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R. Sia, K. S. Bower, C. D. Coe, D. S. Ryan, L. Peppers, B. Fileta, S. Haymes, Y. Zhou, R. S. Howard; Tear Sample Collection Using a Polyvinyl Alcohol (PVA) Foam Tip. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4148.
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To assess the use of polyvinyl alcohol (PVA) foam tips for tear sample collection.
Tear samples were collected from 14 healthy volunteers using both PVA foam (Microstaar foam tip plunger, Staar Surgical, Monrovia, CA) and polyester fiber rod (Transorb Wick, Filtrona, Richmond, VA). Tear volume absorbed (VA) and tear volume recovered (VR) were measured using an analytical balance and the recovery ratio (RR) between recovered and absorbed volume was determined. Recovered tear samples were sent to Walter Reed Department of Clinical Investigation Laboratory for tear protein analysis. Three microliters from each tear sample were fractionated on a SDS-PAGE (4-12% mini-gel) under reducing conditions.
Mean subject age was 34±10. Seventy-nine percent were male. VA by the wick (5.1±6.8 µL) was not significantly different from PVA foam tip (5.1 ±5.8 µL, p= .508). VR from the wick (4.4±6.6 µL) was significantly higher than from the PVA foam tip (2.6±4.8 µL, p = .034). RR from the wick was 66.5% vs. 28.1% from the PVA foam tip (p=.021). The profiles of major tear proteins (79 kDa, 27 kDa, and 18-14 kDa) were identical regardless of the collection material (Figure 1). In terms of comfort 79% of the subjects preferred the PVA foam tip over the wick.
PVA foam tip showed the ability to absorb tear fluid comparable to that of the polyester fiber rod but was less efficient in tear fluid recovery compared with the wick. Tear protein profile in recovered tears were indistinguishable. PVA foam tip was better tolerated in terms of comfort.
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