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Hydrogel Contact Lenses Surface Roughness and Bacterial Adhesion [chapter]

Maria Jesus, Eva Yebra-Pimentel
2012 Ocular Diseases  
doi:10.5772/48436 fatcat:3373nrs34nhyjk2q2aldvbyjym

Effect of lotrafilcon A silicone hydrogel contact lens on intraocular pressure measurement

Carlos García-Resúa, Silvia García-Montero, Hugo Pena-Verdeal, Jorge Gilino, Eva Yebra-Pimentel, Maria J. Giráldez
2014 Optometry Reports  
The present paper aims to assess the effect of lotrafilcon A contact lenses (CL) in situ on intraocular pressure (IOP) measurement performed with three portable tonometers (ICare, Tonopen and Perkins). This cross-sectional study included thirty young healthy subjects. Intraocular pressure measurements without CL were performed first, followed by IOP measurements with CL for twenty minutes. ICare IOP measurements obtained with lotrafilcon A CL overestimated IOP values without CL by 1 mmHg
more » ... .001). However, both techniques displayed close level of agreement (95% LoA, -4.17 to +1.63 mmHg). Also, differences between both methods tended not to increase (P=0.9). No significant differences were observed between IOP measurements without and with CL for Perkins (paired-t test, P=0.23) and Tonopen XL (pairedt test, P=0.17). In conclusion, adequate IOP measurements through zero power lotrafilcon A silicone hydrogel CL can be obtained with all three tonometers in healthy eyes, although, in case of ICare, the practitioner must be aware of the 1 mmHg overestimation with CL.
doi:10.4081/optometry.2014.1846 fatcat:5xjyxsxsfre6tc3wqs6u3akjvu

White light interferometry to characterize the hydrogel contact lens surface

Maria J. Giraldez, Carlos García-Resúa, Madalena Lira, M Elisabete CD Real Oliveira, Eva Yebra-Pimentel
2010 Ophthalmic & physiological optics  
Purpose: The aim of this study was to characterize, qualitatively and quantitatively, the surface morphology of four unworn conventional hydrogel contact lenses (Omafilcon, Hioxifilcon-based, Nefilcon A and Ocufilcon B) by White Light Optical Profiling (WLOP). WLOP is an ideal technique for sampling larger areas as well as for higher measurement speed compared with other topography techniques used in contact lens studies. Methods: Surface roughness was assessed by WLOP in the Vertical Scanning
more » ... ode, with a Wyko Ò NT1100, which is a non-contact optical profiling system that provides high vertical resolution. Representative roughness parameters, the Average Roughness (R a ), Root-mean-square Roughness (R ms ), and Maximum Roughness (R max ), for areas of 625, 2500, 10829 and 67 646 lm 2 were calculated. Results: Higher R a , R ms and R max values were obtained for larger areas in all lenses. Daily disposable contact lenses (Nefilcon A and Ocufilcon B) presented the highest R a , R ms and R max values, the larger changes in these parameters becoming apparent with the increase in the measured area. Differences between lenses were less obvious when data from 625 and 2500 lm 2 area were compared. Conclusions: Daily disposable contact lenses showed the highest roughness surface. Analyzing larger areas might be adequate to detect differences between lenses in terms of surface characteristics, which may not be so obvious if smaller areas are studied.
doi:10.1111/j.1475-1313.2010.00712.x pmid:20444136 fatcat:isn5t3iapfdbjfxoib7mnfnt5y

Accuracy of the ICare rebound tonometer in glaucomatous eyes with topical ocular hypotensive medication

