Abstract
Abstract: :
Purpose: To quantify the diffusion of albumin across human sclera and assess whether cryopreservation influences diffusion. Methods: Scleral tissue from three donor eyes (age 51, 65, and 75 years) was mounted in a modified Ussing chamber. Fluorescein isothiocyanate (FITC) labeled, 0.412 mMol, bovine albumin was placed in one hemi–chamber facing the internal scleral surface, and the rate of trans–scleral diffusion was determined over 24 hours, at 25oC, with a spectrophotometer. Samples were then washed to remove the remaining FITC–albumin and frozen at –35 oC for 1 week. Tissue was then thawed to 25oC and the experiments were repeated. Results: Diffusion for fresh scleral tissue was 11.10, 7.24, and 4.57 pmoles/hour/mm2 for samples one, two and three respectively. Following one freeze–thaw cycle diffusion was 15.88, 9.02, and 6.14 pmoles/hour/mm2 respectively. Conclusions: The study of normal scleral physiology may guide strategies for trans–scleral drug delivery and help understand disease states characterised by abnormal trans–scleral diffusion. The above result quantifies the trans–scleral diffusion of albumin. The process of freezing/thawing increases trans–scleral diffusion by a mean of 34%. This provides control data for other researchers that have published, or plan, experiments using cryopreserved sclera.