Extended Wear Research Articles

International trends in prescribing extended wear soft contact lenses (2000–2023): An update

PurposeExtended wear has long been considered as the ultimate contact lens modality in terms of user convenience. The purpose of this work is to update earlier surveys by describing international trends in extended wear soft lens fitting between 2000 and 2023, inclusive. MethodAn annual contact lens prescribing survey was sent to eye care practitioners in up to 71 countries between 2000 and 2023, inclusive. Data relating to 282,142 soft contact lens fits undertaken in 20 countries returning reliable longitudinal data were analysed in respect of extended wear soft lens fitting. ResultsOver the duration of the work there was a very small decrease in the prescribing of extended wear soft lenses (p < 0.0001). More detailed inspection shows that prescribing of these lenses steadily increased from 5.8 % of all soft lens fits in 2000 to 11.6 % in 2007, then steadily decreased to 5.2 % in 2023. Of all soft contact lenses prescribed to males, 9.2 % were fitted for extended wear, compared with 6.7 % for females (p < 0.0001). The mean age of extended wear soft lens wearers at fitting was 34.7 ± 14.7 years, compared to 31.1. ± 14.10 years for daily soft lens wearers (p < 0.0001). Analysis of 1,948 recent extended wear soft lens fits (2019–2023, inclusive), in terms of material type, revealed that, on average, 86 % and 14 % of extended wear soft lenses were fitted using silicone hydrogel and hydrogel materials, respectively. ConclusionA modest increase in extended wear soft lens prescribing from 2000 to 2007 corresponded with the introduction of high oxygen transmissibility silicone hydrogel lenses. However, prescribing of this lens type declined thereafter, probably due to ongoing concerns over their increased rate of microbial keratitis, resulting in a prescribing rate in 2023 (5.2%) that was little different to that observed in 2000 (5.8%).

Evaluation of mucin changes between daily and extended wear silicone hydrogel contact lenses

Background: Initially, contact lenses were recommended only for daily wear because of infection and discomfort concerns. With rising demand, particularly for overnight use, extended wear lenses have gained significance. Despite concerns, intensive development of materials like Lotrafilcon B aims to meet this demand, focusing on comfort and safety.Aim: This study aimed to evaluate the mucin quantity and quality changes between daily and extended wear (Lotrafilcon B), impacting eye health and comfort.Setting: The study was conducted at Kirana Eye Center, Cipto Mangunkusumo Hospital, Jakarta, Indonesia.Methods: This study was a single-blinded randomised clinical trial with two parallel groups. Forty (40) eligible subjects willingly participated. Mucin 5AC (MUC5AC) and Ferning-type tests were conducted. The 40 subjects with moderate myopia were then divided into a daily wear and an extended wear group. The MUC5AC test was performed at pre-fitting and at 4 weeks, whereas the Ferning-type tests were taken at pre-fitting and 1st and 4th weeks.Results: For both groups, there was a significant increase in MUC5AC levels from pre-fitting to week four, but with no significant difference between them in final MUC5AC levels. Additionally, the comparison of eyes with normal and abnormal Ferning-types between the two groups showed no significant differences at pre-fitting, 1st and 4th weeks.Conclusion: There is no significant difference in MUC5AC levels with the use of daily or extended wear (with Lotrafilcon B).Contribution: This study compares the impact of daily and extended wear Lotrafilcon B contact lenses on eye health and comfort in moderate myopia patients.

Sustained Delivery of Olopatadine from Vitamin-E Loaded Contact Lenses.

