Infectious keratitis after LASIK

Ocular infections associated with atypical mycobacteria: A review

Atypical mycobacteria or non-tuberculous mycobacteria (NTM) are a group of acid-fast bacteria that are pathogenic to different parts of the eye. The organisms can cause a spectrum of ocular infections including keratitis, scleritis, uveitis, endophthalmitis and orbital cellulitis. Trauma, whether surgical or nonsurgical, has the highest correlation with development of this infection. Common surgeries after which these infections have been reported include laser in situ keratomileusis (LASIK) and scleral buckle surgery. The organism is noted to form biofilms with sequestration of the microbe at different inaccessible locations leading to high virulence. Collection of infective ocular material (corneal scraping/necrotic scleral tissue/abscess material/vitreous aspirate, etc.) and laboratory identification of the organism through microbiologic testing are vital for confirming presence of the infection and initiating treatment. In cluster infections, tracing the source of infection in the hospital setting via testing of different in-house samples is equally important to prevent further occurrences. Although the incidence of these infections is low, their presence can cause prolonged disease that may often be resistant to medical therapy alone. In this review, we describe the various types of NTM-ocular infections, their clinical presentation, laboratory diagnosis, management, and outcomes.

Atypical microbial keratitis

Atypical microbial keratitis refers to corneal infections caused by micro-organisms not commonly encountered in clinical practice. Unlike infections caused by common bacteria, cases of atypical microbial keratitis are often associated with worse clinical outcomes and visual prognosis. This is due to the challenges in the identification of causative organisms with standard diagnostic techniques, resulting in delays in the initiation of appropriate therapies. Furthermore, due to the comparatively lower incidence of atypical microbial keratitis, there is limited literature on effective management strategies for some of these difficult to manage corneal infections. This review highlights the current management and available evidence of atypical microbial keratitis, focusing on atypical mycobacteria keratitis, nocardia keratitis, achromobacter keratitis, and pythium keratitis. It will also describe the management of two uncommonly encountered conditions, infectious crystalline keratopathy and post-refractive infectious keratitis. This review can be used as a guide for clinicians managing patients with such challenging corneal infections.

[Complications of femto-LASIK and features of cavitation injuries]

Modern approach to refractive laser surgery features three main types of lamellar surgery. Two of them are types of open laser keratomileusis (LASIK and femtosecond laser-assisted LASIK), and the third - closed (SMILE). All of these techniques allow achieving good clinical outcomes but differ in possible complications. This article reviews the complications of femto-LASIK and specifically the post-operative cavitation injuries, describes the mechanism of their occurrence, variants of their course, and presents the prevention measures.

Metagenomic nanopore sequencing of ocular microbiome in patients with meibomian gland dysfunction

PURPOSE

To explore the composition of the ocular microbiome in patients with Meibomian gland dysfunction (MGD) using metagenomic nanopore sequencing.

METHODS

A total of 98 participants were recruited from September to December 2021, including 86 patients with MGD and 12 controls. Symptoms and signs of dry eye were assessed, and bacterial samples in the conjunctival sac (CS) and meibomian gland (MG) secretions were then identified by bacterial culture identification and metagenomic nanopore sequencing.

RESULTS

The positive rate of CS bacterial culture in the MGD group was significantly higher than that in the normal group. A more complex composition of bacterial genera was detected in the mild and moderate MGD groups than in the control. However, the severe MGD groups had the simplest composition of bacteria. Metagenomic nanopore sequencing detected more species of bacteria than traditional culture.

CONCLUSION

The CS and MG of MGD patients may have different degrees of bacterial microbiota imbalance. Metagenomic nanopore sequencing technology provides a new way for us to understand the composition of "real-world" ocular surface microorganisms.

Very late onset LASIK flap Acremonium fungal keratitis confirmed by metagenomic deep sequencing

Purpose

To describe a unique case of LASIK flap fungal keratitis confirmed by next generation sequencing.

Observations

A 56-year-old female presented with refractory keratitis involving her LASIK flap 21 years after surgery. Confocal was positive for filamentous structures. The patient underwent immediate flap amputation followed by topical antifungal treatment. Corneal culture was positive for Acremonium sp. Metagenomic deep sequencing confirmed Acremonium as the primary source of infection and also identified Fusarium as a likely contributor of a mixed fungal infection. Sequencing also identified hay as the likely source of the infection. Treatment resulted in eradication of the infection. The patient's final best corrected visual acuity was 20/30 with rigid contact lens overrefraction.

Conclusions

Metagenomic deep sequencing is a novel diagnostic tool that is increasingly being utilized for diagnosis of refractory keratitis. This case demonstrates the diagnostic potential of deep sequencing for identifying post-LASIK keratitis and reinforces the utility of LASIK flap amputation in the setting of tectonic flap instability due to keratolysis.

Importance

This case highlights several important clinical points for treating LASIK flap keratitis and highlights the emerging role metagenomic sequencing has in the diagnosis of infectious keratitis. This is first known case using next generation sequencing to diagnose a post-LASIK infectious keratitis.

Paradox of complex diversity: Challenges in the diagnosis and management of bacterial keratitis

Bacterial keratitis continues to be one of the leading causes of corneal blindness in the developed as well as the developing world, despite swift progress since the dawn of the "anti-biotic era". Although, we are expeditiously developing our understanding about the different causative organisms and associated pathology leading to keratitis, extensive gaps in knowledge continue to dampen the efforts for early and accurate diagnosis, and management in these patients, resulting in poor clinical outcomes. The ability of the causative bacteria to subdue the therapeutic challenge stems from their large genome encoding complex regulatory networks, variety of unique virulence factors, and rapid secretion of tissue damaging proteases and toxins. In this review article, we have provided an overview of the established classical diagnostic techniques and therapeutics for keratitis caused by various bacteria. We have extensively reported our recent in-roads through novel tools for accurate diagnosis of mono- and poly-bacterial corneal infections. Furthermore, we outlined the recent progress by our group and others in understanding the sub-cellular genomic changes that lead to antibiotic resistance in these organisms. Finally, we discussed in detail, the novel therapies and drug delivery systems in development for the efficacious management of bacterial keratitis.

