The role of contact lens type, oxygen transmission, and care-related solutions in mediating epithelial homeostasis and pseudomonas binding to corneal cells: an overview

Extracellular vesicles released by host epithelial cells during Pseudomonas aeruginosa infection function as homing beacons for neutrophils

BACKGROUND

Pseudomonas aeruginosa (PA) is an opportunistic pathogen that can cause sight threatening infections in the eye and fatal infections in the cystic fibrosis airway. Extracellular vesicles (EVs) are released by host cells during infection and by the bacteria themselves; however, there are no studies on the composition and functional role of host-derived EVs during PA infection of the eye or lung. Here we investigated the composition and capacity of EVs released by PA infected epithelial cells to modulate innate immune responses in host cells.

METHODS

Human telomerase immortalized corneal epithelial cells (hTCEpi) cells and human telomerase immortalized bronchial epithelial cells (HBECs) were treated with a standard invasive test strain of Pseudomonas aeruginosa, PAO1, for 6 h. Host derived EVs were isolated by qEV size exclusion chromatography. EV proteomic profiles during infection were compared using mass spectrometry and functional studies were carried out using hTCEpi cells, HBECs, differentiated neutrophil-like HL-60 cells, and primary human neutrophils isolated from peripheral blood.

RESULTS

EVs released from PA infected corneal epithelial cells increased pro-inflammatory cytokine production in naïve corneal epithelial cells and induced neutrophil chemotaxis independent of cytokine production. The EVs released from PA infected bronchial epithelial cells were also chemotactic although they failed to induce cytokine secretion from naïve HBECs. At the proteomic level, EVs derived from PA infected corneal epithelial cells exhibited lower complexity compared to bronchial epithelial cells, with the latter having reduced protein expression compared to the non-infected control.

CONCLUSIONS

This is the first study to comprehensively profile EVs released by corneal and bronchial epithelial cells during Pseudomonas infection. Together, these findings show that EVs released by PA infected corneal and bronchial epithelial cells function as potent mediators of neutrophil migration, contributing to the exuberant neutrophil response that occurs during infection in these tissues.

Propolis-Based Nanofiber Patches to Repair Corneal Microbial Keratitis

In this research, polyvinyl-alcohol (PVA)/gelatin (GEL)/propolis (Ps) biocompatible nanofiber patches were fabricated via electrospinning technique. The controlled release of Propolis, surface wettability behaviors, antimicrobial activities against the S. aureus and P. aeruginosa, and biocompatibility properties with the mesenchymal stem cells (MSCs) were investigated in detail. By adding 0.5, 1, and 3 wt.% GEL into the 13 wt.% PVA, the morphological and mechanical results suggested that 13 wt.% PVA/0.5 wt.% GEL patch can be an ideal matrix for 3 and 5 wt.% propolis addition. Morphological results revealed that the diameters of the electrospun nanofiber patches were increased with GEL (from 290 nm to 400 nm) and Ps addition and crosslinking process cause the formation of thicker nanofibers. The tensile strength and elongation at break enhancement were also determined for 13 wt.% PVA/0.5 wt.% GEL/3 wt.% Ps patch. Propolis was released quickly in the first hour and arrived at a plateau. Cell culture and contact angle results confirmed that the 3 wt.% addition of propolis reinforced mesenchymal stem cell proliferation and wettability properties of the patches. The antimicrobial activity demonstrated that propolis loaded patches had antibacterial activity against the S. aureus, but for P. aeruginosa, more studies should be performed.

Anatomical and physiological considerations in scleral lens wear: Eyelids and tear film

Scleral lenses can affect a range of anterior segment structures including the eyelids and the tears. The eyelids, consisting of the outer skin layer, the middle tarsal plate, and the posterior palpebral conjunctiva, provide physical protection and house the meibomian glands and cilia which have important and unique functions. Tears consist of a mix of aqueous, mucus, and lipidomic components that serve vital functions of lubricity, protection, and nourishment to the ocular surface. Both the eyelids and the tear film interact directly with scleral lenses on the eye and can affect but also be impacted by scleral lens wear. The purpose of this paper is to review the anatomy and physiology of the eyelids and tear film, discuss the effects and impacts of the scleral lenses on these structures, and identify areas that require further research.