Purpose: Topical antihistamines, such as olopatadine hydrochloride, an H1 receptor antagonist, are commonly prescribed for treating allergic conjunctivitis. Drug delivery via eye drops has many deficiencies including a short residence time due to tear drainage via the nasolacrimal duct, which results in a low bioavailability and potential for side effects. These deficiencies could be mitigated by a drug-eluting contact lens such as the recently approved ACUVUE® THERAVISION™ WITH KETOTIFEN which is a daily disposable etafilcon, a drug-eluting contact lens with ketotifen (19 μg per lens). Here, we investigate the feasibility of designing a drug-eluting lens with sustained release of olopatadine for treating allergies using an extended wear lens. Methods: Nanobarrier depots composed of vitamin-E (VE) are formed through direct entrapment by ethanol-driven swelling. The drug-loaded lenses are characterized for transparency and water content. In vitro release is measured under sink conditions and fitted to a diffusion control release model to determine diffusivity and partition coefficient. Results: In vitro studies indicate that ACUVUE OASYS® and ACUVUE TruEye™ lenses loaded with ∼0.3 g of VE/g of hydrogel effectively prolong olopatadine dynamics by 7-fold and 375-fold, respectively. Incorporation of VE into the lenses retains visible light transmission and other properties. Conclusion: The VE incorporation in commercial lenses significantly increases the release duration offering the possibility of antiallergy extended wear lenses.

Impact of referral diagnosis on diagnostic yield in 1-day vs 7-day and 14-day extended wear holter

Abstract Background Use of Extended Wear Holter (EWH) with monitoring durations up to 14 days has become common in clinical practice. When ordering a monitor, a referral diagnosis (RefDx) is provided to indicate the reason for the study. We previously presented data showing EWH monitors, irrespective of RefDx, provided a 2x diagnostic yield (DY) at 7d and 2.5x DY at 14d when compared to 1d Holter. Purpose To determine the impact of RefDx on DY for clinically significant arrythmias (CSA) using ePatch EWH monitoring for 1d, 7d, and 14d. Methods From October - December 2021, retrospective data was analyzed for RefDx (ICD-10 diagnosis code) and DY of CSA for ePatch with 1d, 7d, and 14d of analyzable data. RefDx were categorized as Common and Uncommon. Common RefDx included ICD-10 codes which represented at least 1.5% of total referrals on 1d monitors, while all RefDx with &amp;lt;1.5% were grouped together as Uncommon. CSA was defined as Bradycardia &amp;lt; 40 bpm, Pause ≥ 3 seconds, ≥ 2nd Degree AV Block, AF &amp;gt; 30 sec, SVT &amp;gt; 160 bpm for ≥ 3 beats, and VT &amp;gt; 100 bpm for ≥ 3 beats. DY was calculated as the percentage of patients with at least one CSA over the monitoring duration. Patients with Chronic AF were excluded from this analysis. Results RefDx for patients who wore ePatch for 1d (n=21,505), 7d (n=9,252), and 14d (n=11,269) are shown in the Table. Irrespective of monitoring duration, the most frequent RefDx was Palpitations (&amp;gt;35%). For each RefDx, the DY for any CSA at 1d vs 7d, 1d vs 14d, and 7d vs 14d was statistically significant (see Figure). Across all RefDx, DY increased 1.7x - 2.8x when comparing 1d to 7d, 1.9x - 4.2x when comparing 1d to 14d, and 1.1x – 1.5x when comparing 7d to 14d. For 1d, the lowest DY was for RefDx Chest Pain (13%) while the highest was for RefDx Bradycardia (43%). The DY benefit of extending monitoring from 1d to 7d was normally distributed across RefDX, while the DY benefit of extending monitoring from 7d to 14d was greatest (1.5x) for Chest Pain, and the DY benefit of extending from 1d to 14d was greatest (≥3.4x) for Chest Pain, Tachy Unspecified, Palpitations, Syncope/Collapse, and Dizziness/Giddiness. Notably, the most common RefDx of Palpitations demonstrated a DY of only 17% at 1d that increased 2.5x at 7d and 3.4x at 14d. Conclusion The impact of extending monitoring duration from 1d to either 7d or 14d was that a disparity in additive DY was observed when analyzing by RefDx. The 5 RefDx with the lowest DY for 1d of monitoring showed increases of ≥2.5x DY at 7d and ≥3.4x Dy at 14d of monitoring. Conversely, the 3 RefDx with the highest DY for 1d of monitoring showed &amp;lt;2X DY at 7d and &amp;lt;2.2x DY at 14d. Our data suggests that the RefDx can potentially be used to guide an optimal duration of telemetry monitoring.

