Contact Lens Keratitis Research Articles

Clinical factors associated with positive corneal culture in suspected microbial keratitis

AimsDetermine demographic and clinical characteristics associated with positive culture in suspected microbial keratitis. MethodsRetrospective audit of patients that had corneal scrapings between October 1999-September 2004 at Princess Alexandra Hospital. Clinical information was gathered from medical records, smear and culture results from the local microbiology database. Univariate and multivariate analyses of variables associated with positive cultures and calculation of population attributable risk percentage (PAR). ResultsUnivariate analysis showed that positive cultures were associated with patients over 60 years (81% vs 55%; p < 0.001), presenting visual acuity (VA) of 6/24 or worse (74% vs 57%; p = 0.012) or contact lens-related keratitis (CLK 77% vs 62%; p = 0.08). Analysis of patients’ clinical presentation showed that positive culture was associated with a central epithelial defect (74% vs 57%; p = 0.012), anterior chamber reaction of 2 + cells or worse (73% vs 56%; p = 0.03), an epithelial defect of 2 mm or more in diameter (71% vs 50%; p = 0.006) or no prior treatment with antibiotics (68% vs 56%; p = 0.053). Multivariate analysis showed the independent variables associated with positive cultures were VA of 6/24 or worse on presentation, contact lens-related keratitis, age greater than 60 years, an anterior chamber reaction of 2 + cells or worse and no prior treatment with antibiotics. The factor with the highest attributable risk (PAR%) for a positive corneal scraping was VA of 6/24 or worse on presentation (21%). ConclusionsIn this series positive cultures were associated with poor presenting VA contact lens keratitis (CLK), older age, anterior chamber reaction and no prior treatment with antibiotics.

The differences between patient and optometrist experiences of contact lens hygiene education from the perspective of a Scottish university teaching hospital

BackgroundContact lens related keratitis is a frequent presentation to acute ophthalmology services. Patients often do not recall being counselled regarding the safe use of contact lenses therefore fail to comply with guidance.This study aimed to identify the content and format of advice given to patients with contact lens keratitis concerning appropriate hygiene practices, determine their compliance with this and finally characterise optometrist practices regarding contact lens advice provided to patients. MethodsAll adult patients presenting with contact lens related keratitis to the acute ophthalmology clinic were asked to complete a survey. Information was collected on lens type, format of advice received and compliance.Community optometrists were asked to complete an electronic survey on their contact lens review practices and routine patient education. ResultsAll patients surveyed recalled counselling on initiation of contact lenses; however 12% (6/50) were given no advice on return visits. This advice was in written format for 20% (10/50) of patients on initiation increasing to 32% (16/50) on renewal.Many patients slept (22%), showered (44%) or swam (36%) in lenses. 92% cleaned their contact lenses appropriately, but cases were washed infrequently (19% of cases cleaned < monthly) or with tap water (27%).All optometrists surveyed claimed to provide advice to patients in either written or verbal format for new and returning contact lens users. 49% (16/33) of optometrists gave written advice to patients on initial contact lens fitting, but only 1/33 continued with written advice for repeat customers. ConclusionThis study identified that although most patients were informed of appropriate hygiene requirements, compliance was poor. Optometrists regularly provide verbal advice but do not routinely offer written support and there is a mismatch between patient recollection and self-reported optometrist practice. It is suggested that patient education needs greater emphasis and both verbal and written information should be regularly provided on initial review and follow up assessments.

