Hydrogel Contact Lens Water Content is Dependent on Tearfilm pH
| Autor: | Thomas Harding, Morris R. Lattimore, Steven T. Williams |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Analytical chemistry
02 engineering and technology Hydrogel Polyethylene Glycol Dimethacrylate law.invention 03 medical and health sciences Multifactorial analysis 0302 clinical medicine Refractometer law Myopia Logarithmic rate Humans In patient Water content Chemistry Public Health Environmental and Occupational Health General Medicine Hydrogen-Ion Concentration 021001 nanoscience & nanotechnology Lens (optics) Contact lens Pilots 030221 ophthalmology & optometry Alabama Contact Lenses Extended-Wear Gravimetric analysis Contact Lens Solutions 0210 nano-technology |
| Zdroj: | Military medicine. 183(suppl_1) |
| ISSN: | 1930-613X |
| Popis: | Introduction Based on clinical inferences, investigators theorized in situ soft lens hydration was linked to the precorneal tearfilm pH. Methods Forty-one myopic subjects at Fort Rucker, AL, USA were fitted with one of two types of extended-wear soft contact lenses, and were followed quarterly for a period of 33 mo. The anterior soft contact lens surface pH was measured in situ, while the in vitro lens water content was measured immediately after lens removal, using a hand-held refractometer on one lens, and a gravimetric means of hydration measurement on the other lens. Results The in situ pH increased logarithmically across extended wearing time, reaching an asymptote at approximately 5 d' wearing time at a pH of 7.45 ± 0.03. Lens water content was shown to similarly decrease at an inversely logarithmic rate, leveling off at 4-5 d' extended wearing time. Both means of hydration assessment correlated well with each other across days' extended wearing time (R = 0.98; p < 0.0001). Discussion A log-log dual conversion yielded significantly different linear slopes (p < 0.001), based on a multifactorial analysis of both lens types, by the pH, and by their water content. The differing ionic status of each material accentuated their varied polar attraction characteristics. Two soft lenses, identical in all patient-based parameters, could provide differing oxygen availability, as well as differing physical fits in patients of identical physical characteristics, as a result of their unique tearfilm pH differences. Conclusion The in situ hydrogel lens water content is directly dependent on the precorneal tearfilm pH. |
| Databáze: | OpenAIRE |
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