Extended wear hearing aids: a comparative, pilot study.

The study evaluated if there were differences between three types of hearing aids, Lyric extended wear (EW), receiver-in-the-ear canal (RITE), completely-in-the-canal (CIC) hearing aids in terms of audiological and psychosocial outcomes. Fifteen patients were selected. Pure-Tone Average (PTA) air conduction range of hearing threshold at 500, 1000, and 2000Hz from 15dB HL to 75dB HL. Patients were assigned in three groups according to the hearing aid used: Extended wear, RITE, and CIC. Pure-tone audiometry, speech audiometry, free-field pure-tone and speech audiometry with hearing aids, and Matrix sentence test were performed. The Satisfaction with Amplification in Daily Life (SADL) questionnaire and the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire were used to assess the psychosocial and audiological benefits provided by hearing aids. No differences were demonstrated in the Matrix sentence test between the groups. A statistically significant difference was present between the "Personal image" of patients with EW and RITE with a p value of 0.01 (better outcome using EW). For the APHAB questionnaire, a significant difference was present in the "Aversiveness" of the patients with EW in comparison to CIC and RITE with a p value of 0.01 (higher aversiveness of sound using EW). In terms of audiological advantage, extended ear hearing aids are similar to RITE and CIC as demonstrated from the Matrix speech reception threshold. The result was confirmed using the APHAB questionnaire. Extended wear devices are better than daily hearing aids concerning the "personal image".

788-P: Development of an Extended-Wear Infusion Set with Angled Cannula

Objective: Medtronic Mio™ 30 infusion set (M30IS) is a single-use consumable for pump users with pre-loaded inserter, utilizing a 30° insertion angle, and labeled for 3-day use. The M30IS wear duration is impacted by initial local trauma caused by insertion &amp; cannula and sustained inflammation mostly by insulin infusion (especially insulin aggregates and other impurities in the infusate) , with the latter being predominant. Recently, a 7-day Medtronic Extended Infusion Set (MEIS) based on 3-day Mio™ Advance IS with a 90° soft cannula was developed and commercialized in Europe, by improving insulin formulation stability in the fluid path. This study is focused on applying the extended wear (EW) technology from MEIS to the M30IS to develop an EW set with angled cannula (the EM30IS) . Method: This is a cross over study of M30IS and EM30IS on drug-induced Type 1 diabetic Yucatan pigs. Each animal wore both sets multiple times with one each time on the abdomen that was continuously infused with Novolog™ subcutaneously via a pump for 1-week or until failure. Blood glucose were measured 5 times/day. Physical examination and serum panel tests were conducted for safety evaluation. Result: Fourteen wears were completed for each device. No significant safety concern was identified. Compared to the 90° cannula sets tested on the same model having occlusion alarm rate of 0∼20% for MEIS and ∼40% for 3-day sets at 7 days, no occlusion alarm was detected in either M30IS or EM30IS. Survival rate of EM30IS (86%, similar to MEIS) trended higher than that of M30IS (71%) . Average total daily dose of insulin increased with time for M30IS (Day 1: 14.4 U, Day 6: 18.1U) , whereas remained nearly unchanged for EM30IS (Day 1: 14.9 U, Day 6: 15.6 U) . Conclusion: The data indicated that the EM30IS is safe and efficacious on the diabetic porcine model for subcutaneous insulin infusion for 7 days. The EW technology is equally safe and effective on extending the wear duration of M30IS. The EM30IS is moving to the next phase of product development. Disclosure G.Zhang: Employee; Medtronic. E.Anselmo: Employee; Medtronic. J.L.Ortigoza: Employee; Medtronic. S.Chattaraj: Employee; Medtronic.

Surface softness comparison of worn contact lenses by nanoindentation

Purpose: This study was designed to measure surface softness of a new contact lens material (NCLM) with biologically inspired water gradient surface after 30 days of daily wear (DW) and 6 nights/7 days extended wear (EW). These values were compared with fresh lenses and other contact lens benchmarks.

Biocompatibility and Comfort during Extended Wear of Mel4 Peptide-Coated Antimicrobial Contact Lenses.

