Showing 25 results out of 110 in total.

Kondela,T., Dushanov,E., Vorobyeva,M., Mamatkulov,K., Drolle,E., Soloviov,D., Hrubovcak,P., Kholmurodov,K., Arzumanyan,G., Leonenko,Z., Kucerka,N Investigating the competitive effects of cholesterol and melatonin in model lipid membranes Biochimica et Biophysica Acta - Biomembranes 2021;1863(9):183651 [ Show Abstract ]

We have studied the impact of cholesterol and/or melatonin on the static and dynamical properties of bilayers made of DPPC or DOPC utilizing neutron scattering techniques, Raman spectroscopy and molecular dynamics simulations. While differing in the amplitude of the effect due to cholesterol or melatonin when comparing their interactions with the two lipids, their addition ensued recognizable changes to both types of bilayers. As expected, based on the two-component systems of lipid/cholesterol or lipid/melatonin studied previously, we show the impact of cholesterol and melatonin being opposite and competitive in the case of three-component systems of lipid/cholesterol/melatonin. The effect of cholesterol appears to prevail over that of melatonin in the case of structural properties of DPPC-based bilayers, which can be explained by its interactions targeting primarily the saturated lipid chains. The dynamics of hydrocarbon chains represented by the ratio of trans/gauche conformers reveals the competitive effect of cholesterol and melatonin being somewhat more balanced. The additive yet opposing effects of cholesterol and melatonin have been observed also in the case of structural properties of DOPC-based bilayers. We report that cholesterol induced an increase in bilayer thickness, while melatonin induced a decrease in bilayer thickness in the three-component systems of DOPC/cholesterol/melatonin. Commensurately, by evaluating the projected area of DOPC, we demonstrate a lipid area decrease with an increasing concentration of cholesterol, and a lipid area increase with an increasing concentration of melatonin. The demonstrated condensing effect of cholesterol and the fluidizing effect of melatonin appear in an additive manner upon their mutual presence.

Luensmann D, Schulze M, Woods J, Lazon de la Jara P, Vega J, Orsborn G. Fitting success with stenfilcon A daily disposable multifocal lenses
BCLA Virtual Clinical Conference & Exhibition, 2021 [ Show Abstract ][ PDF ]

Purpose: Multifocal contact lens (MFCL) fitting sometimes raises concerns about the number of fitting attempts required to determine the optimal lens prescription. This study compared the fit process and success rates of stenfilcon A (stenA) MFCL with delefilcon A (delA) MFCL when fitted to existing MFCL wearers in a randomized order.

Method: Successful MFCL wearers with <1.00DC of astigmatism were recruited at five clinical sites in the US. The first trial lenses were determined from current subjective refraction and the respective fitting guides. Prescription changes were reviewed at this first fit visit and also when participants returned for an optimization visit after wearing the lenses for 3-7 days. Multiple lens powers could be trialed at each visit, all were recorded.

Results: Fifty-eight subjects (50F:8M), mean age 54.4±7.3 years [42 to 70 years] were included in the analysis. The spherical-equivalent refraction was OD -1.10±2.7D [-6.50D to +3.75D] with near add +2.00±0.4D [+1.00D to +2.50D]. StenA-MFCL was successfully fit with the first pair of trial lenses in 83% (48) participants, while 10% (6) needed one additional lens and 7% (4) needed an extra two lenses to reach their final power. Regarding count of eyes, 12% (14) needed power optimizations. DelA-MFCL was successfully fit with the first pair of trial lenses in 66% (38) participants, while 17% (10) needed one additional lens, 10% (6) needed two extra lenses and 7% (4) needed three extra lenses to reach their final lens power. Regarding count of eyes, 25% (30) needed power optimizations.

Conclusions: Habitual MFCL wearers were successfully fitted with both MF lens types when following the respective fitting guides. There was a higher success rate with the first lens pair for stenA-MFCL (>8/10 patients) compared to delA-MFCL (<7/10 patients), and no more than one additional fitting lens (per eye) was needed when fitting stenA-MFCL.

