Microbial Keratitis After Laser in situ Keratomileusis

Multifunctional Polymer Vesicles for Synergistic Antibiotic-Antioxidant Treatment of Bacterial Keratitis

As an acute ophthalmic infection, bacterial keratitis (BK) can lead to severe visual morbidity, such as corneal perforation, intraocular infection, and permanent corneal opacity, if rapid and effective treatments are not available. In addition to eradicating pathogenic bacteria, protecting corneal tissue from oxidative damage and promoting wound healing by relieving inflammation are equally critical for the efficient treatment of BK. Besides, it is very necessary to improve the bioavailability of drugs by enhancing the ocular surface adhesion and corneal permeability. In this investigation, therefore, a synergistic antibiotic-antioxidant treatment of BK was achieved based on multifunctional block copolymer vesicles, within which ciprofloxacin (CIP) was simultaneously encapsulated during the self-assembly. Due to the phenylboronic acid residues in the corona layer, these vesicles exhibited enhanced muco-adhesion, deep corneal epithelial penetration, and bacteria-targeting, which facilitated the drug delivery to corneal bacterial infection sites. Additionally, the abundant thioether moieties in the hydrophobic membrane enabled the vesicles to both have ROS-scavenging capacity and accelerated CIP release at the inflammatory corneal tissue. In vivo experiments on a mice model demonstrated that the multifunctional polymer vesicles achieved efficient treatment of BK, owing to the enhanced corneal adhesion and penetration, bacteria targeting, ROS-triggered CIP release, and the combined antioxidant-antibiotic therapy. This synergistic strategy holds great potential in the treatment of BK and other diseases associated with bacterial infections.

Delayed onset diffuse lamellar keratitis following enhancement LASIK surgery

BACKGROUND

Diffuse lamellar keratitis (DLK) is a relatively uncommon complication of the refractive procedure, laser-assisted in situ keratomileusis (LASIK). If detected and diagnosed in a timely fashion, it can be treated and should resolve with minimal sequelae. If untreated, or misdiagnosed and treated incorrectly, there may be loss of visual acuity. Optometrists should be familiar with this condition, its signs, symptoms and correct treatment protocol.

CASE HISTORY

A 58-year-old male Caucasian developed delayed onset diffuse lamellar keratitis, seemingly in the absence of an epithelial defect, 25 days following an enhancement LASIK procedure to his right eye. The DLK in this patient is delayed longer than typically reported in the literature. Subsequent management with topical steroids was complicated as the patient was a steroid responder and developed a markedly raised intraocular pressure that was managed with a topical anti-glaucoma agent. The diagnosis, pathogenesis and issues relevant to the treatment of this condition are discussed.

CONCLUSION

Optometrists, particularly those actively participating in the shared care of refractive surgery patients, must be familiar with diffuse lamellar keratitis so that diagnosis is not delayed. As the number of cases of refractive surgery in Australia increases, optometrists will encounter this condition more frequently.

Review: Emerging strategies for antimicrobial drug delivery to the ocular surface: Implications for infectious keratitis

Infectious keratitis is a medical emergency that can cause severe visual morbidity if not treated promptly. Depending upon the causative microorganism, effective management of infectious keratitis requires frequent application of antibacterial, antifungal, or antiviral eye drops, which may have low bioavailability, undesirable side effects, and poor patient compliance. Ocular formulations of antimicrobials that can increase corneal permeation and provide extended presence on ocular surface are being developed. Such formulations include nanoparticles, mucoadhesives, in situ forming hydrogels, and contact lenses. Testing of these formulations in in vitro models and ex vivo excised corneas, and in vivo rabbit testing have demonstrated increased bioavailability and extended presence on the cornea. Many of these formulations have also demonstrated success in treating infectious keratitis in animal models. However, the majority of studies have evaluated fluoroquinolone antibacterials, and more studies are needed to test the delivery of antifungal drugs. Moreover, additional efficacy data in animal models and future studies in humans to determine the duration of inhibitory concentrations of these antimicrobials in tear fluid will be required to prove the effectiveness of these formulations for clinical management of infectious keratitis.

Nontuberculous mycobacterial ocular and adnexal infections

The nontuberculous (also called "atypical") mycobacteria have become increasingly important causes of systemic as well as ocular morbidity in recent decades. All ocular tissues can become infected with these organisms, particularly in patients who are predisposed following ocular trauma, surgery, use of corticosteroids, or are immunocompromised. Because of their relative resistance to available antibiotics, multidrug parenteral therapy continues to be the mainstay of treatment of more serious ocular and adnexal infections caused by nontuberculous mycobacteria (NTM). Periocular cutaneous, adnexal, and orbital NTM infections remain rare and require surgical debridement and long-term parenteral antibiotic therapy. NTM scleritis may occur after trauma or scleral buckling and can cause chronic disease that responds only to appropriate antibiotic therapy and, in some cases, surgical debridement and explant removal. NTM infectious keratitis following trauma or refractive surgical procedures is commonly confused with other infections such as Herpes simplex keratitis and requires aggressive topical therapy and possible surgical debridement, particularly in those cases occuring after laser in situ keratomileusis. Only 18 cases of endophthalmitis due to NTM have been reported. Systemic and intraocular antibiotic therapy and multiple vitrectomies may be needed in NTM endophthalmitis; the prognosis remains poor, however. Disseminated NTM choroiditis in acquired immune deficiency syndrome patients with immune reconstitution during highly active anti-retroviral therapy is a rare infection that can present as a necrotizing chorioretinitis with dense vitritis, mimicking many other entities and needs to be recognized so that timely, life-saving treatment can be administered. Regardless of which ocular tissue is infected, all NTM ocular infections present similar challenges of recognition and of therapeutic intervention. We clarify diagnosis and delineate modern, effective therapy for these conditions.