Enhancement of Contact Lens Disinfection by Combining Disinfectant with Visible Light Irradiation

Multiple use contact lenses have to be disinfected overnight to reduce the risk of infections. However, several studies demonstrated that not only microorganisms are affected by the disinfectants, but also ocular epithelial cells, which come into contact via residuals at reinsertion of the lens. Visible light has been demonstrated to achieve an inactivation effect on several bacterial and fungal species. Combinations with other disinfection methods often showed better results compared to separately applied methods. We therefore investigated contact lens disinfection solutions combined with 405 nm irradiation, with the intention to reduce the disinfectant concentration of ReNu Multiplus, OptiFree Express or AOSept while maintaining adequate disinfection results due to combination benefits. Pseudomonads, staphylococci and E. coli were studied with disk diffusion assay, colony forming unit (cfu) determination and growth delay. A log reduction of 4.49 was achieved for P. fluorescens in 2 h for 40% ReNu Multiplus combined with an irradiation intensity of 20 mW/cm² at 405 nm. For AOSept the combination effect was so strong that 5% of AOSept in combination with light exhibited the same result as 100% AOSept alone. Combination of disinfectants with visible violet light is therefore considered a promising approach, as a reduction of potentially toxic ingredients can be achieved.

Label-Free Quantitative Proteomics Distinguishes General and Site-Specific Host Responses to Pseudomonas aeruginosa Infection at the Ocular Surface

Mass spectrometry-based proteomics enables the unbiased and sensitive profiling of cellular proteomes and extracellular environments. Recent technological and bioinformatic advances permit identifying dual biological systems in a single experiment, supporting investigation of infection from both the host and pathogen perspectives. At the ocular surface, Pseudomonas aeruginosa is commonly associated with biofilm formation and inflammation of the ocular tissues, causing damage to the eye. The interaction between P. aeruginosa and the immune system at the site of infection describes limitations in clearance of infection and enhanced pathogenesis. Here, the extracellular environment (eye wash) of murine ocular surfaces infected with a clinical isolate of P. aeruginosa is profiled and neutrophil marker proteins are detected, indicating neutrophil recruitment to the site of infection. The first potential diagnostic markers of P. aeruginosa-associated keratitis are also identified. In addition, the deepest murine corneal proteome to date is defined and proteins, categories, and networks critical to the host response are detected. Moreover, the first identification of bacterial proteins attached to the ocular surface is reported. The findings are validated through in silico comparisons and enzymatic profiling. Overall, the work provides comprehensive profiling of the host-pathogen interface and uncovers differences between general and site-specific host responses to infection.

Innovative Cold Atmospheric Plasma (iCAP) Decreases Mucopurulent Corneal Ulcer Formation and Edema and Reduces Bacterial Load in Pseudomonas Keratitis

Purpose

To evaluate the effect of application of 3% air in helium cold atmospheric plasma jet, using an inexpensive device termed iCAP, in corneal scratch wound closure in vitro and the treatment of Pseudomonas aeruginosa (P. aeruginosa) keratitis in vivo.

Methods

Thermal imaging to measure temperature of surfaces to which iCAP was applied and UV energy density delivered by iCAP were measured. Scratch wounds inflicted on in vitro cultures of a human corneal epithelial cell line were treated with iCAP and wound widths at various times post-application were measured. Rabbit eyes infected with P. aeruginosa were treated with iCAP and slit lamp biomicroscope examination conducted to determine corneal health outcomes 25h post infection. Corneal homogenates were plated on agar and viable bacterial colonies enumerated to determine the effect of iCAP on bacterial load in vivo in P. aeruginosa keratitis.

Results

iCAP was shown to operate in the non-thermal regime and also shown to deliver much lower UV energy density than that necessary to cause harmful effects on ocular tissue. iCAP treatment significantly improved the rate of scratch wound gap closure in vitro in a human corneal epithelial cell line compared to controls. In vivo, iCAP treatment of P. aeruginosa keratitis infection in the rabbit eyes (N = 20) significantly reduced the incidence of corneal ulcer (P = 0.003) and corneal edema (P = 0.011) and significantly improved total cornea health (P = 0.034) compared to untreated (N = 10). Finally, in vivo iCAP treatment of P. aeruginosa keratitis infection in the rabbit eyes (N = 19) significantly reduced bacterial loads (P = 0.012) compared to untreated (N = 9).