Late onset of microbial keratitis after laser in situ keratomileusis surgery: case series

PURPOSE

To report predisposing factors, clinical features, microbiology spectrum, antibiotic resistance, antimicrobial therapy, and outcomes of patients with a previous laser in situ keratomileusis (LASIK) surgery and diagnosed with presumed microbial keratitis.

SETTING

Sydney Eye Hospital, Sydney, New South Wales, Australia.

DESIGN

Retrospective case review.

METHODS

Patients were identified from pathology and hospital coding data from 2012 to 2016. Inclusion criteria were all patients with a previous LASIK surgery, a presumed diagnosis of microbial keratitis, and a corneal scrape performed and aged older than 18 years. Demographics, clinical details, and outcomes were collated from the medical records.

RESULTS

Sixteen patients were included, with median age of 41.5 years (range 22 to 85 years) and 56.2% of women. The median time between LASIK procedure and microbial keratitis presentation was 38.3 months (interquartile range 6.7 to 77.45 months). Cultures were positive for bacteria in 12 (75%) of 16 scrapes. Of the bacterial isolates, 12 (85.7%) were gram-positive and 2 (14.3%) gram-negative. Sensitivity profiles for the isolated bacteria were similar between fortified antibiotics (cefalotin and gentamicin) and commercial products (chloramphenicol and ofloxacin). Complications included the need for tectonic grafts, nonhealing epithelial defects, thinning, and neovascularization.

CONCLUSIONS

Late onset of keratitis after LASIK can occur with no positive cultures for nontuberculous mycobacteria, no interface involvement, and no other usual features reported in case series of infectious keratitis in LASIK patients. It has a similar clinical course to non-LASIK keratitis, such that the surgery may not have been a risk factor for infection.

CLEAR - Medical use of contact lenses

The medical use of contact lenses is a solution for many complex ocular conditions, including high refractive error, irregular astigmatism, primary and secondary corneal ectasia, disfiguring disease, and ocular surface disease. The development of highly oxygen permeable soft and rigid materials has extended the suitability of contact lenses for such applications. There is consistent evidence that bandage soft contact lenses, particularly silicone hydrogel lenses, improve epithelial healing and reduce pain in persistent epithelial defects, after trauma or surgery, and in corneal dystrophies. Drug delivery applications of contact lens hold promise for improving topical therapy. Modern scleral lens practice has achieved great success for both visual rehabilitation and therapeutic applications, including those requiring retention of a tear reservoir or protection from an adverse environment. This report offers a practical and relevant summary of the current evidence for the medical use of contact lenses for all eye care professionals including optometrists, ophthalmologists, opticians, and orthoptists. Topics covered include indications for use in both acute and chronic conditions, lens selection, patient selection, wear and care regimens, and recommended aftercare schedules. Prevention, presentation, and management of complications of medical use are reviewed.

Multi-Drug Resistant Post Corneal Repair Klebsiella oxytoca's Keratitis

Background

Bacterial keratitis can threaten vision through permanent corneal scarring and even perforation, resulting in loss of the eye. Klebsiella oxytoca is resistant to several antibiotics because it produces extended-spectrum β-lactamase encapsulated with polysaccharide. Thus, this article is aimed at reporting a rare case of Klebsiella oxytoca-induced keratitis in Jimma University Medical Centre, Jimma, Ethiopia.

Case Presentation

TA 25-year-old female patient presented with photophobia, redness, and purulent discharge from the right eye. She had matted cilia of the eyelid, conjunctiva injection, corneal ulcer, and deep fibrinous anterior chamber reaction. She had light perception (LP) visual acuity for the same eye and it was firm when examined digitally. The cornea-scleral repair was performed one month earlier, due to open globe injury. The patient had taken empirical fortified antibiotics before the identification of the specific pathogen. Culture and drug sensitivity test was performed in order to identify the aetiology. The result of the test revealed that the identified pathogen was multi-drug-resistant Klebsiella oxytoca. Based on this result and drug availability, high dose topical fluoroquinolones eye drops (Ciprofloxacin eye drop 0.3% and Ofloxacin 0.3%) were given. Besides, dexamethasone 0.1% eye drop was added to the aforementioned antibiotics. After four months of treatment, the visual outcome was changed from LP to hand motion.

Conclusion

A rare case of multi-drug resistant Klebsiella oxytoca induced keratitis which was isolated in a biochemical test was successfully treated with a high dose of fluoroquinolones.

Refractive surgery in the HIV-positive U.S. Military Natural History Study Cohort: complications and risk factors

PURPOSE

This study sought to assess the frequency of refractive surgery complications in HIV+ individuals and related risk factors.

SETTINGS

Multiple centers in the United States.

DESIGN

Prospective observational cohort study.

METHODS

The U.S. Military HIV Natural History Study is a prospective observational cohort study of HIV+ service members and beneficiaries. Participants were selected who had Current Procedural Terminology codes for laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and other refractive surgeries. The frequency of complications was determined using International Classification of Diseases-9 codes. Covariates included age, sex, antiretroviral therapy, time since HIV diagnosis, history of AIDS, and CD4 (T lymphocytes) count and viral load. Statistical analysis was completed using univariate (χ2 and Wilcoxon-Mann-Whitney tests) and multivariate analyses.