Efficacy and safety of short-duration topical treatment with azithromycin oil-based eyedrops in an experimental model of corneal refractive surgery

PURPOSE

To assess the tolerance and side effects of azithromycin eyedrops at the ocular surface after corneal refractive surgery in an experimental animal model.

METHODS

The effect of azithromycin eyedrops was evaluated in hen corneas that underwent laser-assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) surgery in 1 eye, using the fellow eye (not manipulated) as a control. Animals were treated bid 3 days prior to surgery and 3 days after surgery with T1225 1.5% azithromycin eyedrops or saline eyedrops (balanced salt solution), or were left untreated as a control. Clinical course and cell biology (apoptosis, proliferation, and differentiation) measurements were assessed.

RESULTS

Infections were present in the following proportions of corneas operated on by LASIK: 0% treated with azithromycin, 60% treated with BSS, and 30% untreated. No corneal abscess or keratitis were present in any PRK or unmanipulated corneas. Conjunctival edema and redness were less prevalent in LASIK-operated eyes treated with azithromycin than in BSS-treated or untreated eyes and were not observed in any PRK or unmanipulated corneas. In PRK-operated eyes treated with azithromycin, a decrease was observed in the apoptosis and an increase in the stromal proliferation. There were no differences in these parameters for LASIK and unmanipulated eyes.

CONCLUSIONS

Topical administration of T1225 oil-based azithromycin eyedrops was well tolerated in both unmanipulated hen corneas and those treated with corneal refractive surgery (PRK and LASIK). T1225 demonstrated a potent antibiotic effect after LASIK treatment.

Kill rates of preserved and preservative-free topical 8-methoxy fluoroquinolones against various strains of Staphylococcus

PURPOSE

To assess the kill rates of preserved and preservative-free 8-methoxy fluoroquinolones and benzalkonium chloride (BAC) against isolates of Staphylococcus aureus and coagulase-negative Staphylococcus (CNS) species.

SETTING

Bascom Palmer Eye Institute, Miami, Florida, USA.

METHODS

Ocular and standard isolates of S aureus and CNS were inoculated with saline, 0.005% BAC, gatifloxacin 0.3% containing 0.005% BAC (Zymar), or BAC-free moxifloxacin 0.5% (Vigamox) at 37 degrees C. Bacterial viability was assessed after 15 minutes, 30 minutes, and 60 minutes.

RESULTS

Thirteen isolates of S. aureus and 5 isolates of CNS were used. The mean initial load of bacterial inoculum was 5.45 log colony-forming units (CFU)/mL +/- 0.37 (SD). Saline did not affect the density of staphylococci; BAC significantly decreased the staphylococci count to a mean of 3.80 +/- 0.32 log CFU/mL at 60 minutes (P<.05). Gatifloxacin 0.3% reduced the number of staphylococci significantly more than moxifloxacin 0.5% at 15 minutes (mean 0.47 +/- 1.12 log CFU/mL versus 4.55 +/- 0.60 log CFU/mL), 30 minutes (mean 0.07 +/- 0.31 log CFU/mL versus 3.82 +/- 1.07 log CFU/mL), and 60 minutes (mean 0.00 +/- 0.00 log CFU/mL versus 2.75 +/- 1.29 log CFU/mL) (P<.005). Gatifloxacin 0.3% completely eradicated most S. aureus (10/13) and CNS (3/5) isolates at 15 minutes; moxifloxacin 0.5% did not achieve complete kill in any S. aureus isolate (13/13) or in most CNS isolates (4/5) at 60 minutes.

CONCLUSION

The commercial formulation of gatifloxacin 0.3% containing BAC 0.005% completely eradicated staphylococcal isolates more rapidly than the BAC-free formulation of moxifloxacin 0.5% or BAC 0.005% alone.