Conclusion

Our results strongly suggest that iCAP treatment was effective in improving corneal epithelial defect closure in vitro, reducing ulcer formation and decreasing inflammation in P. aeruginosa infected corneas in vivo and decreasing bacterial loads in P. aeruginosa infected corneas in vivo which led to improved overall cornea health outcomes in vivo. Further studies to investigate iCAP's safety and efficacy against other infectious microbes responsible for causing ulcerative keratitis, with and without co-treatment with antimicrobial therapies are warranted.

Frontline Science: Employing enzymatic treatment options for management of ocular biofilm-based infections

Pseudomonas aeruginosa-induced corneal keratitis is a sight-threatening disease. The rise of antibiotic resistance among P. aeruginosa keratitis isolates makes treatment of this disease challenging, emphasizing the need for alternative therapeutic modalities. By comparing the responses to P. aeruginosa infection between an outbred mouse strain (Swiss Webster, SW) and a susceptible mouse strain (C57BL6/N), we found that the inherent neutrophil-killing abilities of these strains correlated with their susceptibility to infection. Namely, SW-derived neutrophils were significantly more efficient at killing P. aeruginosa in vitro than C57BL6/N-derived neutrophils. To interrogate whether the distinct neutrophil killing capacities were dependent on endogenous or exogenous factors, neutrophil progenitor cell lines were generated. The in vitro differentiated neutrophils from either SW or C57BL6/N progenitors retained the differential killing abilities, illustrating that endogenous factors conferred resistance. Consistently, quantitative LC-MS/MS analysis revealed strain-specific and infection-induced alterations of neutrophil proteomes. Among the distinctly elevated proteins in the SW-derived proteomes were α-mannosidases, potentially associated with protection. Inhibition of α-mannosidases reduced neutrophil bactericidal functions in vitro. Conversely, topical application of α-mannosidases reduced bacterial biofilms and burden of infected corneas. Cumulatively, these data suggest novel therapeutic approaches to control bacterial biofilm assembly and improve bacterial clearance via enzymatic treatments.

Study of the Effectiveness of Multipurpose Solutions on the Bacterial Disinfection of Silicone Hydrogel Contact Lenses In Vitro

OBJECTIVES

To assess the antimicrobial effectiveness of multipurpose solutions in regard to the disinfection of silicone hydrogel contact lenses (CL) using a study of clinical bacterial isolates from ocular material.

METHODS

Three multipurpose solutions (solution A: polyhexamethylene biguanide 0.00025 g/100 mL; solution B: polyquaternary-1 0.001% and myristamidopropyl dimethylamine 0.0006%; and solution C: polyaminopropyl biguanide 0.00013% and polyquaternary 0.0001%) were used as a 3-phase disinfection on silicone hydrogel CL contaminated with bacteria from clinical isolates that were divided into five groups (group 1: Pseudomonas aeruginosa; group 2: Staphylococcus aureus; group 3: Staphylococcus epidermidis; group 4: Streptococcus spp; and group 5: enterobacteria).

RESULTS

No differences were observed between the 24- and 48-hr measurements in any of the samples, and the positivity of microorganisms in T0 was 100% for all solutions; it was 0% in T3. Therefore, only steps T1 (rubbing followed by rinsing) and T2 (rubbing followed by rinsing and immersion of CL into solution) were considered for analysis at the 24-hr measurement time. Throughout the phases, a decrease in the number of bacteria was observed, culminating in the elimination (no recovery) of all microorganisms in the three solutions.

CONCLUSIONS

At the end of the proposed process, the tested solutions were effective.

Performance evaluation of delefilcon a water gradient daily disposable contact lenses in first-time contact lens wearers

PURPOSE

To evaluate the tolerability of and subject and investigator satisfaction with delefilcon A (DAILIES TOTAL1^®) daily disposable contact lenses in first-time contact lens wearers.

METHODS

This European multicenter, open-label, single-arm, two-week trial enrolled first-time contact lens wearers and fitted them with delefilcon A contact lenses. Assessments were made at dispensing and at Weeks 1 and 2. Subject-reported outcomes included comfort, quality of vision, convenience, and intent to purchase, which were ranked by agreement responses. Investigator-reported outcomes included slit-lamp biomicroscopy findings and lens fit satisfaction.

