis in a rat model. METHODS: Experimental rats received an intravitreal injection of viable S. epidermidis (7000 organisms), while control rats received sterile saline. The clinical scores, cellular infiltrate in vitreous, and levels of serum and vitreous IgM, IgG and IgA to glycerol teichoic acid (GTA), the major antigenic determinant of S. epidermidis cell wall, were all measured from day 1 to day 30 after injection. RESULTS: The ocular inflammation was largely resolved by day 14. The red reflex was abolished in 50% of rats between days 3 and 10. The bacteria were cleared from the vitreous by day 7. In vitreous, the neutrophils peaked at day 1 and decreased by day 7, and plasma cells were seen between days 1 and 3. Presence of B cells (CD45+/CD3-) was confirmed by flow cytometric analysis of pooled vitreous humor. IgM and IgG but not IgA antibodies to GTA were found in vitreous of injected eyes. The peak of anti-GTA IgM was observed in vitreous of S. epidermidis-infected rats on day 1 and declined by day 7. In contrast to vitreous antibodies, serum anti-GTA IgM antibodies were significantly elevated throughout the course of S. epidermidis endophthalmitis. A weak IgG but no IgA response were observed in serum. Anti-GTA antibodies were also found in low level in normal sera but not in normal vitreous. CONCLUSIONS: The vitreous antibodies may be involved in neutrophil-mediated opsonophagocytosis leading to 'spontaneous sterility' of the bacteria, and may play a role in the immunopathogenesis of staphylococcal endophthalmitis in the rat.

Combination intravenous ceftazidime and aminoglycosides in the treatment of pseudomonal scleritis.

BACKGROUND: Pseudomonal scleritis is a serious and potentially blinding infection that usually is resistant to medical management. METHODS: Results for three patients with pseudomonal scleritis who were treated with both topical anti-infectives and a combination of intravenous ceftazidime and aminoglycoside are presented in this case series. RESULTS: All three patients had a rapid response to the addition of combination intravenous drug therapy to topical therapy; eradication of the infection and healing of the ocular surface occurred within 8 weeks. Only one patient, in whom cystoid macular edema developed, lost useful vision as a result of the infection. CONCLUSIONS: Combination therapy with intravenous ceftazidime and aminoglycoside may be more effective than single-intravenous agents when used in addition to topical antibiotics and may obviate the need for adjunctive surgical procedures, such ascryotherapy, surgical extirpation, or conjunctival recession.

Air bag-related ocular injuries.

This study reviewed the nature and severity of ocular and orbital air bag-related injuries at a large tertiary care referral center. The records of all patients treated by the ophthalmology trauma service for air bag-related ocular injuries between 1993 and 1995 were reviewed. Five patients were identified who had air bag-related ocular trauma. All of the patients who were referred to the ophthalmology trauma service for air bag-related ocular injuries had significant ocular or orbital injury. The extent and severity of the injuries were variable, ranging from orbital contusion to ruptured globe and retinal detachment. Although air bags substantially reduce the overall rates of mortality and morbidity associated with motor vehicle accidents, they also cause a variety of ocular injuries.

Clinical experience with the Ahmed Glaucoma Valve implant in eyes with prior or concurrent penetrating keratoplasties.

PURPOSE: To evaluate the Ahmed Glaucoma Valve implant, an aqueous shunting device with a unidirectional valve mechanism, in eyes with concurrent or prior penetrating keratoplasties. METHODS: Thirty-one eyes of 31 consecutive patients had placement of an Ahmed Glaucoma Valve implant. Median patient age was 65.1 years (range, 17.2 to 103.4 years). The main outcome measure was time after surgery without failure. Success was defined as no additional glaucoma surgeries or devastating visual complications, no new corneal graft failure, an intraocular pressure greater than or equal to 5 mm Hg on the last two follow-up examinations, and reduction in intraocular pressure. For eyes with preoperative intraocular pressure greater than 22 mm Hg, an average intraocular pressure of less than 22 mm Hg on the last two follow-up examinations was required. For eyes with preoperative intraocular pressure of less than 22 mm Hg, an intraocular pressure lowered by at least 20% from preoperative values was required. RESULTS: Cumulative probabilities of success at 12 and 20 months (mean +/- SD) were 75.4% +/- 8.2% and 51.5% +/- 11.4%, respectively. Eleven of 31 eyes were failures. The risk of failure in eyes with prior infectious keratitis or keratouveitis was estimated to be 5.8 times greater than that associated with eyes that underwent penetrating keratoplasties for other reasons (P = .009). CONCLUSIONS: Twelve- and 20-month success rates of the implant in eyes with prior or concurrent penetrating keratoplasties were comparable to those of other drainage devices. Eyes with prior infectious keratitis or keratouveitis were at increased risk of failure.

The effect of Staphylococcus aureus phage lysate vaccine on a rabbit model of staphylococcal blepharitis, phlyctenulosis, and catarrhal infiltrates.

PURPOSE: To evaluate the effect of Staphylococcus aureus phage lysate (SPL) vaccination on the development of blepharitis, corneal phlyctenules, and catarrhal infiltrates and on the development of antibodies and the delayed-type hypersensitivity response to S. aureus. METHODS: Eighty rabbits received an intradermal immunization of cell wall-complete Freund's adjuvant followed by a booster immunization. Rabbits were given topical applications of viable S. aureus in both eyes and 40 rabbits received subcutaneous SPL vaccinations. Clinical observations were made weekly. An enzyme-linked immunosorbent assay was used to measure IgG, IgA, and IgM antibody levels to ribitol teichoic acid in sera, corneas, and tears. The delayed-type hypersensitivity response was evaluated by skin testing after subcutaneous injection of staphylococcal antigens. RESULTS: In the SPL-vaccinated group, phlyctenules developed in eight of 40 rabbits while blepharitis developed in 13 of 40. In the nonvaccinated group, phlyctenules developed in three of 40 rabbits and blepharitis developed in five of 40. The number of rabbits with blepharitis was significantly higher in the SPL-vaccinated group than in the nonvaccinated group. In general, the antibody response to ribitol teichoic acid was enhanced, while the delayed-type hypersensitivity response to S. aureus was depressed. CONCLUSIONS: Vaccination with SPL was not found to have a beneficial effect on the development of blepharitis, phlyctenules, and catarrhal infiltrates in our rabbit model.