Association study of single nucleotide polymorphisms in IL-10 and IL-17 genes with the severity of microbial keratitis

PurposeExploratory analysis to assess the association of single nucleotide polymorphisms (SNPs) in the interleukin (IL) 10 and IL-17 genes with severity of contact lens keratitis. MethodsThis was a retrospective case control study of 88 contact lens keratitis cases (25 severe) and 185 healthy contact lens wearers recruited from studies conducted at Moorfields Eye Hospital and in Australia-wide during 2003–2005. Buccal swab samples were collected on Whatman FTA cards and mailed by post for DNA extraction and SNP genotyping. IL-10 (rs1800871; rs1800896; rs1800872) and IL-17 (rs1800871; rs1800896; rs1800872) SNPs were screened by pyrosequencing. Genetic association analyses were performed via Cochran-Armitage trend tests and logistic regression models using PLINK software. ResultsNone of the SNPs tested showed evidence of association with severity of contact lens keratitis at P < 0.05. Nevertheless, minor allele G in SNP rs2397084 of the IL-17F gene was associated with increased risk of severe MK, with OR=2.1 (95% CI=0.9-4.8, P = 0.066). ConclusionOur study cannot exclude with confidence that genetic variation in the IL-17 F proinflammatory cytokine is associated with more severe outcomes of MK. However, there is general body of information that the IL-17 pathway is important in the mechanisms of MK. Studies with larger power and the expanded array of laboratory tools will elucidate the exact role of IL-17 in MK.

Contact Lens Solutions and Contact Lens Discomfort: Examining the Correlations Between Solution Components, Keratitis, and Contact Lens Discomfort.

This article will examine the current literature, as it relates to contact lens discomfort (CLD) secondary to contact lens solutions. The reader will better understand the characteristics of contact lenses, as they uniquely interact with each type of contact lens solution and also gain a better comprehension of the components of contact lens solution such as preservatives, surfactants, and chelating agents, which may contribute to discomfort. By investigating corneal staining theory and the mechanisms that contribute to its presence, the reader will gain insight into this clinical finding, which relates to selection of contact lens solutions. The FDA standards for testing solutions and how this relates to contact lens keratitis will also be appraised in regards to current ISO recommendations. Finally, better selection of multipurpose contact lens solution (MPS) and hydrogen peroxide-based solutions for patients should be accessible to the clinician based on this review and preexisting clinical findings or diagnoses. A review of current published literature from peer reviewed journals and online journals was conducted to gain an understanding of contact lens solution's impact on contact lens discomfort. Many studies have been conducted comparing comfort between various types of contact lens solutions. It is challenging to decipher this information and apply it clinically when selecting solutions for patients. By comparing solution components, how contact lens solutions interact with different types of lenses, keratitis related to contact lenses, and preexisting ocular conditions, this review will improve a clinician's ability to eliminate CLD.

Management and treatment of contact lens keratitis

PurposeMicrobial keratitis is an infective process of the cornea with a potentially and serious visual impairments. Contact lenses are a major cause of microbial keratitis in the developed countries especially among young people. Therefore, the purpose of the present study was to evaluate the frequency and microbiological characteristic of contact lens keratitis (CLK) in patients referred to the emergency department of Hospital Clinico Lozano Blesa, ZaragozaMethodsThis is a cross‐sectional study of all patients with contact lens induced corneal ulcers who were reffered to the Hospital Clinico Lozano Blesa in the last 6 months. An ophthalmologist examined patients with the slit‐lamp and clinical features of them were noted and infectious corneal ulcers were scraped for microbial culture. The contact lenses and their liquid storage were analyzed by microbiology.ResultsA total of 18 patients were recuited into the study. The cultures were positive in 36.36% of corneal samples and 80% of culture contact lenses. The most common isolated organism in contact lenses was gram negative bacilli showing cleaning and manteinance system falilure of this type of lenses. Two case of contamination of liquid lenses by fungi were recorded, candida parapsilosis y acremonium spp and two case of contamination by acanthamoeba. The most microorganisms found from the corneal scrapes were gram positive cocci and Pseudomona aeruginosa was the most common gram negative.ConclusionsDue to the percentage of positive results in the cultures of contact lenses is higher than the percentage of corneal scrapings its realization is useful, beacuse the microorganism isolated in the ulcer is also present in maintenance fluids. Due to the high sensitivity of the main microorganisms to quinolones, are recommended as initial empiric therapy in infectious keratitis.