RESULTS

Ninety-two subjects were included in the per protocol dataset. Mean scores at Weeks 1 and 2 for subject-reported quality of vision and ocular comfort were significantly higher with delefilcon A contact lenses than with the subjects' habitual spectacles during the day, at the end of the day, and overall (all p ≤ 0.02). Ninety-one percent of subjects reported that their study lenses were more comfortable than expected, 98% agreed that they were convenient to use, and 92% were interested in purchasing the lenses (all p < 0.001). Investigators reported that study lenses had an acceptable fit in at least 97% of subjects.

CONCLUSIONS

Practitioners can expect favorable outcomes when transitioning first-time contact lens wearers from spectacles to delefilcon A daily disposable contact lenses.

Second harmonic generation imaging of corneal stroma after infection by Pseudomonas aeruginosa

Pseudomonas aeruginosa is a pathogenic gram-negative organism that has the ability to cause blinding corneal infections following trauma and during contact lens wear. In this study, we investigated the directional movement and orientation of an invasive corneal isolate of P. aeruginosa in the corneal stroma during infection of ex vivo and in vivo rabbit corneas using multiphoton fluorescence and second harmonic generation (SHG) imaging. Ex vivo, rabbit corneas were subject to three partial thickness wounds prior to inoculation. In vivo, New Zealand white rabbits were fit with P. aeruginosa laden contact lenses in the absence of a penetrating wound. At all time points tested, infiltration of the corneal stroma by P. aeruginosa revealed a high degree of alignment between the bacteria and collagen lamellae ex vivo (p < 0.001). In vivo, P. aeruginosa traveled throughout the stroma in discrete regions or bands. Within each region, the bacteria showed good alignment with collagen lamellae (P = 0.002). Interestingly, in both the in vitro and in vivo models, P. aeruginosa did not appear to cross the corneal limbus. Taken together, our findings suggest that P. aeruginosa exploits the precise spacing of collagen lamellae in the central cornea to facilitate spread throughout the stroma.

Protective efficacy of a peptide derived from a potential adhesin of Pseudomonas aeruginosa against corneal infection

Dissecting the interactions between Pseudomonas aeruginosa and corneal cells is important to identify a novel target for prevention and treatment of Pseudomonas keratitis. The current study began with a peptide identified by phage display, and was to investigate the protective efficacy against P. aeruginosa infection in cornea. The original peptide Pc-E, with high homology to a hypothetical membrane protein (HmpA) in P. aeruginosa, and the derived peptide Pc-EP, with the same sequence as a region in HmpA, were synthesized. Peptide Pc-EP could directly bind to HCEC, stronger than Pc-E, and specifically activate toll-like receptor 5, and thereby significantly induce the production of pro-inflammatory factors, such as IL-1β, IL-6, IFN-γ and IL-17. Moreover, Pc-EP could act as an antagonist to inhibit the adhesion of wild-type P. aeruginosa to HCEC and mouse corneas. No inhibitory effect was observed on the adhesion of the strain loss of HmpA. When compared to the wild-type strain, the adhesion of the hmpA mutant to corneal cells was significantly decreased. Treatment of infected mouse corneas with Pc-EP before infection significantly decreased the bacterial load in the cornea and attenuated the corneal pathology. These results indicate that Pc-EP can be a useful prophylactic agent for P. aeruginosa keratitis.

Pseudomonas aeruginosa infectious keratitis in a high oxygen transmissible rigid contact lens rabbit model

PURPOSE

To establish a rabbit model of infectious Pseudomonas aeruginosa keratitis using ultrahigh oxygen transmissible rigid lenses and characterize the frequency and severity of infection when compared to a non-oxygen transmissible lens material.

METHODS

Rabbits were fit with rigid lenses composed of ultrahigh and non-oxygen transmissible materials. Prior to wear, lenses were inoculated with an invasive corneal isolate of P. aeruginosa stably conjugated to green fluorescent protein (GFP). Corneas were examined before and after lens wear using a modified Heidelberg Rostock Tomograph in vivo confocal microscope. Viable bacteria adherent to unworn and worn lenses were assessed by standard plate counts. The presence of P. aeruginosa-GFP and myeloperoxidase-labeled neutrophils in infected corneal tissue was evaluated using laser scanning confocal microscopy.