Rate of bacterial eradication by ophthalmic solutions of fourth-generation fluoroquinolones

INTRODUCTION

Antibacterial activity of ophthalmic fourth-generation fluoroquinolones has traditionally been evaluated by comparing only their active ingredients, gatifloxacin and moxifloxacin. However, ophthalmic formulations of fourth-generation fluoroquinolones differ in terms of the inclusion of preservatives. While gatifloxacin ophthalmic solution 0.3% (Zymar; Allergan, Inc., Irvine, CA, USA) contains 0.005% benzalkonium chloride (BAK), moxifloxacin ophthalmic solution 0.5% (Vigamox; Alcon Laboratories, Inc., Fort Worth, TX, USA) is preservative-free. Recent studies have demonstrated that the presence of BAK dramatically affects the antibacterial activity of the ophthalmic formulation of gatifloxacin. This study was designed to compare the kill rates of ophthalmic solutions of fourth-generation fluoroquinolones against isolates of common ocular bacterial pathogens.

METHODS

Approximately 5.6 log(10) colony-forming units (CFU)/mL of Haemophilus influenzae (n=1), Streptococcus pneumoniae (n=1), Staphylococcus aureus (n=2), methicillin-resistant Staphylococcus aureus (MRSA) (n=4), methicillinresistant Staphylococcus epidermidis (MRSE) (n=4), and fluoroquinolone-resistant S. epidermidis (n=1) were incubated with ophthalmic solutions of either gatifloxacin or moxifloxacin. Viable bacteria were quantified at specific time points up to 60 minutes.

RESULTS

Gatifloxacin 0.3% completely eradicated H. influenzae and Strep. pneumoniae in 5 minutes, one of two S. aureus isolates in 15 minutes, and the other S. aureus isolate in 60 minutes. Gatifloxacin 0.3% completely killed all MRSA, MRSE, and fluoroquinolone-resistant S. epidermidis isolates in 15 minutes. Moxifloxacin 0.5% completely eradicated Strep. pneumoniae and one of four MRSA isolates in 60 minutes. All other isolates incubated with moxifloxacin 0.5% retained viable bacteria ranging from 1.8 to 4.4 log(10) CFU/mL.

CONCLUSIONS

The ophthalmic solution of gatifloxacin 0.3% eradicated bacteria that frequently cause postoperative ocular infections substantially faster than did the ophthalmic solution of moxifloxacin 0.5%.

Unilateral Candida parapsilosis interface keratitis after laser in situ keratomileusis: case report and review of the literature

PURPOSE

To describe a rare case of early-onset Candida parapsilosis infection after laser in situ keratomileusis (LASIK) and review the published reports of post-LASIK fungal infections.

METHODS

A 32-year-old woman presented with interface infiltration in the central interface in the right eye 2 days after LASIK surgery. The right eye flap was lifted, and the opacities were scraped. Two days later, a 3- x 3-mm-dense oval opacity and diffuse hazes were noted. Surgical intervention was arranged because of suspicion of interface infectious keratitis.

RESULTS

After an apparent post-LASIK keratitis with related interface inflammation failed to respond to medical therapy, corneal culture results were positive for C. parapsilosis 2 weeks 6 days after presentation. The patient was started on topical drops of amphotericin B 0.15% every hour after the smear showed the presence of yeast. The opacities decreased, and the topical antifungal drops were tapered. One month later, her uncorrected visual acuity recovered to 20/20.

CONCLUSIONS

Candida parapsilosis interface keratitis after LASIK may occur in the early phase. Early diagnosis and proper treatment can result in good outcome.

Fluoroquinolone therapy in a rabbit model of post-LASIK methicillin-resistant Staphylococcus aureus keratitis

PURPOSE

To develop a rabbit model of post-laser in situ keratomileusis (LASIK) methicillin-resistant Staphylococcus aureus (MRSA) keratitis for studying fluoroquinolone prophylaxis and treatment.

SETTING

Department of Microbiology, University of Mississippi Medical Center, Jackson, Mississippi, USA.

METHODS

An MRSA keratitis isolate (5 microL, 500 colony forming units [CFU]) was inoculated underneath a corneal flap. Bacterial growth and pathology were determined by quantitative cultures (CFU) and slitlamp examination, respectively. The effectiveness of commercial moxifloxacin and gatifloxacin formulations was compared in 3 regimens: prophylaxis (4 drops before inoculation), early therapy (single drop hourly from 4 to 9 hours postinfection), and late therapy (single drop hourly from 10 to 15 hours postinfection). Zones of bacterial inhibition to known in vivo antibiotic concentrations were determined.

RESULTS

Bacteria grew to a maximum of approximately 10(6) CFU/cornea within 10 hours postinfection. The slitlamp examination scores showed pathologic changes beginning 10 hours postinfection and progressed throughout the infection. For prophylaxis, eyes treated with moxifloxacin had significantly fewer CFU than gatifloxacin-treated eyes or untreated controls (both P < or = .0001). During early treatment, the antibiotics were equally effective in reducing CFU relative to untreated controls (P < or = .0001). In late treatment, gatifloxacin and moxifloxacin caused significant reductions in CFU relative to untreated controls (P < or = .0007 and P < or = .0001, respectively). Moxifloxacin produced zones of bacterial inhibition significantly larger than those produced by gatifloxacin.