Luensmann D, Schulze M, Woods J, Vega J, Orsborn G. Intermediate vision with multifocal contact lenses American Academy of Optometry, Boston, 2021 [ Show Abstract ]

Fitting multifocal contact lenses (MFCL) typically focusses on optimizing distance and near vision, however many presbyopes require good intermediate vision to focus on targets such as desktop screens. This study determined the performance of habitual MFCL (hab-MFCL), stenfilcon A MFCL (stenA-MFCL) and delefilcon A MFCL (delA-MFCL) for intermediate distance vision in existing MFCL wearers.

Five clinical sites in the US recruited habitual MFCL wearers with <1.00DC of astigmatism. Habitual MFCL were power optimized and both study lens types were fit following the respective fitting guides. After two weeks of hab-MFCL wear, study MFCL were worn in a masked/randomized order for the same period of time. Intermediate visual acuity (VA) at 0.75m was determined and subjective responses (fell short of needs; met needs; exceeded needs) were collected along with preference ratings (strongly prefer, slightly prefer, no preference). Subjective responses and logMAR VA were analyzed using Wilcoxon Matched-Pairs testing for differences and binomial testing was conducted on preference ratings.

Fifty-eight subjects (50F:8M), mean age 54.4±7.3 years [42 to 70 years] were included in the analysis. The mean spherical-equivalent refraction was OD -1.10±2.7D [-6.50D to +3.75D]. The average near spectacle Rx add was +2.00±0.4D [+1.00D to +2.50D] and included 18 participants (31%) who required an add of up to +1.75D and 40 (69%) with an add of at least +2.00D. After two weeks of wear, intermediate logMAR VA with stenA-MFCL (0.08±0.10 logMAR) was statistically significantly better compared to hab-MFCL (0.12±0.11 logMAR, p=0.002) and compared to delA-MFCL (0.12±0.12 logMAR, p0.05 for both).

All MFCL were worn successfully for two weeks, however differences in the intermediate vision clarity were noted between lens types, in favour of stenA-MFCL compared to delA-MFCL. Digital devices are frequently used at work and during leisure time today and form part of the need for optimal intermediate vision. While it may often be overshadowed by distance and near vision assessments, good performance at the intermediate distance can be just as critical to ensure success in MFCL wearers.

Mirzapour,P., McCanna,D. J., Jones,L. In vitro analysis of the interaction of tear film inflammatory markers with contemporary contact lens materials Contact Lens Anterior Eye 2021;44(5):101430 [ Show Abstract ]

Several clinical studies have suggested that reusable silicone hydrogel contact lens materials exhibit a two-times increased rate of corneal infiltrative events compared to reusable hydrogels. One potential factor contributing to this complication relates to the differential uptake of tear film-based pro-inflammatory cytokines. The purpose of this study was to use an in vitro assay to investigate whether four pro-inflammatory cytokines differed in their uptake onto six contemporary contact lens materials.

Conventional hydrogel (etafilcon A, omafilcon A) and silicone hydrogel (balafilcon A, comfilcon A, senofilcon A, somofilcon A) contact lens materials were soaked in solutions containing pro-inflammatory cytokines IL-1β, IL-6, IL-8 and TNF-α. Samples of the soaking solutions were collected over various time points and analyzed using the Meso Scale Discovery system, which served as a measurement of cytokine uptake onto the contact lens materials.

Both conventional hydrogels (etafilcon A, omafilcon A) and two of the four silicone hydrogels tested (balafilcon A, comfilcon A), exhibited some uptake of IL-1β, IL-8 or TNF-α (p 0.05). There was no uptake of IL-6 onto any of the contact lens materials investigated (p > 0.05).

The contact lens materials tested did not exhibit any uptake of IL-6 and furthermore, did not exhibit more than 10 ± 3 % to 25 ± 12 % uptake of IL-1β, IL-8 or TNF-α. Numerous factors could contribute to the reported increase in corneal infiltrative events with reusable silicone hydrogel materials, however, based on these results, it appears that uptake of these four cytokines are unlikely to contribute to this finding.

