Search PubMed⌕ Search

Biomedical subjects

G E Lowther

Publications and source records attributed to G E Lowther.

13 recordsLinked to original sources
PubMed1991

A synopsis of extended-wear lenses and lens care regimens.

The clinical properties of hydrogel and rigid gas-permeable contact lenses for extended wear are examined, with emphasis on oxygen permeability and transmissibility, so that clinicians may select lenses likely to minimize corneal edema or may predict the amount of edema likely with a given lens. Lens deposit formation and related problems are also described, as are lens care systems, particularly their limitations with respect to preventing infections. The advantages, disadvantages, and limitations of lens cleaners are discussed, and recommendations for use are provided.

Contact Lenses, Extended-Wear↗
PubMed1989

One-week vs. 2-week hydrogel extended wear schedules.

Fifteen myopic patients wore 58% water content lenses for extended wear. The lens on one eye was removed weekly for 1 night and the lens on the other eye was removed only every 2 weeks. The patients were followed for 3 months. No significant difference in daytime corneal thickness was found between the two eyes at any visit. In comparing the corneal thickness the day before vs. the day after resuming lens wear, the mean thickness was no different for the 1-week schedule and tended to be slightly greater prior to removal for the 2-week schedule but not statistically different. There was no statistical difference in K-readings or corneal shape factor between the eyes. A mean increase in myopia was recorded, but it was only statistically significant for two visits for the 1-week wearing schedule eye. The number of positive biomicroscopic findings were slightly greater with the 2-week schedule. Two eyes developed corneal ulcers, one occurring on the 1-week schedule and one on the 2-week schedule.

Adult↗
PubMed1987

Effect of some solutions on HGP contact lens parameters.

The effect of five common contact lens solutions on the overall diameter and base curve radii of PMMA, siloxane/acrylate and fluorosiloxane/acrylate lenses was studied. The alcohol containing cleaner, Miraflow, caused a significant swelling and base curve change of the siloxane/acrylate and fluorosiloxane/acrylate lenses with 30 minutes or longer soaking. Miraflow did not affect PMMA lenses. None of the other solutions tested affected any of the lenses tested.

Acrylates↗
PubMed1979

Inspection of back surface aspheric contact lenses.

Two methods of clinically inspecting and verifying rigid back surface aspheric contact lenses were investigated. A modification of the Radiuscope was found to be an accurate method for making such measurements. Measurement data of a number of aspheric lenses obtained by using this procedure are presented.

Contact Lenses↗
PubMed1979

Clinical study of corneal response to the wear of low water content soft lenses.

The changes in central and peripheral corneal thickness and topography during initial (1st-day) wear, adaptation to, and long-term wear of the DuraSoft lens were monitored in a group of 10 patients. Monitoring was by means of the electronic digital pachometer and the photoelectronic keratoscope (PEK). A variety of physiological responses to lens wear was noted in individual patients, but generally the changes occurring were comparable to those reported for other soft lenses. These changes consisted of an average increase of 5-6% in central and peripheral corneal thickness during the initial phase of wear and 4-5% during adaptation; this was followed by a reduction with long-term wear to 2-3%. Corneal topography was relatively stable throughout the period of the study.

Adolescent↗
PubMed1979

The United States Food and Drug Administration and the practice of optometry.

In the past decade the United States Food and Drug Administration has become increasingly involved with the regulation of materials used in the practice of optometry. It is the purpose of this paper to help the practitioner understand the FDA involvement, historically and legally, organization, how one can have input into the process, the procedures for testing and approving new drugs and devices, their regulation and the advantages and disadvantages of such control.

History, 20th Century↗
PubMed1978

Soft lens cleaners: their effectiveness in removing depostis.

The useful life of a hydrophilic lens is often reduced by deposits forming on or within the polymeric structure of the lens. To eliminate this problem, several cleaning agents have been formulated to prevent and/or remove these deposits. The efficacy of these agents in cleaning heavily deposited lenses is the topic of this investigation.

Chemical Phenomena↗
PubMed1977

Effectiveness of an enzyme in removing deposits from hydrophilic lenses.

Bausch and Lomb Soflens contact lenses with various types of deposits were cleaned with the Allergan Enzymatic Contact Lens Cleaner. Its effectiveness in removing the deposits varied with the type of deposit. Effectiveness of the cleaner can be predicted from the initial appearance of the deposit.

Contact Lenses, Hydrophilic↗
PubMed1977

Measured and laboratory-stated parameters of hydrophilic contact lenses.

One hundred thirty-one new hydrophilic lenses made by 3 manufacturers were randomly selected from an optometry clinic for measurement and inspection. Approximately 60% of the base-curve specifications fell within the following ranges for the measured dimensions: Bausch & Lomb Soflens contact lenses, less than 0.150 mm; Milton Roy Naturvue lenses, less than 0.375 mm; Soft Lens Inc. Hydrocurve, less than 0.225 mm. More than 65% of the lenses supplied by all the manufactures were within 0.25 D of the power specification. About two-thirds or more of all lenses had a central thickness and overall diameter within 0.04 mm and 0.40 mm, respectively, of the manufacturers' specifications, although there were notable differences among manufacturers. Most of these new lenses exhibited surface scratches and other surface defects, and many lenses had edge defects.

Contact Lenses, Hydrophilic↗
PubMed1977

The "aging" of a HEMA contact lens.

The physical characteristics and attendant patient complaints associated with termination of the useful service lives of 26 HEMA lenses are compared with the characteristics of a control (undispensed) population of such lenses.

Contact Lenses, Hydrophilic↗
PubMed1976

PMMA material.

Explore the source record for details and available documents.

Contact Lenses↗
PubMed1975

Deposits on hydrophilic lenses: differential appearance and clinical causes.

Deposits on hydrophilic lenses are classified as to appearance and etiology. One readily identifiable type results from using nondistilled water to ascepticize the lens while another is the result of tear film components not properly cleaned off the lens. Clinical inspection can differentiate the types and aid in preventing reocurrence.

Asepsis↗