CONCLUSIONS

Methicillin-resistant S aureus inoculation beneath a rabbit corneal flap produced an infection that was useful for quantitative microbiological studies. A significant advantage in using moxifloxacin relative to gatifloxacin was observed in prophylaxis of keratitis (P = .0001).

Aspergillus fumigatus keratitis following laser in situ keratomileusis

A 31-year-old woman developed pain, decreased vision, and a corneal flap infiltrate 4 days following laser in situ keratomileusis (LASIK). Treatment with topical antibiotic agents did not improve the symptoms. Approximately 2 weeks after surgery, the patient was referred to Stanford University, with 20/400 visual acuity in the left eye and a stromal infiltrate posterior to the flap. Cultures demonstrated Aspergillus fumigatus sensitive to voriconazole. The corneal ulcer progressed despite aggressive antifungal treatment, requiring amputation of the corneal flap and daily debridement. The infiltrate resolved in response to topical voriconazole, natamycin, and oral voriconazole. Aspergillus fumigatus keratitis is a rare but serious complication of LASIK surgery. The infection was successfully treated with flap amputation and daily debridement in addition to antifungal therapy.

Methicillin-resistant Staphylococcus aureus infectious keratitis following refractive surgery

PURPOSE

To elucidate risk factors, clinical course, visual outcomes, and treatment of culture-proven methicillin-resistant Staphylococcus aureus (MRSA) infectious keratitis following refractive surgery.

DESIGN

Interventional case series.

METHODS

Multicenter chart review of 13 cases of MRSA keratitis following refractive surgery and literature review.

RESULTS

Thirteen eyes of 12 patients, nine of whom were either healthcare workers or exposed to a hospital surgical setting, developed MRSA keratitis following refractive surgery. All patients presented with a decrease in visual acuity and complaints of pain or irritation in the affected eye. Common signs on slit-lamp biomicroscopy were corneal epithelial defects, focal infiltrates with surrounding edema, conjunctival injection, purulent discharge, and hypopyon. All patients were diagnosed with infectious keratitis on presentation and treated with two antibiotics. All eyes were culture-positive for MRSA.

CONCLUSIONS

According to a computerized MEDLINE literature search, this is the first case series of MRSA infectious keratitis following refractive surgery, the first reports of MRSA keratitis after refractive surgery in patients with no known exposure to a healthcare facility, the first report of MRSA keratitis after a laser in situ keratomileusis (LASIK) enhancement, and the first reports of MRSA keratitis after prophylaxis with fourth-generation fluoroquinolones. MRSA keratitis is a serious and increasing complication following refractive surgery. Patients with exposure to a healthcare environment should be considered at additional risk for developing MRSA keratitis. However, in addition, surgeons should now be vigilant for community-acquired MRSA. Prompt identification with culturing and appropriate treatment of MRSA keratitis after refractive surgery is important to improve visual rehabilitation.

Avoidance, recognition, and management of LASIK complications

PURPOSE

To provide important concepts of the latest developments in laser in situ keratomileusis (LASIK) complication avoidance, recognition, and management.

DESIGN

A perspective.

METHODS

A comprehensive literature search and review of a total of 816 publications that discussed LASIK complications from 1992 to 2005 was conducted.

RESULTS

The risk of visually threatening complications is inherent in any ophthalmologic surgical procedure. Not only does LASIK require the use of several complex medical devices, but there can be significant human variation in response to this surgical intervention. As a result, many potential complications can occur after LASIK. The risk of many complications can be mitigated by appropriate patient selection and preoperative, surgical, and postoperative care. Unforeseen complications will occur, despite meticulous planning, and must be managed. Important current developments in the avoidance, recognition, and management of LASIK complications are reviewed.

CONCLUSIONS

Complications as a result of LASIK can threaten vision and may cause debilitating symptoms in an otherwise healthy eye. Advancing our understanding of the prevention and management of the complications of LASIK is an endeavor that must be continued as long as refractive surgery is performed.

Effectiveness of fluoroquinolones against Mycobacterium abscessus in vivo

PURPOSE

To determine the effectiveness of fluoroquinolones against Mycobacterium abscessus in vivo.

METHODS

M. abscessus growth was determined quantitatively in rabbit corneas after intrastromal bacterial injection (10(4) CFU/cornea; n >or= 4 corneas per group). Eyes were treated topically with 0.3% ciprofloxacin, 0.5% levofloxacin, or 0.5% moxifloxacin by three protocols: (1) 1 drop of antibiotic applied hourly for 10 hr on day 3 postinfection (PI); (2) 1 drop applied every 2 hr for 10 hr on days 2 and 3 PI; or (3) 1 drop applied every 2 hr for 10 hr on days 1, 2, and 3 PI. Corneas were cultured 1 hr after the last topical drop. Results are expressed as the log CFU.