RESULTS

Seventy-nine of 2073 participants had refractive surgery. Fifty-three patients underwent PRK, 23 LASIK, 2 radial keratotomy (RK), and 1 astigmatic correction. Complications occurred in 6 (7.6%) of 79 participants, including 5 patients who underwent PRK and 1 after RK, occurring between 8 and 217 days after surgery. Five ulcers and 1 unspecified keratitis were noted. In the univariate analysis, type of surgery (P = .02) and history of AIDS (P = .02) were risk factors for complications. In logistic regression analysis, no variables were found to be risk factors for complications.

CONCLUSION

Complications were infrequent among HIV+ participants after refractive surgery. Point estimates suggest that PRK might have more complications than LASIK and that advanced HIV, reflected by previous AIDS, might be associated with an increased risk for complications. Further study will be required to confirm these findings.

Risk for microbial keratitis: Comparative metaanalysis of contact lens wearers and post-laser in situ keratomileusis patients

PURPOSE

To compare the risk for microbial keratitis in contact lens wearers stratified by wear schedule with the risk after laser in situ keratomileusis (LASIK).

SETTING

Hamilton Eye Institute and Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, USA.

DESIGN

Comparative metaanalysis and literature review.

METHODS

An extensive literature search was performed in the PubMed database between December 2014 and July 2015. This was followed by a metaanalysis using a mixed-effects modeling approach.

RESULTS

After 1 year of daily soft contact lens wear, there were fewer microbial keratitis cases than after LASIK, or approximately 2 cases fewer cases per 10 000 (P = .0609). If LASIK were assumed to have essentially a 1-time risk for microbial keratitis, 5 years of extrapolation would yield 11 more cases per 10 000 with daily soft contact lens wear than with LASIK, or approximately 3 times as many cases (P < .0001). The extended use of soft contact lenses led to 12 more cases at 1 year than LASIK, or approximately 3 times as many cases (P < .0001), and 81 more cases at 5 years (P < .0001). When incorporating an estimated 10% retreatment rate for LASIK, these results changed very little.

CONCLUSIONS

Microbial keratitis is a relatively rare complication associated with contact lens use and LASIK postoperatively. The risk for microbial keratitis was similar between patients using contact lenses for 1 year compared with LASIK. Over time, the risk for microbial keratitis was higher for contact lens use than for LASIK, specifically with extended-wear lenses.

Crystalline Keratopathy in Post-LASIK Ectasia: A Case Report

PURPOSE

To report an unusual case of bilateral crystalline keratopathy presenting several years after a laser in situ keratomileusis (LASIK) procedure.

METHODS

Case report and review of the literature.

RESULTS

A healthy 42-year-old woman with post-LASIK ectasia, treated with long-term corneoscleral contact lenses, developed new-onset crystalline keratopathy in both eyes. Anterior segment optical coherence tomography demonstrated bilaterally symmetric paracentral rings of hyperreflectivity, involving the LASIK corneal flaps. There was good clearance of the corneoscleral contact lenses with no corneal-lens touch in all quadrants. There was no evidence of infectious or systemic etiologies. Genetic testing for the UBIAD1 gene for Schnyder corneal dystrophy was negative. Continued clinical observations have exhibited progressive corneal crystalline deposition, yet the patient has remained visually asymptomatic.

CONCLUSIONS

This is the first known reported case of significantly delayed progressive noninfectious crystalline keratopathy in post-LASIK ectasia. The pathophysiology of this condition remains elusive to date and highlights the challenges of noninvasive diagnostic techniques and yet the utility of molecular genetic analysis in elucidating the etiology of this unique clinical presentation.

Very late-onset flap margin corneal ulcer following laser in situ keratomileusis

PURPOSE

To report and characterize cases of very late onset (5 years or more after surgery) flap margin corneal ulcers after laser in situ keratomileusis (LASIK) procedure.

METHODS

A retrospective case series of consecutive patients who were diagnosed with very late flap margin corneal ulcers following LASIK, between January 2014 and July 2017. All patients were treated with topical antibiotics and were followed up until complete resolution.

RESULTS

A total of eight patients, with a mean age of 46.5 ± 11 years, (range 31-64 years), were included in this study. All patients underwent uneventful myopic LASIK 13.3 ± 3 (range 10-20) years before presentation. Patients best corrected visual acuity (BCVA) at presentation was 0.20 ± 0.15 logMAR compared to a final BCVA of 0.10 ± 0.10 logMAR (p = 0.28). The ulcer was located in the bottom two clock hours of the flap margin (5-7 o'clock) in six (75%) patients and superior (11 o'clock) in the remaining two patients (p = 0.048). Seven patients (87.5%) suffered from blepharitis, and only one did not.

CONCLUSIONS

LASIK may be associated with an increased risk of late-onset corneal ulcer occurring years after the procedure. Instability of the flap margin, blepharitis and dry eye are possible causes of epithelial disturbance and may account for this complication.

Direct and Indirect Flap Measurements in Femtosecond Laser-Assisted In Situ Keratomileusis

PURPOSE

To compare direct and indirect LASIK flap thickness measurements using ultrasound and Scheimpflug technology.

METHODS

Eighty-two eyes treated with laser-assisted in situ keratomileusis refractive surgery using a femtosecond laser (IntraLase FS150) were prospectively included in the study. Flap thickness was set to 115 μm. Corneal flap thickness was measured using the direct method-ie, ultrasound pachymetry immediately after flap construction in the presence of cavitation bubbles-and indirect methods, with subtraction of intraoperative post-lift corneal thickness measured using ultrasound pachymetry (intrastroma) from preoperative central corneal thickness using ultrasound (Indirect-US) or Scheimpflug thinnest pachymetry (Indirect-Scheimpflug).

