Estimation of the useful lifetime of polypropylene fiber in the anterior chamber.
A study of the stability of polypropylene fiber, size 4-0, to ultraviolet light was performed. Samples were radiated in physiological saline solution at 35.5 +/- 1.5 degrees C using a xenon-arc lamp at an intensity of 650 milliwatts per square centimeter. The light was filtered to remove wavelengths below 300 nanometers and thus simulated transmittance of the cornea. Tensile strength, elongation and modulus, and the surface morphology of the fiber by scanning electron microscopy (SEM) were determined as a function of exposure time. The average ultraviolet (UV) light intensity which irradiates the eye was determined from available meteorological data and was used to calculate human exposure at various geographical locations. This information along with the light energy of the xenon-arc lamp was used to calculate the useful lifetime of polypropylene fiber in the anterior chamber. Using an average exposure of 2.2 hours per day for a 60-year-old implant recipient, the useful lifetime ranges from 53 years in Miami, Florida, to 75 years in Seattle, Washington. Polypropylene loops from lenses which had been implanted in human eyes for up to 4.8 years showed no molecular degradation as compared to control material. Polypropylene fiber is therefore safe for use in anterior chamber implants.
D000867:Anterior Chamber / Q000601:surgery; D001673:Biodegradation, Environmental / Q000528:radiation effects; D006801:Humans; D066298:In Vitro Techniques; D007910:Lenses, Intraocular; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D010969:Plastics / Q000009:adverse effects; D011126:Polypropylenes / Q000009:adverse effects / Q000528:radiation effects; D013537:Sutures; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects
D010969:Plastics; D011126:Polypropylenes