RESULTS

Bacteria in control group reached maximal numbers in vivo by day 3 PI (approximately 6 logs CFU/cornea). Treatment of infected eyes on day 3 with moxifloxacin or levofloxacin resulted in approximately 2.0 log decrease in CFU/cornea relative to the untreated control. Treatment on days 2 and 3 with moxifloxacin or levofloxacin resulted in approximately 3.0 and 2.5 log CFU/cornea decrease, respectively. Ciprofloxacin had no effect on bacterial load. Treatment on days 1, 2, and 3 with moxifloxacin resulted in a 5.5 log CFU decrease, whereas treatment with levofloxacin or ciprofloxacin resulted in a approximately 4.0 log CFU decrease.

CONCLUSIONS

Moxifloxacin, and to a lesser extent levofloxacin and ciprofloxacin, demonstrated significant effectiveness for reducing the number of M. abscessus in vivo, suggesting the potential usage of these agents in prevention of M. abscessus keratitis.

Pseudomonas keratitis after laser in situ keratomileusis

We report a 32-year-old woman who presented with infectious keratitis in the right eye 3 weeks after laser in situ keratomileusis (LASIK). On microbiological investigations, the microorganism isolated was Pseudomonas aeruginosa that was sensitive to ciprofloxacin. To our knowledge, this is the only case report in the literature of post-LASIK infectious keratitis caused by P aeruginosa.

Overview of the Potency of Moxifloxacin Ophthalmic Solution 0.5% (VIGAMOX®)

Antibiotics have been the mainstay of therapy for infectious diseases since their origins in the 1940s. As microorganisms changed and resistance developed, more advanced antibiotics were ultimately needed to provide adequate coverage and spectrum. By selecting optimal antibiotics and dosing regimens, clinicians can avoid treatment failures and adverse events and can help prevent the emergence of further antibiotic resistance. The fourth-generation ophthalmic fluoroquinolones include moxifloxacin (VIGAMOX, Alcon Laboratories, Inc., Fort Worth, TX) and gatifloxacin (Zymar, Allergan, Irvine, CA), and they are now approved for the treatment of bacterial conjunctivitis. This review highlights four scientific methods that compare and rank antibiotic potencies and predict their clinical efficacy and their propensity to develop resistance: 1) in vitro assay for minimum inhibitory concentrations, 2) in vivo models for pharmacokinetic and pharamacodynamic properties, 3) therapeutic index or inhibitory quotient, and 4) in vitro assay for mutant prevention concentration. The fourth-generation ophthalmic fluoroquinolones perform well in these assays. Both antibiotics have better in vitro activity against gram-positive bacteria than ciprofloxacin or ofloxacin. Moxifloxacin penetrates better into ocular tissues than gatifloxacin and older fluoroquinolones; in vitro activity of moxifloxacin and gatifloxacin against gram-negative bacteria is similar to that of older fluoroquinolones. Moxifloxacin also has better mutant prevention characteristics than other fluoroquinolones. These findings support the use of the newer fluoroquinolones for the prevention and treatment of serious ophthalmic infections (e.g., keratitis, endophthalmitis) caused by susceptible bacteria.

Effect of propolis in the treatment of experimental Staphylococcus aureus keratitis in rabbits

PURPOSE

The aim of this study was to investigate the antimicrobial and anti-inflammatory properties of an ethanolic extract of propolis, a natural resin produced by honeybees, and to determine synergistic activity between ciprofloxacin and propolis in the treatment of experimental Staphylococcus aureus keratitis.

METHODS

Sixteen young New Zealand white rabbits were given intrastromal injections of S. aureus strains. Twenty-four hours later, the rabbits were randomly divided into 4 groups: group 1 was treated with topical 0.3% ciprofloxacin drops along with the ethanolic extract of propolis drops; group 2 received topical 0.3% ciprofloxacin drops; group 3 was administered the ethanolic extract of propolis drops, and group 4, the control group, was treated with phosphate-buffered saline (PBS) drops. Drugs were instilled 8 times/day for 72 h. Twenty-four and 96 h after inoculation of bacteria, the eyes were examined by slit lamp to assess corneal opacity. Corneas were removed to count bacteria.

RESULTS

Slit lamp examination showed that the corneal opacity scores were significantly lower in eyes that received propolis plus ciprofloxacin than in those treated with ciprofloxacin (p = 0.041) or propolis (p = 0.006) or control eyes treated with PBS (p = 0.0001). There was no significant difference in eyes treated with ciprofloxacin and propolis (p = 1.00). There were significantly fewer bacteria in eyes that received propolis plus ciprofloxacin than in those treated with ciprofloxacin (p = 0.0001) or propolis (p = 0.0001) or control eyes treated with PBS (p = 0.0001). There was no significant difference in eyes treated with ciprofloxacin and propolis (p = 0.38).

CONCLUSIONS

Taking these findings into consideration, we suggest that the ethanolic extract of propolis has antimicrobial and anti-inflammatory properties for S. aureus keratitis. The combination of ciprofloxacin and propolis had better therapeutic effects than either agent alone.

Fluoroquinolone therapy in Mycobacterium chelonae keratitis after lamellar keratectomy

PURPOSE

To characterize a rabbit model of Mycobacterium chelonae keratitis after lamellar keratectomy and assess the effectiveness of fluoroquinolone therapy.