RESULTS

Mean flap thickness was overestimated using the indirect methods, Indirect-US and Indirect-Scheimpflug (122.6 ± 24.5 μm and 128.1 ± 26.1 μm, respectively; P < 0.0060 and P < 0.0001, respectively). There were no significant correlations between the direct and indirect methods. Indirect-Scheimpflug was significantly higher (P = 0.0122) than Indirect-US. The closest average flap thickness compared with the set parameter of 115 μm was that of the direct method (115.6 ± 8.6 μm; 95% confidence interval: -1.3 to 2.5; P = 0.5163). The direct method provided the lowest SD of all groups (SD: 8.64).

CONCLUSIONS

The direct method of flap thickness measurement was the most comparable to the set parameter compared with the indirect subtraction methods. Additional studies are needed to determine which method allows for the most accurate measurement of flap thickness.

Identification of the Infection Source of an Outbreak of Mycobacterium Chelonae Keratitis After Laser in Situ Keratomileusis

PURPOSE

Nontuberculous mycobacteria keratitis is a rare but challenging complication of laser in situ keratomileusis (LASIK). This study was conducted to determine the source(s) of infection in a cluster of cases of keratitis after LASIK and to describe this outbreak and patients' outcomes.

METHODS

In this retrospective, case series, single-center study, 86 patients were included who underwent LASIK or photorefractive keratectomy between December 2011 and February 2012. Corneal scrapes from the affected eyes, samples of tap and distilled water, water from the reservoir of the distilling equipment, steamer, and autoclave cassette; antiseptic and anesthetic solutions and surgical instrument imprints were cultivated in liquid and on solid media. Gram-negative bacteria and yeasts were identified using automated systems and mycobacteria by polymerase chain reaction-restriction enzyme analysis of the hsp65 gene (PRA-hsp65) and DNA sequencing. Mycobacterial isolates were typed by pulsed-field gel electrophoresis. The cases and outcomes are described. The main outcome measure was identification of the source(s) of the mycobacterial infections.

RESULTS

Eight (15 eyes) of 86 patients (172 eyes) who underwent LASIK developed infections postoperatively; no patients who underwent photorefractive keratectomy developed infections. Mycobacterium chelonae was isolated from 4 eyes. The distilled water collected in the surgical facility contained the same M. chelonae strain isolated from the patients' eyes. Different gram-negative bacteria and yeasts were isolated from samples collected at the clinic but not from the patients' eyes.

CONCLUSIONS

Tap water distilled locally in surgical facilities may be a source of infection after ocular surgery and its use should be avoided.

Nasal and conjunctival screening prior to refractive surgery: an observational and cross-sectional study

OBJECTIVES

To investigate bacterial flora of clinically healthy conjunctiva and nasal cavity among patients prior to refractive surgery, as well as the characteristics of patients with methicillin-resistant Staphylococcus aureus (MRSA) colonisation.

DESIGN

Observational and cross-sectional study.

SETTING

A single-centre study in Japan.

PARTICIPANTS

120 consecutive patients pre-refractive surgery.

PRIMARY AND SECONDARY OUTCOME MEASURES METHODS

Samples were obtained from the right conjunctival sac and the nasal cavity of 120 consecutive patients prior to refractive surgery and were then measured for the levels of the minimum inhibitory concentration (MIC) of antibiotics. Patients were interviewed regarding their occupation, family living situation and any personal history of atopic dermatitis, asthma, smoking or contact lens wear.

RESULTS

Propionibacterium acnes (P. acnes) (32.5%) and Staphylococcus epidermidis (4.2%) were detected from the conjunctival sac. S. epidermidis was the most commonly isolated (68.3%) in the nasal cavity. Of the 30 patients (25.0%) with colonisation by S. aureus, 2 patients, both of whom were healthcare workers with atopic dermatitis, were found to be positive for MRSA in the nasal cavity. A history of contact lens wear, asthma or smoking, as well as patient gender and age, was not associated with MRSA colonisation.

CONCLUSIONS

There were only 2 patients who were colonised with MRSA, both of whom were healthcare workers with atopic dermatitis. P. acnes was predominantly found in the conjunctival sac. Further study is needed to investigate the involvement between nasal and conjunctival flora, and risk factors for infectious complications.

Microencapsulation of rifampicin for the prevention of endophthalmitis: In vitro release studies and antibacterial assessment

Rifampicin encapsulated microparticles were designed for intraocular injection after cataract surgery to prevent postoperative endophthalmitis. Microparticles were formulated by emulsification diffusion method using poly(lactic acid-co-glycolic acid) (PLGA) as polymer in order to propose a new form of rifampicin that overcome its limitations in intraocular delivery. Depending on processing formulation, different types of microparticles were prepared, characterized and evaluated by in vitro release studies. Two types of microparticles were selected to get a burst release of rifampicin, to reach minimal inhibitory concentrations to inhibit 90% of Staphylococcus epidermidis mainly involved in postoperative endophthalmitis, combined with a sustained release to maintain rifampicin concentration over 24h. The antibacterial activity and antiadhesive property on intraocular lenses were evaluated on S. epidermidis. Microparticles, with a rapid rifampicin release profile, showed an effect towards bacteria development similar to free rifampicin over 48h. However, slow-release profile microparticles exhibited a similar antibacterial effect during the first 24h, and were able to destroy all the S epidermidis in the medium after 30h. The association of the two formulations allowed obtaining interesting antibacterial profile. Moreover, rifampicin-loaded microparticles have shown a very efficient anti-adherent effect of S. epidermidis on intraocular lenses at 24h. These results propose rifampicin microparticles as suitable for antibioprophylaxis of the postoperative endophthalmitis.