RESULTS

The frequency and severity of infectious keratitis was significantly greater with inoculated ultrahigh oxygen transmissible lenses. Infection severity was associated with increasing neutrophil infiltration and in severe cases, corneal melting. In vivo confocal microscopic analysis of control corneas following lens wear confirmed that hypoxic lens wear was associated with mechanical surface damage, whereas no ocular surface damage was evident in the high-oxygen lens group.

CONCLUSIONS

These data indicate that in the absence of adequate tear clearance, the presence of P. aeruginosa trapped under the lens overrides the protective effects of oxygen on surface epithelial cells. These findings also suggest that alternative pathophysiological mechanisms exist whereby changes under the lens in the absence of frank hypoxic damage result in P. aeruginosa infection in the otherwise healthy corneal epithelium.

Biometric risk factors for corneal neovascularization associated with hydrogel soft contact lens wear in Korean myopic patients

PURPOSE

To investigate the biometric risk factors for corneal surface complications associated with hydrogel soft contact lens (SCL) fitting in myopic patients in Korea.

METHODS

This is a retrospective case-control study. The records of 124 subjects (124 eyes) who wore SCLs on a daily basis were reviewed. Thirty-one patients (31 eyes) who were diagnosed with corneal neovascularization (NV) while wearing SCLs were included in the complication group. Ninety-three age- and sex-matched patients (93 eyes) who wore SCLs, who did not have corneal NV and who visited our clinic for correction of refractive errors were included in the control group. The degree of spherical equivalent, astigmatism and corneal base curve radius (BCR) were compared in both groups.

RESULTS

Patients with NV exhibited poorer best corrected visual acuity and more myopia than controls (p = 0.008 and 0.006, respectively). In univariate analysis, highly myopic patients (-9 diopters [D] or higher) were more likely to experience NV (odds ratio [OR], 2.232; 95% confidence interval [CI], 1.602 to 3.105). High astigmatism (≥2 D) increased the risk of complications (OR, 2.717; 95% CI, 1.141 to 6.451). Steep cornea, in which BCR was <7.5 mm, also raised the risk of complications (OR, 4.000; 95% CI, 1.661 to 9.804). Flat cornea was not a risk factor for the development of NV.

CONCLUSIONS

High myopia, high astigmatism, and steep cornea seemed to be risk factors in the development of corneal NV in SCL wearers.

Galectin-1-mediated suppression of Pseudomonas aeruginosa-induced corneal immunopathology

Corneal infection with Pseudomonas aeruginosa leads to a severe immunoinflammatory lesion, often causing vision impairment and blindness. Although past studies have indicated a critical role for CD4(+) T cells, particularly Th1 cells, in corneal immunopathology, the relative contribution of recently discovered Th17 and regulatory T cells is undefined. In this study, we demonstrate that after corneal P. aeruginosa infection, both Th1 and Th17 cells infiltrate the cornea with increased representation of Th17 cells. In addition to Th1 and Th17 cells, regulatory T cells also migrate into the cornea during early as well as late stages of corneal pathology. Moreover, using galectin-1 (Gal-1), an immunomodulatory carbohydrate-binding molecule, we investigated whether shifting the balance among various CD4(+) T cell subsets can modulate P. aeruginosa-induced corneal immunopathology. We demonstrate in this study that local recombinant Gal-1 (rGal-1) treatment by subconjunctival injections significantly diminishes P. aeruginosa-mediated corneal inflammation through multiple mechanisms. Specifically, in our study, rGal-1 treatment significantly diminished corneal infiltration of total CD45(+) T cells, neutrophils, and CD4(+) T cells. Furthermore, rGal-1 treatment significantly reduced proinflammatory Th17 cell response in the cornea as well as local draining lymph nodes. Also, rGal-1 therapy promoted anti-inflammatory Th2 and IL-10 response in secondary lymphoid organs. Collectively, our results indicate that corneal P. aeruginosa infection induces a strong Th17-mediated corneal pathology, and treatment with endogenously derived protein such as Gal-1 may be of therapeutic value for the management of bacterial keratitis, a prevalent cause of vision loss and blindness in humans worldwide.

Why does the healthy cornea resist Pseudomonas aeruginosa infection?

PURPOSE

To provide our perspective on why the cornea is resistant to infection based on our research results with Pseudomonas (P) aeruginosa. We focus on our current understanding of the interplay between bacteria, tear fluid, and the corneal epithelium that determines health as the usual outcome, and propose a theoretical model for how contact lens wear might change those interactions to enable susceptibility to P aeruginosa infection.