SETTING

University Laboratory, University of California, Irvine, California, USA.

METHODS

Twenty-eight New Zealand white rabbits had unilateral lamellar keratectomy with placement of 2.5 x 10(5) colony-forming units of log-phase M chelonae under each flap. Eyes (7 per group) were randomized and treated with sterile balanced salt solution, gatifloxacin 0.3%, ciprofloxacin 0.3%, or levofloxacin 0.5% 4 times daily. Two masked observers examined all eyes on days 2, 5, and 7 and weekly for 4 weeks. Severity of disease and bacterial culture results were the main outcomes measured. The means and standard deviations were calculated, and differences between the groups were statistically analyzed.

RESULTS

All eyes developed clinical disease. At the time the rabbits were killed, eyes treated with balanced salt solution, ciprofloxacin, levofloxacin, and gatifloxacin were culture positive in 6 (85.7%), 7 (100%), 6 (85.7%), and 3 (42.9%) of 7 eyes per group, respectively. Frequency of positive culture and the severity of clinical disease in gatifloxacin-treated eyes were significantly less (P < .05) than in the other groups combined.

CONCLUSIONS

The rabbit model of M chelonae keratitis was successfully developed in our study. A fourth-generation quinolone (gatifloxacin) showed the best performance among the fluoroquinolones tested in our experimental approach. The fourth-generation fluoroquinolone, gatifloxacin, could be effectively used for the treatment of mycobacterial keratitis.

Two Cases of Pneumococcal Keratitis Following Myopic LASIK

PURPOSE

To report two cases of pneumococcal keratitis after LASIK.

METHODS

Retrospective interventional small case series of two patients who underwent bilateral LASIK for myopia and developed pneumococcal keratitis after surgery. This complication was encountered 2 days after surgery in one eye in both cases. The corneal flap was lifted, and irrigation and cultures from the stromal bed performed. Topical and subconjunctival antibiotics were started.

RESULTS

Culture revealed Streptococcus pneumoniae in both cases. The infiltrates responded well to treatment. One year after the procedure, uncorrected visual acuity is > 20/40 in both cases.

CONCLUSIONS

Pneumococcal keratitis can complicate LASIK. Patients should be informed of this potential complication, as prompt treatment is crucial.

Moria M2 Single Use Microkeratome Head in 100 Consecutive LASIK Procedures

PURPOSE

To evaluate the safety and efficacy of the Moria M2 single use 130 microkeratome head in consecutive LASIK procedures for correction of myopia and myopic astigmatism.

METHODS

One hundred eyes of 55 patients underwent LASIK in which the flaps were created with the Moria M2 microkeratome using the single use 130 head and excimer laser ablation was done with the Allegretto Wave-light laser. Flap parameters measured were: thickness, diameter, hinge length, and overall quality. Preoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, wavefront aberrations, and low contrast sensitivity were compared to postoperative values at 6-month follow-up.

RESULTS

Mean flap thickness was 145 +/- 17.5 microm, mean flap diameter was 8.5 +/- 0.40 mm, and mean hinge cord length was 4.05 +/- 0.35 mm. At 6-month follow-up, UCVA improved from 20/200 (+/-0.24) to 20/18.5 (+/-0.12) and BSCVA improved from 20/20.5 (+/-0.18) to 20/17.5 (+/-0.11).

CONCLUSIONS

The Moria M2 single use 130 microkeratome head appears to be safe and effective in performing LASIK procedures.

Mikrobielle Keratitis nach Laser-in-situ-Keratomileusis

Laser in situ keratomileusis (LASIK) is an effective option and currently one of the most commonly applied surgical techniques in the correction of refractive errors such as myopia, hyperopia, and astigmatism. In contrast to photorefractive keratectomy, it maintains the integrity of Bowman's membrane and the epithelium leading to faster visual rehabilitation as well as less pain and discomfort. Nevertheless, following LASIK the stroma is exposed to infectious organisms. Sight-threatening complications after LASIK are reported to be as rare as 1 in 1000 procedures. However, any infectious keratitis remains potentially devastating. Reports about infectious keratitis following LASIK have increasingly surfaced in recent years. We present a review of the literature on microbial keratitis and present our own cases and recommendations for possible prophylaxis and therapy.

Early bacterial keratitis after laser-assisted subepithelial keratectomy

We report a case of bacterial keratitis that occurred after laser-assisted subepithelial keratectomy. The patient presented with a decrease in visual acuity and pain 2 days after the procedure. Culture was positive for Staphylococcus haemolyticus. The infiltrate slowly resolved with topical antibiotics, and the best corrected visual acuity improved to 20/20. Although bacterial keratitis occurs rarely after refractive surgery, patients should be informed of the potential risk for visual loss caused by this infection.

Candida parapsilosis keratitis following treatment of epithelial ingrowth after laser in situ keratomileusis

PURPOSE

To present a case of Candida parapsilosis following laser in situ keratomileusis (LASIK).

METHODS

Retrospective chart review.