Immune defense single nucleotide polymorphisms associated with contact lenskeratitis

Immune defense single nucleotide polymorphisms associated with contact lenskeratitis

Immune Defense Single Nucleotide Polymorphisms and Recruitment Strategies Associated with Contact Lens Keratitis

To determine the association of single nucleotide polymorphisms (SNPs) of defensin 1B and toll-like receptor 4 with contact lens keratitis susceptibility and severity, and to understand the factors that influence study participation. Retrospective, case-control study. Ninety cases of keratitis and 185 controls recruited from studies conducted at Moorfields Eye Hospital and throughout Australia from 2003 to 2005 were analyzed for genetic associations. The reasons for participation of a subset of 146 participants from 1 site were also investigated. Buccal swab samples were collected on Whatman FTA cards and mailed by post for analysis. DEFB1 (rs1799946, -52, rs1800972, -44, and rs11362, -20) and TLR4 (rs4986790, D299G) SNPs were screened by pyrosequencing and analyzed using a regression model for susceptibility (sterile, microbial keratitis [MK], controls) and severity. Study participation was investigated for age, gender, condition, and phone follow-up also using regression analysis. Relative risk of developing contact lens-related keratitis and more severe forms of the disease based on genetic profiles. Carriers of risk alleles of DEFB1 -52 and -20 showed a trend toward increased susceptibility to keratitis (-52: odds ratio [OR], 1.45; 95% confidence interval [CI], 0.99-2.11; P = 0.051; -20: OR, 1.37; 95% CI, 0.95-1.98; P = 0.088). A DEFB1 promoter haplotype (G-G-A) had a tendency toward decreased susceptibility of MK (OR, 0.68; 95% CI, 0.45-1.03; P = 0.062) and reduced severity (OR, 0.56; 95% CI, 0.30-1.07; P = 0.066). The TLR4 D299G was not associated with type and severity of keratitis. Older age (OR, 1.07; 95% CI, 1.05-1.08) and follow-up phone call (OR, 2.0; 95% CI, 1.2-3.5) were independent predictors of study participation. Genetic variation in DEFB1 that may lead to decreased protein expression of hBD-1 exhibits a tendency toward increased susceptibility and severity of contact lens-related keratitis. Investigation of these and other hBD genes that play important roles in animal models in a larger sample size is warranted. The approach of requesting samples from retrospective case series was generally feasible, although significant resources, including repeat phone calls, are required. More targeted strategies to recruit younger individuals to participate in genetic studies may be useful.

Association of Single Nucleotide Polymorphisms of Interleukins-1β, -6, and -12B with Contact Lens Keratitis Susceptibility and Severity

To investigate whether single nucleotide polymorphisms (SNPs) in interleukin (IL)-1β, IL-6, and IL-12β are associated with the susceptibility and severity of contact lens-related keratitis. Retrospective, case control study. One hundred twelve cases of keratitis and 225 controls were recruited from studies conducted at Moorfields Eye Hospital and in Australia during 2003 through 2005. Buccal swab samples were collected on Whatman FTA cards and were mailed by post for analysis. IL-1β (-31), IL-6 (-174, -572, -597), and IL-12B (3'+1158) genotypes were analyzed with pyrosequencing and analyzed using a regression model for susceptibility (sterile, microbial keratitis, controls) and severity. Statistical significance was set at 0.05. The relative risk of developing contact lens-related keratitis and more severe forms of the disease based on allele, genotype, and haplotype associations. Carriers of IL-6 SNPs were more likely to experience moderate and severe events compared with those with nonmutated genotypes (-174 heterozygous: odds ratio [OR], 3.1; 95% confidence interval [CI], 1.1-8.3; homozygous: OR, 6.4; 95% CI, 1.4-28.4; -174/-597: OR, 4.1; 95% CI, 1.6-11.0). More severe keratitis and microbial keratitis were less likely to occur in wearers with the nonmutated IL-6 haplotype (severity OR, 0.4 [95% CI, 0.2-0.7]; microbial OR, 0.6 [95% CI, 0.4-0.9]). Wearers carrying an IL-12B SNP had an increased risk of sterile keratitis (OR, 9.7; 95% CI, 1.2-76.9) compared with controls. The IL-6 SNPs are known to reduce protein expression of this cytokine and thus ocular immune defense, and carriers of these SNPs were more likely to experience more severe and microbial keratitis, suggesting that IL-6 decreases the severity and susceptibility of contact lens-related keratitis. Carriers of a functional SNP of IL-12B that is known to increase IL-12 expression and stability are more likely to experience sterile keratitis, suggesting that this is associated with the intense inflammatory reaction that occurs in this condition.