Generation of complement membrane attack complex in normal human corneas.

PURPOSE: To determine whether complement-derived SC5b-9, the soluble nonlytic-fluid phase of the membrane attack complex, can be generated in normal human corneas when they are injured with lipopolysaccharide (LPS), ribitol teichoic acid (RTA) immune complexes, acid, or alkali. METHODS: The experimental cornea of each donor pair was injected with 50 microliters of sterile saline containing 0.5 mg of LPS or 50 microliters of sterile saline containing 250 micrograms of RTA immune complexes. Other experimental corneas were treated topically for 35 seconds with either 200 microliters of 1N HCl or 2N NaOH. The control cornea of each donor pair was injected with 50 microliters of sterile saline or was treated topically for 35 seconds with 200 microliters of sterile saline. After injury, all corneas were incubated in medium 199 for 6 hours at 37 degrees C in 5% CO2, then eluted for 24 hours in phosphate-buffered saline with 10 mM ethylenediaminetetraacetic acid. Each corneal eluate was collected and stored at -70 degrees C until assayed for SC5b-9 by an enzyme immunoassay. RESULTS: Compared with control corneas, SC5b-9 levels were increased significantly in corneas injected with LPS or RTA immune complexes. However, when compared with controls, SC5b-9 levels were decreased significantly in corneas treated with HCl or NaOH. CONCLUSIONS: Normal human corneas injured immunologically with LPS or RTA immune complexes activate the classical or alternate pathway and generate SC5b-9. Corneas injured chemically with acid or alkali do not produce SC5b-9.

Corneal scarring after photorefractive keratectomy in a penetrating keratoplasty.

PURPOSE: To report severe scarring in a corneal graft after excimer laser photorefractive keratectomy. METHODS: A 35-year-old man underwent photorefractive keratectomy twice for severe compound myopic astigmatism and anisometropia after penetrating keratoplasty. RESULTS: Corneal opacity corresponded to areas of irregular epithelial thickness, focal absence of the basement membrane, loss of Bowman's layer, and stromal scarring in the ablation zone. CONCLUSION: There may be an increased risk of severe corneal stromal scarring from photorefractive keratectomy in eyes that have had previous penetrating keratoplasty.

Immunopathologic features of Staphylococcus aureus endophthalmitis in the rat.

PURPOSE: To study the clinical, histopathologic, and immunologic responses to Staphylococcus aureus endophthalmitis in rats. METHODS: Experimental Lewis rats received an intravitreal injection of viable S. aureus (65 organisms), and control rats received sterile saline. The clinical scores, cellular infiltrate, delayed hypersensitivity reaction in skin tests, and serum and vitreous enzyme-linked immunosorbent assay titers of immunoglobulin (Ig) M, IgG, and IgA to ribitol teichoic acid (RTA), the major antigenic determinant of S. aureus cell wall, were measured and compared on days 3, 7, 10, 14, 21, and 30. The differences were statistically assessed using Mann-Whitney nonparametric t-tests and analysis of variance. RESULTS: The red reflex was abolished in the majority of rats between days 3 and 21. Ocular inflammation resolved by day 30. The vitreous of eyes injected with S. aureus showed bacterial growth on days 3 and 7, followed by a decrease in numbers on days 10 and 14 and disappearance on days 21 and 30. In the vitreous, a peak neutrophil count was observed at day 3 that rapidly declined by day 7. The number of lymphocytes and plasma cells peaked on day 3 but declined more slowly. Plasma cells and Mott cells were seen on days 10 and 14, suggesting intraocular antibody production. IgM titers to RTA increased progressively in serum and vitreous, reached a peak on day 21, and declined on day 30. A weak IgG but absent IgA response to RTA was observed in serum and vitreous. S. aureus endophthalmitis was not associated with delayed hypersensitivity to the bacteria in skin tests. CONCLUSIONS: S. aureus endophthalmitis is associated with the infiltration of neutrophils, lymphocytes, monocytes, and plasma cells in vitreous. Neutrophils, the predominant infiltrating cells, may be involved in bactericidal activity and opsonophagocytosis. In rat staphylococcal endophthalmitis, IgM rather than IgG may be the protective antibody.

Complement-derived anaphylatoxins in human donor corneas treated with excimer laser.

BACKGROUND AND OBJECTIVE: An inflammatory response produced by excimer laser photorefractive keratectomy (PRK) may be associated with the subsequent corneal haze and regressions in refractive error observed after treatment. Complement-derived anaphylatoxins, potent mediators of inflammation, may have a role in postoperative healing. MATERIALS AND METHODS: Twenty right human donor corneas underwent a 6-D excimer laser PRK treatment. The corresponding left donor corneas served as the controls. After incubation in tissue culture media for 6 hours and elution in phosphate-buffered saline with EDTA for 24 hours, complement-derived anaphylatoxins C3a, C4a, and C5a were measured in corneal eluates by radioimmunoassay. RESULTS: Compared with control corneas, the excimer PRK corneas failed to demonstrate a significant increase in C3a, C4a, or C5a levels (P > .05). CONCLUSIONS: These results suggest that the excimer laser at this dose does not activate significant complement in the cornea.