(1) Purpose: This study aimed to investigate the effects of Mel4 antimicrobial contact lenses (MACL) on the ocular surface and comfort during extended wear. (2) Methods: A prospective, randomised, double-masked, contralateral clinical trial was conducted with 176 subjects to evaluate the biocompatibility of contralateral wear of MACL. The wearing modality was 14-day extended lens wear for three months. The participants were assessed at lens dispensing, after one night, two weeks, one month and three months of extended wear and one month after study completion. (3) Results: There were no significant differences (p > 0.05) in ocular redness or palpebral roughness between Mel4 and control eyes at any of the study visits. There was no significant difference (p > 0.05) in corneal staining between Mel4 and control eyes. There were no significant differences in front surface wettability or deposits or back surface debris (p > 0.05). No statistically significant differences (p > 0.05) were found in comfort, dryness, CLDEQ-8 scores lens or edge awareness. There was no evidence for delayed reactions on the ocular surface after cessation of lens wear. (4) Conclusion: The novel MACLs showed similar comfort to control lenses and were biocompatible during extended wear. Thus, these lenses were compatible with the ocular surface.

Long-term effect of contact lens wear: A citation network study

BackgroundContact lenses can cause complications in 2/3 of the total population, but in most cases, they are mild and easy to manage. However, most of the studies are short-term. The aim of the study was to analyze the publications on the long-term effects of contact lens wear to understand the current research landscape through the analysis of dating networks as well as determining the different research areas and the most cited publications. MethodsThe Web of Science database was used to perform the publication search, looking for the terms “Long-term” AND “contact lens wear” within the period between 1977 and January 2021. The CitNetExplorer and CiteSpace software were then used to conduct the publication analysis. To obtain the graphics, the VOSviewer software was used. ResultsA total of 721 publications were found with 2999 citations generated within the network. The year 2010 was singled out as a “key year”, considering the number of publications that emerged in that year and increase in adaptations of contact lens worldwide. The most widely cited publication was “Effects of long-term extended contact lens wear on the human cornea”, an article by Holden et al., which was published in 1985. By using the clustering function, we were able to establish three clusters that encompassed the different research areas within this field: morphological changes, the loss of corneal sensitivity, tear film characteristics and longitudinal changes in ocular physiology. ConclusionsThe main research topic in this field focuses on the morphological changes that take place in the corneal endothelial cell layer.

A pilot study investigating the effect of extended contact lens wear on limbal and central corneal morphology

PurposeTo investigate the effect of long-term extended soft contact lens wear on limbal and central corneal cell morphology, and limbal architecture. MethodsEach participant attended a study visit involving in vivo confocal microscopy of central corneal and limbal epithelium. Scans were graded by five masked graders for three features: central epithelial irregularity, limbal epithelial irregularity and the prominence of palisades of Vogt. The variability of grades between different graders and the difference of grades between extended wearers and daily soft/non-contact lens wearers were assessed. ResultsNineteen participants (9 extended soft contact lens wearers and 10 daily soft/non-contact lens wearers) aged 31–65 years were enrolled in this study. Scans from 37 eyes were included in the analysis. Agreement between graders for each feature was moderate to good with inter class correlation >0.7. While there were no significant differences in central epithelial cell irregularity (p = 0.527) and the prominence of palisade of Vogt (p = 0.182) between extended or daily soft/non-contact lens wearers, limbal epithelial cell irregularity showed a trend with increased irregularity in extended soft contact lens wearers (p = 0.091). ConclusionsWhile no differences in limbal cell morphology and structureor central epithelial cell wasfound in thissubjective grading study of extended wearers compared to daily soft/non-contact lens wearers, further studies using a larger sample size or a longitudinal study design are warranted.

Effect of Antimicrobial Contact Lenses on Corneal Infiltrative Events: A Randomized Clinical Trial.