METHODS

Use of "null-infection" in vivo models, cultured human corneal epithelial cells, contact lens-wearing animal models, and bacterial genetics help to elucidate mechanisms by which P aeruginosa survives at the ocular surface, adheres, and traverses multilayered corneal epithelia. These models also help elucidate the molecular mechanisms of corneal epithelial innate defense.

RESULTS

Tear fluid and the corneal epithelium combine to make a formidable defense against P aeruginosa infection of the cornea. Part of that defense involves the expression of antimicrobials such as β-defensins, the cathelicidin LL-37, cytokeratin-derived antimicrobial peptides, and RNase7. Immunomodulators such as SP-D and ST2 also contribute. Innate defenses of the cornea depend in part on MyD88, a key adaptor protein of TLR and IL-1R signaling, but the basal lamina represents the final barrier to bacterial penetration. Overcoming these defenses involves P aeruginosa adaptation, expression of the type III secretion system, proteases, and P aeruginosa biofilm formation on contact lenses.

CONCLUSION

After more than 2 decades of research focused on understanding how contact lens wear predisposes to P aeruginosa infection, our working hypothesis places blame for microbial keratitis on bacterial adaptation to ocular surface defenses, combined with changes to the biochemistry of the corneal surface caused by trapping bacteria and tear fluid against the cornea under the lens.

The effects of silicone hydrogel lens wear on the corneal epithelium and risk for microbial keratitis

Previous studies using animal models and human clinical trials have demonstrated that the use of low-oxygen-transmissible contact lens materials produce corneal epithelial surface damage resulting in increased Pseudomonas aeruginosa (PA) adhesion and raft-mediated internalization into surface corneal epithelial cells. These findings led to the testable clinical predictions that (1) microbial keratitis (MK) risk is expected to be the greatest during the first 6 months of wear; (2) there is no difference between 6 and 30 night extended wear; and (3) that wear of hyperoxygen-transmissible lenses would reduce the reported incidence of infection. Subsequent epidemiologic studies have confirmed the first two predictions; however, increased oxygen transmissibility with silicone hydrogel (SiHy) lens wear has not altered the overall incidence of MK. In this review, more recent clinical and basic studies that investigate epithelial alterations and bacterial adhesion to corneal epithelial cells after the wear of SiHy lenses with and without concomitant exposure to chemically preserved multipurpose solutions (MPS) will be examined. The collective results of these studies demonstrate that even in the absence of lens-related hypoxia, MPS induce ocular surface changes during SiHy lens wear that are associated with a pathophysiologic increase in PA adherence and internalization in the corneal epithelium, and therefore, predict a greater risk for PA-MK. In addition, new data supporting an interactive role for inflammation in facilitating PA adherence and internalization in the corneal epithelium will also be discussed.

Patient compliance during contact lens wear: perceptions, awareness, and behavior

OBJECTIVES

Patient noncompliance with recommended hygienic practices in contact lens wear is often considered a significant risk factor for microbial keratitis and adverse contact lens-related events. Despite advancements in lens materials and care solutions, noncompliant behavior continues to hinder efforts to maximize contact lens safety. The objective of this pilot study was to assess the relationship between perceived and actual compliance with awareness of risk and behavior.

METHODS

One hundred sixty-two established contact lens wearers were sequentially evaluated after their routine contact lens examination at the Optometry Clinic at the University of Texas Southwestern Medical Center at Dallas, TX. Each patient was questioned by a single trained interviewer regarding his or her lens care practices and knowledge of risk factors associated with lens wear.

RESULTS

Eighty-six percent of patients believed they were compliant with lens wear and care practices; 14% identified themselves as noncompliant. Using a scoring model, 32% demonstrated good compliance, 44% exhibited average compliance, and 24% were noncompliant; age was a significant factor (P = 0.020). Only 34% of patients who perceived themselves as compliant exhibited a good level of compliance (P<0.001). Eighty percent of patients reported an awareness of risk factors, but awareness did not influence negative behavior. Replacing the lens case was the only behavior associated with a positive history for having experienced a prior contact lens-related complication (P = 0.002).

