Shape of Ex-Vivo Primate Lenses in Relation to Temperature and Post Mortem Time

Abstract

Abstract: : Purpose: To analyze effects of temperature and post mortem time on ex-vivo primate lenses. Methods: Human and non-human primate eyes were donated by the Florida Lions Eye Bank and Diabetes Research Institute. The lenses were prepared and imaged by shadowphotogrammetry according to the same experimental protocol as in our previous study that quantified the effect of preservation solutions on lens shape (ARVO 2002, #448). Temperature experiments were conducted at 24°C and 35°C on 4 pairs of human lenses and 2 unpaired human lenses. One pair was tested in BSS and all other lenses in DMEM/F12. For each pair, one lens was tested at 24°C and the other at 35°C. For post-mortem time experiments, 4 pairs of cynomolgus monkey lenses were tested at room temperature in DMEM/F12. One lens of each pair was tested at 1 hr and the other lens at 48 hrs post mortem. In all experiments, the change in lens diameter and thickness during immersion was quantified. Results: Independent of temperature, human lens diameter decreased by 0.5 to 2% and thickness increased by 1 to 5%. Conversely, independent of post-mortem time, nonhuman primate lens diameter decreased by 0.9 to 3.1% and thickness increased by 0.3 to 3.3%. No statistically significant correlation was found between post mortem time and change in lens shape. However, direct comparison of contralateral lenses showed that lenses tested at 48h post mortem displayed approximately 1% greater changes in both diameter and thickness compared to lenses tested at 1h post mortem. Human lenses tested at 35°C displayed 2 to 3% greater changes in diameter and thickness than lenses tested at 24°C. Conclusions: Human and nonhuman primate lenses immersed in liquid preservation media display insignificant shape changes when tested at room temperature and shortly after death. Increased temperatures and prolonged post mortem times result in greater dimensional changes. Temperature and post-mortem time must be taken into account in experiments designed to study the optics of explanted crystalline lenses.

Keywords: shape and contour • accommodation