Determinants of visual quality after endothelial keratoplasty

Endothelial keratoplasty is now favored over full-thickness penetrating keratoplasty for corneal decompensation secondary to endothelial dysfunction. Although endothelial keratoplasty has evolved as surgeons strive to improve outcomes, fewer patients than expected achieve best corrected visual acuity of 20/20 despite healthy grafts and no ocular comorbidities. Reasons for this remain unclear, with theories including anterior stromal changes, differences in graft thickness and regularity, induced high-order aberrations, and the nature of the graft-host interface. Newer iterations of endothelial keratoplasty such as thin manual Descemet stripping endothelial keratoplasty, ultrathin automated Descemet stripping endothelial keratoplasty, and Descemet membrane endothelial keratoplasty have achieved rates of 20/20 acuity of approximately 50%, comparable to modern cataract surgery, and it may be that a ceiling exists, particularly in the older age group of patients. Establishing the relative contribution of the factors that determine visual quality following endothelial keratoplasty will help drive further innovation, optimizing visual and patient-reported outcomes while improving surgical efficacy and safety.

[Purulent corneal ulcers: etiology, pathogenesis, classification]

Advanced purulent corneal ulcer, as well as abscess, is a serious vision-threatening condition notable for its fulminant course and possible loss of the eye due to endophthalmitis. Its leading causes, pathogenesis, and classifications are described and analyzed in this paper.

Nontuberculous Mycobacterial Ocular Infections: A Systematic Review of the Literature

Nontuberculous or atypical mycobacterial ocular infections have been increasing in prevalence over the past few decades. They are known to cause periocular, adnexal, ocular surface and intraocular infections and are often recalcitrant to medical therapy. These infections can potentially cause detrimental outcomes, in part due to a delay in diagnosis. We review 174 case reports and series on nontuberculous mycobacterial (NTM) ocular infections and discuss etiology, microbiology, risk factors, diagnosis, clinical presentation, and treatment of these infections. History of interventions, trauma, foreign bodies, implants, contact lenses, and steroids are linked to NTM ocular infections. Steroid use may prolong the duration of the infection and cause poorer visual outcomes. Early diagnosis and initiation of treatment with multiple antibiotics are necessary to achieve the best visual outcome.

Post-laser in situ keratomileusis interface fungal keratitis

PURPOSE

To report outcomes of post-laser in situ keratomileusis (LASIK) interface filamentous fungal keratitis.

METHODS

This retrospective interventional case series included 6 eyes of 5 patients with microbiologically proven post-LASIK interface fungal keratitis from August 2008 to August 2013. Patients presenting with concurrent bacterial/viral keratitis, systemic illness, prior ocular pathology, or those without a minimum follow-up of 3 months were excluded. Every case underwent microbiological scrapings from residual bed and undersurface of the flap after flap lift at presentation followed by voriconazole interface wash. Flap amputation was performed when required. The outcome measure was complete resolution of infection.

RESULTS

The mean age was 24 ± 3.1 years. The male:female ratio was 4:1. The mean interval between LASIK and symptom onset was 4.16 ± 2 days; and the mean interval between symptom onset and patient referral was 3.16 ± 1.16 days. Interface scrapings showed filamentous fungal filaments in KOH wet mount. The culture grew Aspergillus in case 1 and case 5. Infiltrated LASIK flap needed to be amputated in 4 eyes of 3 patients. Voriconazole wash (100 μg/mL) of the stromal bed was performed in all cases. A positive response to therapy with resolution of infection was seen in all cases at a mean of 6.5 ± 4.6 days. No intraoperative or postoperative complications after interface scraping or voriconazole wash were observed. The final best-corrected visual acuity ranged from 20/20 to 20/80 at a mean follow-up of 9.1 ± 6.5 months.

CONCLUSIONS

Post-LASIK interface fungal filamentous keratitis can present early and gives good outcomes with early microbiological diagnosis and appropriate management. Voriconazole is an efficient and probably safe adjunct in the armamentarium of corneal surgeons to treat such cases.

[Purulent corneal ulcers: clinical presentation, diagnosis, and conservative treatment]

This is a detailed review of purulent corneal ulcer signs and symptoms, problems in diagnosis, and conservative treatment options.

Ocular penetration and pharmacokinetics of topical clarithromycin eye drops to rabbits

PURPOSE

To evaluate the ocular pharmacokinetics of clarithromycin (CLA) eye drops topically applied to the corneas of rabbits.

METHODS

One 50-μL drop of CLA (0.25%) was administered to each New Zealand white rabbit in a single dose group, and one 50-μL drop of CLA was administered 6 times at 5-min intervals to each rabbit in a loading dose group. The effect of debridement on corneal penetration was also investigated in a de-epithelium group. The drug concentrations in the cornea and aqueous humor (AH) were assayed using high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) analysis.

RESULTS

Maximum CLA levels were achieved in the corneas and AH at 15 and 60 min, respectively, in the intact epithelium eyes in the single dose group (24.54±10.64 μg/g and 0.78±0.22 μg/mL, respectively, mean±the standard error of the mean, n=8). In the loading dose group, 30 min after the last application, the CLA level in the corneas reached 92.26±17.62 μg/g. In the loading dose group, the drug levels in the corneas and AH were significantly increased compared with the drug levels in the corneas with the intact epithelium and de-epithelium eyes in the single dose group at the corresponding time points (P<0.05). The estimated CLA half-lives in the corneas and AH for the intact eyes were 103.28 and 132.61 min, respectively.

CONCLUSION

Therapeutic CLA levels can be achieved in rabbit corneas after topically applying the drug with eye drops.

Riboflavin/UVA Photochemical Therapy for Severe Infectious Keratitis

Purpose

To describe the antibacterial activity of treatment with riboflavin and ultraviolet A light (UVA) in cases of severe infectious keratitis.

Methods

A retrospective analysis was performed of an interventional case series in which 6 eyes of 6 patients with severe infectious keratitis, all of whom were refractive to multidrug conventional therapy, were treated with riboflavin/UVA. The procedure was conducted according to the standardized protocol of corneal collagen crosslinking (CXL) for keratoconus. Best spectacle-corrected visual acuity and clinical outcomes were evaluated before and during the follow-up period.

