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Clinical & Experimental Optometry Jan 2020Ophthalmic lens design concerns the control of spectacle lens aberrations which occur when the eye rotates away from the optical centre of the lens. The most significant... (Review)
Review
Ophthalmic lens design concerns the control of spectacle lens aberrations which occur when the eye rotates away from the optical centre of the lens. The most significant aberrations are oblique astigmatism and mean oblique error (power error). A brief review of these aberrations is given, explaining how the lens designer can control them using just the bending of the lens, and what results can be achieved using simple spherical and toroidal surfaces. Before 1985, aspherical surfaces were used only for post-cataract spectacle lenses and high-power magnifiers. Today, aspherical surfaces are used by all major lens manufacturers to produce thinner, lighter and more attractive best-form lenses in the normal power range. Aspherical surfaces are employed because the surface itself is astigmatic and the surface astigmatism is used to combat aberrational astigmatism due to oblique incidence. The various types of aspherical surface and how the surface astigmatism arises is described, before considering how this feature is used to produce flatter, thinner lenses. In the case of astigmatic prescriptions, the surface requires different asphericities along its principal meridians and the geometry of these atoroidal surfaces is also described. The advent of free-form manufacturing techniques requires the lens designer to convert the surface description to the (x,y,z) co-ordinates needed to generate the surface. Examples of how these co-ordinates can be obtained from the equation to the surface are given for toroidal and aspherical surfaces. In the case of free-form progressive surfaces, the pre-determined z-co-ordinates must be added to the z-co-ordinates of the prescription surface to obtain the final free-form surface. In the case of optimised prescription surfaces, on-board software will analyse the result by ray tracing to obtain the final z-co-ordinates.
Topics: Equipment Design; Eyeglasses; Humans; Optics and Photonics; Refraction, Ocular; Visual Acuity
PubMed: 31222837
DOI: 10.1111/cxo.12930 -
Science China. Technological Sciences 2022Antibacterial surfaces are surfaces that can resist bacteria, relying on the nature of the material itself. It is significant for safe food and water, human health, and... (Review)
Review
Antibacterial surfaces are surfaces that can resist bacteria, relying on the nature of the material itself. It is significant for safe food and water, human health, and industrial equipment. Biofilm is the main form of bacterial contamination on the material surface. Preventing the formation of biofilm is an efficient way to develop antibacterial surfaces. The strategy for constructing the antibacterial surface is divided into bacteria repelling and bacteria killing based on the formation of the biofilm. Material surface wettability, adhesion, and steric hindrance determine bacteria repelling performance. Bacteria should be killed by surface chemistry or physical structures when they are attached to a material surface irreversibly. Killing approaches are usually in the light of the cell membrane of bacteria. This review summarizes the fabrication methods and applications of antibacterial surfaces from the view of the treatment of the material surfaces. We also present several crucial points for developing long-term stability, no drug resistance, broad-spectrum, and even programable antibacterial surfaces.
PubMed: 35018171
DOI: 10.1007/s11431-021-1962-x -
Sensors (Basel, Switzerland) Mar 2020Designing and development of electrochemical biosensors enable molecule sensing and quantification of biochemical compositions with multitudinous benefits such as... (Review)
Review
Designing and development of electrochemical biosensors enable molecule sensing and quantification of biochemical compositions with multitudinous benefits such as monitoring, detection, and feedback for medical and biotechnological applications. Integrating bioinspired materials and electrochemical techniques promote specific, rapid, sensitive, and inexpensive biosensing platforms for (e.g., point-of-care testing). The selection of biomaterials to decorate a biosensor surface is a critical issue as it strongly affects selectivity and sensitivity. In this context, smart biomaterials with the intrinsic self-assemble capability like bacterial surface (S-) layer proteins are of paramount importance. Indeed, by forming a crystalline two-dimensional protein lattice on many sensors surfaces and interfaces, the S-layer lattice constitutes an immobilization matrix for small biomolecules and lipid membranes and a patterning structure with unsurpassed spatial distribution for sensing elements and bioreceptors. This review aims to highlight on exploiting S-layer proteins in biosensor technology for various applications ranging from detection of metal ions over small organic compounds to cells. Furthermore, enzymes immobilized on the S-layer proteins allow specific detection of several vital biomolecules. The special features of the S-layer protein lattice as part of the sensor architecture enhances surface functionalization and thus may feature an innovative class of electrochemical biosensors.
Topics: Biosensing Techniques; Electrochemical Techniques; Humans; Ions; Membrane Glycoproteins; Metals; Point-of-Care Testing
PubMed: 32204503
DOI: 10.3390/s20061721 -
Materials (Basel, Switzerland) Mar 2022Physical surface modification is an approach that has been investigated over the last decade to reduce bacterial adhesion and improve cell attachment to biomaterials.... (Review)
Review
Physical surface modification is an approach that has been investigated over the last decade to reduce bacterial adhesion and improve cell attachment to biomaterials. Many techniques have been reported to modify surfaces, including the use of natural sources as inspiration to fabricate topographies on artificial surfaces. Biomimetics is a tool to take advantage of nature to solve human problems. Physical surface modification using animal and vegetal topographies as inspiration to reduce bacterial adhesion and improve cell attachment has been investigated in the last years, and the results have been very promising. However, just a few animal and plant surfaces have been used to modify the surface of biomaterials with these objectives, and only a small number of bacterial species and cell types have been tested. The purpose of this review is to present the most current results on topographic surface modification using animal and plant surfaces as inspiration to modify the surface of biomedical materials with the objective of reducing bacterial adhesion and improving cell behavior.