Moezzi A. CLEAR report summary: Effect of Contact Lens Materials and Designs on the Anatomy and Physiology of the Eye 2021;60

Morgan P, Woods CA, Tranoudis IG, Efron N, Jones L, Grupcheva CN, Jones D, Beeler-Kaupke M, Qi P, Tan KO, Rodriguez Cely LM, Belova S, Ravn O, Santodomingo-Rubido J, Bloise L, Plakitsi A, Végh M, Erdinest N, Montani G, Itoi M, Bendoriene RL, Mulder J, van der Worp E, Ystenaes AE, Romualdez-Oo J, Abesamis-Dichoso C, Gonzalez-Meijome JM, Belousov V, Johansson O, Hsiao J, Nicholes JJ.. International contact lens prescribing in 2020 Contact Lens Spectrum 2021;36, January: 26-32 [ Show Abstract ]

This article is our 20th consecutive annual report of international contact lens prescribing for Contact Lens Spectrum. The premise of the work is simple. As an alternative to asking a cross section of contact lens wearers about the lenses that they use and the basis on which the lenses are worn, we move upstream in the process and directly survey those who are fitting contact lenses in numerous markets around the world. This presents a more “leading edge” indicator of contact lens fitting habits; the lenses fitted today are those sold tomorrow. The aim here is to provide summary information for colleagues in clinical practice, industry, and academia about contact lens prescribing behaviors to inform their patient management, research and development, and educational curricula, respectively.

Morgan,P. B., Murphy,P. J., Gifford,K. L., Gifford,P., Golebiowski,B., Johnson,L., Makrynioti,D., Moezzi,A. M., Moody, K., Navascues-Cornago,M., Schweizer,H., Swiderska,K., Young,G., Willcox,M. CLEAR - Effect of contact lens materials and designs on the anatomy and physiology of the eye Contact Lens Anterior Eye 2021;44(2):192-219 [ Show Abstract ]

This paper outlines changes to the ocular surface caused by contact lenses and their degree of clinical significance. Substantial research and development to improve oxygen permeability of rigid and soft contact lenses has meant that in many countries the issues caused by hypoxia to the ocular surface have largely been negated. The ability of contact lenses to change the axial growth characteristics of the globe is being utilised to help reduce the myopia pandemic and several studies and meta-analyses have shown that wearing orthokeratology lenses or soft multifocal contact lenses can reduce axial length growth (and hence myopia).

However, effects on blinking, ptosis, the function of Meibomian glands, fluorescein and lissamine green staining of the conjunctiva and cornea, production of lid-parallel conjunctival folds and lid wiper epitheliopathy have received less research attention. Contact lens wear produces a subclinical inflammatory response manifested by increases in the number of dendritiform cells in the conjunctiva, cornea and limbus. Papillary conjunctivitis is also a complication of all types of contact lenses. Changes to wear schedule (daily disposable from overnight wear) or lens materials (hydrogel from SiHy) can reduce papillary conjunctivitis, but the effect of such changes on dendritic cell migration needs further study. These changes may be associated with decreased comfort but confirmatory studies are needed. Contact lenses can affect the sensitivity of the ocular surface to mechanical stimulation, but whether these changes affect comfort requires further investigation.

In conclusion, there have been changes to lens materials, design and wear schedules over the past 20+ years that have improved their safety and seen the development of lenses that can reduce the myopia development. However, several changes to the ocular surface still occur and warrant further research effort in order to optimise the lens wearing experience.

Muntz A, Walther H.. Das trockene Auge im digitalen Alter: Updates aus der Forschung Sichtkontakte, Virtual Conference, October 9, 2021

Ng AY. CLEAR report summary: Contact Lens Complications 2021;60

Ng AY, Yang M. Why you shouldn’t neglect eye care during the pandemic The Conversation 2021;March 7 [ Show Abstract ]

Since COVID-19 emerged, access to eye care has continued to change. Lockdowns and concerns about virus exposure have caused people of all ages to cancel and delay routine appointments, raising red flags among eye-care professionals. As the pandemic continues into its second year, can ocular health be neglected any longer?

Our team of optometrists and clinical scientists at the Centre for Ocular Research & Education (CORE) hear the confusion and concerns about people’s eyes during COVID-19. Addressing the most common questions — many of which we keep up to date at — can help you and your family maintain the best vision while staying safe.