Alberto Diaz, Eva Yebra-Pimentel, Carlos García Resua, Jorge Gilino, Mª Jesus Giraldez
2008 Ophthalmic & physiological optics  
The purpose of this study was to assess the accuracy of the ICare tonometer, using the Perkins applanation tonometer (AT) as the reference, in a sample population being treated with travaprost 0.004% for glaucoma. Material and methods: Twenty-eight consecutive patients with open-angle glaucoma or ocular hypertension who had been receiving travaprost 0.004% to control elevated intraocular pressure (IOP) were included in the study. IOP was measured in the entire sample with ICare and Perkins AT.
more » ... he difference between the methods was plotted against the mean to compare the tonometers. The hypothesis of zero bias was examined by a paired t-test. The 95% limits of agreement (LoA) were also calculated. Results: As previously found in young healthy subjects, ICare showed a tendency to overestimate Perkins IOP measurements by a mean of 3.57 mmHg. The agreement between the two methods is shown by the 95% LoA which was from )9.37 to +2.23 mmHg: 53% of the IOP differences fell within ±3 mmHg. Conclusions: The performance of the ICare tonometer in glaucomatous patients being treated with travaprost 0.004% to lower the IOP appears to be similar to that of young healthy patients. The tendency of ICare to overestimate the IOP readings should be considered when the instrument is used in the follow-up of glaucomatous patients.
doi:10.1111/j.1475-1313.2007.00526.x pmid:18201333 fatcat:ybd7hvvs5zf3dci5v6i3iksgem

Symptoms in a Population of Contact Lens and Noncontact Lens Wearers Under Different Environmental Conditions

2007 Optometry and Vision Science  
Purpose. To investigate ocular symptoms related to dryness in an adult population of contact lens (CL) and non contact lens wearers (n-CL) using video display terminals (VDT) for different periods of time under different indoor conditions related to air conditioning (AC) and heating units (HU) exposure. Methods. A questionnaire was distributed to 334 people within a university population of which 258 were part of the n-CL group and 76 of the CL wearers to assess symptoms of ocular discomfort
more » ... entially related to dryness. Only soft contact lens (SCL) wearers (n ϭ 71) were included for further statistical analysis because of the reduced number of people wearing other lens types. A 2:1 match by gender group of 142 subjects in the n-CL group was used as a control sample. Results. There was a marked difference between the prevalence of symptoms and the way they are reported by CL and n-CL wearers. Red eye, itching, and scratchiness are more common among CL wearers, but the difference is statistically significant only for scratchiness (p Ͻ 0.01, 2 ). The vast majority of subjects who reported symptoms often and at the end of the day are significantly more prevalent among CL wearers (p Ͻ 0.01, 2 ). Gender differences were also encountered. Female CL wearers reported more scratchiness than males in the n-CL wearing group (p ϭ 0.029, 2 ) and in the CL group (p Ͻ 0.008, 2 ). Females wearing CL reported symptoms of red eye (p ϭ 0.043, 2 ) and scratchiness (p Ͻ 0.001, 2 ) more significantly than those in the n-CL group. Within the CL group, the prevalence of symptoms occurring sometimes or often and at the end of the day was higher among females (p Ͻ 0.001, 2 ). The use of VDT was associated with a higher level of scratchiness among CL wearers (p Ͻ 0.05, 2 ). The number of hours working with VDTs seemed to be associated with an increase in the prevalence of burning sensation in the CL group (p Ͻ 0.01, 2 ), whereas symptoms like red eye and scratchiness also increased significantly among n-CL wearers. Compared to n-CL wearers, all symptoms increase in CL wearers in environments with AC and HU, except excessive tearing. However, these differences are only statistically significant for scratchiness. Conclusions. Our results show that people who wear soft CL and work with VDTs for longer periods of time are more likely to develop symptoms like eye burning and scratchiness than n-CL wearers. This risk could be higher for women than men. Scratchiness and the appearance of symptoms near the end of the day are typically associated with ocular discomfort during CL wear in this sample, and clinicians should question their patients about these symptoms to anticipate serious discomfort. (Optom Vis Sci 2007;84:1-•••)
doi:10.1097/opx.0b013e318041f77c pmid:17435502 fatcat:hg6pfn5my5c3tmnc3wywnac4va

Central and peripheral corneal thickness measurement with Orbscan II and topographical ultrasound pachymetry

Jose Manuel González-Méijome, Alejandro Cerviño, Eva Yebra-Pimentel, Manuel A Parafita
2003 Journal of cataract and refractive surgery  
From the Department of Physics, School of Sciences, University of Minho, Braga, Portugal (González-Méijome), and the Departments of Surgery (Cerviño, Parafita) and Applied Physics (Yebra-Pimentel),  ... 
doi:10.1016/s0886-3350(02)01815-1 pmid:12551679 fatcat:3gcyjogggvh3bartkh4cnw7eva