PurposeTo determine whether Mel4-coated antimicrobial contact lenses (MACLs) can reduce the incidence of corneal infiltrative events (CIEs) during extended wear.MethodsA prospective, randomized, double-masked, single-center, contralateral, extended contact lens wear clinical trial was conducted with 176 subjects. Each participant was randomly assigned to wear a MACL in one eye and an uncoated control contact lens in the contralateral eye or an extended-wear biweekly disposable modality for 3 months. The main outcome measures were the incidence of CIEs per 100 eye-months, identification of the microbial types colonizing the contact lenses or eyes at the time of the CIEs, and their susceptibility to Mel4.ResultsNine participants (5.1%) experienced unilateral CIEs; six participants had contact lens acute red eye, and three participants had infiltrative keratitis. The incidence rate for CIEs (0.4 events per 100 participant months; 1.7%) in the Mel4-coated lenses (test) was 69% less than that of the control lenses (1.3 events per 100 participant months; 3.4%; P = 0.29). All Gram-negative bacteria isolated from lenses and lids of participants with CIEs (Citrobacter diversus, Acinetobacter haemolyticus, and Acinetobacter lwoffii) were susceptible to Mel4 peptide; minimum inhibitory concentrations ranged from 15.6 to 62.5 µg/mL. Reduction of adhesion of these bacteria by Mel4-coated lenses ranged from 2.1 to 2.2 log10 colony-forming units/lens.ConclusionsMACLs had the capacity to reduce CIEs by at least 50% compared with uncoated control lenses during extended wear over 3 months; however, due to the relatively low rates of CIEs, the reduction was not statistically different compared with control lenses.Translational RelevanceThis study provides evidence that antimicrobial contact lenses have the potential to reduce the incidence of corneal infiltrative events during extended wear.

The improved survival rate and cost-effectiveness of a 7-day continuous subcutaneous insulin infusion set

Aims The purpose of this article is to compare the insulin cost-savings of the Medtronic Extended Infusion Set (or EIS, a.k.a. Extended Wear Infusion Set) designed and labeled for up to 7-day use with rapid-acting insulins to the current standard of care, 2- to 3-day infusion sets. Methods There are three major improvements (reducing insulin waste, plastic waste, and adverse events) with the extended duration of infusion set wear. This analysis focuses on cost savings from reduced insulin wastage during set changes. Studies published on insulin infusion set survival and EIS clinical trial data (NCT04113694) were used to estimate device lifetime performance using a Markov chain Monte Carlo model, including the assessment of adverse effects and device failure. Total costs associated with infusion set change or failure were systematically found in published literature or estimated based on physical usage, and the direct impact on insulin costs was calculated. Results Based on the model and clinical data, EIS users can expect to change their infusion sets about 75 fewer times than standard set users each year. The costs related to unrecoverable insulin during an infusion set and reservoir change in the US were estimated to range from $19.79 to $22.48, resulting in approximately $1324 to $1677 in annual cost-savings for the typical user from minimizing insulin wastage. Limitations The study only assessed devices used within a monitored setting, that is, clinical trials. In addition, the variability associated with healthcare standards and costs and individual treatment variability including insulin dosages, contribute to the uncertainties with the calculations. Conclusions Our analysis demonstrates that by extending the duration of infusion set wear, there may be substantial cost savings by reducing insulin wastage.

Clinical Performance of Samfilcon A, a Unique Silicone Hydrogel Lens, on a 7-Day Extended Wear Basis.

PurposeThe objective of this study was to evaluate and compare the clinical performance of samfilcon A, a unique, polyvinylpyrrolidone (PVP)-containing, silicone hydrogel contact lens with that of the balafilcon A silicone hydrogel contact lens when worn on a 7-day extended wear basis.Subjects and MethodsA total of 669 subjects completed this 12-month, controlled, parallel group, masked, randomized study; of these, 340 wore samfilcon A lenses and 329 balafilcon A lenses. Subjects wore their respective assigned lenses bilaterally on a 7-day extended wear basis. On the seventh night of each wearing week, lenses were removed, cleaned, and disinfected using Biotrue multi-purpose solution (MPS), then re-inserted the following morning. Lenses were replaced with new lenses monthly. At each follow-up visit, investigators completed a slit lamp evaluation, and subjects rated lenses based upon a predefined set of performance criteria.ResultsThe samfilcon A lens performed comparably to the balafilcon A lens in terms of most graded and ungraded slit lamp findings, differing significantly only for corneal staining Grade 2 or greater, which favored samfilcon A, and anterior segment abnormalities, which favored balafilcon A. Subjects rated both lenses highly when queried about various lens-wearing characteristics. When comparing the number of subjects with findings on either eye on at least one follow-up visit, the two lenses were comparable in many aspects but favored samfilcon A with respect to cleanliness upon removal, overall comfort, comfort at end of day, dryness, vision, vision in low light, vision at end of day, and overall impression (all p < 0.05).ConclusionWhile subjects rated both highly, samfilcon A lenses worn for 7-day extended wear and replaced on a monthly basis performed comparably to or better than balafilcon A lenses when worn for the same 7-day wear time and replacement cycle.