PubMed: 35407716
DOI: 10.3390/ma15072383 -
Asia-Pacific Journal of Ophthalmology... Dec 2020The ocular surface is exposed continuously to the environment and, as a consequence, to a variety of different microbes. After the results of the Human Microbiome... (Review)
Review
The ocular surface is exposed continuously to the environment and, as a consequence, to a variety of different microbes. After the results of the Human Microbiome Project became publicly available, international research groups started to focus interest on exploring the ocular surface microbiome and its physiopathological relationship to the eye. For example, numerous research studies the existence of the ocular surface's bacterial flora, typically gathering cultures from healthy patients and finding few variations in the bacterial species. More recently, culture-independent methods, including 16S ribosomal ribonucleic acid (rRNA) gene sequencing, are being used to define the ocular microbiome. These newer methods suggest that the microbial communities have a greater diversity than previously reported. These communities seem to serve an immune-modulating function and maintain relationships with other microbes and organs, even distant ones. This review summarizes the literature exploring the ocular microbiome, both in health and in different diseases.
Topics: Bacteria; Eye; Humans; Microbiota; RNA, Ribosomal, 16S
PubMed: 33323705
DOI: 10.1097/APO.0000000000000330 -
Journal of International Society of... 2019Main purpose of this review was to present an update on various coating materials utilized in improving the surface chemistry of the dental implants. (Review)
Review
OBJECTIVES
Main purpose of this review was to present an update on various coating materials utilized in improving the surface chemistry of the dental implants.
METHODS
Literature search was carried out in various on-line databases such as PubMed, Medline, Google scholar, EBSCO, Wiley Science Library, and Saudi Digital Library using appropriate keywords (dental implant surface coatings, dental implant surface modifiers, and dental surface coatings).
RESULTS
Total of 569 studies were retrieved. All the relevant studies among them were reviewed and compiled.
CONCLUSION
Current implant surface's biomimetic coatings offer many benefits compared to the traditional plasma sprayed coatings. Further incorporation of biomimetic coatings with various material has lead improvement in mechanical and biological properties of implants.
PubMed: 30923686
DOI: 10.4103/jispcd.JISPCD_303_18 -
Indian Journal of Dental Research :... 2017Anodized implants with moderately rough surface were introduced around 2000. Whether these implants enhanced biologic effect to improve the environment for better... (Comparative Study)
Comparative Study Review
PURPOSE
Anodized implants with moderately rough surface were introduced around 2000. Whether these implants enhanced biologic effect to improve the environment for better osseointegration was unclear. The purpose of this article was to review the literature available on anodized surface in terms of their clinical success rate and bone response in patients till now.
MATERIALS AND METHODS
A broad electronic search of MEDLINE and PubMed databases was performed. A focus was made on peer-reviewed dental journals. Only articles related to anodized implants were included. Both animal and human studies were included.
RESULTS
The initial search of articles resulted in 581 articles on anodized implants. The initial screening of titles and abstracts resulted in 112 full-text papers; 40 animal studies, 16 studies on cell adhesion and bacterial adhesion onto anodized surfaced implants, and 47 human studies were included. Nine studies, which do not fulfill the inclusion criteria, were excluded.
CONCLUSIONS
The long-term studies on anodized surface implants do favor the surface, but in most of the studies, anodized surface is compared with that of machined surface, but not with other surfaces commercially available. Anodized surface in terms of clinical success rate in cases of compromised bone and immediately extracted sockets has shown favorable success.
Topics: Animals; Dental Implantation, Endosseous; Electrodes; Humans; Osseointegration; Surface Properties; Titanium; Treatment Outcome
PubMed: 28393822
DOI: 10.4103/ijdr.IJDR_386_16 -
Journal of Functional Biomaterials Dec 2023Biomimetic dental implants are regarded as one of the recent clinical advancements in implant surface modification. Coatings with varying thicknesses and roughness may... (Review)
Review
Biomimetic dental implants are regarded as one of the recent clinical advancements in implant surface modification. Coatings with varying thicknesses and roughness may affect the dental implant surface's chemical inertness, cell adhesion, and antibacterial characteristics. Different surface coatings and mechanical surface changes have been studied to improve osseointegration and decrease peri-implantitis. The surface medication increases surface energy, leading to enhanced cell proliferation and growth factors, and, consequently, to a rise in the osseointegration process. This review provides a comprehensive update on the numerous biomimetic coatings used to improve the surface characteristics of dental implants and their applications in two main categories: coating to improve osseointegration, including the hydroxyapatite layer and nanocomposites, growth factors (BMPs, PDGF, FGF), and extracellular matrix (collagen, elastin, fibronectin, chondroitin sulfate, hyaluronan, and other proteoglycans), and coatings for anti-bacterial performance, covering drug-coated dental implants (antibiotic, statin, and bisphosphonate), antimicrobial peptide coating (GL13K and human beta defensins), polysaccharide antibacterial coatings (natural chitosan and its coupling agents) and metal elements (silver, zinc, and copper).
PubMed: 38248682
DOI: 10.3390/jfb15010015