Accuracy of the New ICare Rebound Tonometer vs. Other Portable Tonometers in Healthy Eyes

2006 Optometry and Vision Science  
doi:10.1097/01.opx.0000200673.96758.7b pmid:16501412 fatcat:mzdacetm4jcsfobzqsnprnxjpi

The influence of surface treatment on hydrophobicity, protein adsorption and microbial colonisation of silicone hydrogel contact lenses

Lívia Santos, Diana Rodrigues, Madalena Lira, M. Elisabete C.D. Real Oliveira, Rosário Oliveira, Eva Yebra-Pimentel Vilar, Joana Azeredo
2007 Contact lens & anterior eye  
Purpose: To evaluate the influence of surface treatment of silicone-hydrogel CL on lens hydrophobicity, protein adsorption and microbial colonisation by studying several silicone hydrogel contact lenses (CL) with and without surface treatment. The lenses used in this study were Balafilcon A, Lotrafilcon A, Lotrafilcon B and Galyfilcon A. A conventional hydrogel CL (Etafilcon A) was also tested. Methods: Hydrophobicity was determined through contact angle measurement using the advancing type
more » ... nique on air. The type and quantity of proteins adsorbed were assessed through SDS-PAGE and fluorescence spectroscopy, respectively. Microbial colonisation was studied by removing the microbes from the lenses through sonication, and counting the colony-forming units on agar plates. Results: Regarding hydrophobicity, both surface and non-surface-treated silicone hydrogel CL were found to be hydrophobic, and the conventional hydrogel CL was found to be hydrophilic. Concerning protein adsorption, different protein profiles were observed on the several lenses tested. Nevertheless, the presence of proteins with the same molecular weight as lysozyme and lactoferrin was common to all lenses, which is probably related to their abundance in tears. In terms of total protein adsorption, silicone hydrogel CL did not exhibit any differences between themselves. However, the conventional hydrogel Etafilcon A adsorbed a larger amount of proteins. Regarding microbial colonisation, Balafilcon A exhibited the greatest amount of colonising microbes, which can be due to its superior hydrophobicity and higher electron acceptor capacity. Conclusion: This study suggests that silicone hydrogel lenses adsorb a lower amount of proteins than the conventional hydrogel lenses and that this phenomenon is independent of the presence of surface treatment. Concerning microbial colonisation, the surface treated Balafilcon A, exhibited a greater propensity, a fact that may compromise the lens wearer's ocular health.
doi:10.1016/j.clae.2006.12.007 pmid:17291818 fatcat:wedbjkqvxjhxvjlkk7bwhxz7bm

The influence of lens material and lens wear on the removal and viability of Staphylococcus epidermidis

Lívia Santos, Diana Rodrigues, Madalena Lira, M. Elisabete C.D. Real Oliveira, Rosário Oliveira, Eva Yebra-Pimentel Vilar, Joana Azeredo
2008 Contact lens & anterior eye  
Purpose: The aim of this study was to evaluate the influence of lens material and lens wear on the removal capability of Staphylococcus epidermidis. Assessment of viability of remaining adhered bacteria was another goal of this work. Four silicone hydrogel materials (galyfilcon A, balafilcon A, lotrafilcon A, lotrafilcon B) and one conventional hydrogel material (etafilcon A) were assayed. Methods: Detachment studies on S. epidermidis were carried out in a parallel plate flow chamber. Contact
more » ... nses (CLs) were fitted to the bottom of the flow chamber and a bacterial suspension was perfused into the system, promoting bacterial adhesion. Afterwards, detachment was stimulated using a multipurpose solution (MPS, ReNu Multiplus 1 ) and the percentage of removed bacteria estimated through microscopic observation and enumeration. Remaining adhered bacteria were stained with propidium iodide (PI) and enumerated in order to assess their viability. Additionally, the worn lenses were observed by confocal laser scanning microscopy (CLSM) to visualize bacterial distribution along the lens surfaces. Results: Bacterial removal was significant ( p < 0.05) for both unworn and worn galyfilcon A and etafilcon A. Galyfilcon A exhibited a detachment percentage of 59.1 and 63.5 while etafilcon A of 62.6 and 69.3, both for unworn and worn lenses, respectively. As far as bacterial viability is concerned, it was found that worn lenses exhibit a superior amount of non-viable bacteria than unworn CLs. Images obtained by CLSM revealed an irregular bacterial distribution for all lens materials. Conclusions: It appears that surface and/or bulk structure of the lens material affects removal of S. epidermidis while CL wear influences their viability.
doi:10.1016/j.clae.2008.01.003 pmid:18314377 fatcat:yhrhvtcki5b3doria3ddefezca

