Adherence of Pseudomonas aeruginosa onto surfactant-laden contact lenses

Rational design of antibiotic-free antimicrobial contact lenses: Trade-offs between antimicrobial performance and biocompatibility

Microbial keratitis associated with contact lenses (CLs) wear remains a significant clinical concern. Antibiotic therapy is the current standard of care. However, the emergence of multidrug-resistant pathogens necessitates the investigation of alternative strategies. Antibiotic-free antimicrobial contact lenses (AFAMCLs) represent a promising approach in this regard. The effectiveness of CLs constructed with a variety of antibiotic-free antimicrobial strategies against microorganisms has been demonstrated. However, the impact of these antimicrobial strategies on CLs biocompatibility remains unclear. In the design and development of AFAMCLs, striking a balance between robust antimicrobial performance and optimal biocompatibility, including safety and wearing comfort, is a key issue. This review provides a comprehensive overview of recent advancements in AFAMCLs technology. The focus is on the antimicrobial efficacy and safety of various strategies employed in AFAMCLs construction. Furthermore, this review investigates the potential impact of these strategies on CLs parameters related to wearer comfort. This review aims to contribute to the continuous improvement of AFAMCLs and provide a reference for the trade-off between resistance to microorganisms and wearing comfort. In addition, it is hoped that this review can also provide a reference for the antimicrobial design of other medical devices.

Comparison of two methods for obtaining and transporting corneal samples in suspected infectious keratitis

BACKGROUND AND PURPOSE

The purpose of this study is to compare two alternative methods of collecting and transporting media for the diagnosis of corneal ulcers, as not all clinical settings have conventional culture materials and transport media available.

METHODS

In this open-label, prospective, comparative, and randomized study, patients with clinical suspicion of infectious keratitis with high risk of loss of vision had corneal specimens collected using two methods and transport media: Eswab scraping with Amies transport medium and 23-gauge needle scraping in BACTEC Peds broth. The order of each collection method was randomized. The samples were processed by standard methods, comparing the positivity frequencies for both by parametric and nonparametric tests, according to normality criteria.

RESULTS

Corneal infiltrates from 40 eyes of 40 patients were analyzed. Culture positivity rate was 50% for Eswab and 35% for 23-gauge needle (P=0.258). The overall growth rate of the two methods combined was not higher than with the swab alone. The results obtained with a swab were not influenced by the collection sequence (P=0.112); however, the positivity rate was significantly higher when the sample taken with the needle was performed first (P=0.046).

CONCLUSIONS

The single sample Eswab method of collection and transportation for the diagnosis of high risk corneal ulcers is a valid alternative and can be used in cases in which, for various reasons, there is no access to the full set of traditional culture materials.

Influence of Selected Surfactants on Physicochemical Properties of Calcium Phosphate Bone Cements

The influence of the three nonionic surface active agents such as Tween 20, Tween 80, and Tetronic 90R4 on hydrolysis, setting reaction, microstructure, and mechanical properties of alpha tricalcium phosphate (α-TCP) based materials was determined. The study revealed that the addition of any of the surfactants mentioned above slightly prolonged the setting time of the tested cements (up to 5 min). On the other hand, it was found that surfactants influence the long-term hydrolysis reaction. The addition of surfactants also affected the microstructure of the final materials, especially after incubation in a simulated body fluid. Surface active agents also had an impact on mechanical behavior of the obtained cements. Sorbitan esters, Tween 20 and Tween 80, decreased compressive strength in comparison to the reference material (6.56 ± 1.59 MPa) to 3.54 ± 1.18 and 3.68 ± 1.03 MPa, respectively. Interestingly, Tetronic 90R4, never used before as an additive to calcium phosphate bone cements (CPCs) caused a 2-fold increase of this value (up to 13.28 ± 1.59 MPa). All the developed materials exhibited bioactivity in vitro. The obtained results shed new light on surfactants as CPCs additives. They should not only be considered as foaming agent or binders, but also they deserve more attention as modifiers affecting the physicochemical properties of α-TCP based materials.

Contact Lens Technology: From Fundamentals to Applications

Contact lenses are ocular prosthetic devices used by over 150 million people worldwide. Primary applications of contact lenses include vision correction, therapeutics, and cosmetics. Contact lens materials have significantly evolved over time to minimize adverse effects associated with contact lens wearing, to maintain a regular corneal metabolism, and to preserve tear film stability. This article encompasses contact lens technology, including materials, chemical and physical properties, manufacturing processes, microbial contamination, and ocular complications. The function and the composition of the tear fluid are discussed to assess its potential as a diagnostic media. The regulatory standards of contact lens devices with regard to biocompatibility and contact lens market are presented. Future prospects in contact lens technology are evaluated, with particular interest given to theranostic applications for in situ continuous monitoring the ocular physiology.