RESULTS

A case report of a 51-year-old woman who underwent bilateral LASIK is presented. Two weeks after the procedure, the patient presented with epithelial ingrowth OD. The ingrowth was treated with flap lifting and scraping, followed by postoperative antibiotics. Four weeks later, the patient presented with numerous interface infiltrates. Smears were positive for yeast forms and cultures grew Candida parapsilosis. Administration of topical and systemic antifungal therapy resulted in clearing of the infection with partial visual recovery.

CONCLUSIONS

To our knowledge, this represents the first reported case of a post-LASIK Candida parapsilosis keratitis. A high degree of suspicion coupled with rapid and appropriate treatment can result in visual recovery.

Infections following laser in situ keratomileusis: an integration of the published literature

Infections occurring after laser in situ keratomileusis (LASIK) surgery are uncommon, but the number of reports have steadily increased in recent years. This systematic, comprehensive review and analysis of the published literature has been performed in order to develop an integrative perspective on these infections. We have stratified the data by potential associations, microbiology, treatment, and the degree of visual loss, using Fisher's exact tests and Student's t-tests for analysis. In this review, we found that Gram-positive bacteria and mycobacterium were the most common causative organisms. Type of postoperative antibiotic and steroid use was not associated with particular infecting organisms or severity of visual loss. Gram-positive infections were more likely to present less than 7 days after LASIK, and they were associated with pain, discharge, epithelial defects, and anterior chamber reactions. Fungal infections were associated with redness and tearing on presentation. Mycobacterial infections were more likely to present 10 or more days after LASIK surgery. Moderate or severe visual reductions in visual acuity occurred in 49.4% of eyes. Severe reductions in visual acuity were significantly more associated with fungal infections. Flap lift and repositioning preformed within 3 days of symptom onset may be associated with better visual outcome.

Topical antibacterial therapy for mycobacterial keratitis: potential for surgical prophylaxis and treatment

BACKGROUND

Mycobacterium chelonae and Mycobacterium fortuitum are the 2 most commonly implicated species of nontuberculous mycobacteria in cases of bacterial keratitis.

OBJECTIVES

This article summarizes available data on the in vitro antibacterial activity against M chelonae or M fortuitum of 2 agents-amikacin and clarithromycin-that have been used in the treatment of bacterial keratitis. In addition, the article reviews the in vitro activity of 5 commercially available topical ocular fluoro-quinolones (in order of availability, ciprofloxacin, ofloxacin, levofloxacin, gatifloxacin, and moxifloxacin) that may have potential in the surgical prophylaxis and treatment of keratitis caused by M chelonae or M fortuitum.

METHODS

A search of the English-language literature indexed on the MEDLINE, Life Sciences, EMBASE, BIOSIS, and Pharmaprojects databases from 1966 to October 7, 2003, was conducted using the terms Mycobacterium chelonae, Mycobacterium fortuitum, bacterial keratitis, topical antibiotic therapy, ocular infection-mycobacteria, and LASIK infections. Data on the minimum concentrations at which 90% of isolates were inhibited (MIC(90)s) were reviewed and compared.

RESULTS

In the literature reviewed, the MIC(90) against M fortuitum was from 1 to 16 microg/mL for amikacin, from </=2 to >/=8 microg/mL for clarithromycin, from 0.1 to 1 microg/mL for ciprofloxacin, from 0.5 to 3.13 microg/mL for ofloxacin, and </=2 microg/mL for levofloxacin. The results were similar against M chelonae. The fourth-generation fluoroquinolones-gatifloxacin and moxifloxacin-had similar MIC(90)s against M fortuitum (both, 0.2 to 1 microg/mL); however, moxifloxacin had greater activity than gatifloxacin against M chelonae (minimum inhibitory concentration range: moxifloxacin, </=1 to 1.6 microg/mL; gatifloxacin, 3.2 to 6.25 microg/mL).

CONCLUSIONS

Topical fluoroquinolones may be beneficial for ocular surgical prophylaxis and for the treatment of keratitis caused by M chelonae or M fortuitum. Based on their reported MIC(90)s, none of the antibacterials reviewed had greater in vitro activity than moxifloxacin. In addition, moxifloxacin had greater in vitro activity than gatifloxacin against M chelonae, one of the predominant nontuberculous mycobacterial species involved in bacterial keratitis. Pending the conduct of controlled clinical studies, these findings suggest that moxifloxacin may have utility in the prevention and treatment of atypical mycobacterial keratitis.

Ulcerative keratitis caused by Serratia marcescens after laser in situ keratomileusis

We report 2 cases of severe corneal infections caused by Serratia marcescens after laser in situ keratomileusis (LASIK). Twenty-four hours after LASIK, 2 patients developed infectious keratitis, 1 bilaterally. In each eye, the corneal flap was edematous, ulcerated, and detached from the stromal bed. Treatment included removal of the necrotic flap and aggressive antibiotic therapy. Cultures from corneal exudates were positive for S marcescens. After 1 year, both patients had a loss of best corrected visual acuity (BCVA) ranging from 20/40 to 20/22 because of irregular astigmatism. Overrefraction with a hard contact lens resulted in a BCVA of 20/20 in the 3 affected eyes. Slitlamp examination showed trace subepithelial haze without severe corneal scarring. Videokeratography disclosed areas of paracentral inferior steepening resembling keratoconus. Refraction and videokeratography remained stable after 6 months of follow-up. Ulcerative keratitis caused by S marcescens is a potential complication of LASIK. Bilateral involvement may occur if bilateral simultaneous surgery is performed.