The Effect of Octylglucoside and Sodium Cholate in Staphylococcus epidermidis and Pseudomonas aeruginosa Adhesion to Soft Contact Lenses

2007 Optometry and Vision Science  
Purpose. In this study, the effect of the natural surfactants octylglucoside and sodium cholate in inhibiting Staphylococcus epidermidis and Pseudomonas aeruginosa adhesion to conventional and silicone-hydrogel contact lenses (CL) was assessed. Hydrophobicity was also evaluated to conditioned and nonconditioned CL. Methods. The inhibiting effect of the tested surfactants was determined through "in vitro" adhesion studies to conditioned and nonconditioned CL followed by image acquisition and
more » ... enumeration. Hydrophobicity was evaluated through contact angle measurements using the advancing type technique on air. Results. Sodium cholate exhibits a very low capability to inhibit microbial adhesion. Conversely, octylglucoside effectively inhibited microbial adhesion in both types of lenses. This surfactant exhibited an even greater performance than a multipurpose lens care solution used as control. Octylglucoside was the only tested surfactant able to lower the hydrophobicity of all CL, which can explain its high performance. Conclusions. The results obtained in this study point out the potential of octylglucoside as a conditioning agent to prevent microbial colonization. (Optom Vis Sci 2007;84:429-434)
doi:10.1097/opx.0b013e318058a0cc pmid:17502827 fatcat:7gdsexomgrfb3hi4fbmnfin4t4

Recent Research in Ocular Cystinosis: Drug Delivery Systems, Cysteamine Detection Methods and Future Perspectives

Ana Castro-Balado, Cristina Mondelo-García, Iria Varela-Rey, Beatriz Moreda-Vizcaíno, Jesús F. Sierra-Sánchez, María Teresa Rodríguez-Ares, Gonzalo Hermelo-Vidal, Irene Zarra-Ferro, Miguel González-Barcia, Eva Yebra-Pimentel, María Jesús Giráldez-Fernández, Francisco J. Otero-Espinar (+1 others)
2020 Pharmaceutics  
Cystinosis is a rare genetic disorder characterized by the accumulation of cystine crystals in different tissues and organs. Although renal damage prevails during initial stages, the deposition of cystine crystals in the cornea causes severe ocular manifestations. At present, cysteamine is the only topical effective treatment for ocular cystinosis. The lack of investment by the pharmaceutical industry, together with the limited stability of cysteamine, make it available only as two marketed
more » ... entations (Cystaran® and Cystadrops®) and as compounding formulations prepared in pharmacy departments. Even so, new drug delivery systems (DDSs) need to be developed, allowing more comfortable dosage schedules that favor patient adherence. In the last decades, different research groups have focused on the development of hydrogels, nanowafers and contact lenses, allowing a sustained cysteamine release. In parallel, different determination methods and strategies to increase the stability of the formulations have also been developed. This comprehensive review aims to compile all the challenges and advances related to new cysteamine DDSs, analytical determination methods, and possible future therapeutic alternatives for treating cystinosis.
doi:10.3390/pharmaceutics12121177 pmid:33287176 fatcat:mdenjacv75egzc2k2gd5j2sj5u

A 180 My-old female-specific genome region in sturgeon reveals the oldest known vertebrate sex determining system with undifferentiated sex chromosomes [article]

