title: Tear flow and soft contact lenses.
abstract: Tear flow was determined in 14 persons before and after one month of adaptation to a soft contact lens, (Soflens, Bausch & Lomb), by means of a radioactive tracer (technetium, Tc99m, as pertechnetate), a gamma camera and a computer system. The elimination of the radioisotope from the conjunctival sac was diphasic with a significant increase of the fractional turnover rate after the adaptation period in the initial phase with a rapid elimination, but no change in the basal phase with a slower elimination. The fractional turnover rate was also determined with the soft contact lens placed on the cornea after having been pre-soaked in the technetium solution resulting in a value of 0.021 +/- 0.003 min-1 (mean +/- SEM, n = 12). The fractional turnover rate resulting from instillation of the radioisotope on the non-pre-soaked soft contact lens placed in the eye was found to 0.020 +/- 0.004 min-1 (mean +/- SEM, n = 6). In the studies with the soft contact lens in the eye the elimination curves was monophasic and not diphasic as in normal tear flow studies.
mesh_terms: D000328:Adult; D003261:Contact Lenses; D005123:Eye / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007765:Lacrimal Apparatus / Q000000981:diagnostic imaging; D008297:Male; D011877:Radionuclide Imaging; D013666:Tears / Q000378:metabolism*; D013667:Technetium
chemical_list: D013667:Technetium