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Current insulin infusion sets are approved for only 2-3 days. The novel ConvaTec infusion set with Lantern technology is designed to extend infusion set wear time. The goal of this pilot study was to evaluate the duration of wear for this set. This was a pilot safety study in adults with type 1 diabetes using tethered insulin pumps. Participants inserted the set and wore it for 10 days or until failure. Among 24 participants, two were excluded. Forty-five per cent of the sets lasted 10 days. Median wear time was 9.1 (7.1, 10.0) days. Among 12 premature failures, six (50%) involved adhesive failures, four (33%) hyperglycaemia unresponsive to correction, one (8%) hyperglycaemia with ketones and one (8%) infection. Average CGM glucose per day of infusion set wear showed a statistically significant increase over time, while total daily insulin over the same period did not change. In this pilot study, the duration of wear for the novel infusion set exceeded previously reported commercial sets (P < .001). This extended wear technology may eventually allow for a combined glucose sensor and infusion set.

BACKGROUND Although surface characteristics of food contact materials are known to alter the efficacy of cleaning procedures there is a lack of data establishing how cleaning/sanitization practices affect the surface characteristics of materials used for produce handling on-farm. The overall objective of this work was to characterize the effects of cleaning and sanitization procedures on the surface properties of new and extended-wear polyethylene bins used for produce harvest and handling. RESULTS Compared to detergent cleaned samples, chlorine and quaternary ammonium sanitization resulted in a decrease in advancing contact angle from 100° to 88° and 59°, respectively, after 2 min exposure. However, changes in surface chemistry were not observed. Increasing sanitization time to 144 min (representative of 4320 sanitization cycles) resulted in an increase in contact angle to 73° for quaternary ammonium sanitization and a decrease in contact angle to 75° for chlorine sanitization. Abrasion increased contact angle hysteresis due to enhanced surface roughness. The hysteresis effect of abraded material was reduced with quaternary ammonium treatment. CONCLUSIONS This work indicates that sanitizing agents employed in on-farm cleaning can alter the surface characteristics of polyethylene picking bins and should be considered in developing cleaning and sanitization procedures. © 2013 Society of Chemical Industry

Eighty-two hydrogel extended wear contact lenses (EWCL) from four brands were tested for overall quality and variations in specified parameters. Two of the EWCL brands were approved by the United States Food and Drug Administration (FDA) for wear by the public, while two of the brands were uninvestigated. In addition, the packaging solution was examined for osmolarity and pH. All brands were delivered with solutions that had estimated means of pH and osmolarity departing from what may be considered ideal physiologically. The EWCLs all had a consistent power and an acceptable thickness reproducibility. One of the FDA approved brands, demonstrated diameter variations of a magnitude that may produce an unpredictability in the lens fit. Several lenses of one brand suffered from edge quality deficiencies. Although the FDA clinical trial is designed to control the clinical performance of contact lenses prior to the market entry, the results of the present investigation indicate that an authority independent of the manufacturer should regularly sample the lens quality. It is for this purpose imperative that standards for contact lenses are established.

Purpose Individuals with PFL have problems moving about, and there are some optical aids that are proposed to enhance mobility performance. However, currently the efficacy of these aids cannot be determined without extended wear. This study aims to design a new clinical measure to assess the visual awareness in PFL patients, so that this new test could be used to determine the efficacy of optical aids in a clinical setting Methods PFL was simulated using goggles in 50 normally-sighted subjects. The simulated field of view (FoV) was varied from 5° to 20°. In the new test, observers were asked to search for a stimulus in a 60° field of view and the detection time (DT) & detection efficiency (DE) (DE is the Inter-quartile range of the DT responses at each eccentricity for every subject) were measured. Head and eye movements were allowed and the presentation time was unlimited. Clinical validity was investigated by correlating the DT and DE scores with the percentage preferred walking speed (PPWS) and the number of collisions on an indoor mobility course Results The DT and DE scores were inversely correlated with the FoV (r=-0.60; p

Purpose: The aim of the study was to measure the effects of long-term extended wear of hydrogel lenses. Methods: Nine subjects wearing disposable hydrogel lenses and age- and sex-matched non-lens-wearing control subjects were enrolled. Using confocal microscopy, stromal keratocyte cell densities were measured. Results: Anterior stromal keratocyte density was reduced in the lens-wearing group (544 ± 206 cells/mm2) compared to the non-lens-wearing group (804 ± 145 cells/mm2) (P < 0.01). Posterior stromal keratocyte density was lower in the lens-wearing group (514 ± 111 cells/mm2) than in the control group (628 ± 101 cells/mm2) (P < 0.05). Conclusions: These preliminary findings indicate that extended wear of hydrogel lenses reduces stromal keratocyte density. The mechanisms for this alteration may include hypoxic, cytokine-mediated or mechanical effects.