Heiner Kuhl, Yann Guiguen, Christin Hoehne, Eva Keuz, Christophe Klopp, Kang Du, Celine Lopez-Roques, Elena Santidrian Yebra-Pimentel, Mitica Ciorpac, Joern Gessner, Daniela Holostenco, Wibke Kleiner (+15 others)
2020 biorxiv/medrxiv   pre-print
B -Issue Heiner Kuhl, Yann Guiguen, Christin Höhne, Eva Kreuz, Kang Du, Christophe Klopp, Céline Lopez-Roques, Elena Santidrian Yebra-Pimentel, Mitica Ciorpac, Jörn Gessner, Daniela Holostenco, Wibke Kleiner  ... 
doi:10.1101/2020.10.10.334367 fatcat:aa336gmbfzdy5ktqjokmbdejsu

A 180 Myr-old female-specific genome region in sturgeon reveals the oldest known vertebrate sex determining system with undifferentiated sex chromosomes

Heiner Kuhl, Yann Guiguen, Christin Höhne, Eva Kreuz, Kang Du, Christophe Klopp, Céline Lopez-Roques, Elena Santidrian Yebra-Pimentel, Mitica Ciorpac, Jörn Gessner, Daniela Holostenco, Wibke Kleiner (+15 others)
2021 Philosophical Transactions of the Royal Society of London. Biological Sciences  
Several hypotheses explain the prevalence of undifferentiated sex chromosomes in poikilothermic vertebrates. Turnovers change the master sex determination gene, the sex chromosome or the sex determination system (e.g. XY to WZ). Jumping master genes stay main triggers but translocate to other chromosomes. Occasional recombination (e.g. in sex-reversed females) prevents sex chromosome degeneration. Recent research has uncovered conserved heteromorphic or even homomorphic sex chromosomes in
more » ... l clades of non-avian and non-mammalian vertebrates. Sex determination in sturgeons (Acipenseridae) has been a long-standing basic biological question, linked to economical demands by the caviar-producing aquaculture. Here, we report the discovery of a sex-specific sequence from sterlet ( Acipenser ruthenus ). Using chromosome-scale assemblies and pool-sequencing, we first identified an approximately 16 kb female-specific region. We developed a PCR-genotyping test, yielding female-specific products in six species, spanning the entire phylogeny with the most divergent extant lineages ( A. sturio, A. oxyrinchus versus A. ruthenus, Huso huso ), stemming from an ancient tetraploidization. Similar results were obtained in two octoploid species ( A. gueldenstaedtii, A. baerii ). Conservation of a female-specific sequence for a long period, representing 180 Myr of sturgeon evolution, and across at least one polyploidization event, raises many interesting biological questions. We discuss a conserved undifferentiated sex chromosome system with a ZZ/ZW-mode of sex determination and potential alternatives. This article is part of the theme issue 'Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part I)'.
doi:10.1098/rstb.2020.0089 pmid:34247507 fatcat:wfjpu5kxmzaozmjntbawqu4qqq

Bibliografía de filología hispánica

Nueva Revista De Filología Hispánica
2021 Nueva Revista de Filología Hispánica  
Mestre-Mestre, Eva María y Teresa Molés-Cases -"Promoción NRFH, LXX BIBLIOGRAFÍA 70-460.  ...  Gómez Yebra (N. 68-2768). || ALE, 31 (2019), 331-333 (Ayala Aracil). 70-969. Jiménez Morales, M.I. -Los relatos de Salvador Rueda (1886-1893) (N. 67-1080). || ALE, 31 (2019), 331-333 (Ayala Aracil).  ... 
doi:10.24201/nrfh.v70i1.3800 fatcat:uozi2ylyvvf4bllylm4fufai74

Bibliografía de filología hispánica

Nueva Revista de Filología Hispánica
2007 Nueva Revista de Filología Hispánica  
GARCÍA YEBRA, VALENTÍN -El buen uso de las palabras. -Gredos, Madrid, 2003 . 467 pp. 11 RIil, 2005 6, [232] [233] [234] [235] . .  ...  VALERO JUAN, EVA M. -"Martín Adán: de la urbe moderna a la ciudad ancestral". -PHisp, 2004, núm. 18, 215-225 . Aira, César .  ... 
doi:10.24201/nrfh.v55i1.2363 fatcat:iagmlmerancs7cii7xitfrwyxq
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