Ng AY, Yumori J. Rethinking Eye Cosmetics and Cosmetic Procedures: What Should We be Telling Our Patients? Best of Boston Academy (Virtual), 2021 [ Show Abstract ]

Cosmetics are used widely to enhance our appearance, clean, and maintain the condition of our skin. With face mask-wearing on the rise many cosmetic users are choosing to accentuate their eyes further with eye cosmetics. However, patients might not have considered the effects that some eye cosmetic products and procedures may have on their eyes. This session will explore the complications that can arise from some common products and procedures, and highlight points of discussion where we should be engaging with our patients.

Ngo W. CLEAR report summary: Anatomy and Physiology of the Anterior Eye 2021;60

Ngo W.. Face masks, digital screens and winter weather are a triple threat for dry eyes The Conversation 2021;December 16

Nichols,J. J., Jones,L., Morgan,P. B., Efron,N. Bibliometric analysis of the meibomian gland literature Ocular Surface 2021;20(April):212-214 [ Show Abstract ]

There is a rich history of interest in the sebaceous glands located posterior to the tarsal plates in the eyelids, to which we refer today as the meibomian glands (MGs). Although there is acknowledgement of the MGs preceding the work of Johann Heinrich Meibom in the 1600's, he is credited with advancing our knowledge and study of these glands.

The MGs produce a distinct lipid secretion (‘meibum’) made up of a variety of lipid classes, mostly composed of nonpolar wax and cholesterol esters, although other nonpolar and polar lipids are certainly known to exist in the meibum. The normal function of meibum is to make its way to the tear film lipid layer, ultimately forming a resistive barrier to evaporation of the aqueous component of the tear film. In disease, the MGs lose their ability to secrete a normal meibum composition and/or are impeded due to factors such as atrophy of the MGs, keratinization of the orifice of the gland from which the meibum is secreted onto the eyelid margin, or bacterial colonization of the eyelid, altering the secretion itself once expressed. These conditions today are known as blepharitis, including anterior and posterior blepharitis (which includes meibomian gland dysfunction).

Given the extensive study of MGs, a bibliometric analysis is warranted to acknowledge and celebrate those contributing to this important part of ophthalmic research.

Nichols,J. J., Jones,L., Morgan,P. B., Efron,N. Bibliometric analysis of the orthokeratology literature Contact Lens Anterior Eye 2021;44(4):101390 [ Show Abstract ]

The wearing of rigid lenses can result in changes to corneal curvature and the planned, temporary reduction of myopia by wearing flat-fitting rigid lenses (termed orthokeratology) was first reported in the 1960’s [1]. In the late 1970’s and early 1980’s, several studies evaluated this concept and concluded that the reduction in myopia was relatively short-lived, unpredictable, inconsistent and limited to only a low degree of myopia; as such, orthokeratology was largely ignored at this time [2, 3, 4].
A renewed interest in orthokeratology occurred in the late 1990’s and early 2000’s due to the simultaneous development of corneal topographers, highly oxygen permeable rigid lens materials and the development of sophisticated reverse geometry lenses that produced more predictable reductions in myopia [5, 6, 7, 8, 9]. This permitted contact lens fitters to adopt the concept of ‘overnight orthokeratology’, where patients wore the lenses during sleep and corneal shape changes occurred that reduced the degree of myopia to the point where the patient could remove the lens on waking and spend several days with no vision correction being required [10,11].
In 2005, Cho and colleagues reported that orthokeratology lenses used in children could slow the progression of myopia and this observation resulted in a resurgence in interest in orthokeratology [12]. Numerous publications since have shown that this myopia control effect is repeatable and many practitioners now adopt this modality on a routine basis to slow the progression of myopia, particularly in Asian countries [9,13, 14, 15, 16, 17].
The purpose of this paper is to report a bibliometric analysis of the literature on orthokeratology lenses so as to determine the most widely cited papers and most prolific authors, institutions, countries and journals related to this topic, and to recognise and celebrate the key stakeholders in this area of contact lens research.