Confocal Microscopy of Contact Lens Keratitis Presenting as Central Toxic Keratopathy

Central toxic keratopathy (CTK) after refractive surgery is a syndrome characterized by central corneal opacification, thinning, and a hyperopic shift. We report a similar presentation after extended contact lens wear. No prior confocal imaging has been reported in this contact lens case syndrome. A 45-year-old white man presented with 3 weeks of photophobia and foreign body sensation after extended contact lens wear. Initial examination showed central stromal opacities, thinning, and hyperopic shifts, more in the right eye than in the left eye. Initial confocal microscopy showed collagen fibril edema and rearrangement with cellular infiltration and sparse refractile elements similar in appearance to immunoglobulin. The patient was treated with topical corticosteroids and was told to discontinue contact lenses. At 7 months, there was trace corneal haze, resolved corneal thinning, a 2-D residual hyperopic shift in the right eye, and a 1.5-D shift in the left eye. The clinical findings in our patient having contact lens keratitis resemble those of CTK postrefractive surgery cases, suggesting a similar mechanism. The lack of necrotic debris supports a cytokine-triggered apoptosis over an inflammatory cell-mediated necrosis as the cause of stromal tissue loss. Future confocal microscopy at different stages will help clarify the pathophysiologic condition of this rare syndrome.

Antibiotic susceptibility patterns of pseudomonas corneal ulcers in contact lens wearers

Purpose:To evaluate the resistance or susceptibility of Pseudomonas aeruginosa, the most common pathogen in contact lens keratitis and corneal ulcer, to different antibiotic regimens.Materials and Methods:This cross-sectional study included all patients with recently diagnosed contact lens corneal ulcer whose culture results were positive for P. aeruginosa, from March 2009 to March 2010. The empirical antibiotic therapy was changed to appropriate antibiotics according to the culture results, provided that satisfactory clinical improvement was not achieved with the initial antibiotic regimen. The overall sensitivity or resistance of P. aeruginosa to the most commonly used antibiotics was assessed based on the results of the antibiograms.Results:Fifty-two patients (43 females and 9 males) were included. Forty-five patients (86%) were wearing cosmetic contact lenses, while 7 patients (14%) were using therapeutic contact lenses. Thirty-nine patients (75%) were hospitalized and13 patients (25%) were followed up through an outpatient clinic. Thirty patients (58%) had central ulcers, whereas 22 patients (42%) had peripheral ulcers. Twelve patients (23%) had hypopyon in their first exam. The mean time to diagnose the ulcer after the last time wearing was 2 days (range: 12 hours to 5 days). AMT was required for 10 patients (19%). Based on the antibiograms, PA was shown to be sensitive in 100% of cases to ceftazidime and ciprofloxacin. Amikacin, imipenem, and gentamicin were the second most effective antibiotics.Conclusion:P. aeruginosa was highly sensitive to ceftazidime, ciprofloxacin, and amikacin. All cases were resistant to cefazolin. Resistance to multiple antibiotics might be a significant concern in patients with corneal ulcers. In referral centers dealing with corneal ulcers, the initial antibiotic regimens should be changed from time to time to prevent this phenomenon.