Results

Five of the 6 patients showed rapid reduction in symptoms and decreased infiltrate size after riboflavin/UVA photochemical therapy. Signs of infection and inflammation mostly resolved within 1 to 2 weeks after the treatment. Despite this therapy, one patient continued to deteriorate, and penetrating keratoplasty was performed.

Conclusions

The adjunctive use of riboflavin/UVA photochemical therapy has a positive effect on refractory infectious keratitis. The treatment seems to be safe and effective and should be considered as part of the first-line therapy in severe cases of infectious keratitis.

Candida albicans interface infection after deep anterior lamellar keratoplasty

The clinical features of interface Candida keratitis after deep anterior lamellar keratoplasty (DALK), may imitate rejection or crystalline keratopathy. We report here an 18-year-old woman presented with red eye, 4 months after undergoing DALK. Slit lamp examination revealed keratic precipitates (KPs) and cojunctival injection. She was prescribed corticosteroid treatment for endothelial rejection by another ophthalmologist because of misdiagnosis, but suffered a recurrence of symptoms after reduction of the corticosteroid treatment. At that time, she was referred to our office. The recurrence persisted despite antibiotic and antifungal therapies. Ten days after treatment with interface irrigation with amphotericin, the infiltration and hypopyon were resolved. Topical steroid was added after 3 months of antifungal monotherapy. Irrigant cultures confirmed the presence of Candida albicans. The corneal graft appeared semi-clear with no signs of infection at 17-month follow-up. We recommend a close follow-up and a timely intervention to prevent the need for more invasive treatment such as penetrating keratoplasty.

LASIK interface complications: etiology, management, and outcomes

PURPOSE

To describe the etiology, diagnosis, clinical course, and management of LASIK interface complications.

METHODS

Literature review.

RESULTS

Primary interface complications include infectious keratitis, diffuse lamellar keratitis, central toxic keratopathy, pressure-induced stromal keratopathy (PISK), and epithelial ingrowth. Infectious keratitis is most commonly caused by Methicillin-resistant Staphylococcus aureus (early onset) or atypical Mycobacterium (late onset) postoperatively, and immediate treatment includes flap lift and irrigation, cultures, and initiation of broad-spectrum topical antibiotics, with possible flap amputation for recalcitrant cases. Diffuse lamellar keratitis is a white blood cell infiltrate that appears within the first 5 days postoperatively and is acutely responsive to aggressive topical and oral steroid use in the early stages, but may require flap lift and irrigation to prevent flap necrosis if inflammation worsens. In contrast, PISK is caused by acute steroid response and resolves only with cessation of steroid use and intraocular pressure lowering. Without appropriate therapy PISK can result in severe optic nerve damage. Central toxic keratopathy mimics stage 4 diffuse lamellar keratitis, but occurs early in the postoperative period and is noninflammatory. Observation is the only effective treatment, and flap lift is usually not warranted. Epithelial ingrowth is easily distinguishable from other interface complications and may be self-limited or require flap lift to treat irregular astigmatism and prevent flap melt.

CONCLUSIONS

Differentiating between interface entities is critical to rapid appropriate diagnosis, treatment, and ultimate visual outcome. Although initial presentations may overlap significantly, the conditions can be readily distinguished with close follow-up, and most complications can resolve without significant visual sequelae when treated appropriately.

A case of interface keratitis following anterior lamellar keratoplasty

Anterior lamellar keratoplasty (ALK) is indicated in patients with anterior corneal opacities. Benefits over penetrating keratoplasty include quicker visual rehabilitation, less postoperative astigmatism, and preservation of the host endothelium, thus minimizing the chances of graft rejection. A rare complication of lamellar corneal surgery is infectious interface keratitis between the donor and host tissue. We report a case of infectious interface keratitis following automated ALK successfully treated medically and by removal of the ALK disk, eventually having a deep anterior lamellar keratoplasty with good visual recovery.

Microbial keratitis after corneal laser refractive surgery

Corneal laser refractive surgery is increasingly being performed on patients with the aim of improving unaided vision. Most candidates for surgery have excellent spectacle- or contact lens-corrected vision. Although microbial keratitis following refractive surgery is a rare complication, and usually has a good visual outcome, it can be sight-threatening. The spectrum of pathogens differs to other causes of microbial keratitis, such as contact lens-associated keratitis, and a different management approach is required. Postoperatively, patients are prescribed topical steroids and broad-spectrum topical antibiotics, typically fluoroquinolones. These do not cover unusual organisms, such as fungi, Nocardia, Acanthamoeba and some atypical mycobacteria. In post-laser-assisted in situ keratomileusis microbial keratitis, the lamellar flap should be lifted to acquire samples for specific microbiological examination, including these atypical organisms. Confocal microscopy is a noninvasive test that provides morphological information, and is operator dependent, but may assist in the rapid diagnosis of fungal, Acanthamoeba or Norcardia keratitis. PCR is not in widespread use, but has high sensitivity and specificity, and may facilitate early diagnosis and specific treatment of the causative organism, which is critical in obtaining the best clinical outcome.

Ocular infections caused by non-tuberculous mycobacteria: update on epidemiology and management

BACKGROUND

  To provide an update on the frequency, distribution, risk factors and in vitro susceptibility of ocular infections caused by non-tuberculous mycobacteria.

DESIGN

  Retrospective study of university clinic patients.

PARTICIPANTS

  One hundred thirty-nine patients with culture confirmed non-tuberculous mycobacteria infections seen at Bascom Palmer Eye Institute from January 1980 to July 2007.

METHODS

  Chart review of data collected included patients' demographics, risk factors, microbiological profiles and clinical outcomes.