Synthesis and Characterization of Monosaccharide-Containing 2-(α-D-mannopyranosyloxy)Ethyl Methacrylate as a Surface Modifier for Hydrogels.

We introduce a hydrophilic monosaccharide-containing 2-(α-D-mannopyranosyloxy)ethyl methacrylate (ManEMA) in this study to achieve more extended and comfortable wear silicone hydrogel contact lenses by increasing water content. Molecular structure of ManEMA contains a monosaccharide moiety with four hydroxyl groups, which provide a strong interaction with water. Therefore, the ManEMA-containing hydrogels are expected to have high water content. The structure of synthesized ManEMA is confirmed by 1H and 13C NMR spectroscopy. Contact lenses containing silicone polymers are coated with a monosaccharide-containingManEMA monomer with the help of plasma treatment and the use of 3-(trimethoxylsilyl)propyl methacrylate to provide an increased hydrophilicity. The feasibility of ManEMA as a surface modifier of silicone lenses is investigated in terms of water content and surface energy.

Tribofilm Formation, Friction and Wear-Reducing Properties of Some Phosphorus-Containing Antiwear Additives

The film-forming, friction and wear properties of a range of model and commercial ashless P and P/S antiwear additives have been studied. A method has been developed for removing the tribofilms formed by such additives in order to effectively quantify mild wear. In general the P/S additives studied formed thinner tribofilms but gave lower wear than the S-free P ones. In extended wear tests, three P/S additives gave wear as low, or lower, than a primary zinc dialkyldithiophosphate (ZDDP). For almost all lubricants tested the wear rate measured in short tests was considerably higher than that in long tests due to the greater contribution of running-in wear in the former. This highlights the importance of basing antiwear additive choice on reasonably long tests, where running-in becomes only a small component of the wear measured. It has been found that for both P and P/S ashless additives the addition of oil-soluble metal compounds based on Ti and Ca boosts tribofilm formation and can lead to very thick films, comparable to those formed by ZDDP. However, this thick film formation tends to be accompanied by an increase in mixed friction and also does not appear to reduce wear but may even increase it.

Non-adherence with compression garment wear in adult burns patients: A systematic review and meta-ethnography

ObjectiveUp to 40% of adult burn-injured patients are non-adherent with prescribed compression garment wear. The aim of this paper is to systematically review the literature to understand barriers to adherence with compression garment wear. MethodPapers were included if they: investigated adults who required compression garment wear for the management of burns scars; focussed on reasons for non-adherence to compression garment wear; and were available in English. The process of meta-ethnography was then followed to synthesise the findings. ResultsThe factors impacting adherence to compression garment wear were grouped into six themes: sensory factors, psychological state, the impact of the garment on the patient’s function, the availability of social support, the degree of choice, and the education provided to patients by their therapists. A model of compression garment adherence was developed detailing how these factors fit within the continuum of treatment for a burn-injured patient. ConclusionsAdherence to compression garment wear post-burn injury is a complex, dynamic phenomenon impacted by a range of factors. Findings from this review may inform approaches to support more consistent and/or extended garment wear, potentially improving scar outcomes and quality-of-life. Further research is recommended to investigate how each of the six identified themes impact adherence.

Comparative Analysis of Adverse Events From a Series of Proof-of-Principle Extended Wear Studies.