CONCLUSIONS

Perceived compliance is not an indicator for appropriate patient behavior. A large proportion of patients remain noncompliant despite awareness of risk. Education alone is not a sufficient strategy to improve behavior; newer approaches aimed at improving compliance with lens care practices are urgently needed.

[Documentation of ophthalmological findings in contact lens wearers: software-based symbol library of the Efron grading scale]

BACKGROUND

To prevent complications through the use of contact lenses the efforts spent on documentation will have to be increased to meet the demands of quality management. How can ophthalmologists benefit from the use of software-based graphical documentation?

METHODS

To make a standardized documentation of contact lens complications possible a software module with a graphically intuitive visualization scheme of the Efron grading scale was developed. The Efron grading scale defines 16 different classes of findings scaled to 5 grades.

RESULTS

The software module shows a schematic view of the eye which allows an easy sectoral assignment of all 16 Efron findings. The designated sector can simply be marked with a mouse click. A subsequently appearing context menu offers all 16 Efron findings together with the corresponding 5 grades. Finally the chosen Efron grade is graphically visualized in the corresponding sector.

CONCLUSION

The software module supplies a feasible way for high quality documentation in the clinical routine with illustrative visualization. The practical application of software tools to assist clinical documentation can help to meet the challenges of quality management in contact lens utilization.

Inhibition of macrophage migration inhibitory factor ameliorates ocular Pseudomonas aeruginosa-induced keratitis

Pseudomonas aeruginosa causes severe sight-threatening corneal infections, with the inflammatory response to the pathogen being the major factor resulting in damage to the cornea that leads to loss of visual acuity. We found that mice deficient for macrophage migration inhibitory factor (MIF), a key regulator of inflammation, had significantly reduced consequences from acute P. aeruginosa keratitis. This improvement in the outcome was manifested as improved bacterial clearance, decreased neutrophil infiltration, and decreased inflammatory responses when P. aeruginosa-infected MIF knock out (KO) mice were compared to infected wild-type mice. Recombinant MIF applied to infected corneas restored the susceptibility of MIF deficient mice to P. aeruginosa-induced disease, demonstrating that MIF is necessary and sufficient to cause significant pathology at this immune privileged site. A MIF inhibitor administered during P. aeruginosa-induced infection ameliorated the disease-associated pathology. MIF regulated epithelial cell responses to infection by enhancing synthesis of proinflammatory mediators in response to P. aeruginosa infection and by promoting bacterial invasion of corneal epithelial cells, a correlate of virulence in the keratitis model. Our results uncover a host factor that elevates inflammation and propagates bacterial cellular invasion, and further suggest that inhibition of MIF during infection may have a beneficial therapeutic effect.

Properties of PASP: a Pseudomonas protease capable of mediating corneal erosions

PURPOSE

To analyze PASP in terms of its gene distribution and expression, its corneal pathologic effects, its enzymatic properties, and the protectiveness of the immune response to this protease.

METHODS

Twenty-five strains of P. aeruginosa were analyzed for the PASP gene and secreted protein by PCR and Western blot analysis, respectively. Active recombinant (r)PASP (10 microg/20 microL) or heat-inactivated rPASP was intrastromally injected into rabbit corneas. Pathologic changes were monitored by slit lamp examination (SLE) and histopathology. Purified rPASP was assayed for cleavage of collagens and susceptibility to TLCK. Rabbit antibody to rPASP was produced and tested for enzyme inactivation, and actively immunized rabbits were challenged by intrastromal injection of active rPASP (5 microg).

RESULTS

All 25 strains of P. aeruginosa analyzed were positive for the PASP gene and protein. SLE scores of eyes injected with active rPASP were significantly higher than control eyes at all postinjection times (PI; P <or= 0.004). Histopathologic studies documented the destruction of the corneal epithelial layer and portions of the corneal stroma at 9 hours PI, and polymorphonuclear (PMN) leukocyte infiltration into the cornea by 24 hours after active rPASP injection. PASP cleaved type I and IV collagens and was susceptible to TLCK inhibition. PASP was present in the cytoplasm and periplasm, but only secreted PASP was enzymatically active. A high antibody titer (ELISA titer >or= 10,000) was produced, but this antibody did not protect against active rPASP challenge.

CONCLUSIONS

PASP is a commonly produced Pseudomonas protease that can cleave collagens and cause corneal erosions.