Preparation and hydration control of corneal tissue strips for experimental use

Purpose: The purpose of this study was to develop an experimental protocol to maintain corneal tissue strips at normal hydration and avoid swelling or dehydration during experimental studies on corneal biomechanics and thermal stability. Methods: The corneal thickness of 9 whole Eye-Bank eyes was brought back to normal values by immersion in a 25% dextran solution for 24 hours. Corneal buttons were then removed and cut into 2 x 6 mm strips. The 9 strips were immersed successively in Dextran solutions at 25%, 22.5%, and 20% concentration at 35degreesC. The thickness of the immersed strip in solution was measured every 5 minutes for 1 hour using a modified optical comparator. Results: The mean final thickness for the nine corneal strips after one hour in 25%, 22.5%, and 20% dextran solution was 508 38, 563 56, and 592 33 pm, respectively. Average swelling in 25%, 22.5%, and 20% dextran solutions was 1.06 +/- 0.03, 1.20 +/- 0.07, and 1.24 +/- 0.07 times the initial thickness, respectively. Conclusion: The hydration of corneal tissue strips is maintained at normal values when the strips are immersed in 25% Dextran solution. Corneal strips swell to thicknesses above normal values in solutions with lower molecular weights.