Purpose: To determine secretory IgA epitopes in tears of extended-wear soft contact lens wearers and non-wearing controls. Methods: We developed enzyme-linked immunosorbent assays (ELISA) to determine the tear concentrations of two epitopes of secretory IgA, the IgA alpha-chain and the secretory component. These epitopes were measured in basal tears of 20 individuals in 6 nights of extended wear of etafilcon A soft contact lenses and in 19 non-lens-wearing individuals. Results: Levels of IgA alpha-chain immunoreactivity were significantly decreased in the lens-wearing group compared to non-lens wearers. However, the level of secretory component immunoreactivity was not significantly different between groups. IgA alpha-chain and secretory component immunoreactvity were highly correlated; however, some samples showed a marked variation between these two values. Conclusion: Tear concentrations of sIgA epitopes are significantly reduced in extended-wear contact lens wearers, and may contribute to the increased susceptibility to ocular infection seen in this group.

Purpose To investigate the magnitude and aetiology of structural and optical changes in the cornea after short-term hydrogel contact lens wear and to explore the effect of these changes on visual performance. Methods Sixteen healthy subjects were fitted with a low-Dk hydrogel contact lens (CH) in one eye and a silicone hydrogel (SH) lens in the contralateral eye. Subjects wore the lenses for 1 month in daily wear (DW) and 1 week in extended wear (EW), with at least 1 week ‘wash out’ in between. All lenses were plano powered and were manufactured in matched designs with the same specifications. Measurements of corneal topography, corneal pachymetry (apical and peripheral), and corneal and ocular aberrations were performed at baseline and after lens wear using a Scheimpflug imaging system (Oculus Pentacam) and a Hartmann-Shack aberrometer (IRX3). Best corrected visual acuity (BCVA, logMAR) and contrast sensitivity measurements (CS, Pelli-Robson) were also performed. Results The optical and structural changes in the cornea after 1 month of DW and 1 week of EW for both the CH and SH materials were of low magnitude. The topographic and pachymetric changes observed were not found to be significant (p>0.05, repeated measures ANOVA). After 1 month of DW, however, the corneal root mean square of quatrefoil aberrations was found to be significantly different after CH contact lens wear (mean difference -0.021 µm; 95% confidence interval for difference: -0.037 to -0.06 µm; p=0.003). BCVA and CS did not change significantly after lens wear. Conclusion Our data showed that the CH and SH lenses tested do not significantly alter the structure or the optical performance of the cornea after one month of daily wear and 1 week of extended contact lens wear.

The nature of hydrogel polymers is described together with the range of biomedical applications in which their use has been suggested or described in the literature. The field of contact lens materials has provided the greatest variety of synthetic hydrogels and the material requirements for extended wear lenses present problems that are typical of those encountered in biomedical applications in general. The patient literature relating to contact lenses is reviewed and the development of the composition of hydrogel materials is thereby traced and compared with the range of lens materials currently available. In contrast the most commonly encountered, in fact almost the sole, hydrogel material in the literature relating to those areas more conventionally regarded as biomedical, is poly(2-hydroxeythyl methacrylate) or polyHEMA. The use of this and related hydrogels in various applications including prostheses, ocular surgery, sature coatings, artificial internal organs and drug delivery systems is reviewed.

Summary The chemistry and properties of silicone rubbers are described. Silicone rubber appears favourable for contact lenses because it is inert, relatively soft, has high gas transmission, is hydrophobic and can be moulded. Gas permeability is probably not as high as claimed and many properties are still unknown. Moulding has limited the parameters that are available. Surface wettability is still inadequate, and the surface degenerates with lipid-mucus adhesion. The results of fitting silicone rubber lenses for aphakia are described. They are useful alternatives where hard lenses are not tolerated. Extended wear beyond six days is not advised.

The interest in rigid gas-permeable contact lenses for extended wear has promoted a re-evaluation of the theoretical and practical aspects of the oxygen transport characteristics of contact lens materials. Oxygen permeability has been considered by some authors to be a parameter which is dependent upon the measurement conditions; however, this paper demonstrates that an intrinsic permeability coefficient may be derived for a given material when the basic principles of the transport mechanisms are considered. Two basic methodologies have been described for measuring oxygen permeability--dual-chamber and electrochemical methods, the latter being the more popular. Although consistency in measured oxygen transmissibility of a given lens may be achieved among laboratories, current analytical techniques do not allow the intrinsic permeability coefficient of materials to be determined. Future research should be directed towards developing methods to fully correct for surface and edge effects, and to achieve standardization among laboratories.