Clinical management of infectious contact lens complications: from antibiotics to quorum-sensing inhibitors

Although effective drugs have become available, improvements in the treatment of contact lens-associated microbial keratitis are required. Over the last decade, the outcome of contact lens-associated bacterial keratitis has improved owing to fluoroquinolones, leading to a better control of infection, earlier institution of anti-inflammatory therapy and surgical intervention. The antimicrobial effectiveness of some antibiotics may be increased by preservatives. Antibiotic resistance according to serum standard limits has not been found to be relevant for the eye, with the exception of methicillin-resistant Staphylococcus aureus. Newer antifungals (voriconazole, itraconazole) are being evaluated, but the mainstay is liposomal amphotericin B and econzole or natamycin. Therapy for acanthamebic (biguanides and combinations) and microsporidial (fluoroquinolones) infections remains unchanged. New hydrophilic contact lens materials may slow down the formation of biofilm. Antibiofilm research has introduced substances that interfere with quorum sensing, and affect enzymatic and peptide-mediated matrix dispersal. Nanotechnology will be used to penetrate the biofilm matrix as well as nanoetching to prevent biofilm development on surfaces. Management of contact lens keratitis comprises of management of the biofilm. Early aggressive antimicrobial treatment, and surgery in certain cases, have resulted in better outcomes. The role of corticosteroids seems beneficial, but has to be further studied. Further improvements rely on biofilm-active agents added to antimicrobials.

Risk Factors for the Development of Corneal Infiltrative Events Associated with Contact Lens Wear

To identify risk factors for the development of corneal infiltrative events (CIEs) associated with contact lens wear, and to report other relevant clinical characteristics. A series of symptomatic contact lens wearers presenting consecutively to a large hospital clinic over a 1-year period were examined. The clinical severity of any CIE was determined with a scoring system, and general and lens-specific information was captured with a questionnaire. Logistic regression analyses were performed to investigate the association between a range of risk factors and the occurrence of any CIE and the subset of cases categorized as severe keratitis. Three quasi-independent control groups were used for this analysis: hospital, lens-matched, and population. The relationship between clinical severity and the delay in attending the hospital was investigated. The prevalence of symptoms and initial actions taken by patients are reported. Factors identified as being associated with an increased risk of development of a CIE include: wearing modality/lens type (greatest risk for extended-wear hydrogel lenses of 7.1 vs. daily wear hydrogel lenses), male gender (relative risk 1.4), smoking (1.4), the absence of relevant ocular (1.8) and general health (2.4) problems, and the late winter months (greatest risk in March of 3.6 vs. July). The overall predictive value of these risk factors for a given individual was low. Shorter time delays in hospital attendance were associated with increasing severity of keratitis. Eye soreness was the most common initial symptom (prevalence 69%), and the most frequent initial course of action taken by the patient was lens removal (prevalence 50%). Risk factors for the development of contact lens keratitis were identified that, although being of limited predictive value for individual patients, highlight general associations that may assist in the management of contact lens wearers. Such risk factors may also assist in the development of a more complete understanding of the etiology of contact-lens-associated CEIs.

The role of Serratia marcescens in soft contact lens associated ocular infections. A review.

Serratia marcescens is a Gram negative rod which for a century and a half was considered a harmless saphrophyte. However, medical technology and the use of antibacterial agents have created ecological niches for this bacterium, which is now a medical problem. The bacterium is encountered in connection with contact lens keratitis, often associated with contaminated contact lens solutions. The concentrations of chlorhexidin and thiomersal required in contact lens solution to suppress the bacterium have been proved toxic to the eye. Modern contact lens solutions with biguanids have rapid killing kinetics, while in solutions with polyquaternium S. marcescens can survive in reduced numbers for up to 72 hours. The adherence of a specific isolate of Serratia to hydrogel lenses increased with decreased water content of the lenses. However, there has been no correlation between hydrophobicity markers or hemagglutinins and adherence to contact lenses or urinary tract epithelium. When handling medical plastic devices, such as contact lenses, strictly enforced hygiene remains the most important method to combat environmental bacteria such as Serratia marcescens.