Nichols,J. J., Morgan,P. M., Jones,L. W., Efron,N 21st century bibliometric analysis of the field of dry eye disease Clinical and Experimental Optometry 2021;104(5):639-640 [ Show Abstract ]

In 2012, the lead author of this paper (JJN) conducted a citation analysis of dry eye research to identify the leading papers, authors, institutions, countries and journals in the field. That analysis was essentially an historical overview of publications on this topic extending back over the past century. Because a strong and growing foundation of scientific literature is a fundamental component of evidenced-based clinical care of patients, the current work was conducted to update the research community on trends in the 21st century dry eye literature, and to compare this new literature with the prior analysis in the context of events or trends in the dry eye field.

Nogueira CL, Boegel SC, Shukla M, Ngo W, Jones L, Aucoin MG. Antiviral activity of contemporary contact lens solutions against human seasonal coronavirus strains American Academy of Optometry, Boston, November, 2021

Omali,N. B., Subbaraman,L. N., Heynen,M., Lada,M., Canavan,K., Fadli,Z., Ngo,W., Jones,L. Lipid deposition on contact lenses in symptomatic and asymptomatic contact lens wearers Cont Lens Anterior Eye 2021;44(1):56-61 [ Show Abstract ]

Lipid deposition on contact lenses (CL) has traditionally been believed to reduce comfort during CL wear. The purpose of this study was to quantify lipid deposition on CL in a group of symptomatic and asymptomatic adapted CL wearers.

This was a single-masked, randomized clinical trial. Only confirmed symptomatic (comfortable lens wear time (CWT) 10 h and minimal reduction in comfort over the course of the day) participants were recruited to participate in the study. Participants wore senofilcon A lenses in combination with a polyquaternium-based care solution (OPTI-FREE Replenish). Worn CL samples were collected on Day 14. Deposited lipid amounts from the lenses (including cholesteryl ester, cholesterol and triolein) were quantified using a liquid chromatography-mass spectrometry technique.

Lipid deposition was significantly higher in CL extracts of asymptomatic wearers compared to the symptomatic wearers for all lipid types quantified, including cholesteryl ester (2.1 ± 0.6 vs 1.6 ± 0.5 log μg/lens), cholesterol (1.5 ± 0.3 vs 1.1 ± 0.3 log μg/lens) and triolein (0.3 ± 0.2 vs 0.1 ± 0.1 log μg/lens) (all p < 0.002). The amount of cholesteryl ester deposited was greatest (p = 0.0001), followed by cholesterol, then triolein, for both the asymptomatic and symptomatic groups (both p = 0.0001).

This study demonstrated that the asymptomatic group deposited a significantly greater amount of lipid on their CL. Although lipid levels measured are considered low to trigger any observable clinical deposition, they may influence other clinical outcomes, particularly comfort.

Patel K, Draper M, Bull Z, Walsh K. Contact lenses: So much more than simple correction of refractive error Optician 2021, February: 25-29

Patel K, Walsh K. Soft toric contact lenses: Aligning patient expectations and eye care professional attitudes Optician 2021, March: 32-36 [ Show Abstract ]

In this article Krupa Patel and Karen Walsh examine the expectations around soft toric lenses from both the practitioner and patient’s point of view. It serves as a timely review of current toric fitting practices and how they relate to the prevalence of astigmatism, highlighting a number of opportunities for enhancing patient satisfaction and increasing practice revenue (C77594, one distance learning CET point suitable for optometrists, contact lens opticians and dispensing opticians).
Some simple facts help set the scene for this global review. It has been established that modern soft toric contact lenses are as quick and simple to fit as spherical lenses, with good visual outcomes and rotational stability across many visual tasks. However, when 400 eye care professionals (ECPs) in the US were asked, only around half agreed soft torics are as easy to fit as the equivalent spherical lens (49%), and that they have excellent rotational recovery (55%). How does this disparity between reported product performance and practitioner attitude influence fitting practices? Ultimately, what is the impact on patients, and how close does current practice come to meeting their

Phan C. CLEAR report summary: Contact Lens Technologies of the Future 2021;60

Phan C. Can we simulate the anterior eye to further improve contact lenses of the future? BCLA Virtual Clinical Conference & Exhibition, June 13, 2021

Phan,C. M., Qiao,H., Yee,A., Jones,L. Deposition of Fluorescently Tagged Lysozyme on Contact Lenses in a Physiological Blink Model Eye & Contact Lens 2021;47(2):127-133 [ Show Abstract ]

PURPOSE: To visualize the deposition of fluorescein isothiocyanate (FITC) lysozyme on daily disposable contact lenses (CLs) using a novel blink model.

