Narrow Results

In this paper we present applied physics research results of gas-permeable contact lenses (CL) that are manufactured from fluorosilicone acrylate based material (Boston™ type). During contact lenses production the conformation states of polymers belonging to near surface layers of CL surface are changed. Since CL quality crucially depends on surface roughness and optical properties, the properties of surface molecules conformation state and their orientation come into perspective as important factors acting on the molecular level. Therefore, we investigated CL surface by phase contrast atomic force microscopy (PC-AFM), magnetic force microscopy (MFM), and optomagnetic fingerprint (OMF) technique and found out that surface quality and magnetic properties of contact lenses have influence on physical properties of light transmission and that these changes can be detected on the nanolevel of magnetism, as well as optomagnetism. These results carry important biophysically based implications for CL industry, biomedical application industry and applied optical science.

We present a new approach to compute the suction pressure under a soft contact lens. When a soft contact lens is placed on an eye, it is subjected to forces from the tear film in which it is immersed and from the blinking eyelid. In response, the lens bends and stretches. The equilibration of these forces generates a suction pressure that keeps the lens on the cornea. In this paper, we develop a mathematical model of the elastic equilibrium of a soft contact lens that allows us to predict the suction pressure distribution under such a lens. We explore the influence of the shape of the lens and its elastic properties on the suction pressure.

Implantable Contact Lens Developed.

Study Shows GM-free Zones Unnecessary.

Melbourne Scientists Grow Thymus Organ.

Artificial Livers to Cure Hepatitis.

University of Tokyo Selects Olympus SNP Typing System for Research.

Chronic Fatigue Linked to Low Serotonin.

Tanabe Seiyaku and GSK to Collaborate on Genome Drug Discovery.

Anti-alcoholic Gene in Polynesians Shows Asia-pacific Ancestry.

Tooth Minerals Replenished by Milk.

Korean Kimchi — A Possible Cure for Avian Influenza?

The Contact Lens That Heals.

Unraveling the X Chromosome Code.

Tracking Diabetic Sugar.

The following topics are under this section:

• ASIA-PACIFIC — Collaborative research effort reveals chemical compound that kills drug-resistant bacteria
• ASIA-PACIFIC — Big Data Analytics used for Personalized Assessment Tool for Cancer Diagnosis
• ASIA-PACIFIC — Identifying the Molecular Mechanisms of Creating a Memory
• ASIA-PACIFIC — Funding for New Stem Cell Research provides Hope for Premature Born Babies
• ASIA-PACIFIC — Human Cortical Organoids used to Identify Mechanisms behind Epilepsy in Angelman Syndrome
• ASIA-PACIFIC — The Future of Contact Lenses: Self-Moisturising Technology
• ASIA-PACIFIC — Glycosylation of Protein Structure on Virus provide Insight to Molecular Understanding
• ASIA-PACIFIC — Comprehensive Mapping of the Human Brain using Synchrotron X-rays
• REST OF THE WORLD — Uncovering New Tricks for Old Drugs
• REST OF THE WORLD — Combination of Prenatal Smoking and Drinking adds on to Risk of SIDS
• REST OF THE WORLD — Blood Pressure Readings Could Provide Valuable Information on Early Warning Signs of Heart Disease
• REST OF THE WORLD — Study finds Households in the United States Wastes nearly a Third of the Food they Buy

Purpose: The examination of the effects of second generation lotrafilcon 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 refitted with lotrafilcon 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 fitted 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 the first two to four weeks of use. In Group 1, objective examinations identified a decrease in endothelial cell density. In Group 2, the endothelial cell density increased slightly in the first two years but decreased after three years. The results indicate that lotrafilcon B slows down the deleterious effects of contact lenses. The coefficient of variation significantly decreased after six months in Group 1 (0.47 vs 0.44; p = 0.049), whereas, in Group 2, the hexagonal cells improved significantly after one month (27.78 vs 28.25; p = 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.

Hydrogel polymers are the material of choice for optical prostheses, particularly in the form of soft contact lenses. In the development of lens materials, it is essential that their mechanical properties be determined. However, there are currently no standards (or recommended procedures) for the testing of this type of materials. In this investigation, various standards for testing plastic sheets were assessed for testing hydrogel membranes and appropriate testing procedures were established. The membranes for novel contact lenses were supplied by an established lens manufacturer. Mechanical characterisation consisted of tensile and tear tests. Three ASTM standards for testing plastics were evaluated for such tests. Miniature specimens were employed both for the ease of handling and for economical reasons. It was found that the tensile stress-strain relationship was different for different lens materials. The mechanical parameter which produced the most repeatable data for hydrogel membranes was tensile modulus. Values of both ultimate tensile strength and fracture strain demonstrated significant variability, especially for soft membranes. Tear testing of hydrogel membranes required the use of two ASTM standards due to different mechanical behaviour of lens materials. Mechanical characterisation provided useful information about hydrogel polymers that were being developed for novel contact lenses.