Biomedical subjects

Deborah Sweeney

Publications and source records attributed to Deborah Sweeney.

4 recordsLinked to original sources

PubMed2005

Corneal oxygen deficiency.

OBJECTIVES: To compare the ocular effects of low Dk hydrogel and high Dk silicone hydrogel contact lenses. METHODS: A review of recent literature was conducted to determine the effects of wearing low and high Dk soft lenses on corneal swelling, vascular response, refractive error and the corneal epithelium. RESULTS: High Dk silicone hydrogel contact lenses became available for research and clinical practice almost 10 and 5 years ago respectively. During that time many studies have been conducted and it has been demonstrated repeatedly how much improvement there has been to the physiological response of the eye particularly when wearing the lenses on an overnight basis. CONCLUSIONS: Although silicone hydrogels only constitute about 2% of current wearers, their positive effects on the eye compared with low Dk hydrogel lenses should make them the most dominant lenses in the near future.

Bacterial Infections↗

PubMed2005

OOKP.

Explore the source record for details and available documents.

Alveolar Process↗

PubMed2004

Changes in myopia with low-Dk hydrogel and high-Dk silicone hydrogel extended wear.

PURPOSE: This study compared changes in myopia between wearers of high-oxygen permeability (Dk) silicone hydrogel lenses and low-Dk hydrogel lenses after 1 year of extended wear (EW). METHODS: Ninety-two adult subjects were randomly assigned to a lens type. Subjective refraction and autokeratometry were performed at baseline and at 6 and 12 months. RESULTS: After 6 months of EW, myopia (spherical equivalent) regressed by 0.18 +/- 0.33 D (p < 0.001) in the high-Dk silicone hydrogel group and progressed by -0.23 +/- 0.36 D (p < 0.001) in the low-Dk hydrogel group. There were no further changes after 12 months. Previous lens wear history, baseline refractive error, and age and gender did not have an impact on the change in myopia, and only 35% of the variation could be accounted for by changes in corneal curvature and lens type. CONCLUSION: Soft contact lens type significantly affects the direction of change in myopia during EW. We hypothesize that these changes are driven by pressure-related redistribution of corneal tissue in high-Dk silicone hydrogel lens wearers and by hypoxia-associated corneal thinning in low-Dk hydrogel wearers. More long-term studies are required to confirm whether the effects of high-Dk silicone hydrogel lens wear on myopia are permanent.

Adult↗

PubMed2003

Differences in clinical parameters and tear film of tolerant and intolerant contact lens wearers.

PURPOSE: To determine whether intolerance to contact lens wear is attributable to clinical or protein characteristics of the tear film. METHODS: Thirty-eight subjects participated; 20 were successful contact lens wearers and 18 had discontinued contact lens wear because of discomfort. Baseline tear film (no lens wear) was analyzed with a range of clinical measurements and protein analyses (lactoferrin, sIgA, and lysozyme). Comfort was determined after 6 hours of lens wear, and differences in tear film characteristics between subject groups were determined. In half of the subject group (n = 19), discriminant analysis was used to develop an equation for predicting the likelihood of intolerance to lens wear. Sensitivity and specificity were determined by testing the formula on the remaining subjects. These formulas were also tested on a separate group of subjects enrolled in a contact lens-wearing trial. RESULTS: Tear volume (meniscus height and phenol red thread test) and tear stability (noninvasive tear break up time [NI-TBUT]) were significantly reduced in intolerant wearers (P < 0.05). A greater number of symptoms were reported by intolerant than by tolerant wearers (P < 0.05). Tolerance was associated with clinical but not protein characteristics of the tear film. Formulas best able to predict contact lens intolerance included NI-TBUT, number of symptoms experienced, and tear film meniscus height. Formulas had high sensitivity, and specificity which ranged from 29% to 57%. CONCLUSIONS: Contact lens intolerance appears to be best predicted by a combination of clinical variables, including tear film stability, tear volume, and symptom reporting.

Adult↗