MAIN OUTCOME MEASURES

  Frequency, distribution, risk factors and in vitro susceptibility of ocular infections caused by non-tuberculous mycobacteria.

RESULTS

  A total of 183 non-tuberculous mycobacteria isolates from 142 eyes were identified, with a fourfold increase in the number of eyes infected with non-tuberculous mycobacteria from 1980-1989 (13.4%) to 2000-2007 (56.3%). Eighty-three percent of non-tuberculous mycobacteria isolates were identified as M. abscessus/chelonae. The majority (91%) of isolates were recovered within 10 days. Common diagnoses included keratitis (36.6%), scleral buckle infections (14.8%) and socket/implant infections (14.8%). Identifiable risk factors were presence of biomaterials (63.1%), ocular surgery (24.1%) and steroid exposure (77%). The median time from diagnosis of culture positive non-tuberculous mycobacteria infection to resolution was 13 to 24 weeks. Combination therapy was used to treat 80% of infected eyes. In vitro susceptibility of non-tuberculous mycobacteria isolates were: amikacin, 81%; clarithromycin, 93%; and moxifloxacin, 21%.

CONCLUSIONS

  The incidence of ocular infections caused by non-tuberculous mycobacteria has increased within the last 8 years, with a high number of biomaterial associated infections among this group. Clinical diagnosis and microbiological confirmation of non-tuberculous mycobacteria infections remains challenging. Patient outcomes may be improved by early diagnosis, appropriate therapy and removal of biomaterials.

Microbial keratitis trends following refractive surgery: results of the ASCRS infectious keratitis survey and comparisons with prior ASCRS surveys of infectious keratitis following keratorefractive procedures

In 2008, the American Society of Cataract and Refractive Surgery (ASCRS) surveyed its 9121 United States and international members to evaluate the changing trends and incidence, culture results, treatment, and visual outcomes of infectious keratitis following keratorefractive procedures worldwide. This paper presents and analyzes the results with comparisons to the data in surveys conducted in 2001 and 2004. Nineteen infections were reported by 14 surgeons who had performed an estimated 20,941 keratorefractive procedures, an incidence of 1 infection in every 1102 procedures. Sixteen cases presented in the first postoperative week, 1 case during the second week, 1 case between the second and fourth weeks, and 1 case at 1 month or later. The 16 cases that presented in the first week were diagnosed at initial presentation. The most common organism cultured was methicillin-resistant Staphylococcus aureus (MRSA). Microbial keratitis following refractive surgery is an increasingly recognized sight-threatening complication.

Laser in-situ keratomileusis infection: review and update of current practices

PURPOSE OF REVIEW

To review new clinically relevant data regarding the prevention cause and treatment of laser in-situ keratomileusis (LASIK) infections.

RECENT FINDINGS

Many recent studies of post-LASIK infectious keratitis show the predominance of atypical mycobacteria and Gram-positive cocci and the growing number of other rare pathogens. The American Society of Cataract and Refractive Surgery White Paper treatment paradigm remains the model for initial treatment of LASIK-associated infectious keratitis.

SUMMARY

Improved understanding of the risk factor, different causes, along with a high degree of suspicion on initial presentation is crucial in order to provide the appropriate management in LASIK-associated infectious keratitis.

Infectious keratitis in 18,651 laser surface ablation procedures

PURPOSE

To evaluate the incidence, culture results, risk factors, treatment strategies, and visual outcomes of infectious keratitis after surface ablation.

SETTING

Multicenter study in Spain.

DESIGN

Case series.

METHODS

The medical records of patients who had surface ablation between January 2003 and December 2009 were reviewed to identify cases of infectious keratitis. The incidence, risk factors, clinical course, days to diagnosis, medical and surgical treatment, and visual outcome were recorded. Main outcome measures were incidence of infectious keratitis after surface ablation, culture results, response to treatment, and visual outcomes.

RESULTS

The study reviewed the records of 9794 patients (18,651 eyes). Infectious keratitis after surface ablation was diagnosed in 39 eyes of 38 patients. The onset of infection was early (within 7 days after surgery) in 28 cases (71.79%). Cultures were positive in 13 of 27 cases in which samples were taken. The most frequently isolated microorganism was Staphylococcus species (9 cases). The final corrected distance visual acuity (CDVA) was 20/20 or better in 23 cases (58.97%), 20/40 or better in 36 cases (92.30%), and worse than 20/40 in 3 cases (7.69%).

CONCLUSIONS

The incidence of infectious keratitis after surface ablation was 0.20%. Infectious keratitis is a potentially vision-threatening complication. Prompt and aggressive management with an intensive regimen of fortified antibiotic agents is strongly recommended. Proper management can preserve useful vision in most cases.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Review of moxifloxacin hydrochloride ophthalmic solution in the treatment of bacterial eye infections

Moxifloxacin hydrochloride ophthalmic solution 0.5% (Vigamox((R))) is the ocular formulation/adaptation of moxifloxacin. Moxifloxacin is a broad spectrum 8-methoxyfluoroquinolone which terminates bacterial growth by binding to DNA gyrase (topoisomerase II) and topoisomerase IV, essential bacterial enzymes involved in the replication, translation, repair and recombination of deoxyribonucleic acid. Affinity for both enzymes improves potency and reduces the probability of selecting resistant bacterial subpopulations. Vigamox is a bactericidal, concentration dependent, anti-infective. It is preservative free, and well tolerated with minimal ocular side effects. It provides increased penetration into ocular tissues and fluids with improved activity against Streptococci and Staphylococci species and moderate to excellent activity against clinically relevant, gram-negative ocular pathogens.

Pseudomonas keratitis 4 years after laser in situ keratomileusis

PURPOSE

To report a patient who presented an infectious keratitis 4 years after laser in situ keratomileusis (LASIK) without any other predisposing risk factor than the LASIK procedure itself.