METHODS: Three daily disposable conventional hydrogel CLs (etafilcon A, omafilcon A, and nelfilcon A) and three silicone hydrogel CLs (delefilcon A, senofilcon A, and somofilcon A) were evaluated in the study. The CLs were mounted onto a novel blink model and exposed to an artificial tear solution containing FITC lysozyme for 2 and 10 hr. The flow rate and blink speed were set to 1 μL/min and 6 blinks/min, respectively. After the incubation period, a 5-mm-diameter disc was punched out from the center of the lens and mounted on a microscope slide. The slides were imaged using the Zeiss 510 Meta confocal laser scanning microscope, which scanned the lens from the front to the back surface at 5-μm increments.

RESULTS: There was an increase in deposition of FITC lysozyme for all lens types with increasing incubation time (P0.05). The conventional hydrogel CLs deposited higher amounts of FITC lysozyme than the silicone hydrogel CLs (P<0.001), with etafilcon A depositing the highest at all time points (P<0.05). Interestingly, at the 2-hr incubation time, most CLs showed a higher amount of deposition at the front surface than the back surface of the lens. In particular, etafilcon A showed preferred deposition at the front surface at all time points.

CONCLUSION: The results suggest that there is differential deposition at the front surface of the CL, which is exposed to the prelens tear film, compared with the back surface of the CL, which is exposed to the postlens tear film. Therefore, it may be beneficial to design CL materials with differing surface properties for the front and back surfaces of the CL to enhance interactions with the tear film and ocular surface.

Phan,C. M., Shukla,M., Walther,H., Heynen,M., Suh,D., Jones,L. Development of an In Vitro Blink Model for Ophthalmic Drug Delivery Pharmaceutics 2021;13(Article 300):1-10 [ Show Abstract ]

Purpose: The purpose of this study was to develop an advanced in vitro blink model that
can be used to examine the release of a wide variety of components (for example, topical ophthalmic
drugs, comfort-inducing agents) from soft contact lenses. Methods: The model was designed using
computer-aided design software and printed using a stereolithography 3D printer. The eyelid and
eyeball were synthesized from polyvinyl alcohol and silicone material, respectively. Simulated
tear fluid was infused through tubing attached to the eyelid using a syringe pump. With each
blink cycle, the eyelid slides and flexes across the eyeball to create an artificial tear film layer. The
flow-through fluid was collected using a specialized trough. Two contact lenses, etafilcon A and
senofilcon A, were incubated in 2 mL of a water-soluble red dye for 24 h and then placed on the eye
model (n = 3). The release of the dye was measured over 24 h using a tear flow rate of 5 µL/min.
Results: Approximately 25% of the fluid that flowed over the eye model was lost due to evaporation,
nonspecific absorption, and residual dead volume. Senofilcon A absorbed more dye (47.6 ± 2.7 µL)
than etafilcon A (22.3 ± 2.0 µL). For etafilcon A, the release of the dye followed a burst-plateau
profile in the vial but was sustained in the eye model. For senofilcon A, the release of the dye was
sustained in both the vial and the eye model, though more dye was released in the vial (p < 0.05).
Overall, the release of the dye from the contact lenses was higher in the vial compared with the eye
model (p < 0.05). Conclusion: The blink model developed in this study could be used to measure
the release of topical ophthalmic drugs or comfort agents from contact lenses. Simulation of a blink
mechanism, an artificial tear film, and nonspecific absorption in an eye model may provide better
results than a simple, static vial incubation model.

Ranch KM, Shukla MR, Maulvi FA, Desai DT. Chapter 7: Carbon-based nanoparticles and dendrimers for delivery of combination drugs In: Nanocarriers for the Delivery of Combination Drugs , ed. Baboota S, Ali J. Elsevier Inc.. 2021.