Nattrassia mangiferae keratitis after laser in situ keratomileusis

A 32-year-old man had photophobia and blurred vision 2 weeks after uneventful laser in situ keratomileusis to correct myopia. He was treated with steroids for suspected diffuse lamellar keratitis, antiherpetics, and antibiotic eyedrops, but the condition worsened and the patient developed further blurred vision, an inflamed eye, and pain. When referred to us, the patient had an extensive corneal ulcer with hypopyon and mycelia were reported in scrapings of the ulcer bed. Nattrassia mangiferae (Hendersonula toruloidea) was cultured from the specimen. The patient was treated with antifungal agents and 2 penetrating keratoplasties. At the last examination, the uncorrected visual acuity was 20/200.

Infectious keratitis after laser in situ keratomileusis: Results of an ASCRS survey

To investigate the incidence, culture results, treatment, and visual outcomes of infectious keratitis after laser in situ keratomileusis (LASIK) worldwide, the Cornea Clinical Committee of the American Society of Cataract and Refractive Surgery (ASCRS) contacted 8600 United States and international ASCRS members by e-mail and asked them to respond to a questionnaire about post-LASIK infectious keratitis. One hundred sixteen infections were reported by 56 LASIK surgeons who had performed an estimated 338 550 procedures. Seventy-six cases presented in the first week after surgery, 7 during the second week, 17 between the second and fourth weeks, and 16 after 1 month. Forty-seven cases were not diagnosed on initial presentation. The most common organisms cultured were atypical mycobacteria and staphylococci. Empiric therapy is not recommended as most of the organisms are opportunistic and not responsive to conventional therapy. Flap elevation and culturing should be performed when post-LASIK infectious keratitis is suspected.

Bilateral Candida parapsilosis interface keratitis after laser in situ keratomileusis

We report a case of Candida infection after laser in situ keratomileusis (LASIK) and review the literature for reports of post-LASIK fungal infections. Risk factors may include postoperative surgical intervention and extended use of topical steroids.

Physicians' liability in ophthalmology practice

PURPOSE

The aims of this paper are to point out the importance of coherence in established guidelines in daily practice, highlight the value of signed patient informed consent forms and stress the value of a good understanding of the law, while focusing on issues related to malpractice in ophthalmology.

METHODS

Search of the current relevant literature.

RESULTS

The most common causes of medical litigation in ophthalmology are related to LASIK surgery, cataract surgery, glaucoma care, radial keratotomy for myopia reduction and failure to diagnose binocular vision anomalies in children and adults in a timely fashion. The litigation raised in most cases is driven by unfavourable outcomes and not by malpractice.

CONCLUSION

Maintenance of high standards in daily practice, with continuous training and clear communication along with the appropriate documentation of any procedure carried out, may improve the professional safety of practising eye specialists in the event of medical litigation. Although the use of patient informed consent varies substantially among European countries, it may serve as useful evidence in the physician's defence.

Fluoroquinolone therapy in multiple-drug resistant staphylococcal keratitis after lamellar keratectomy in a rabbit model

PURPOSE

To assess the effectiveness of a fourth-generation fluoroquinolone for prophylaxis against multiple drug-resistant staphylococcal keratitis after lamellar keratectomy in a rabbit model.

DESIGN

Experimental study.

METHODS

Twenty-eight New Zealand white rabbits underwent unilateral lamellar keratectomy using a manual microkeratome followed by the placement of 1000 colony-forming units (CFUs) of log-phase Staphylococcus aureus bacteria under each flap. Eyes (seven in each group) were randomized and treated with one of the following agents: sterile balanced salt solution, gatifloxacin (0.3%), ciprofloxacin (0.3%) or levofloxacin (0.5%) immediately and 6, 12, and 18 hours after surgery. Inflammation was graded by two masked observers at 24 and 48 hours, and the presence or absence of infectious infiltrates was determined. The means and standard deviations were calculated, and differences among the groups were statistically analyzed.

RESULTS

There were no flap complications encountered during surgery. Eyes treated with ciprofloxacin, levofloxacin, and balanced salt solution developed infectious infiltrates in five of seven eyes per group. Gatifloxacin-treated eyes did not develop clinical infection and exhibited lower mean inflammation scores (P <.01 compared with the other groups).

CONCLUSION

The fourth-generation fluoroquinolone, gatifloxacin, is an effective prophylaxis against the development of keratitis after lamellar keratectomy in rabbits with an organism resistant to methicillin, levofloxacin, and ciprofloxacin.