CASE REPORT

We report a 32-year-old man operated by LASIK in January 2006 who presented with infectious keratitis in the OD in April 2010. Clinical examination showed a corneal abscess at 10-o'clock position in the interface and fibrin and Tyndall 4+ in the anterior chamber. Microbiological analysis identified Pseudomonas aeruginosa as the cause of infection. The patient was given ofloxacin, sulfate neomycin, polymyxin B, and prednisolone acetate to be used every 2 h. Treatment led to clinical improvement with resolution of corneal infiltrate. Keratitis with intact epithelium by Pseudomonas can occur up to 4 years after LASIK.

CONCLUSIONS

LASIK treatment is a predisposing factor for bacterial keratitis even years after surgery. This report demonstrates the importance of continued postoperative vigilance by patient and his/her clinician.

Surface ablation techniques

The ongoing quest for a safe, simple, effective, minimally invasive, and stable refractive surgical procedure to correct refractive errors has stimulated the development of surface ablation techniques and laser in situ keratomileusis. In this review, we describe the history, patient assessment, techniques, outcomes, and complications of surface ablation (photorefractive keratectomy, laser-assisted sub-epithelial keratectomy, epithelial laser-assisted in situ keratomileusis) and compare the results of various surface techniques. Surface ablation procedures will continue to evolve, with potential improvements in outcomes accompanying future sophisticated ablation profiles and laser technology.

A rare devastating complication of LASIK: bilateral fungal keratitis

Purpose. To report an unusual case of severe bilateral fungal keratitis following laser in situ keratomileusis (LASIK). Method. A 48-year-old man developed bilateral diffuse corneal infiltration two weeks after LASIK. The corneal scrapings revealed fungal filaments but cultures were negative. Results. The corneal ulceration was improved on the left eye whereas spontaneous perforation occurred and finally evisceration was needed on the right eye despite topical and systemic antifungal treatment. Conclusions. Fungal keratitis, especially with bilateral involvement, is a very rare and serious complication of LASIK surgery. Clinical suspicion is crucial because most of fungal keratitis are misdiagnosed as bacterial keratitis and can lead serious visual results, even eye loss.

[Infectious keratitis in 266,191 laser in situ keratomileusis]

OBJECTIVE

To study the incidence of infectious keratitis (IK) after laser-assisted in situ keratomileusis (LASIK), along with its diagnosis, therapeutic action taken, its management and the results.

MATERIAL AND METHOD

We carried out a retrospective study of 262,191 eyes intervened consecutively with LASIK, in our 20 centres, during the period from September 2002 and December 2009. All the cases susceptible to being diagnosed with IK, either clinically or due to the biological findings were analysed.

RESULTS

A total of 82 cases were found with infectious keratitis, which assumed an incidence of 0.031%. Distributions are presented by gender, mean age of the patients, mean days since the surgery, the clinical signs and symptoms, predisposing factors, therapeutic action, complications, details of the causal germ, and the loss of lines of vision.

CONCLUSIONS

Infectious keratitis after LASIK is a rare complication. The early diagnosis and management of the process are determining factors when establishing the prognosis. In our series all the cases were resolved without causing any other serious complications.

Brevundimonas vesicularis keratitis after laser in situ keratomileusis

A 45-year-old woman developed a corneal infiltrate 14 months after laser in situ keratomileusis (LASIK) enhancement in the left eye. The LASIK flap was lifted, scraped, and irrigated with fortified vancomycin and ceftazidime. Scraped samples were cultured and grew Brevundimonas vesicularis. The patient remained on topical ceftazidime until improvement was noted and was then switched to topical levofloxacin. The keratitis resolved on antibiotic agents with strong gram-negative coverage and a steroid. To our knowledge, this is the first report of a B vesicularis ocular infection.

Infectious keratitis in 204 586 LASIK procedures

PURPOSE

To investigate the incidence, culture results, risk factors, and visual outcomes of infectious keratitis after LASIK, and examine treatment strategies.

DESIGN

Retrospective study.

PARTICIPANTS

We included 107 613 patients who underwent LASIK at Clínica Baviera (Instituto Oftalmológico Europeo, Spain) from September 2002 to May 2008.

METHODS

The medical records of post-LASIK patients (204 586 eyes) were reviewed to identify cases of infectious keratitis. Incidence, risk factors, clinical course, days to diagnosis, medical and surgical treatment, and final visual outcomes were recorded.

MAIN OUTCOME MEASURES

Incidence of post-LASIK infectious keratitis, culture results, response to treatment, and visual outcome.

RESULTS

Post-LASIK infectious keratitis was diagnosed in 72 eyes from 63 patients. Onset of infection was early (within 7 days after surgery) in 62.5% of cases. Cultures were positive in 21 of 54 cases in which samples were taken. The most frequently isolated microorganism was Staphylococcus epidermidis (9 cases). Immediate flap lifting and irrigation with antibiotics was performed in 54 eyes; late flap lifting was subsequently required in 10 out of 18 cases initially treated with topical antibiotics alone. One case required flap amputation owing to flap necrosis. Final best spectacle-corrected visual acuity (BSCVA) was >or=20/20 in 38 cases (52.7%) and >or=20/40 in 67 cases (93.05%); final BSCVA was <20/40 in 5 cases (6.94%).

CONCLUSIONS

The incidence of post-LASIK infectious keratitis was 0.035% per procedure. Infectious keratitis after LASIK is a potentially vision-threatening complication. The appearance of infections in asymptomatic patients highlights the need for a proper schedule of follow-up appointments. Prompt and aggressive management of this LASIK complication with early flap lifting, scraping, culture, and irrigation with antibiotics is strongly recommended. Proper management can result in preserving useful vision.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any of the materials discussed in this article.