A NOVEL METHOD OF TEAR COLLECTION - COMPARISON OF GLASS-CAPILLARY MICROPIPETTES WITH POROUS POLYESTER RODS

Purpose. To develop a rapid, user-friendly method of tear collection t o facilitate tear-protein analysis. Methods. Tears were collected from a total of 19 normal volunteers without evidence of ocular-surface di sease with either porous polyester rods or glass-capillary micropipett es. Tear-collection rate and recovery of two tear proteins, epidermal growth factor (EGF, low abundance) and lactoferrin (LFR, high abundanc e) were compared between polyester rods and glass-capillary micropipet tes. The recovery of LFR and EGF and the stability of these proteins a fter storage at -70 degrees C were quantitated by specific monoclonal enzyme-linked immunosorbent assay (ELISA), Results. Polyester rods col lected tears an average of 3.9-fold faster than glass-capillary microp ipettes (p < 0.001). Both methods were comparable in efficacy of prote in recovery. The polyester rods demonstrated a trend toward enhanced r ecovery, but this difference was not statistically significant (p = 0. 12, LFR; p = 0.055, EGF). Analysis of the reliability and reproducibil ity of the tear-collection assay system revealed that ELISA analysis i s highly reproducible, but there is significant day-to-day variation i n tear-protein levels of both LFR and EGF for a given volunteer. Both LFR and EGF displayed a trend toward enhanced detection by ELISA short ly after freezing at -70 degrees C and slow decay after storage al -70 degrees C for up to 72 and 105 days, respectively. After stimulation of reflex rearing via the nasolacrimal reflex, LFR levels remained rel atively constant, whereas EGF levels for most patients declined and th en plateaued. Conclusions, Polyester rods provide a more rapid, user-f riendly alternative to glass-capillary micropipettes far the collectio n and analysis of tear fluid and tear proteins. Polyester rods may hav e greater clinical utility, facilitating routine analysis of the preoc ular tear film.