The significance of oxygen during contact lens wear

Papas, Eric

doi:10.1016/j.clae.2014.07.012

Cited by 33 publications

(20 citation statements)

References 122 publications

(153 reference statements)

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“…Therefore for thinner lenses, the detrimental effect on light transmittance may be attenuated. Regarding oxygen permeability, all hydrogels exhibited typical values of soft contact lenses 29 ; ranking in the order hydrogel C [65 × 10 −11 cm 3 cm 2 /(cm 3 s mmHg)] < E F G B A [70 × 10 −11 cm 3 cm 2 /(cm 3 s mmHg)] < D [80 × 10 −11 cm 3 cm 2 /(cm 3 s mmHg)]. This order correlates well with the degree of swelling of the hydrogels ( Table 2).…”

Section: Hydrogels Preparation and Physical Propertiesmentioning

confidence: 93%

Imprinted Contact Lenses for Sustained Release of Polymyxin B and Related Antimicrobial Peptides

Malakooti

Alexander

Alvarez‐Lorenzo

2015

Journal of Pharmaceutical Sciences

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The aim of this work was to develop drug-soft contact lens combination products suitable for controlled release of antimicrobial peptides on the ocular surface. Incorporation of functional monomers and the application of molecular imprinting techniques were explored to endow 2-hydroxyethyl methacrylate (HEMA) hydrogels with the ability to load and to sustain the release of polymyxin B and vancomycin. Various HEMA:drug:functional monomer:crosslinker molar ratios were evaluated to prepare polymyxin B imprinted and non-imprinted hydrogels. Acrylic acid-functionalized and imprinted hydrogels loaded greater amounts of polymyxin B and led to more sustained release profiles, in comparison to non-functionalized and non-imprinted networks. Polymyxin B-loaded hydrogels showed good biocompatibility in HET-CAM tests. Functionalized hydrogels also loaded vancomycin and sustained its release, but the imprinting effect was only exhibited with polymyxin B, as demonstrated in rebinding tests. Microbiological assays carried out with Pseudomonas aeruginosa allowed identification of the most suitable hydrogel composition for efficient bacteria eradication; some hydrogels being able to stand several continued challenges against this important bacterial pathogen.

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Section: Hydrogels Preparation and Physical Propertiesmentioning

confidence: 93%

Imprinted Contact Lenses for Sustained Release of Polymyxin B and Related Antimicrobial Peptides

Malakooti

Alexander

Alvarez‐Lorenzo

2015

Journal of Pharmaceutical Sciences

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“…51 CLs create physical barriers that prevent oxygen from reaching the cornea, leading to hypoxia, 34,52 which is suggested by an elevated lactate dehydrogenase level in the tear film of CL wearers. 53 Hypoxia due to CL use has been proposed as an underlying cause of LSCD. 8,13,14,40,51 Hypoxia with CL use is most significant underneath the upper lid, explaining localization of disease to the superior limbus.…”

Section: Pathogenesismentioning

confidence: 99%

“…Based on our understanding of how CLs cause mechanical trauma, 13,41,42,44 disrupt the tear film, 47 create hypoxia, 34,52,53 promote inflammation, 34 and are associated with irritating effects of preservatives, 33,49 we propose the following hypothesis on the multifactorial pathogenesis of CL-induced LSCD.…”

Section: Pathogenesismentioning

confidence: 99%

Contact Lens-induced Limbal Stem Cell Deficiency

et al. 2016

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Limbal stem cell deficiency (LSCD) is a pathologic condition caused by the dysfunction and/or destruction of stem cell precursors of the corneal epithelium, typified clinically by corneal conjunctivalization. The purpose of this review is to critically discuss a less well-known cause of limbal stem cell disease: contact lens (CL) wear. A literature search was conducted to include original articles containing patients with CL-induced LSCD. This review describes epidemiology, diagnostic strategies, pathogenesis, differential diagnosis, and treatment modalities for this condition.

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“…Hypoxia appears to take place at all corneal levels. 1,2 Oxygen passes through a contact lens by di®usion. The International Organization for Standardization (ISO) standard measure of the oxygen permeability of a lens material (at a uniform, standardized thickness) is called Dk.…”

Section: Introductionmentioning

confidence: 99%

“…Dk/t has the unit of 10 À9 (cm/s) Â [ml O 2 Þ/(ml Â hPa)] or (cm/sec) Â (ml O 2 /ml Â mmHg). 2,3 A transmissibility graph shows the Dk/t values across the entirety of any given lens and describes the distribution of maximum and minimum oxygen transmissibility (power, base curve).…”

Section: Introductionmentioning

confidence: 99%

A survey of corneal changes caused by daily wear silicone hydrogel contact lenses

Kettesy

Vardai

Berta

et al. 2015

J. Innov. Opt. Health Sci.

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Purpose: The examination of the e®ects of second generation lotra¯lcon B silicone hydrogel (SiH) lenses on the cornea when worn for three years of daily wear. Material and Methods: 55 healthy patients were divided into two groups: current hydrogel contact lens wearers re¯tted with lotra¯lcon B lenses (Group 1; 28 patients) and neophyte contact lens wearers (Group 2; 27 patients). Each patient's subjective eye comfort was measured with a self-administered questionnaire. The corneas were analyzed using contact specular microscope to measure corneal thickness and the endothelium before the SiH lenses were¯tted after four weeks, one month, six months, one year, two years, and three years of lens wear. Results: Subjective complaints of patients in Group 1 were reduced; however patients in Group 2 experienced discomfort during thē rst two to four weeks of use. In Group 1, objective examinations identi¯ed a decrease in endothelial cell density. In Group 2, the endothelial cell density increased slightly in the¯rst two years but decreased after three years. The results indicate that lotra¯lcon B slows down the deleterious e®ects of contact lenses. The coe±cient of variation signi¯cantly decreased after six months in Group 1 (0.47 vs 0.44; p ¼ 0:049), whereas, in Group 2, the hexagonal cells improved signi¯cantly after one month (27.78 vs 28.25; p ¼ 0:025). Conclusion: Based on the subjects involved and the period of time under examination, it can be concluded that high-Dk SiH lenses support the physiological metabolism and functions of the cornea by improving oxygen provision.

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The significance of oxygen during contact lens wear

Cited by 33 publications

References 122 publications

Imprinted Contact Lenses for Sustained Release of Polymyxin B and Related Antimicrobial Peptides

Imprinted Contact Lenses for Sustained Release of Polymyxin B and Related Antimicrobial Peptides

Contact Lens-induced Limbal Stem Cell Deficiency

A survey of corneal changes caused by daily wear silicone hydrogel contact lenses

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