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Tawnya Wilson, Rudolf Aeschlimann, Samuele Tosatti, Kathrine E Lorenz; Defining ‘Fresh’ Corneal Tissue for Utilization in Determining Human Cornea Coefficient of Friction Values. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1506.
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Develop definition of ‘fresh’ in relation to human donor corneal tissue for use measuring coefficient of friction (CoF) values.
Multiple sources, including the Eye Bank Association of America certified cornea preservation standard operating procedures, were evaluated with regards to approximate corneal tissue quality expectations post expiration. Qualifying corneas meeting the ‘fresh’ standard were procured for CoF measurements in 4 different solutions (tear mimicking solution (TMS-PS), tear mimicking solution with phosphate buffer saline (TMS-PBS), and tear mimicking solution with HEPES buffer and NaCL (TMS-HEPES). Following CoF measurements in the TLF-PBS solution, corneal staining was evaluated with Lissamine Green and Fluorescein Sodium dye. A descriptive statistical analysis test of r2 values was conducted comparing CoF values and time of death to CoF measurements.
The definition of ‘fresh’ human corneal tissue was determined as 7 hours or less from death to globe enucleation. This was based on three time points: death to ocular cooling (initial preparation ocular tissue for donation), death to enucleation (ocular tissue moist-only preservation outside of donor), and projected death to corneal excision (initial removal of cornea from eye for total submersion in testing solution). Twenty-seven (27) out of 28 received corneas met this definition. Corneal staining was not observed in the 5 corneas evaluated post CoF measurements. Comparing CoF values and time of death to CoF measurements revealed no clear trends with r2 values of 0.0161 in TMS-PS, 0.2158 in TMS-PBS, 0.4055 in TMS-HEPES, and 0.0139 in TLF-PBS.
This novel evaluation aimed to address the need for a definition of fresh human corneal tissue to be utilized in investigational studies, specifically measurement of CoF. The lack of corneal staining post CoF measurements coupled with the generally low r2 values, gives some confidence to the definition of fresh corneal tissue among this limited sample size.
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