Abstract
Purpose:
To determine whether temperature has an effect on the accommodative response of primate lenses during simulated accommodation in a lens stretcher.
Methods:
Lens shape was measured during ex vivo simulated accommodation on 4 cynomolgus monkey (4.5-6.9 years) lenses from 4 donors (PMT 9.5+/-11 hours). Tissue samples were mounted in the EVASII lens stretching system (Ehrmann et al, Clin Exp Opt, 2008) and stretched in a step-wise fashion (0.25mm/step up to 2.5mm radially). In EVAS II, the tissue is immersed in preservation medium (DMEM) throughout the experiment. A temperature controller with thermocouple feedback was used to control the temperature of the medium. For each lens, a stretching experiment was first performed at 24°C (room temperature). At the end of the experiment, the temperature of the medium was increased to 35°C (ocular temperature). A second stretching experiment was then performed. The power, anterior and posterior curvatures, and thickness of the lens, and the force exerted to stretch the lens were measured at each step at both temperatures. The change in lens power, thickness, radius and the maximum force produced at the two temperatures were compared.
Results:
At 25°C, the average+/-SD of the change was 19.5+/-2.1D for lens power, 0.58+/-0.09mm for lens thickness, -2.54+/-0.74 for lens anterior radius; -0.94+/-0.12mm for lens posterior radius. The maximum force was 1.50+/-0.22g. At 35°C, the average+/-SD of the change was 18.1+/-2.7D for lens power, 0.57+/-0.09mm for lens thickness, -2.46+/-0.86mm for lens anterior radius; -0.91+/-0.29mm for lens posterior radius. The maximum force was 1.30+/-0.26g.
Conclusions:
Within the range of temperatures tested in this study (25-35°C), temperature does not have significant effect on the changes in lens shape, power and force during simulated accommodation in a lens stretcher.
Keywords: 404 accommodation •
653 presbyopia