A series of proof-of-principle extended wear (EW) contact lens studies were conducted to assess what effect different interventions had on adverse events (AEs). Comparative analysis of AEs across studies was conducted to determine whether some interventions were more effective at reducing inflammatory AEs. Multiple logistic regression analysis of AEs from 30-day EW studies each with a different intervention including (1) nightly replacement (NR) of lenses, (2) morning replacement (MR) of lenses, (3) instillation of prophylactic antibiotic drops (AB) each morning/evening, (4) daily lens cleaning (LC) each morning. All studies conducted at the same site using same lens type (lotrafilcon A) and EW schedule. Comparison of the different interventions to the individual control groups showed no difference in significant corneal infiltrative event (CIE) or mechanical events. Replacing lenses nightly, during an EW schedule, had the highest incidence of significant CIEs (4.9% [NR] vs. 2.5% [MR] vs. 1.8% [AB] vs. 0% [LC]); however, adjusted logistic regression analysis of the combined control data compared with the individual interventions showed no difference in significant CIEs (P=0.086) or mechanical AEs (P=0.140). Replacing lenses each night seemed to be inferior compared with the other interventions of replacing lenses each morning, daily lens cleaning, and daily antibiotic drop instillation during EW. The results of the collective studies and additional analysis suggest that overnight wear of contact lenses seems to create an adverse environment that remains, despite the various interventions intended to improve this adverse environment.

Comparative study of abrasion via microindentation and microscratch tests of reinforced and unreinforced lamellar cast iron

This study compares micro-abrasive wear in two kinds of grey cast iron. Classical lamellar cast iron with fully pearlitic matrix (FGL1) and lamellar micro-alloyed cast iron with phosphorus and boron (FGL2) are used. FGL2 has a fully pearlitic matrix reinforced by the hard phosphorus eutectic phase. The microstructures of these two types of iron are mechanically characterized using nanoindentation tests. Vickers microindentation and microscratch tests are also performed on these iron samples. The indent and scratch images obtained via scanning electron microscopy were used to compare the scratch damage to the two kinds of iron. The friction coefficient is discussed in terms of applied load, indenter attack angle, and scratch damage. Nanoindentation tests show an improvement in graphite’s mechanical properties and an increase in the matrix hardness of the FGL2, relatively to FGL1. The same damage forms for both microindentation and microscratch testing were observed for the two iron samples. However, cracking of the hard phase is observed in FGL2. The results show that the scratching of the micro-alloyed iron (FGL2) leads to less matrix damage and to an extended microploughing wear mechanism. However, at low normal load, the reinforcement of the matrix can increase the friction coefficient.

Case series: Extended wear of rigid gas permeable scleral contact lenses for the treatment of persistent corneal epithelial defects

To report the successful treatment of persistent corneal epithelial defects that failed to respond to alternative treatment methods using extended wear of three different rigid gas-permeable scleral lenses. Eight eyes of eight patients with persistent corneal epithelial defects were treated with Blanchard Onefit 2.0 Scleral lens, BostonSight Scleral lens, and BostonSight PROSE device and were observed for defect resolution and improvement in best-corrected visual acuity over the duration of treatment. All eyes observed complete re-epithelialization with a mean time of 11.1 ± 5.5 days. At the conclusion of the treatment, visual acuity improved in all but one patient. No complications were observed during treatment. Scleral lenses provide the corneal epithelium with hydration, oxygen permeation, and protection from mechanical forces; thereby facilitating healing of persistent corneal epithelial defects. This case series demonstrates the successful use of continuous wear scleral lenses in a number of patients for the treatment of persistent epithelial defects refractory to other interventions.

The association between mucin balls and the development of CIEs during extended wear with silicone hydrogel contact lenses

Purpose: To determine whether mucin ball (MB) formation is protective against corneal infiltrative events (CIEs) as previously reported.(Szczotka-Flynn, Cornea 2011) This study was designed to determine the influence of early MB formation via a provocative run-in phase vs. longer term physical presence of MBs on the rate of CIEs while controlling for lens type and bacterial bioburden during extended wear (EW).