Direct Noninvasive Measurement of Tear Oxygen Tension Beneath Gas-Permeable Contact Lenses in Rabbits

摘要: Purpose. To develop a noninvasive measurement of tear oxygen tension and to determine calculated flux rates during wear contact lenses varying transmissibility (Dk/L). Methods. The basis the (Po2) is phosphorescence quenching Pd-meso-tetra-(4-carboxyphenyl) porphine by oxygen. A fiber-optic bundle, positioned approximately 2 mm from cuvette or corneal surface, delivers an excitation flash ( 645 nm) dye at 1 MHz for ms. Porphine (500 (JM) + 1% albumin instilled directly into tears sedated rabbit, measured before after lens insertion. Results. Phosphorescence intensity decay lifetimes are related inversely Po2 follow Stern-Volmer relationship. Calibration control experiments revealed temperature effect on lifetime per degree, concentration independence over 100-fold dilution, no significant pH between 6.8 7.9. indicated that beneath reached steady state within 3 8 minutes. Mean (mm Hg ± SE; n > 7) was: polymethylmethacrylate (Dk/L = 0), 0.58 0.22; Oxyflow f30 15.3), 27.7 3.4; Fluorex 700 (Dk/ L 30), 52.5 3.8; 151 51.9), 78.7 23.9. Steady application topical anesthetic 10 minutes was 41 1.2 Hg, significandy higher than without anesthetic. Conclusions. Phosphorescence-based measurements allow direct, sensitive, assessment availability lens. Oxygen levels permeable found direct lower what mathematical models predict. values, however, close estimates using equivalent percentage (EOP) technique. Tear may be used examine metabolic disturbances as shown reduced consumption Invest Ophthalmol Vis Sci. 1996;37:1026-1036.